D750 with primes - is this camera or lens issue or neither?

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I'm not sure if this is normal behaviour of a prime or if I have some bigger issues?

The shots on the left were using the viewfinder, the pics on the right are from live view. As you can see the ones using the viewfinder are pretty rubbish - these were not hand held either.

I tried both lenses and got pretty much the same results... is this what you would call normal behaviour? I'm slightly concerned or maybe these is not really a very good test?

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Interestingly... these were taken with the Tamron 28-75 at f2.8 using the viewfinder... much improved? I'm so confused!

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Looks as though the AF is out a bit which is why your camera has AF fine-tune, this is actually fairly normal for a DSLR.

If your lenses fall outside of what can be corrected in camera then you could send it away for recalibration.
 
The left shot of the 85mm at 1.8 looks more like motion blur or camera shake to me (on my phone).
 
Not tried any sort of adjustment - have no idea where I would start? How do you AF adjust when it seems in focus in live view? The Zoom is certainly the best of the lot.
 
JJ! said:
Not tried any sort of adjustment - have no idea where I would start? How do you AF adjust when it seems in focus in live view? The Zoom is certainly the best of the lot.
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Try reading the manual ;)

Basically, when in live view the focussing system is actually on the sensor and therefore it is always going to get it right.

The normal phase detect AF unit in the top of your camera is not on the sensor and unless the distances are exactly right then the AF is off slightly.
 
JJ! said:
Oh its you!!! The cheap and cheerful zoom that is renowned for issues is the best of the lot lol.
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Imagine how good an expensive and heavy one would be. :D

As above, try the AF fine tune. It can work wonders. But i agree with grotty re the 85. Thats camera movement rather than a softness issue.
 
Right about the 85 movement - just tried another one:

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I'd wait until there's more light so you can use a sensible shutter speed and try again - the auto focus should work better then too. TBH I've never found a need to fine tune any lenses. When I get out of focus shots it's always down to operator error.
 
Never had to fine tune anything before so this is all new too me. Perhaps I have just been lucky in the past.
 
Well, you are using fast primes on a high resolution FF body at short distances, the DoF is wafer thin and any inaccuracies are easily shown up.

The thing is, in real life shooting handheld YOU will probably contribute far more to missed focus than the camera or lens.

This is why most people say that unless you are getting consistent obvious problems in your normal shooting situations then its just as good to leave be.

Another thing is that the focussing error can change with distance to subject so unless you normally shoot little lego men on a tripod at close range then adjusting for that might throw it out at a different point.
 
JJ! said:
Right about the 85 movement - just tried another one:

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I thought so. As mentioned, wait until the light is better and try shooting a real life subject. i.e. something you are likely to photograph other than for testing purposes and see how it performs. The 35mm does look way out but again, use it for proper purposes in decent light first.
 
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Ed Sutton said:
I'd wait until there's more light so you can use a sensible shutter speed and try again - the auto focus should work better then too. TBH I've never found a need to fine tune any lenses. When I get out of focus shots it's always down to operator error.
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Went up to a better lit room.... results were a marked improvement (actually, pretty decent as these are 100%) f1.8 and f2.8 through the viewfinder(85mm):

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The D750 actually focusses well in the dark. You can send the camera to Nikon for calibration along with one or both of the lenses - I have two bodies and use 35 on one and 85 on the other. Both have been back and forth from Nikon til I was happy. I had use of a D3s on which both lenses worked perfectly at 1.4?!?!?!?
 
I actually think the 85 is not the issue - looking at the original ones there must have been some sort of shake... but the latest ones look pretty sharp on such a small subject. The 35mm however, may need some seeing too!
 
Looking at the side by side pics in image #2. the base the figure is standing on (left) is sharper than the figure itself, so guess it's front focusing. Try + adjustment in the AF fine tune, but as Ned says it can affect focusing accuracy at further distances.
It's a bit of trial & error really, but try to adjust at a distance you most use if poss.
 
OldCarlos said:
Looking at the side by side pics in image #2. the base the figure is standing on (left) is sharper than the figure itself, so guess it's front focusing. Try + adjustment in the AF fine tune, but as Ned says it can affect focusing accuracy at further distances.
It's a bit of trial & error really, but try to adjust at a distance you most use if poss.
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Yeah, just noticed the base is sharper so think the 35 is defiantly off. The 85 looks pretty good in better light.

But will go try some more useful shots.
 
The D750 is a decent camera but it's not the marvel some would have you believe. Certainly not when it comes to focusing. If a lens is front or back focusing wouldn't that affect viewfinder and live view images?
 
minnnt said:
It is, yes, but it's quite a big purchase for me to justify. The 85 (my third!!) is next for me i think. I have been considering the Siggy 105 but i do like the 85.
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The 1.8g? Its actually pretty nice. Bigger than the 35, but not much heavier. Sits on the 750 quite nicely.
 
ryanyboy said:
The D750 is a decent camera but it's not the marvel some would have you believe. Certainly not when it comes to focusing. If a lens is front or back focusing wouldn't that affect viewfinder and live view images?
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No, not LV.
 
AF adjustment is pretty normal if you shoot wide open. My lenses are all over the place on my 750 but well within the tolerance. I could tell my 85 was front focussing allot, you'd get a sharp nose instead of an eye, +15 is the amount to correct it.

Google the dot tune method, once you get your head round it it's fairly easy.

Only got my 610 back up body today but I can tell straightaway that the lens calibration seems much better than the 750 out of the box. I will check when I have half hour with my main couple of primes.
 
One important factor when doing these tests, are you using a single focus point on the lego man? The other thing to bear in mind is sometimes actual focus points are larger than they appear in the viewfinder so what you're focusing on may not necessarily what you think you are. I found a good graphic of this a while back but i can't find it now :(

For example, in the first shots you have the lego man on a placemat or something, it's perfectly possible the camera has chosen this to focus on as it's contrasty which focus points like. On the second set there's nothing in front, the lego man is more contrasty than anything around it so the camera has locked onto him.

I always get the best results from following this guide HERE Believe me though, the best thing to do is make sure your lenses are working acceptably then forget all about this as it will drive you insane, believe me!
 
I did the basic 5 battery test this morning. The 85 looked good. I think the problem lies with the 35. Will post when on PC.
 
This was the basic battery test, results look better than my dodgy testing yesterday!

35mm @ 1.8 and 2.8

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85mm @ 1.8 and 2.8

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Those battery tests still seem to be out a little. Did you use a tripod for these tests? Also, you seem very close to the subject and the batteries look very close to each other.

Have a look at this if you are going to try the battery method > http://cameralightlens.com/newsblog/?p=264
 
I used above methods and pics are cropped. Batteries are actually further apart than they look and at 45 angle.

I actually took camera and lens to place of purchase today and they happily exchanged the 35mm for another. We tested in shop and its much much better.

The 85 looks pretty good so not going to mess around with any adjustment just yet until I start getting some pics done.

Was going out shortly but the heavens have opened!
 
I used to be OTT over the lens focussing / sharpness etc..............and in the end I just don't bother anymore unless it's very obvious in real life use. I would go looking for problems which weren't there!

Glad you now have a better copy of the 35mm, shame about the weather though!
 
My D750 had a misaligned AF module, the right side points were noticeably out. Do you notice any difference using centre vs outside points?
 
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