Testng a used Tamron 24-70mm help.

[LittleSparrow]

So i purchased a use Tamron 24-70mm and am giving a it a test run. I feel like the focus is soft. Unless im not testing it correctly in my settings. I used spot focus and focused on the tear on the mat. What do you think? This is my first used lens purchase.

SOOC images.

At 24mm
https://farm2.staticflickr.com/1781/42450061905_876a58b898_c.jpg (https://flic.kr/p/27FaEt4)24 (https://flic.kr/p/27FaEt4) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

At 35mm
https://farm2.staticflickr.com/1803/29483996018_b78fe58c3e_c.jpg (https://flic.kr/p/LVpbNW)35 (https://flic.kr/p/LVpbNW) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

At 50mm
https://farm1.staticflickr.com/926/42637310944_35ceab182e_c.jpg (https://flic.kr/p/27XHn5L)50 (https://flic.kr/p/27XHn5L) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

At 70mm
https://farm1.staticflickr.com/842/42637311904_7024cd24fc_c.jpg (https://flic.kr/p/27XHnnj)70 (https://flic.kr/p/27XHnnj) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

[mudman]

what aperture are you using
you may be inside the minimum focal didtance

[ameerat42]

... What do you think?...

Assuming that you are not getting focus and then moving the camera slightly to miss it again, then
I think that the lens is focusing slightly in front of the subject. It appears a fairly constant amount at
the distance shown, and you notice it more as you zoom in - not that it gets worse as you zoom, just
that you see it better.

You have used f/2.8 for all these shots and that's OK. It might reduce with smaller apertures, but to have
it at all is still a pain.

Do a few more tests, and if you can, do it with a ruler perched at 45°. Focus on a particular measurement,
say 20cm, and see where the focus actually lands.

If you determine that it is front-focusing, then **hope** that your camera has micro-AF adjustment
(which I could not see in the manual:()

Alternatively, get accurate results with manual focus.

PS: It's not unusual to have an AF mismatch. I had it on a lens and fixed it with the micro-AF adjustments.
The camera remembers it for that lens. -- But again, do more tests.

[LittleSparrow]

Assuming that you are not getting focus and then moving the camera slightly to miss it again, then
I think that the lens is focusing slightly in front of the subject. It appears a fairly constant amount at
the distance shown, and you notice it more as you zoom in - not that it gets worse as you zoom, just
that you see it better.

You have used f/2.8 for all these shots and that's OK. It might reduce with smaller apertures, but to have
it at all is still a pain.

Do a few more tests, and if you can, do it with a ruler perched at 45°. Focus on a particular measurement,
say 20cm, and see where the focus actually lands.

If you determine that it is front-focusing, then **hope** that your camera has micro-AF adjustment
(which I could not see in the manual:()

Alternatively, get accurate results with manual focus.

PS: It's not unusual to have an AF mismatch. I had it on a lens and fixed it with the micro-AF adjustments.
The camera remembers it for that lens. -- But again, do more tests.

Thank you. Yes i agree, the focusing appears to be off so i think it may need adjusting. My camera has AF Fine tuning which i believe is the same thing as micro af adjustment. I will hunt down a ruler and see what happens.

[LittleSparrow]

Ok so i couldn't find a ruler but i had some batteries so i lined them up on a 45 degree angle. I turned vc off, i used a timer to avoid shake. I refocused each shot. I used aperture 2.8, iso 100 and shutter 1/200. I single focused on the middle battery for 24mm, 35mm, 50mm, 70mm and got mixed results. Is this something i can fix in camera or should i send back for a refund?

24mm (i think the first battery has the best sharpness)
https://farm2.staticflickr.com/1788/41547930180_b6dc150fe3_c.jpg (https://flic.kr/p/26is18N)24 (https://flic.kr/p/26is18N) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

35mm (looks like second battery gets the focus this time)
https://farm2.staticflickr.com/1784/29486716188_97e8fc217e_c.jpg (https://flic.kr/p/LVD8qq)35 (https://flic.kr/p/LVD8qq) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

50mm (i think focus lands between second and third battery as both are not sharp)
https://farm1.staticflickr.com/918/41547930080_f7c98c338d_c.jpg (https://flic.kr/p/26is175)50 (https://flic.kr/p/26is175) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

70mm (looks like middle battery got the best focus here, although i still think its off by a smidge)
https://farm2.staticflickr.com/1806/29486715878_a1915c6efd_c.jpg (https://flic.kr/p/LVD8k5)70 (https://flic.kr/p/LVD8k5) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

[ameerat42]

Hmm! - It sure looks like it. BTW, a white cardboard marked off with black pen would also do,
though nothing beats a ruler. I'm not 100%, but the disparate results you get could be the
result of front element moving. You can check if it does when you zoom, or whether it's all
done internally.

Good luck with your AF tuning. I have no advice as to which FL to start on. Maybe try f=50mm,
which is close to f=45.5 - the mid-point. Check it again across the range after that.

If you cannot get decent results across the zoom range after that, perhaps consider a return.
Steer clear of that lens, then.

- - - Updated - - -

PS (I forgot): If it has front element movement, get a good bit farther from your subject.

[MarkChap]

What you are testing here is Depth of Field NOT sharpness
It certainly looks like your lens might be front focusing a tad, which is easily tested and fixed with this same type of test you are doing here.

Find yourself a newspaper and photograph a page flat, forget trying to throw things out of focus with narrow DoF if you are trying to test sharpness.
Shoot the same image (framing) with decreasing aperture, you will most likely find that as you stop down, your images gets sharper

[MarkChap]

Ok, so I have gone back and re-read each post
There is a chance that any particular Body and Lens combination can have a varying amount of front/back focus at different focal lengths, that does not necessarily make the lens faulty. What would make the lens faulty would be consistency, does the focus fall on the same spot each time, for a given focal length.
What you are also contending with in this type of test, is an ever decreasing DoF, for any given focal distance, at a given aperture, your DoF will change as your focal length changes. So at 24mm you have more DoF than in your image at 70mm, which makes it a bit harder to pinpoint the exact battery that gets best focus.

What I am seeing here, is a small amount of front focus at 24mm and zero front/back at 70mm
Which depending on your body, is easily corrected in camera, I know my 5D MkIII allows me to adjust each lens a different amount at both the wide and the zoom focal length.

In Real Life Though, how often are you going to shoot 24mm and f2.8 at such a close focal distance, a quick calculation shows that at a focal distance of 10 mt at 24mm f2.8 your near focus would be at 8.43mt and your far focus would be at 12.3mt giving you a total of 3.85 mt of Depth of Field, so even if you are back focusing a small amount, it is not going to effect your images

Now to your original question - "I feel like the focus is soft..........What do you think?"
From what I can see here, I think it is every bit as sharp as I would expect that lens to be, but as I said before, these are not good tests to determine sharpmess

[fillum]

My understanding, which might be outdated (or more likely wrong :o), is that the actual AF sensor is not necessarily dead-centre in the rectangular focus guide thingy in the viewfinder. So when testing focus it's a good idea to have your focus target fill the guide rectangle and also be parallel to the plane of the camera (ie flat).

So for testing sharpness Mark's idea of using a flat page of newspaper is a good one. Take a shot normally, then take a shot using Live View and then compare the images for sharpness. 'Unfocus' the lens between shots so that it fully re-focuses. As Mark suggests, try at different apertures to determine the 'sweet spot'. (LiveView uses contrast-detect AF which can be more accurate, but slower than phase-detect which is used in normal AF operation).

To check front/back-focus I'd suggest using a test chart like this one (https://1.img-dpreview.com/files/p/E~forums/54407518/582143d4fd794c2689029d4ac66e5191). Obviously in this case the target is not parallel to the camera plane but at 45 degrees so you just need to frame so that only the dark line across the centre fills the focus guide.




Cheers.

[ameerat42]

I don't think you're outdated or wrong, Phil. Mark's method will certainly tell you that the lens is not focusing properly,
but it does not tell you which way it needs to go, hence the suggestion of a ruler earlier, and the better-looking chart
you linked to. It's just that with the latter you'd have to mount it on a stiff board. Recently I used an extended tape
measure set at an angle to check the AF accuracy of a lens.

[LittleSparrow]

Ok so i dont know what im doing wrong! I printed the test chart, set it up at 45 degrees, had my camera at about 1 metre away. I shot on the 70mm end which is what i read i should do. So it was focusing forward and needed and adjustment of around +13. All seemed well at 70mm. I tested the other end and 24 was still out of align but i just left it because i cant fix both ends on my camera. I used my FX D750 for the test as it's the one i'll be using primarily. Any ways, i took so snaps of my son after and found that at 70mm the lens was seeming to back focus so i decided to test it with the chart one more time. Sure enough it was back focusing a bit. SO i adjusted the dial again and took it down to +11 and it fixed it. I then decided to double check so i snapped again and it was front focusing again (grrr) so i put it back up to +13 which again seemed not too bad. I then double, triple and quadruple checked it and the stupid thing moved way back into a back focus position again. Ugh! Why is this so hard! I've included 2 photos. Both are on +13 and taken a couple of shots apart without any changes. Why is it doing this? (editing to add that i used a tripod and a timer)

+13 seemed to get it almost perfect according to my eyes.
https://farm1.staticflickr.com/918/43331991342_745e8330c0_b.jpg (https://flic.kr/p/2926Mn1)1 +13 (https://flic.kr/p/2926Mn1) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

double checked and this happened...
https://farm2.staticflickr.com/1809/43380401301_0ab8976950_b.jpg (https://flic.kr/p/296nTXt)2 +13 (https://flic.kr/p/296nTXt) by Joanne Sparrow Photography (https://www.flickr.com/photos/131030088@N07/), on Flickr

[ameerat42]

I have no idea how the Nikon system works for retaining lens AF info.
Certainly on mine (a Σ camera) it "stuck". Wait till some Nikonites see this
post. In the meantime, in some hope, I searched on the rather obvious
sounding "af front focus for tamron lens on nikon camera", and came up
with a heap of refs. This one seemed useful as it indicated a way of saving
the fine-tuning adjustments. See if it's useful (almost 3 yrs old but...):
https://www.dpreview.com/forums/thread/3927045

(This should not be an insurmountable problem.)

- - - Updated - - -

PS: I don't think you're necessarily doing anything wrong.

- - - Updated - - -

PPS: Another thing you might search on is "save af fine tuning on nikon d7100".

[arthurking83]

I've replied with a short summary version down below as many folks hate my long replies.
Can't be helped when the answer is not simple.
FWIW: I'd say most likely you have a front focus issue at 24mm, but all possible errors need to be eliminated before it drives you crazy.

1/. I wouldn't use AF fine tune on this lens.(or on any zoom if it's not a problem across the entire focal length range).
reason: it works fine at 70mm, where your DOF is likely to be shallower(ie. at 24mm your DOF/focus plane, is deeper).
Problem with AF fine tune is that it affects the entire lens system, that is at 24mm all the way to 70mm and all in between.
So to fix the 24mm end, you will almost certainly ruin the 70mm end. ... ie. be warned!

2/. it's unclear as to what focus distance you're using for each focal length. Did you crop the images to show more detail, or did you move the camera for each focal length.
reason this is important: most incorrect focusing lenses seem to have a focus inaccuracy related to focus distance. Not always, but my bet is that you may see it too.
That is, you may see AF inaccuracy(eg. front focus at close distances) but less inaccurate focus at longer distances(always noting the difference between focus inaccuracy and DOF).

eg. at 24mm and (lets say) MFD on this lens, where MFD is about 0.40 meters, using a constant aperture value, you have shallower DOF than you would at say 1m focus distance. DOF is a fixed physical property.
So if you test at different focus distances, you need to be aware of this and be able to differentiate between DOF and best plane of focus.
So you will have more in focus at 1m compared to 0.4m, but even at 1m you should still see a better plane of focus and differentiate between them.

3/. one more test to try: compare the differences between Live view AF and TTL(through the lens) AF. This will help determine what may be causing the front focusing at 24mm.
You may find that at 24mm and live view focusing it may be spot on, whereas TTL focusing without touching/moving anything on the camera may be front focusing.
if this is the case, then the lens is fine, it's the camera part of the camera/lens combo.(ie. the camera is having trouble understanding what the lens is telling it to do).
If Lv focusing in the above case is also out of whack, then it's the lens alone.

4/. I stopped using the 45° angled test on the 'focus chart' for many reasons. mainly it was not always reproducible with 100% accuracy and the limitation of the focusing system of the camera.
I've written a lengthy reply to another thread a few years back on how the focus system is physically set up in the camera, which kind of explains why that 45° on the focus chart can be ambiguous for AF testing.
The battery test method is my got to method too, but I do it differently.
Do the battery test again with more batteries, arranged in a V formation, and they HAVE to be spaced apart laterally. I usually set them one battery apart from each other both laterally(across ways) and longitudinally(fore/aft/depth ways).
I start with a V pattern according to whether the focus issue is rear or front biased. so if I think it's front focusing(as in your case), then arrange the V formation with the central battery at the back, and the side batteries coming forward towards the camera.
Note it's important to not arrange the camera battery relationship with any angle/tilt. So batteries and camera need to be square on in every plane. get the camera lower/higher to keep the batteries all squared up, and the idea of the V shape is to remove doubt about focal plane setup errors.

Have a read in this thread re focus inaccuracy (http://www.ausphotography.net.au/forum/showthread.php?130477-Nikon-D7000-Back-Focusing-Issue&highlight=focus+errors). My reply a couple of posts down.
if it gets too arcane, I can try to re explain it again, but it's actually quite simple.

FWIW: I've had focus troubles with my Tamron 28-75/2.8 and my Nikon 80-200/2.8 lenses(only two lenses with back/front focusing issues.
Tammy was manageable and affected at the 75mm setting. Nikon was unmanageable and at the 200mm setting. I sold the Nikon only because of the back focusing issue. If not for that, I'd probably still have it too.
I still have the Tammy. Have always had it in mind to retest it now on the D800E, but never get around to it.
So it's important to note that this may not be a lens issue, or a camera issue, but a camera/lens issue. If you have another camera to test with, it'd be a good idea. If not, not important.

Summary:
Do the test again. Use the batteries, not the lens focus chart test, set batteries in the V formation.
Don't move the camera between different focal length changes, always the same.
Test at close focus distances, AND at slight longer distances too.
Try to set up camera with no angle/tilt to the focus subjects. If not using a tripod(the assumption is always that it is) .. camera has to be steadied at all times.
Also try using continuous focus mode and see if that changes anything. When you say spot focusing, I assume you refer to AF-S(single shot AF mode).
Check how Lv focusing is working too.

[LittleSparrow]

Thank you, that is a huge help! I will give this a try tomorrow. I have 3 bodies i can try it on. I will post my results :)

[LittleSparrow]

I ended up returning it for a refund. Too many sleepless nights worrying about it and too many wasted days trying to get it to focus! I will be avoiding second hand lenses in the future i think. Not a good experience for my first time buying used :(

[ameerat42]

If it wasn't working properly/as reasonably expected to (as it sounded from your story), sure.
OTOH. I have mostly 2nd-hand lenses, though now only use a max of 3: two new and one used.

[Lance B]

Don't use a chart or test subject at 45 degree angle as this just puts too many variables into the mix. The issue is that the actual focus point may not be perfectly in the focus square of the viewfinder and when you test it on a 45 degree angle, then is is difficult to ascertain whether you have the exact point of focus. Use a set up like this:
https://www.ebay.com.au/p/LensAlign-MKII-Focus-Calibration-System-Is/1261283181?iid=401511542533&chn=ps

You just need a flat target with something the lens can focus on reasonably in line/parallel with the camera sensor, like some writing on the side of a box, and then put a ruler at a 45 degree angle next to it as this will give an indication of how for front or back focused the AF is. You can see the focus targets each side of the 45 degree pattern on the linked to Lens Align tool. This then removes any slight misalignment of the actual focus sensor being slightly out of alignment with the actual focus indicator in your viewfinder. Trust me, it is a much more accurate method to ascertain AF accuracy.

This is my home made set up and I have tested my D850 + 105f1.4E @ f1.4 specifically to show you how it can be done.

http://www.pbase.com/lance_b/image/167845032/original.jpg

I focused on the area "CON" of the word "CONNOTE" on the box and the 250 mark of the ruler was set on the plane of the front of the box where the writing is and as you can see, the accuracy was spot on.

Here is a crop of the focus area.

http://www.pbase.com/lance_b/image/167845040/original.jpg

Looking at your original photos, it looks reasonably accurate for AF and quite sharp. However, I think that a home made focus test such as that I have shown would be more beneficial and costs almost nothing!