Is a teleconverter superior to a crop

[enseth]

I've been mucking around with a 1.4 x teleconverter lately. It seems to produce good results but I have been unable to firmly establish whether you gain superior IQ using a teleconverter against just cropping. I'm sure there is a technical analysis of the two processes. Does anyone have the answer to which is "best"?

[ameerat42]

Yes, no, and not necessarily (=maybe, sometimes).

If a good lens and good TC, then generally yes.
If either bad, then pretty much the same.
If both not hot, give up.

What makes it good is that you end up with a larger image, but if that is bad, then...

You might not get 200% IQ with a TC, but something past, say, 180% would be WW.

You'd really have to do tests.

[mpb]

I'm not an expert in relation to TC'er ( or anything for that matter) but:-
You also need to consider the reduced light available when using a TC, from memory you lose 1 stop with a 1.4xTC and 2 stops with a 2xTC.
If you are shooting with plenty of light this may not be a problem.

Also camera shake becomes more of an issue.
May also affect focus speed or even the ability to autofocus.
(need someone with some expertise to confirm above)

[John King]

Gidday enseth

Basically, I agree with Am.

Further warnings - TCs are worth roughly what you have to pay for them.

I have two 2x TCs from my film days, both Teleplus branded. One's highest function was to donate its lens caps to a higher purpose (MC4). It was as bad as that! This was a real cheapie, <$100. The other, an MC7, is a focusing TC for macro type close up work. The MC7 cost a bomb in the early 1980s with a RRP of over $800. It is still worth using to this day.

e.g. Rosa taken with my OM1 plus f/4 200 plus MC7 TC from about 5-6m away (scanned from Agfa Vista 400 negative (print) film:

http://canopuscomputing.com.au/gallery2/d/4247-4/Film_1901_N24A_IG-USM_Web.jpg

The harsh, flat light is due to the time of day (around midday/early afternoon), not due to lack of contrast in the TC or lens.

I also have an Olympus EC-14 1.4x TC for my Olympus ILCs. It also cost a bomb, with a RRP of over $700 when released. It does degrade the image quality very slightly, but not really significantly. It does exaggerate any faults in the lens it is used with, however!

It gives me an effective FL in 135 format terms of f/5 and 566mm using my f/2.8-3.5 50-200. As long as I stop the 50-200 down to at least f/5.6, this combo works very well. However, My 50-200 by itself has to be stopped down to f/5.6 to produce the goods. While usable wide open in some circumstances (e.g fairly low DR), it falls apart in others. At f/5.6 and smaller, it is excellent.

[nardes]

Here we go. Our Moon taken as follows:

400mm F5.6
400mm F5.6 digitally resampled x2 in Photoshop
400mm with x2 EF II Extender

Cheers

Dennis

[arthurking83]

I think Dennis just proved that with the right lens, a TC works pretty damned well! :th3:

One thing that we know(as in a known known) is that a TC always reduces contrast a little from the bare lens.
So in a low contrast scene, a TC may not be an ideal way to extend a lens's ability.
How much contrast is lost depends on the primary lens tho .. so imagine a lens with low contrast levels shooting in a low contrast scene situation with a TC added that further reduces contrast!

Then you have the added side effect of increased chromatic aberrations due to the TC and so on and so forth.

Personally I'd go with the TC for the most part, rather than shoot with the view to crop.

[tduell]

I have been having some trials and tribulations with my 1.4xTC and my 150-450 (see my sig for lens details).
Basically my problems have been less sharp images when using the TC and shooting birds. Usually this is with the lens at full zoom and handheld.
In my case I think some of the problem has been down to the in-body shake reduction not coping with the FL and my shakes.
In an effort to overcome this I have tried (again) to use a monopod, and my latest efforts are much better, but still not up to the quality I can get when not using the TC.
I have just had (another) look at the AF fine adjustment, but I think it is possible to convince yourself that every time you run through this test process you have made an improvement.
I have yet to see how the latest settings perform.
Quite extensive and well controlled tests of the 150-450, 1.4xTC and other long lenses were reported on PentaxForums, with the conclusion that Pentax's 1.4xTC didn't reduce the IQ of the 150-450, although I think the tests were all done using a tripod.

Cheers,
Terry

[nardes]

I have found that the localised atmospheric conditions play a huge part in IQ when using the 400mm F5.6L, either “naked” or with the x1.4 or x2 EF II Extenders.

Basically if you are looking at mirage-like conditions through the viewfinder – forget it!

Hot air rising above warm concrete, buildings, roads, etc. plays havoc with IQ. The Moon shots were taken through more stable air, over grass and pointing up.

Cheers

Dennis

[enseth]

Thank you for the comprehensive answers. Nardes moon photos illustrate the benefits of a TC under ideal conditions. I will continue with the TC where appropriate and once again thank you all for your input.

[Lance B]

As others have said, it depends.

As a rule, I would suggest that if you need to gain 1.5 times the image size, then generally a TC will be better but it depends on the light because you are shooting at 1 stop slower and this may affect the AF speed of the lens and you may miss the shot. Your ISO will also need to go up in accordance as well. It also depends on how big you are going to display your images before any drop off in IQ is detected. The thing is with all this stuff is that it's all a compromise and you have to judge which compromise fits the situation best.

On a "fast" lens, like an f2.8 telephoto, TC's can work brilliantly and they generally work at their best. On "slower" lenses, they may not work quite as well, but the 1.4x TC's generally have little impact on most lenses as far as IQ is concerned. The other thing to consider is that AF speed and acquisition is also compromised but has less affect on a "fast" lens compared to a "slower" lens and this can be a real issue when chasing birds, wildlife etc. Again, the 1.4x TC will have less impact on AF speed and acquisition than an 2x TC but generally, they both will affect an f4 or slower lens more than an f2.8 lens.

I am speaking from my experience with my Nikon gear: On my Nikon 300 f2.8 VRII and Nikon 400 f2.8E FL VR, the Nikon 1.4x TCIII almost makes no difference to IQ and little difference to AF speed, it has a 1 stop light penalty thus an f2.8 lens "becomes" a max aperture f4 lens. The Nikon 1.7x TCII has a little more of a hit on IQ and AF speed, an f2.8 lens "becomes" a max aperture f5 lens. The Nikon 2x TCIII has about the same IQ drop off as the 1.7x TCII and a slightly more of a hit to AF speed and acquisition.

Here is a sample of my 400 f2.8E FL VR + 1.4x TCIII showing that if it has affected IQ I can't tell it from the lens bare!! These are large images:

http://www.pbase.com/lance_b/image/162239065/original.jpg

http://www.pbase.com/lance_b/image/162239066/original.jpg

[fillum]

Some good info already, but a couple of additional points (although not really related to IQ)...

Autofocus (AF) :- although a TC may have a negative impact on AF speed, the magnified view can make it easier to track your subject and keep the focus point on it. Probably not too applicable for moon shots but can be helpful for sport and wildlife.

Depth-of-Field (DoF) :- with a crop you are 'faking' the angle-of-view of a longer focal length (FL) but you are basically getting the DoF of the actual lens FL. This may or may not be relevant and really depends on your intent. Shooting field sports for example, you typically want to minimise DoF to separate the subject from the background. A shot taken with a 2.0x TC at 400mm and f/5.6 will show less DoF (i.e. more separation) than a shot taken at 200mm and f/2.8 which is cropped to give the same angle-of-view. [The reduced max aperture will increase the DoF, but the increase in FL decreases DoF by a larger amount, resulting in an overall decrease in DoF].

I shoot junior Aussie Rules with a 70-200/2.8 and initially used a 1.4x TC (Kenko I think). Was ok but I found that I get sharper results more consistently by not using the TC and cropping instead. I've been intending to get the Nikon 2.0x TC in order to get more field coverage.


Cheers.

[ameerat42]

...Depth-of-Field (DoF) :- with a crop you are 'faking' the angle-of-view of a longer focal length (FL) but you are basically getting the DoF of the actual lens FL. This may or may not be relevant and really depends on your intent. Shooting field sports for example, you typically want to minimise DoF to separate the subject from the background. A shot taken with a 2.0x TC at 400mm and f/5.6 will show less DoF (i.e. more separation) than a shot taken at 200mm and f/2.8 which is cropped to give the same angle-of-view. [The reduced max aperture will increase the DoF, but the increase in FL decreases DoF by a larger amount, resulting in an overall decrease in DoF]...

Fillum, this has to be clarified.

...Depth-of-Field (DoF) :- with a crop you are 'faking' the angle-of-view of a longer focal length (FL) but you are basically getting the DoF of the actual lens FL.

By "faking', do you mean only because you are getting the DOF of the original lens?
If so, it is incorrect. The crop is effectively a magnification of that part of the scene, as would the same scene rendered by a TC where the APERTURE of the original lens has not changed.

Ie, if you set f/2.8 on the lens and did not change that setting with the TC, then the TC would multiply that f-stop (let's say by 2X) to f/5.6. But the actual aperture would still be the same size as it was before you put on the TC.

So, all you have done is magnify the scene IN-camera through the same aperture as you used whether with TC or without.

To change the DOF you need to change either the Aperture or the subject distance.

[fillum]

By "faking', do you mean only because you are getting the DOF of the original lens?What I'm saying is that the (appropriately) cropped view with the native lens will show the same amount of the scene as the TC version - I used the word 'faking' (in quotes) as the reduced angle-of-view is achieved in post rather than on-camera.

I also stated that there would be a variation in the DoF between the two scenarios due to the change in FL and effective aperture. HOWEVER, something I thought of but didn't mention, as I considered it to be negligible (and confusing), is the effect on the circle-of-confusion on the cropped image which will affect the DoF on the final output (similar to shooting with a smaller sensor - oh no, not that again :)). At the moment (Friday arvo :scrtch:) I can't get my head around how much cropping you would need to do to match the lens with TC. If it's considerable then the DoF may be the same / similar between the two scenarios. I've always felt that a TC on a lens at max aperture and FL gives reduced DoF compared to the lens alone, but I've never done any testing into it so could be way wrong.


To change the DOF you need to change either the Aperture or the subject distance.Or focal length - which is what the TC is doing.


Cheers.

[ameerat42]

(I wasn't worried about any "fakery" at all.)
The last part is what I disagree with - changing focal length.

Have a look at the CIC Reference here (http://www.cambridgeincolour.com/tutorials/depth-of-field.htm) and scroll down to the part
"CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD".

This is what I mean. In have seen many times when they try to implicate focal length (incorrectly AFAIK) as a DOF factor.

A simple test would be to try it. I'm up and down ladders (escaping snakes?) today, but ASAP I will give it a whirl.

- - - Updated - - -

Note: If anyone else wants to try, make sure your subject distance is fairly large, because if only across, say, a few
to 50 m, then there will be some effect from the movement towards the subject of the lens itself. Mmm!, maybe not
less than 20 m.

[William W]

Apropos DoF and Extenders or Tele-converters:

I think that it is important to grasp three practical concepts:

Concept 1.

> A tele-converter (Extender) when added to a lens, can be thought of and for practical purposes can be treated as ‘a lens’

Example 1: x1.4 Extender + 200mm F/2.8 prime Lens ≡ 280mm F/4 Prime Lens.
Example 2: x2.0 Extender + 70 to 200 F/2.8 zoom lens ≡ 140 to 400 F/5.6 Zoom Lens
Example 3: x1.4 Extender + 100 to 400 F/4.5~5.6 zoom lens ≡ 140 to 560 F/6.3~8 Zoom Lens

*

Concept 2.

> if the FRAMING of a scene; the APERTURE used; the Camera FORMAT are all kept CONSTANT -
then the DoF - for all practical purposes will be the same.

(This is the Axiom of DoF and applies for general photography at typical Subject Distances: not Macro-photography and not at SD when approaching infinity).

*

Concept 3.

> DoF when it is in discussion about or comparisons of FINAL IMAGE(S) - must assume that the Final Images are all Viewed at the SAME distance and are all of the SAME enlargement.

(This point is critical to this conversation, where commentators want to COMPARE the DoF between FINAL IMAGES of differing ENLARGEMENTS).

***

So, if one wants to compare the DoF between the image made with a native lens and then that image is cropped - to that lens used with a tele-converter and when both images are the SAME SIZE and are to be viewed at the SAME Viewing Distance - then one needs to:

> firstly reckon the DoF of the native lens at the Aperture used

> secondly reckon the DoF for the "lens assembly" comprising lens and the tele-converter at the Resulting Aperture used

> thirdly adjust the computation for the DoF for the ENLARGEMENT of the cropped image (i.e. so it appears the SAME SIZE for viewing, as the SIZE of the other image) - this can be done by adjusting the CoC - or - by using a factor for the enlargement.


WW

[ameerat42]

A most erudite exemplification and exposition, WW.

I have eluded the serpents and descended from the ladder, but I won't be up to running a test until,
hopefully, tomorrow.

[William W]

Ta. I appreciate that comment.

WW

[William W]

I've been mucking around with a 1.4 x teleconverter lately. It seems to produce good results but I have been unable to firmly establish whether you gain superior IQ using a teleconverter against just cropping. I'm sure there is a technical analysis of the two processes. Does anyone have the answer to which is "best"?

- and -


Thank you for the comprehensive answers. Nardes moon photos illustrate the benefits of a TC under ideal conditions. I will continue with the TC where appropriate and once again thank you all for your input.


But there is the unanswered question still remaining . . . (referencing Post #2)

Will you make the time to do the various tests to get closer to an answer for the gear that you are using under different conditions?

REF Post #2:
. . . You'd really have to do tests.

Here is an example of a simple Field Test. (http://photo.net/photodb/folder?folder_id=978596) - After you open each image, you can click on that image to view it LARGE.

WW

[arthurking83]

......


The crop is effectively a magnification of that part of the scene, as would the same scene rendered by a TC where the APERTURE of the original lens has not changed.

.....

This is a common mythconception!

You don't ACTUALLY magnify anything .. you're only cropping.

Magnification actually has a standardised definition .. and cropping isn't part of that definition.

Of course in every day lingo, we do tend to use the term 'magnify' (incorrectly) .. but this is exactly what is NOT happening when you crop, or use a cropped sensor!

OTOH: when adding a TC between a camera and lens, and keeping all other relevant variables the same .. then you are in fact magnifying the scene.

[ameerat42]

AK. It is used in the sense that the thread is about, viz:
"Do I enlarge using a teleconverter, or by cropping and [something that means magnifying but which is enlarging in PP]..."

[ameerat42]

Well, that was easier said than done:eek:
Somewhere above I gave some suggestions for how to do a test for comparing the DOF when changing focal length (FL).
Well, I had to revise them. The results below are the 4th attempt at photographic a suitable subject/scene. In the end,
a relatively close object was used: some weeds on the driveway.

So the original Q was (essentially): Is a teleconverter (TC) better than enlarging in Post Processing (PP)?
And a related Q arose (essentially): Is there a difference in Depth Of Field (DOF) between the two methods?

My main aim:
To test the 2nd Q - any difference in DOF with change in focal length (using a TC).

Why a completely manual and fixed lens:
Could not control all settings on a later lens.

How I got the pics:
One was with the 2XTC attached to n F=135mm fixed, manual, legacy lens, all mounted on a tripod.
The other was with the same lens but without the TC.
The lens was set to maximum aperture as f/2.5 for both shots, with and without TC.
(The EXIF will show the same f-stop for both files because it is just an indicator in the camera of the manual setting of the physical aperture.)
The change in subject distance was considered minimal: 50 mm over 3.7m (1.35% diff).

In PP:
Copy the wider view image and paste the layer onto the narrow view image. Double the size of the pasted layer (wide view)
to match the size of the narrow view.
Change the layer opacity to see both overlay and background image and align carefully so that they superimpose.
Restore the opacity of the overlay and then flatten the image.
Copy the result back onto the original wide view image and flatten it.
Save and Rename the new file as ...cx2 (cropped and doubled).
Close the original narrow view file without any changes.
Take a screen shot of the two images side-by-side for display here. (Links to the original LARGE files are provided.)

Conclusion:
No change for me, but opinions welcome.
1) Resulting IQ depends on equipment and PP methods.
2) No change in DOF with change in FL.

Screen shot of TC vs PP test...
124319

Link to folder with original images (LARGE FILES:nod:)
https://onedrive.live.com/redir?resid=E15FFD049D805436!1538&authkey=!AJze13IEQebdfl8&ithint=folder%2cjpg

[Mark L]

So the original Q was (essentially): Is a teleconverter (TC) better than enlarging in Post Processing (PP)?
And a related Q arose (essentially): Is there a difference in Depth Of Field (DOF) between the two methods?

My main aim:
To test the 2nd Q - any difference in DOF with change in focal length (using a TC).



I'm more interested in the original question as am currently considering buying a TC (with known compromises).
So let's do another kinda related question. :)
Am considering going FF, so would adding x1.4 TC to FF be better than my current APS-C without the TC?:D

[MissionMan]

From my personal experience, I won't go beyond a 1.4x. I.e. the moment I need more than a 1.4x, the lost of quality is either worth cropping for or buying a longer lens (subject to finances). My reasons are largely due to sports so AF is important, along with sharpness as wide open as possible.

[ameerat42]

I'm more interested in the original question as am currently considering buying a TC (with known compromises).
So let's do another kinda related question. :)
Am considering going FF, so would adding x1.4 TC to FF be better than my current APS-C without the TC?:D

The 1.4 TC on any lens would end up giving you approximately the same FOV as you now have with the 60D with the same lens.
But the resulting image would of course be bigger. The still wide field would help in framing birds in flight. If the combo maintains a
good IQ, then all up it would be a good way to go.

So if it gives a bigger picture with approximately the same field of view, the answer would have to be in the affirmative. I don't think
that the one stop light loss from the TC will be much of a drawback for most reasonably lit scenes.

- - - Updated - - -

Of course, if you want to use AF, make sure the TC supports the function.

[William W]

From my personal experience, I won't go beyond a 1.4x. I.e. the moment I need more than a 1.4x, the lost of quality is either worth cropping for or buying a longer lens (subject to finances). My reasons are largely due to sports so AF is important, along with sharpness as wide open as possible.

(Nikon D750, Nikon D700, MB-D16, MB-D10, Nikon 24-70 f/2.8, Niko 70-200 f/2.8 VR2, Nikon 50 f/1.4, Tamron 90mm f/2.8 Macro, Nikon 1.4x, Kenko Extensions, SB700, SB600, Benro C3580T, Benro GH-1, Benro C48T)

My experience differs.

I agree that (as one example) a 400/2.8 Lens will out-perform a 70 to 200 + x2.0 Extender, but, I think that it is important to reckon what 70 to 200 lens and what Extender is being used.

From the gear-list provided it is most likely that the 70 t0 200 is the obvious lens to which an Extender be added. I have used Nikon. The 70 to 200/2.8 VR is a very good lens. It is unclear if that is a Kenko x1.4 Extender in the gear list or not. My experience is that Nikon Extenders are better than Kenko, however I am not sure IF a x2.0 Nikon Extender is compatible with that particular Nikon 70 to 200 lens and the Camera Bodies in the gear list: these might be factors in not wanting to extend longer than x1.4, but choosing to crop the image instead.

As we are comparing experiences and especially for the readership interested in Canon Gear: note that the Canon Extenders EF: x1.4 MkII and MkIII; and x2.0 MkII and MkIII are compatible with the three (3) EF 70 to 200F/2.8 L Series Lenses. The best pairing being the EF 70 to 200 F/2.8 L IS MkII USM and the Extenders EF MkIII.

As a general point nonspecific to any brand of camera or lens - Post Production is an important phase in the representation of the final image, and because the optic of any Extender will result in a softer image the PP of these Image Files requires a different PP technique be employed than what otherwise would be the normal workflow for an Image File made with the ‘naked lens’.

Apropos - Reduction of AF Acquisition Time and EF Zoom Lenses:

It being STATED by the Manufacturer that there is compatibility apropos AF Functionality is the first consideration. Amongst the small group of EF Zoom Lenses which ARE compatible with Extenders EF in regard to AF when used with MANY EOS Bodies, the three 70 to 200/2.8 lenses. In my experience, all perform very good to excellent.

Apropos Reports and Lab Testing of AF Functionality:

Several notable reports reckon that the slower AF using the EF70 to 200 F/2.8L USM; the EF70 to 200 F/2.8L IS USM; the EF 70 to 200F/2.8L IS MkII USM and either the two Extenders EF 1.4MkII and MkIII, is in the order of 30%~50% SLOWER than if no Extender is used. The Extenders EF 2.0MkII and MkIII are usually quoted as having a tad more SLOWER AF acquisition, though no tha much slower.

These are (almost always) a bench test using a fixed Subject and then measuring (in "time taken") the AF acquisitions comparatively from several prescribed out of focus distances to difference in AF acquisition distances. The results are then averaged in some way. It is noteworthy that some tests do not even describe the methodology used.

However, whilst I acknowledge that theory, I think that the salient point is to ask “what does that mean in real life shooting?”

And as a result of asking that question, I consider a more useful, though less scientific approach, is to tally the number of shots lost as a result of AF being too slow.

Note also that one major point being, whilst we accept that the AF with a x1.4 Extender EF will be slower - and let's say it is 50% SLOWER - the critical question is: "How much IN TIME is that slower?" – and purely from my analyses over several years, using several cameras, it is not that much slower - for my purposes and outputs.

*

Another salient point is, (most of) the bench tests which tabulate the relative slowness of AF are intrinsically biased askew of what is, actual and typical real-world shooting.

As an example, let’s take a simple bench which is designed to make an A/B comparison of the time taken to acquire AF using a Lens ALONE and then that Lens with Extender EF added. Let’s assume beginning at four OoF distances and then measuring the time for AF to acquire the Subject set at four different Focus Distances. The two resultant grids would appear like this:

http://gallery.photo.net/photo/18195319-lg.jpg

In this grid, we assumed that 0 (zero) is time is taken to acquire AF to any distance from which the lens is set as a starting point. This is not so: but is is a very short time and I used "0" for simplicity.

The grid implies that the greater the actual acquisition distance from the staring point the longer the time taken to acquire (all other factors consistent). This is actually so.

We would make two grids of results one with the Extender and Lens and one with the Lens 'naked' and then quantify the DIFFERENCE of the time taken to Acquire AF - and as mentioned most test results then describe the difference as a "percentage slower" figure. And the test summary is such as: "using the Extender EF the AF acquisition is 50% slower.”

However in most typical real world shooting, the AF acquisition is from a starting point which is around and about the final “acquired” Focus Distance, and this is so even if the action is moving (quickly), so therefore this type of bench testing will provide biased results which are skewed toward the actual impact of the “Slow AF” appearing in print much more severe that it is in reality and for mostly all practical purposes.

*

"Practical" AF Acquisition & 'Slowness', in my experience - details:

All three of those mentioned 70 to 200 "L Series" lenses work very good to excellent with the 1.4 Extenders EF MkII and MkIII. The ultimate and the best combination being the EF 70 to 200F/2.8L IS MkII USM and the 1.4 Extender EF MkIII.

BTW - The worst being either Extender with the EF 70 to 200 F/2.8 L IS USM.

Moreover apropos AF acquisition and taking into account the type of shooting I generally do, that being Field Sports such as Hockey; Rugby; Football (soccer); Cricket and indoor Swimming, my opinion is based upon using Centre Point AF in Daylight and Telecast Floodlight Banks - typically EV = 9~15. The three lenses were used variously over 12 years with: 20D; 30D; 50D; 7D; 7DMkII; 5D; 5DMkII; 1DsMkII; and 1DSMkIII Camera Bodies.

I cannot honestly recount any major trouble with AF Acquisition which lead to shots being lost.

For a shot that is static for example a B&G at an Alter - any of the three 70 to 200/2.8:L's and Extender will eat it.

The main reason why I would choose to use a 70 to 200/2.8L and an Extender, rather than the 400/2.8L is, after considering the Image usage are WEIGHT (about 3lbs vs. 12lbs) and manoeuvrable factors. I use the 70 to 200 + Extender mostly always hand-held, as opposed to using the 400/2.8L on a Monopod and thus the 400/2.8 slows me down, especially running a sideline, or I have to dump the Monopod - and on some Ovals I am not keen to do that.

*

Expectations and Realities:

As already mentioned, the final Image quality has a lot to do with the processing of the image and although in theory there will be degradation using any Extender with any Lens, in my experience a x2.0 Extender EF is a very useable tool combined with the EF 70 to 200/2.8 L Series lenses. An example is here below. The top image represents the final printed image which is a slight CROP from the Full Frame. Below it is a further enlargement. The client’s Final Product was printed 20 inches along the long side and is “excellent”:

http://gallery.photo.net/photo/10291553-lg.jpg
(EF70 to 200F/2.8L USM + 2.0MkII used at 400mm
F6.3 @ 1/1600s @ ISO250 Head-On Motion - Hand Held)
(Note this is the lens stopped down only 1/3 stop. This was using the x2.0 Extender EF MkII and the EF 70 to 200 F/2.8 L USM - better results are attained with either of the EF 70 to 200 F/2.8L IS MkII USM and the x2.0 Extender EF MkIII)


Summary Comment:

Having done many A/B comparisons - a result of those comparative tests is this general comment: compered to any (heavy) CROP in Post production which is necessary to get to x1.4 (or x2.0) - using an Extender EF will arguably be better in every case.

Those A/B tests are comparing Lens + Extender to SAME lens and cropping using the SAME camera – AND – considers that the Extender/ Lens/ Camera are manufacturer stated as ‘compatible’ – what I mean is just because the extender fits onto the lens and the camera and allows images to be made that does not mean that rig is ‘compatible’

WW
All Images © AJ Group Pty Ltd Aust 1996~2016 WMW 1965~1996

[arthurking83]

....
Am considering going FF, so would adding x1.4 TC to FF be better than my current APS-C without the TC?:D

Actually, I think(I'm sure actually) that the Canon APS-C crop factor is 1.6x .. so a 1.7x TC would be more accurately reflective of the Canon APS-C sensor.

Pentax, Nikon, Sony, Sigma .. all use a 1.5x crop ratio for their respective APS-C sensors .. Canon went it alone! :p

Dunno if Canon make a 1.7xTC, but they do lose 1.5Ev of aperture value compared to the 1Ev of a 1.4xTC.

I think what you have to research is, does the Canon full frame sensor give you more than 1 stop of ISO quality for any given situation.
That is, if you went with a full frame Canon, and it's high ISO advantage over an APS-C Canon is more than 1Ev, then you will be ahead in terms of overall image quality.

To put that into numbers that make any sense:
Say a Canon FF has 2 stops advantage over the best Canon APS-C camera: you're already shooting at max ISO6400 to keep noise IQ to an acceptable level. So with the Canon FF, with 2 stops of extra ISO ability you give yourself an ISO25600 limit to work with.
Add a 1.7x TC to give you a smidge more reach(I doubt you'd really call that an advantage of any type tho) .. but with a loss of only 1.5Ev, you're still ahead(by 0.5Ev) in terms of IQ when the light gets difficult.
You could use that 0.5Ev advantage in ISO to stop the lens down by 0.5Ev of aperture instead, which may also give an increase in detail rendering .. But this could be dependent on what you set as your min aperture already.
You could also use that 0.5Ev advantage for more shutter speed allowance too ..

Just work out if there is an appropriate advantage in high ISO performance between what you could get(eg. latest APS-C Canon vs latest FF Canon)

[William W]

I'm more interested in the original question as am currently considering buying a TC (with known compromises).
So let's do another kinda related question. :)
Am considering going FF, so would adding x1.4 TC to FF be better than my current APS-C without the TC?:D

Notwithstanding Arthur King's suggestions of research. What gear specifically are you comparing?

i.e. what do you have now and (if you know) what are you considering buying - specifically lenses / cameras / extenders.


The other important factor to disclose is - what are you intending to typically shoot and under what lighting scenarios? For one example high ISO performance might not necessarily be a main consideration if (comparatively) you would typically need to bump from ISO200 to ISO400 or ISO800 when using a x1.4 or 2.0 Extender.

*

Canon's APS-C Format "crop factor" is (approx.) x1.6 and APS-H is (approx.) x1.3.

Canon does not make a x1.7 Extender - only x1.4 and x2.0.


WW

[Mark L]

What gear specifically are you comparing?

i.e. what do you have now and (if you know) what are you considering buying - specifically lenses / cameras / extenders.

Not comparing anything yet really, though it was not a rhetorical question.
60D is the current camera. Thinking things may have moved on a little there.
Gave up smoking last week and if it stays given up :crossed: the $15 a day :eek: saved will be spent on some photographic equipment.
So just starting to think before focusing on what to research really.
I do like photographing them birds though.:)

[MissionMan]

My experience differs.

I agree that (as one example) a 400/2.8 Lens will out-perform a 70 to 200 + x2.0 Extender, but, I think that it is important to reckon what 70 to 200 lens and what Extender is being used.

From the gear-list provided it is most likely that the 70 t0 200 is the obvious lens to which an Extender be added. I have used Nikon. The 70 to 200/2.8 VR is a very good lens. It is unclear if that is a Kenko x1.4 Extender in the gear list or not. My experience is that Nikon Extenders are better than Kenko, however I am not sure IF a x2.0 Nikon Extender is compatible with that particular Nikon 70 to 200 lens and the Camera Bodies in the gear list: these might be factors in not wanting to extend longer than x1.4, but choosing to crop the image instead.

As we are comparing experiences and especially for the readership interested in Canon Gear: note that the Canon Extenders EF: x1.4 MkII and MkIII; and x2.0 MkII and MkIII are compatible with the three (3) EF 70 to 200F/2.8 L Series Lenses. The best pairing being the EF 70 to 200 F/2.8 L IS MkII USM and the Extenders EF MkIII.

As a general point nonspecific to any brand of camera or lens - Post Production is an important phase in the representation of the final image, and because the optic of any Extender will result in a softer image the PP of these Image Files requires a different PP technique be employed than what otherwise would be the normal workflow for an Image File made with the ‘naked lens’.

Apropos - Reduction of AF Acquisition Time and EF Zoom Lenses:

It being STATED by the Manufacturer that there is compatibility apropos AF Functionality is the first consideration. Amongst the small group of EF Zoom Lenses which ARE compatible with Extenders EF in regard to AF when used with MANY EOS Bodies, the three 70 to 200/2.8 lenses. In my experience, all perform very good to excellent.

Apropos Reports and Lab Testing of AF Functionality:

Several notable reports reckon that the slower AF using the EF70 to 200 F/2.8L USM; the EF70 to 200 F/2.8L IS USM; the EF 70 to 200F/2.8L IS MkII USM and either the two Extenders EF 1.4MkII and MkIII, is in the order of 30%~50% SLOWER than if no Extender is used. The Extenders EF 2.0MkII and MkIII are usually quoted as having a tad more SLOWER AF acquisition, though no tha much slower.

These are (almost always) a bench test using a fixed Subject and then measuring (in "time taken") the AF acquisitions comparatively from several prescribed out of focus distances to difference in AF acquisition distances. The results are then averaged in some way. It is noteworthy that some tests do not even describe the methodology used.

However, whilst I acknowledge that theory, I think that the salient point is to ask “what does that mean in real life shooting?”

And as a result of asking that question, I consider a more useful, though less scientific approach, is to tally the number of shots lost as a result of AF being too slow.

Note also that one major point being, whilst we accept that the AF with a x1.4 Extender EF will be slower - and let's say it is 50% SLOWER - the critical question is: "How much IN TIME is that slower?" – and purely from my analyses over several years, using several cameras, it is not that much slower - for my purposes and outputs.

*

Another salient point is, (most of) the bench tests which tabulate the relative slowness of AF are intrinsically biased askew of what is, actual and typical real-world shooting.

As an example, let’s take a simple bench which is designed to make an A/B comparison of the time taken to acquire AF using a Lens ALONE and then that Lens with Extender EF added. Let’s assume beginning at four OoF distances and then measuring the time for AF to acquire the Subject set at four different Focus Distances. The two resultant grids would appear like this:

http://gallery.photo.net/photo/18195319-lg.jpg

In this grid, we assumed that 0 (zero) is time is taken to acquire AF to any distance from which the lens is set as a starting point. This is not so: but is is a very short time and I used "0" for simplicity.

The grid implies that the greater the actual acquisition distance from the staring point the longer the time taken to acquire (all other factors consistent). This is actually so.

We would make two grids of results one with the Extender and Lens and one with the Lens 'naked' and then quantify the DIFFERENCE of the time taken to Acquire AF - and as mentioned most test results then describe the difference as a "percentage slower" figure. And the test summary is such as: "using the Extender EF the AF acquisition is 50% slower.”

However in most typical real world shooting, the AF acquisition is from a starting point which is around and about the final “acquired” Focus Distance, and this is so even if the action is moving (quickly), so therefore this type of bench testing will provide biased results which are skewed toward the actual impact of the “Slow AF” appearing in print much more severe that it is in reality and for mostly all practical purposes.

*

"Practical" AF Acquisition & 'Slowness', in my experience - details:

All three of those mentioned 70 to 200 "L Series" lenses work very good to excellent with the 1.4 Extenders EF MkII and MkIII. The ultimate and the best combination being the EF 70 to 200F/2.8L IS MkII USM and the 1.4 Extender EF MkIII.

BTW - The worst being either Extender with the EF 70 to 200 F/2.8 L IS USM.

Moreover apropos AF acquisition and taking into account the type of shooting I generally do, that being Field Sports such as Hockey; Rugby; Football (soccer); Cricket and indoor Swimming, my opinion is based upon using Centre Point AF in Daylight and Telecast Floodlight Banks - typically EV = 9~15. The three lenses were used variously over 12 years with: 20D; 30D; 50D; 7D; 7DMkII; 5D; 5DMkII; 1DsMkII; and 1DSMkIII Camera Bodies.

I cannot honestly recount any major trouble with AF Acquisition which lead to shots being lost.

For a shot that is static for example a B&G at an Alter - any of the three 70 to 200/2.8:L's and Extender will eat it.

The main reason why I would choose to use a 70 to 200/2.8L and an Extender, rather than the 400/2.8L is, after considering the Image usage are WEIGHT (about 3lbs vs. 12lbs) and manoeuvrable factors. I use the 70 to 200 + Extender mostly always hand-held, as opposed to using the 400/2.8L on a Monopod and thus the 400/2.8 slows me down, especially running a sideline, or I have to dump the Monopod - and on some Ovals I am not keen to do that.

*


When I say the AF is effected, there are a couple of areas:

1. There are situations where even the 70-200 which has one of the fastest AF systems can't keep up. Having half the AF speed is then a bigger issue.
2. If you use the converter across multiple lenses, the AF is effects some lenses and not others. I.e. you can use the 1.4 on most decent ED lenses but you can't use the 2x on all of them without a substantial impact to performance or loss of AF. Case in point, the Nikon 200-500 f/5.6 which works perfectly with a 1.4x and has limited AF with 2x. So you 1.4x can be used across virtually every lens, but the 2x is quite selective.

[William W]

Not comparing anything yet really, though it was not a rhetorical question.
60D is the current camera. . . 60D, Canon 28-105, Sigma 120-400, a speedlite and a tripod.

Using the Sigma 120 to 400 I suggest taking a close look at a 7DMkII and forget the extender.

Good that you gave up smoking.

WW

- - - Updated - - -


When I say the AF is effected, there are a couple of areas:

1. There aresituations where even the 70-200 which has one of the fastest AF systems can't keep up. Having half the AF speed is then a bigger issue.
2. If you use the converter across multiple lenses, the AF is effects some lenses and not others. I.e. you can use the 1.4 on most decent ED lenses but you can't use the 2x on all of them without a substantial impact to performance or loss of AF. Case in point, the Nikon 200-500 f/5.6 which works perfectly with a 1.4x and has limited AF with 2x. So you 1.4x can be used across virtually every lens, but the 2x is quite selective.

Thanks for the details. I understand.

On point 1.

Though in any shooting scenario where the AF of the 70 to 200 cannot keep up (with only the naked lens), then another shooting solution has to be found, so that is either irrelevant to this discussion or relevant in so far as that same shooting solution could be used if an Extender were employed. And - it is very likely NOT halving that AF speed - even more important - it is likely NOT halving the Acquisition - that was one major point of the explanation of how the comparison tests are performed

*

On point 2.

Those specific details you gave about extenders across lenses pertain to my summary, I expect, - as mentioned (my bold & underline now for emphasis:

"Having done many A/B comparisons [edit] Those A/B tests are comparing Lens + Extender to SAME lens and cropping using the SAME camera – AND – considers that the Extender/ Lens/ Camera are manufacturer stated as ‘compatible’ – what I mean is just because the extender fits onto the lens and the camera and allows images to be made that does not mean that rig is ‘compatible’ "

For me, the fact that Nikon stayed with a legacy lens system created many complications, and not all facets are explained, not even through NPS. Though I do appreciate Nikon's rationale for keeping legacy lenses. And that's one reason why I moved both my own gear and the studio gear when we cut over to digital.

WW

[Mark L]

Good that you gave up smoking.



Good that I'm on my way to giving up smoking. After 4 days not a done deal yet.:(
The camera you suggest was in my thoughts. :th3: Am also prepared to change lens.
Thanks for our indolence enseth.;)

[tduell]

Mark,
A few thoughts about your question, as it also affects me.
We both shoot birds with a crop sensor, and both shoot with 400-ish FL.
In your case the 60D is about 18MP (5184x3456) if I have got that right; mine is the K-3 II, 24 MP (6000x4000).
The problem I have had is that my 150-450 lens is a bit 'short' for small birds, so I bought a Pentax 1.4xTC, which brings it up to 630 at full zoom.
This allows the small birds to better fill the frame, but I lose a stop, and on top of that I have had a lot of trouble getting sharp images using shutter speeds that I would have expected to be OK with the Shake Reduction (SR). To counter this I have had to up the shutter speed, but this brings the dreaded high ISOs.
So I would like a less noisy sensor and better shake reduction, and maybe the new Pentax K-1 will help. The sensor noise story sounds good, it is said that K-1 at 12800 is as good as K-5 at 3200, and K-5 is noticeably better than the K-3 II, so there maybe a couple of stops there.
The K-1 SR is supposed to be a half stop better than the K-3 II...not much there, but it might help.
One last significant issue is sensor pixel density. If I went to the K-1, in crop mode (i.e. same subject coverage on sensor as my K-3 II) the image is approx 15MP, which has ramifications when cropping an image a lot, which isn't unusal for small birds...for me anyway.
In your case, if you stay with Canon you probably need something like the 5Ds to end up with a crop mode of similar pixel density to your current camera. I don't know if the 5Ds is a lower noise sensor, that would be something to think about. Almost everything else is going to put you roughly where I am looking i.e 36MP sensor, and a less dense crop mode.
If you use a TC with your lens, which I expect has SR (or whatever canon call it) in the lens, will that SR work OK with the TC? Given my experiences I doubt that you would want to have to run to much higher shutter speeds to ensure sharp images, whilst also giving up a stop as a result of adding the TC.
Maybe you rank some of these issues differently, this is just the way my mind is attempting to crunch the problem, and it some of it may be helpful.
Gives us something to think about :D

Cheers,
Terry