New lens autofocus problem
Discussion
I've just invested in a Tokina 11-16mm f/2.8 DX-II to go on my Nikon D5100. The first few test shots were disappointingly soft so I tried quite a number at different focal lengths, subject distances and light settings none of which were any good. A bit rubbish for £500 worth of glass with good reviews I thought. As a test I flipped the camera into live view mode and took some more shots and they came out looking as sharp as they should. Very odd I thought so I took some back to back shots using the viewfinder and then live view and for all of them the latter came out much better. I now think it could be some sort of AF problem in the body. Can anybody think what could be the cause of this?
In the viewfinder I was using the centre AF point and single servo mode. I'm puzzled right now!
In the viewfinder I was using the centre AF point and single servo mode. I'm puzzled right now!
Ok I have just tried with my 35mm f/1.8 and the results are the same. In focus on live view and out of focus through the viewfinder. I tried another AF spot in the viewfinder and that's no better.
Live view AF mode is single servo and wide area mode. The focus spot is right in the centre.
Viewfinder is single servo and single point mode.
I'll boot up my laptop and get some test shots up.
Live view AF mode is single servo and wide area mode. The focus spot is right in the centre.
Viewfinder is single servo and single point mode.
I'll boot up my laptop and get some test shots up.
I'm not sure what the problem is exactly, but if you want to use the VF then does your camera have a 'focus fine tune' function?
_rubinho_ said:
Live view AF mode is single servo and wide area mode. The focus spot is right in the centre.
What does 'wide area' add to the equation if it's using a single central focus point?Simpo Two said:
I'm not sure what the problem is exactly, but if you want to use the VF then does your camera have a 'focus fine tune' function?
Live view 'normal' mode doesn't seem to make a difference. Seems like somebody has also spotted this on the D5200 http://www.dpreview.com/forums/post/53873061. _rubinho_ said:
Live view AF mode is single servo and wide area mode. The focus spot is right in the centre.
What does 'wide area' add to the equation if it's using a single central focus point?There's no AF Fine Tune in the D5100's menus. A video online suggests you can do it manually. http://www.youtube.com/watch?v=Pfxz-Z_uEfU.
Don't want to send it in for adjustment as I'm off on holiday on Monday. Typical!
_rubinho_ said:
I put a tape measure down and the camera seems to back focus when using the viewfinder by about 300mm. That is the area around 300mm behind the focus point is in sharp focus.
That's not good; I'd suggest you send the camera body back for replacement or check/calibration.(that distance will depend on the subject distance - a foot out on a landscape doesn't matter)
Anyone else have a view?
Well I've had a crack at fixing it using the linked video as a guide.
It was ambiguous in places but to fix back-focus (like I had) the screw needs to be turned anti-clockwise. To fix front focus the screw needs to be turned clockwise.
I settled on about one flat (1/6th of a turn) anti-clockwise.
It's not perfect but significantly better. It's definitely usable. I've got no excuses when my holiday shots are out of focus now!
It was ambiguous in places but to fix back-focus (like I had) the screw needs to be turned anti-clockwise. To fix front focus the screw needs to be turned clockwise.
I settled on about one flat (1/6th of a turn) anti-clockwise.
It's not perfect but significantly better. It's definitely usable. I've got no excuses when my holiday shots are out of focus now!
To bring this to a conclusion the reason live view and viewfinder autofocus were different is that they use different methods. Live view uses contrast based focussing like a compact camera whereas the viewfinder uses the standard DSLR focus point array.
I'm going to make sure my next body supports AF Fine Tune.
Thanks for all your input.
I'm going to make sure my next body supports AF Fine Tune.
Thanks for all your input.
_rubinho_ said:
....
I'm going to make sure my next body supports AF Fine Tune.
TBH 300mm out @ 1m is not fine-tune territory....it's very much send it back territory! But as long as you got it sorted out and are happy with it that's what counts. I'm going to make sure my next body supports AF Fine Tune.
Edited by tim-b on Sunday 3rd August 22:45
^ Yes. I foolishly spent ages MF tuning one of my lenses so it was totally useless at the distance I normally use it at. Never again.
I normally use live view to get the focus spot on (review the images on a computer and make sure im happy focus is okay), flick the lens to MF and come out of live view, I then use the AF-ON button and i'll move the MA about until I get a solid green light. If you're feeling really anal about it you can go through the range and see what the middle of the solid green light range is and set that to be your MA value. I probably haven't explained it well, but it's how I did it.
I normally use live view to get the focus spot on (review the images on a computer and make sure im happy focus is okay), flick the lens to MF and come out of live view, I then use the AF-ON button and i'll move the MA about until I get a solid green light. If you're feeling really anal about it you can go through the range and see what the middle of the solid green light range is and set that to be your MA value. I probably haven't explained it well, but it's how I did it.
Edited by Janesy B on Monday 4th August 13:10
I recently focus tuned a d800 with a whole range of lenses and found it to be very effective. Some lenses are prone to back focusing issues, best you can do is send it back or try messing with different focusing modes, through live view the focusing system is different to when it is done through the mirror.
RobDickinson said:
...
Always try test at a realistic focus distance
True, but...Always try test at a realistic focus distance
RobDickinson said:
Depends on how often you shoot things at 1m..
...
...not really (if it's as bad as OP's), unless you are 100% sure you won't want to sell that lens to someone who may have different needs......
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