THINKING of buying a "primary" (telephoto?) lens for my Canon. [Archive] - AusPhotography:: Australia's Premier Photography Forum::

Mr Felix

28-11-2012, 2:08pm

Hi folks.

Not wanting to upset people, I shall ask for a bit of info.

First off though: Telephoto. To me that means a lens which is not a zoom.
Though these days they seem to be called "primary" lenses I see/belive.

I have my 550D and would like to get a 35mm FAST lens.

The lenses I have only go to F4.5 I think at the fastest.

1.8 or 2 would be nice.

One place had canon lenses 35 and 50mm for $500-ish dollars and I explained I was only looking and researching.

To me that seems quite expensive.

I have heard that I can get a 35mm Canon for about $100-130.
That is a fair way from $500.

Why (do I want the lens)?

Well, I would like to try with small depth of fields to help me hone my "of what is it I am taking a picture?" skills.

With the lens I have, I am getting a big DOF and may be losing the impact of what I want as the subject.

Rather than have "everything" in focus.

So if I get a faster lens I can drop the DOF and really work at selecting what it is I want to be the thing in focus rather than .......

Ok.

Yeah, I know my pictures posted here have been of "varying standards" and not really of any acceptable quality - from what has been said.

However, I want to keep trying, trying and trying.

Maybe one day things will click and I will have the "magic moment" from which things are better.

But to do so, I need to try things.

So there lies the question.

I am not going to say I am going to buy one tomorrow, or any time soon. I was just wondering the price, so I can budget it into things.

Thanks.

ameerat42

28-11-2012, 2:42pm

Hi Mr Felix.
It sounds like you want a "PRIME" lens (not "primary", not "telephoto").

A prime lens is one with a fixed focal length - by usually understood definitions.

Supposedly too, they have potentially better definition than a zoom lens, because of the fixed focal length.
In addition, they can have wider apertures (lower f-stops, like f/1.4, etc), so allowing you to get better "bokeh" than
lenses with higher f-stops.

I have heard of "nifty-fifty" lenses that seem to be a class that fit the bill and that are relatively cheap. Of course, it will
be f=50mm focal length. I'm not sure what aperture they can open up to.

Anyway, something to chase up.

Am.

agb

28-11-2012, 3:07pm

For Canon here are 3 50mm prime lenses. The f 1.2 for over $1000, the f 1.4 for about $400, and the f 1.8 for about $150.
There are also 3 35mm prime lenses, from f1.4 over $1000, f 2 with IS and about $850 and the f 2 without image stabilizer for about $400.
The canon lens lineup is readily available on the canon web site.

A prime lens is one which has a fixed focal length, as against a zoom lens which has a variable focal length and which may be also a telephoto zoom

A telephoto lens is a lens which is shorter than the focal length. So a 200mm lens that is made shorter than 200mm in length can be called a telephoto lens, or a 100mm lens or even a 50mm lens.

JM Tran

28-11-2012, 3:18pm

I swear by my 35L 1.4 as my primary lens for travel and walkabouts

BUT

You should wait for the Sigma 35 1.4 coming out soon, if it follows the same trend as the Sigma 50 1.4 - it will perform much better than the Canon cheap equivalent - which is the 35 f2, no idea how the new IS version has improved optics or not. But there is quite a difference between 1.4 and f2

cinvala

28-11-2012, 3:27pm

I have the nifty fifty. Bang for bucks its a great lens. Having a single focal length lens is a lot different from having a zoom. You have to use your legs to frame the shot, which is not necessarily a bad thing. Being able to actually go to 1.8 makes you think more about your DOF choice, and where you target your focal point.
I found using a prime a great learning experience.

Rattus79

28-11-2012, 3:58pm

You should wait for the Sigma 35 1.4 coming out soon, if it follows the same trend as the Sigma 50 1.4 - it will perform much better than the Canon cheap equivalent - which is the 35 f2, no idea how the new IS version has improved optics or not. But there is quite a difference between 1.4 and f2

I've seen a couple of rave reviews for the Sigma 35 1.4 already.
I want one for street and pano use. I find 50 too narrow for panos and my 10-20 @ 20 too wide ...

Xenedis

28-11-2012, 4:46pm

There are also 3 35mm prime lenses, from f1.4 over $1000

Boy, has the price of that come down.

I was stunned to see that Discount Digital Photographics is offering it for $1,250.

When I bought mine in January of 2007, its price tag was over $2K, even from 21st century suppliers.

agb

28-11-2012, 5:53pm

Kym

28-11-2012, 6:05pm

Re: the terminology it's all covered in the NTP book... http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Using_different_lenses

arthurking83

28-11-2012, 10:54pm

Hi folks.

.......

Why (do I want the lens)?

Well, I would like to try with small depth of fields to help me hone my "of what is it I am taking a picture?" skills.

With the lens I have, I am getting a big DOF and may be losing the impact of what I want as the subject.

Rather than have "everything" in focus.

So if I get a faster lens I can drop the DOF and really work at selecting what it is I want to be the thing in focus rather than .......

.....

There is an alternative option here(actually two!) .. but the one that comes to my mind could save you many hard earned dollars.

Take the time to rad up on a few basic principles of photography before you invest more money on something that potentially may not give you the results you are looking for!!!

With a limited knowledge of what the concepts you are chasing actually involve, you may only end up with a lighter hip pocket and not much difference in the results you are currently seeing now!

So the initial step is to search out ALL the necessary info about what you are interested in(in this instance the concept of DOF).

ie. what are the alternatives for controlling DOF!!

You will then come back armed with more info, asking more relevant questions about the best ways to achieve your intended goal.

All it takes is a small amount of reading up on some easy to follow concepts and then experiment with some practical application of those concepts.(this may vary in time between a few hours to maybe an afternoon)

You may potentially have the ability to achieve your desired result with the gear you currently have.

Don't get me wrong ... I'm a(the!!) primary advocate for the acquisition of more lenses for specific purposes(which I regularly do myself anyhow) .. but my point is that with your opening post, I feel as though you don't have a full understanding of how DOF actually works, and how to control it.

Mr Felix

29-11-2012, 6:33am

Thanks folks for the replies.

Food for thought.

Way back when (about 35 years) when I had my AE-1 Program, I had a 50mm 2.8 and a 28mm 1.8 lens.

My prime lens was the 50mm.

Compared to the lenses now, they were way better for small DOF. But! They were also bigger (wider) lenses than these also.

So "you" may be right in that I may not have been using the 1.8 side of things too much and it was possibily more the 3.5 side of things, it is just that the lens let in more light and so the pictures were better.

I also used 400 ASA film - which some of you may dislike because of the lower quality.

I have lots of films/prints and I am happy with their quality.
And alas sometimes looking at them, they are BETTER than the ones I am getting now.
That is upseting.

With a 50mm, that will translate to about an 85mm equ for the digital and someone did mention it is too "narrow" for use.

Where as a 35mm would translate to about a 50mm, which would be a lot better for "general use".

Thanks for the link. I shall have a look when I get time. It is sometimes difficult finding them because I don't know the right word/s to use and as per the original post, I said PRIMARY instead of PRIME.

In the book/s which came with the AE-1 they were talking about lenses and the terms ZOOM and TELEPHOTO were used to describe the two types of lens.

They didn't drill down on TELEPHOTO other than FIXED FOCAL LENGTH, so I associated them as being the same.

Granted, I may have mis-read what they said, or any number of things.
Suffice to say I can only explain myself how I understand things.
However, the new term is now understood.

Anyway, I had better get to work. I am not being paid to write stuff on the interweb.

Thanks again to all.

Analog6

29-11-2012, 1:26pm

A lot is also dependant on what type of photography you wish to do with the lens. For general purpose photography, zoom lenses as primary (ie most used lens) in lengths such as the Canon 24-105 are good lenses.

If you want to shoot landscaopes, then you will want a wider lens - 50mm or less. I use a 17-40 on full frame and it is a good length.

For sport many togs have dedicated prime lengths of 400/500/600 - big investments but necessary for any event where you cannot get close to the action (eg surfing, motor racing).

So have a think about what you want to do with the lens. Maybe write down a few photographic 'goals' you'd like to meet. Then enter the type of photography as s search on here, or google it on line and I guarantee you will get lots of hits to read up on and fire your imagination and send you off on many other tangents - but don't let yourself get too distracted.

And why not attend a few Sydney meet ups. Most of us are friendly folk and will let you have a little play with our lenses so you can get the feel of the various options.

Mr Felix

29-11-2012, 2:02pm

Analog6

I have been to one.

Alas scheduling is difficult.

I really would like to come to/go to more.

I think that actually meeting people and talking to them would help me more than doing it this way.

I am a bit of a luddite.
Probably not the right word actually.

But I do enjoy get togethers.

I shall see if I can get myself to the next one.

Thanks again for the info.

William W

01-12-2012, 12:04pm

. . . I have my 550D and would like to get a 35mm FAST lens . . . I have heard that I can get a 35mm Canon for about $100-130. . . . I would like to try with small depth of fields to help me hone my "of what is it I am taking a picture?" skills.

You might get the EF35F/2 second hand for about that price, but new it will be closer to AU$300.

There are actually four Canon 50mm Primes available new: F/1.2L; F/1.4; F/1.8MkII and F/2.5Macro. But although the F/2.5 Macro is a very handy Prime Lens; the most economical and best to suit shallow DoF, would be the EF50/1.8MkII – but note that all these 50mm lenses will act as a short telephoto lens on your camera.

The EF50F/1.8MkII should be about AU$ 110~130 new – perhaps that is the lens for which you are quoting prices?

I suggest you use your kit lens (18 to 55) at both 35mm and at 50mm and use it that way for a week at each setting, to better understand how a Prime Lens will affect your Photography and better equip you for choosing what Focal Length you might actually want to buy.

***

Way back when (about 35 years) when I had my AE-1 Program, I had a 50mm 2.8 and a 28mm 1.8 lens. My prime lens was the 50mm. Compared to the lenses now, they were way better for small DOF.

The AE-1 is a 135 format camera. The 550D is a smaller, APS-C format camera.
The smaller the format of the camera, the LESS it is possible to make shallow DoF for any given Aperture.

The ‘equivalence’ DoF value between the AE-1 and your 55oD is about 1⅓ Stops.

ROUGHLY speaking - what that means is: if you have the same Framing and Perspective of a Subject and had your AE-1 with your 50mm lens on it and also your 550D with a 35mm lens on it, the DoF would be the same if the AE-1 was shot at F/3.2 and the 550D was shot at F/2.

So therefore (for equivalent shots) your 550D can never attain such as shallow DoF as your AE-1 with that 28/1.8 lens you had, even if you buy an F/1.8 lens.

Also as a general comment I suggest you not confuse DoF with Subject Separation.

Also I suggest that you look closely at what shallow DoF you actually do require for most of your shots, as an F/2.8 lens (on APS-C) can manage a most suitable Shallow DoF for the greater percentage of General Photography.

WW

Footnote: If you want to buy the EF35/2 new, it is my opinion that it will be withdrawn from the Canon line up soon, because of the newer IS version has been listed as a 'replacement'.

arthurking83

01-12-2012, 12:20pm

......

The AE-1 is a 135 format camera. The 550D is a smaller, APS-C format camera.
The smaller the format of the camera, the LESS it is possible to make shallow DoF for any given Aperture.

The ‘equivalence’ DoF value between the AE-1 and your 55oD is about 1⅓ Stops.

ROUGHLY speaking - what that means is: if you have the same Framing and Perspective of a Subject and had your AE-1 with your 50mm lens on it and also your 550D with a 35mm lens on it, the DoF would be the same if the AE-1 was shot at F/3.2 and the 550D was shot at F/2.

......

Note that the DOF for a given aperture and lens will be the same irrespective of format size.

That is, a 50mm lens at f/1.4 on any format, be that large format, medium format, 35mm or APS-C(or even the smaller compact formats!) will produce the same DOF.

The only thing that changes is the framing when you move from one format to another.

So as William W said, if your primary objective is to produce a shallower DOF for a given lens (or framing of subject), then a change of format is the better(but most expensive) way forward.

That is one of the alternative options to achieving greater subject isolation for your images .... there are other ways too, and I think that for greater information retention, the OP may be better off, reading the New To Photography section and applying some of the concepts explained into practice.

William W

02-12-2012, 6:35am

On the matter of cost: certainly buying another camera body could be more expensive than buying one fast lens. Certainly given the content of this thread and the consideration of a budget around a couple of hundred dollars, this is so.

But the bigger picture (pun intended): once one has a "Full Frame" camera then having that format allows for the possible shallower DoF using ALL of the lenses in the camera bag, which will mount to the camera.

The 135 Digital Format (aka "Full Frame") has the most and also the most comprehensive range of very fast lenses available to it: for example there is not an equivalent 24mm F/1.4 lens for APS-C Format - in fact all the wide coverage is lacking fast lenses for APS-C. Similarly there are few, sub F/2.8 lenses available for Medium Format.

I'd argue that this is one major reason why those Photographers seeking extremely shallow DoF in their work: for example many Available Light Portrait Photographers, use exclusively 135 Format DSLR, and an array of very fast Prime Lenses, for example very fast 24; 35; 50; 85; 135; 200 and 300mm Primes.

WW

vk2gwk

02-12-2012, 3:52pm

For one thing... I don't think any of the other posted pointed out that with a crop sensor camera like the 550D the actual focal lenght is 1.6 times the one printed on the lens. So your camera "sees" a 35mm lens as a 56mm one. Your 18 - 135mm IS lens (if that is the Canon one) has a widest aperture of 3.5 and stops down to 5.6 at 135mm.

Depth of field has three basisc parameters: focal length, aperture and distance to the subject you are shooting. If you want to go for a shallow depth of field and do not have a fast lens (say F/1.4) then the thing to do is getting closer to your subject or increase the focal length. Especially shooting small objects the opening angle of the lens is not that important and you can create the same or shallower depth of field with a focal length of say 100mm and aperture F/5.6 as with a 35mm @ F/1.8. With a distance to the subject of 1 meter in the first example (100mm) your DOF will be just about 2cm (1.93 cm) while with the 35mm lens @ F/1.8 you would still have 5.34 cm DOF.....
Get an app for your iPhone (if you got one with a DOF calculator) or go to www.dofmaster.com (http://www.dofmaster.com) where you can calculate the DOF at any given setting for your camera and lens.
Another thing with shooting "wide open" with fast lenses is that usually the image quality is not really very good compared to shots that are stopped down a bit (say F/4 or F/5.6). This especially noticeable in close ups and less in landscapes.
Use a tripod and a tape-measure (I have one in my photo bag all the time) and use your current lenses to experiment.... Save your money for when you really need another lens.

Xenedis

02-12-2012, 5:16pm

For one thing... I don't think any of the other posted pointed out that with a crop sensor camera like the 550D the actual focal lenght is 1.6 times the one printed on the lens.

That is incorrect.

A focal length is a physical property of a lens.

Placing a lens on a camera with a smaller sensor but compatible mount, does not alter the focal length.

What alters is the framing.

The imaging circle of the full-frame (135-format) lens is larger than what can be projected onto the APS-C sensor, so the result is a cropped view.

It is incorrect to call this effect 'multiplication' of the focal length; a 50mm lens will always be a 50mm lens, but when it is mounted on an APS-C camera, the resulting field of view is what you would get natively with an 80mm lens on a 135-format camera.

vk2gwk

03-12-2012, 8:45am

That is incorrect.

A focal length is a physical property of a lens.

Placing a lens on a camera with a smaller sensor but compatible mount, does not alter the focal length.

What alters is the framing.

The imaging circle of the full-frame (135-format) lens is larger than what can be projected onto the APS-C sensor, so the result is a cropped view.

It is incorrect to call this effect 'multiplication' of the focal length; a 50mm lens will always be a 50mm lens, but when it is mounted on an APS-C camera, the resulting field of view is what you would get natively with an 80mm lens on a 135-format camera.
In theory you are absolutely correct, but for all practical purposes everyone uses the multiplication factors to distinguish betwee full frame and cropped sensors of various brands and models. Maybe I should have said" virtual focal length" instead of actual..... :)

The point I was making was: "you don't need a "fast" lens to create shallow depth of field."

Xenedis

03-12-2012, 4:32pm

In theory you are absolutely correct

In practice I am absolutely correct, too.

but for all practical purposes everyone uses the multiplication factors to distinguish betwee full frame and cropped sensors of various brands and models.

The fact that lots of people make an incorrect assertion doesn't make that assertion correct.

Once upon a time, lots of people said the earth was flat; but as we know, it isn't.

Maybe I should have said" virtual focal length" instead of actual..... :)

It's not even a virtual focal length.

The focal length does not change. It is a physical and optical property of the lens, not the sensor.

A 50mm lens is a 50mm lens whether you mount it on an APS-C camera or a 135-format camera (assuming the lens mount is compatible).

If you stand outside and look at the house across the road, and then look at the same house through toilet paper rolls, the size of the subject, and its magnification with respect to the focal plane (ie, your eyes) does not change.

The only thing that changes is the field of view, or framing. You see less of the subject because the view has been restricted, but the size of the subject matter you can see, is larger in relativity to the frame.

In the case of APS-C cameras, the sensor can 'see' less subject matter than the 135-format lens.

In the case of the toilet rolls, the toilet rolls restrict your angle of vision.

The point I was making was: "you don't need a "fast" lens to create shallow depth of field."

That's a valid and correct point, but it remains utterly incorrect to state that "with a crop sensor camera like the 550D the actual focal lenght is 1.6 times the one printed on the lens".

The actual focal length is what's printed on the lens's barrel.

The framing that lens provides looks like what you'd get with a lens 1.6x the marked focal length when used on a 135-format camera.

50mm on APS-C looks like 80mm on 135-format. However, the persepctive effects on the subject matter will be different, as a true 80mm lens has a higher compression ratio than a 50mm lens.

- - - Updated - - -

To add to my last post, let's analyse what the term focal length actually means.

A focal length is the distance between the focal plane and the optical centre of the lens.

If the distance between the bayonet mount and the sensor is the same on both an APS-C camera and its full-frame cousin, it stands to reason that if you mount a 50mm 'full-frame' lens on both camera systems, the distance between the sensor and the optical centre of the lens will remain the same in both cases.

Therefore, the focal length remains the same.

A 50mm lens can never be anything other than a 50mm lens.

The APS-C camera has a smaller sensor, onto which only part of the lens's imaging circle can be projected.

Canon EF-S lenses have a shorter back focus; ie, the rear element is closer to the sensor than is the case with EF lenses.

This, therefore, reduces the focal length, which is why EF-S lenses typically have smaller marked focal lengths. An EF-S 10-22mm lens is actually a 10-22mm lens for the APS-C camera format. It happens to provide the same kind of framing you'd get with an EF 16-35mm lens on a 5D.

Kym

03-12-2012, 5:18pm

Peeps!!! Focal length is ALWAYS Focal length!

I made a pretty diagram to show it http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Focal_Length_vs_Crop_Factor

Also example: http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Full_Frame_vs_APS-C_DX_crop_factor_w_example

So use the right terminology and don't use the mis-term 'multiplication' when all it's only a crop factor. :xmas:

Mr Felix

03-12-2012, 5:55pm

Thanks guys.

I don't want to start WWIII here. ;-)

I can sort of "read between the lines" of what vk2gwk was saying.

There are many discussions about how to explain things to make them understandable to others without dumbing down the information.

Rather putting it in a way which is easier understood.

Though thanks for the explanation that the focal length doesn't change. Most/many people to whom I have spoken use the x1.6 analogy.

However, now I understand it isn't quite THAT simple. There are perspectives, and all that stuff which I haven't considered.

As I said though: I am only thinking about it at this point.

Money doesn't go as far nowadays and I guess like many: The bills seem to keep coming.

arthurking83

03-12-2012, 8:50pm

In theory you are absolutely correct, but for all practical purposes everyone uses the multiplication factors .....

Most reliable sources of information actually give an equivalent FOV value .. ie. as Xenedis says a crop factor value ... for a lens on the full frame 35mm format, not an actual multiplication factor of the lens.

The reason many of us prefer not to use any reference to lens multiplication or focal length multiplier, is more of a technical one, as already said .. for example that of DOF for a given lens and aperture value.

while I don't worship the DOF calculator site, it is a good indication of expectations of DOF for a given application:

Canon APS-C crop camera @ 35mm and 3m focus distance:

Subject distance 3 m

Depth of field
Near limit 2.77 m
Far limit 3.27 m
Total 0.49 m

In front of subject 0.23 m (46%)
Behind subject 0.27 m (54%)

Canon full frame @ 56mm and 3m focus distance(ie. supposedly for a similar FOV)

Subject distance 3 m

Depth of field
Near limit 2.86 m
Far limit 3.16 m
Total 0.3 m

In front of subject 0.14 m (47%)
Behind subject 0.16 m (53%)

Hyperfocal distance 58.7 m
Circle of confusion 0.03 mm

As you can see, while it may appear that the 35mm lens looks like a 56mm lens equivalent on the full frame camera, the reality is that it will actually look nothing like it as the DOF is much more shallow on the full frame camera.
Just one reason why focal length multiplier is not a good choice of wording as a substitute for crop factor.

For most of us, we understand the terminology and what is being described, but for someone looking for accurate info it's always best to give them the correct info to begin with.

Xenedis

03-12-2012, 9:19pm

As you can see, while it may appear that the 35mm lens looks like a 56mm lens equivalent on the full frame camera, the reality is that it will actually look nothing like it as the DOF is much more shallow on the full frame camera.

Yes, there is that issue, too, but I didn't want to go there. :-)

Essentially, all that's common between a 50mm lens on a 650D and an 80mm lens on a 5D II is the field of view. Even then, it's not precise, as the 5D's sensor is not exactly 1.6x the size of the 650D's sensor. Fun, innit?

For most of us, we understand the terminology and what is being described, but for someone looking for accurate info it's always best to give them the correct info to begin with.

Unfortunately, many people mistakenly think that placing a 50mm lens on a 650D turns it into an 80mm lens, and when I read or hear someone making a claim along those lines, I feel it needs to be corrected. There's too much mis-information floating around about this subject, and marketing hype in the form of erroneous terms like 'focal length multiplication factor' is largely to blame.

Without getting overly technical (as indeed this subject is when it comes to exact sensor size, variations between lenses with the same marked focal length, DOF and perspective, etc.), the simplest explanation we can give to people who don't understand the consequence of using an EF lens on an APS-C camera is that the field of view or framing is cropped.

ameerat42

05-12-2012, 4:01pm

Look! Forget all that's gone before. Where's Mr Felix?

Xenedis

05-12-2012, 5:39pm

Look! Forget all that's gone before. Where's Mr Felix?

He had probably had enough of all this APS-C and full-frame stuff, and went out to buy a medium-format camera system...

ameerat42

05-12-2012, 8:03pm

^:2biggn: (It being the latest craze in laughs!)
Am.

Mr Felix

05-12-2012, 8:10pm

No, I'm still here.

Just trying to get my head around it all and process it so I am not simply emptying my pocket/s as someone suggested.

I sort of understand what is being said and how the FOV is changed rather than the focal length.

I posted a couple of thanks...

But I guess being "reminded" the real difference I do want to make sure I know what it is all about.

Again, thanks for the explanations.

I am also trying to organise my time for the Get together on Sat at middle head.

I am also trying to get my head around Broad Band.
As that is off topic, I won't go into the details. Suffice to say it is painful/confusing/annoying.

Mark L

05-12-2012, 9:50pm

........
I am also trying to get my head around Broad Band.
As that is off topic, I won't go into the details. Suffice to say it is painful/confusing/annoying.

reckon someone'll help if you go into details here ..... http://www.ausphotography.net.au/forum/forumdisplay.php?9-Out-Of-Focus

Mr Felix

06-12-2012, 6:42am

Mark,

Thanks much for the offer, but I am at information overload just now as well.

Kym

06-12-2012, 7:54am

I am also trying to get my head around Broad Band.
As that is off topic, I won't go into the details. Suffice to say it is painful/confusing/annoying.

Easy Broadband ... http://bc.whirlpool.net.au/
And http://www.internode.on.net/residential/adsl_broadband/

Roosta

09-12-2012, 12:42pm

Good day Mr Felix,

Not with standing some very valid and technical points here from William W and Xenedis (Who both know what their on about) I find this site (http://www.thedigitalpicture.com/)to be a wealth of information. If you go there, then access the REVIEWS (http://www.thedigitalpicture.com/Reviews/)section top of page, then you can research the lenses you've mentioned.

There is also a section here (http://www.thedigitalpicture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=105&Camera=453&FLI=0&API=0&LensComp=122&Sample=0&CameraComp=453&FLIComp=0&APIComp=0) Where I have preselected two of the lenses you've mentioned, if you click on the down arrow, at the end of the lens description, you can choose another lens to compare.

Please bear in mind, that some of these lenses are designed to be used on FF (135) format cameras, so you're limited to a camera body selection with lens.

Hope this is of some help to you, but I know it's hours of fun research to be had.

Also check this site (http://dofmaster.com/) out, may give you a better understanding of DOF againt Bokkeh, and how to achieve your desired results.

Oh and while I'm on a role, beside the great amount of information on the AP Library pages and How To's, you can always try here (http://www.cambridgeincolour.com/).

P.S. William W makes a very valid point re using your 18-55mm on the preset lengths you want. Trial and error here, may save you some of your hard earned.

Have Fun.

Mr Felix

16-03-2013, 4:32pm

Thanks folks.

Lots of reading done.

Am trying to do light painting as well, but it is getting the time, equipment and things all to align allowing me to go out and experiment.

Ok, what I have "learned".....

I shall probably use the incorrect names but it isn't done on purpose and I hope you can read around my honest mistakes and ones which may lead me to problems.

Looking at one site - won't post link as I am still not sure how Ric will take it - I was shown a good example of how DOF is used for "subject separation" and they went into it a bit.

It makes sense and I understand it.

As my lenses are 4.5 fastest, even 3.5 is beyond me. (that is talking all digital.)

So although my 2.8 "analogue" lens (or FILM) would only be 3.5 on the digital, it would be better than the 4.5 which I now have.

I also know that moving away from the subject shrinks the DOF, but sometimes that isn't possible, and with a fixed focal length lens, it will be harder again for obvious reasons.

So when I am out and I am wanting to take pictures of things and really draw them out from the for/back ground, it is difficult.

Sure, "post editing" can do it and I have tried. Gee did I cop an ear full on my efforts with them.

I'd prefer to get it right the first time as though using film, where post production isn't really possible.

So, yes, I understand that buying a "50mm" lens would be like buying an 85mm for the film camera, and all the changes to things between the technologies. But I can't change that. It is a constant.

I shall have to look if I want a "50mm" or a "35mm" and the F stop size.

I am going through the links supplied and found a few myself. So there is a lot of data to take in.

So, if you were wondering, I am still here. Hanging in. Waiting for the next meeting I can attend and enjoy - AND LEARN something.

That's always nice. And the people are nice too. It is good to catch up with people and "talk".

Anyway, I'll get back to reading now.

Bye.

MarkChap

16-03-2013, 5:08pm

It makes sense and I understand it.

But do you really ??

So although my 2.8 "analogue" lens (or FILM) would only be 3.5 on the digital, it would be better than the 4.5 which I now have.

NO, the aperture of a lens does not change, it is a physical property of the lens and nothing to do with the recording medium used behind the lens

I also know that moving away from the subject shrinks the DOF, but sometimes that isn't possible, and with a fixed focal length lens, it will be harder again for obvious reasons.

No, moving away from your subject increases DoF, as you get closer to your subject you shrink your DoF

So, yes, I understand that buying a "50mm" lens would be like buying an 85mm for the film camera, and all the changes to things between the technologies. But I can't change that. It is a constant.

Buying a 50mm lens is like buying a 50mm lens end of story. It is not like buying an 85mm lens for a film camera. The lens dynamics don't change ONLY the field of view changes
On your canon you will have the same field of view as an 85mm lens (or there abouts) but a 50mm lens will ALWAYS be a 50mm lens

ricktas

16-03-2013, 5:24pm

Looking at one site - won't post link as I am still not sure how Ric will take it - I was shown a good example of how DOF is used for "subject separation" and they went into it a bit.

You can post links to any site as long as it is relevant to the topic. Only members with less than 30 days membership and 50 posts cannot link to other sites. Neither of these two restrictions apply to you as you have exceeded both.

Mr Felix

16-03-2013, 5:29pm

But do you really ??

NO, the aperture of a lens does not change, it is a physical property of the lens and nothing to do with the recording medium used behind the lens

No, moving away from your subject increases DoF, as you get closer to your subject you shrink your DoF

Buying a 50mm lens is like buying a 50mm lens end of story. It is not like buying an 85mm lens for a film camera. The lens dynamics don't change ONLY the field of view changes
On your canon you will have the same field of view as an 85mm lens (or there abouts) but a 50mm lens will ALWAYS be a 50mm lens

Ok, maybe not 100%.

Part 2 was a bit of paraphrasing.

I read someone said that a film lens with F2 would be only a 3.5 on a digital camera.
Can't find it now.

Not familiar with how to look at older posts WHILE editing/posting a reply.

DOF, ok, got it the wrong way around.

So the CROP thingy/factor is the word - I think.
But as it changes what is finally made, I shall call it that for the sake of simplicity.

Yes it is wrong, but I am not doing it to be difficult. I am just not getting the EXACT words out every time.
I'm human. I make mistakes.

- - - Updated - - -

This is what I was reading then:

http://desmond-downs.blogspot.com.au/2010/05/creating-separation.html

arthurking83

17-03-2013, 10:48am

.....

I read someone said that a film lens with F2 would be only a 3.5 on a digital camera.
Can't find it now.

......

Totally incorrect!

As Mark has already said ... the aperture doesn't change, and using that same f/2 lens on either a full frame body or cropped body still gives you the same aperture and the exact same DOF!!!

This is why some of us try to be more specific about lens focal length and that a 50mm lens is the same irrespective of the format that it's used on.

A 50mm f/2 lens will give you exactly the same aperture value and DOF no matter what camera it's used with.

What you have confused with respect to that statement is that for the same field of view and subject distance, the DOF on the smaller sensor will be deeper for the same aperture value compared to the larger sensor camera body.

Also, for the same FOV and DOF, the smaller senor will give the illusion that the aperture value will approximate a smaller aperture on the larger sensor.
There is no exact ratio or percentage values associated, as DOF is not a fixed quality, but in general the rule is that for the same apparent DOF, the larger sensor camera will require an aperture adjustment of about 1.5 stops smaller.

What that means in actual usage is something like where a 50mm f/2 lens is used on a 35mm camera, for the same DOF and FOV on an APS-C camera you require (roughly speaking) 35mm and f/1.2.

Canon(1.6x) has a differently sized crop sensor to Nikon, Sony and Pentax(1.5x).

But for all intents and purposes, using a lens at f/2 on a film camera, will give you the same DOF on a crop camera too when set to f/2.
The only thing that changes in using the cropped camera is that you miss out on the periphery of the scene .. nothing else!

ameerat42

18-03-2013, 5:21pm

Mr Felix.
(I am reading this from far away, peering into a little "lapdog" screen and it's as slow as a wet week!) However...
If it helps, I will try to tell you "why" f-stops are constant for any lens, and whatever camera the lens is on.

(In think you know already that) the f-stop is just the ratio of the focal length over the aperture you are (actually, but don't particularly know) using. The reason for "not particlularly knowing" is that the primary aspect of the exposure you are trying to make is the "intensity of the light" reaching your film/sesnsor. There are two other factors (as you know) determining the exposure, and they are time exposed for (shutter speed) and sensitivity of the recording medium (ISO). (At this point, if you want to research T-factors, or transmission factors, that also affect exposure, go ahead, but for now the three above will do.)

When you swap any given lens with set f-stops and so set light intensity onto any other recording medium, that intensity does not change, even though the area it falls on may change. That's because the intensity is constant for any unit area. (Are you still there?)

That is the nub of it.

Now, if you want a spanner in the works, try to understand why the f-stop changes when you have a zoom lens and you change the focal length (by zooming in/out). In fact, you will conclude that the f-stop actually changes as you zoom in or out. OK, leave aside "constant f-stop" zoom lenses. They stay "constant" because the aperture changes.

HELP: draw a diagram, label it correctly, do some simple ratios, and Bingo! (Fr. "voila!", Ancient Greek. "Eureka", Colonial Australian "Stockade", etc.) There you have it.
A(I will now stop peering into this tiny compewter)m.

Mr Felix

23-04-2013, 7:37am

Wow, what a can of worms.

So, here's the state of the nation now as for me:

I would like to do/take/make some shallow DOF pictures. The lenses I have won't allow that. 3.5 is just not fast enough.

Most of what I want to take is "medium range" pictures. So from fairly close to maybe 10 metres distance.

I still am not sure if I "want" a 50mm or 35mm, or what.

But looking at prices I am amazed at the difference between shops, even with the same lens! :confused013

Then there are the different brands as well. Haven't even looked into that part of the equation yet. :(

So really I am just as confused as I was at the start - which is why I haven't really put out any money to get one yet. (and partly because I don't really have money to "burn".)

I've seen prices from about $70 (au) to $150 for the SAME LENS.

Anyway, I'd better get back to researching the topic.

This is just to let you know I haven't given up.