D7100 Issues with Aperture Priority Mode

gustafson

Senior Member
I'm finally getting around to shooting regularly with my recently acquired refurb D7100, and am having trouble getting good photographs in Aperture Priority mode. I was wondering if others have experienced these issues and know of a fix.


  • Manual lenses (AI, AI-S, AI-converted) are the main issue. The photos seem consistently overexposed and / or blurry. For some reason, the calculated shutter speeds for a given aperture seem lower than they should be. I usually shoot in Auto ISO mode and have tried tinkering with the Max ISO and shutter speed settings to no avail. Ultimately, I'm having to shoot in M mode with these lenses for acceptable photos, but would love to hear of a workaround to get good shots in A mode.
  • AF-S kit zooms: These give me better shots in A mode, but occasionally I get overexposed / blurry shots and have to switch to S with a shutter speed of 1/125s or faster to get proper shots.
  • modified TC-16a: This is a special case where I'm mounting manual lenses on a modified TC-16a that the camera thinks is a 70-210 F4 AF. Here, performance in A mode is terrible, but its not fair to blame the camera, and I'm having to shoot in S mode with 1/125s or faster shutter speeds to get decent exposures. (@salukfan111 - have you experienced this and perhaps know of a fix?)
  • Alternatively, is there a way to confirm if my D7100 body has an inherent problem with A mode? Because its still within the 90-day warranty, so I could still send it in for a fix if needed.

Thanks for reading!
 

Fred Kingston

Senior Member
Just a data point....

I just tried an Converted AI 55mm f1.2 on a D600...

I use back button focus on the camera... and hold the button to achieve continuous focus... and manually focus until I get the Green Focus dot in the lower right of the view finder... I used A mode, auto-iso with max set to 1600... exposure was correct... I'm old, wear glasses, so without extraordinary steps, I have to pay particular attention to focus anyway...
 

gustafson

Senior Member
Thanks for the input! Just to clarify, was your note about using back button focus meant for autofocus lenses? Or does that somehow work in conjunction with manual lenses?

Other question: did you try different aperture settings?


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Fred Kingston

Senior Member
My back button is setup to be "single" focus when pressed once. When you hold the button down, it stays in Continuous focus mode until you release the button... While in Continuous mode, as you turn the lens's focus ring on a manual lens like the AI... you'll notice the green focus lights in the lower left of the viewfinder cycle... I use spot focus with a single point... when the green dot comes on, the lens/camera has achieved focus for that focus point... Try it...

Yes... I tried several aperture settings using the above processes... and all exposures are fine within the limits of the max ISO... I'm using Matrix metering incidentally...
 

gustafson

Senior Member
Wow, I'll have to go try that out. Sounds like an awesome hack to get sharp photos with manual lenses.


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Pretzel

Senior Member
Is there a way to post some of these "off" photos so we can see what ISO/Shutter the camera is choosing on them as well? It would help troubleshoot other possible issues as well.
 

gustafson

Senior Member
Is there a way to post some of these "off" photos so we can see what ISO/Shutter the camera is choosing on them as well? It would help troubleshoot other possible issues as well.

Absolutely! Might be this weekend, will have to dig through a few 100 shots to pick out the ones where I had this problem.


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gustafson

Senior Member
My back button is setup to be "single" focus when pressed once. When you hold the button down, it stays in Continuous focus mode until you release the button... While in Continuous mode, as you turn the lens's focus ring on a manual lens like the AI... you'll notice the green focus lights in the lower left of the viewfinder cycle... I use spot focus with a single point... when the green dot comes on, the lens/camera has achieved focus for that focus point... Try it...

Yes... I tried several aperture settings using the above processes... and all exposures are fine within the limits of the max ISO... I'm using Matrix metering incidentally...

Fred, just to confirm, what AF-servo mode are you in, and is it in focus priority or shutter release? And does this work with half pressing the shutter instead of back button? Wondering if it might work on my D3300 too


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gustafson

Senior Member
My back button is setup to be "single" focus when pressed once. When you hold the button down, it stays in Continuous focus mode until you release the button... While in Continuous mode, as you turn the lens's focus ring on a manual lens like the AI... you'll notice the green focus lights in the lower left of the viewfinder cycle... I use spot focus with a single point... when the green dot comes on, the lens/camera has achieved focus for that focus point... Try it...

Yes... I tried several aperture settings using the above processes... and all exposures are fine within the limits of the max ISO... I'm using Matrix metering incidentally...

I was able to set up the back button to Continuous focus, but with an AI converted lens mounted, my D7100 doesn't seem to allow autofocus operations, as one would expect. I get the focus confirmation dot by turning the focus ring, but I don't need any button pressed for that, and the shutter releases whenever pressed, even when out of focus. I wonder if the D600 behaves differently, or I just have the wrong settings on my D7100? Or perhaps your AI converted lens has been CPU-chipped?


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Blacktop

Senior Member
Is there a way to post some of these "off" photos so we can see what ISO/Shutter the camera is choosing on them as well? It would help troubleshoot other possible issues as well.

Agreed. (BTW,Hi Pretzel, we don't see you often enough round here anymore). Yes, also would like to see pics just to see if the "blurry" part of your problem is a focus problem or just regular old camera shake.
 

Fred Kingston

Senior Member
It probably works the same, we just have back button focus setup a bit different. My focus is set to only come on when the button is pressed... yours sounds like it's on continuous... There's also a separate setting for whether the shutter activates with/without a focus lock...
 

gustafson

Senior Member
Sorry for the confusion, I had set the servo mode to AF-C, and back button to autofocus when pressed, so when I keep it pressed, it is continuously focusing. But that only seems to work with CPU lenses, not with non-CPU lenses. Thanks for the heads up on the shutter activation on focus Iock setting, I will look for that and report back.


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Fred Kingston

Senior Member
Ok... so far so good... My lens is definitely NOT chipped... It was almost a new untouched lens sourced from Japan 6 months ago, and machined by John at AIConversion.com...
 

gustafson

Senior Member
Ok, I was able to set the AF-C shutter activation to focus priority, and program the AE-L/AF-L back button to AF-ON . However, with an AI-S lens mounted on the D7100, the shutter activates any time it is pressed, even without focus confirmation. Pressing the back button seems to have no effect. I can get the focus confirmation dot without pressing the back button - all it seems to be is an indication of whether the central focus point is in focus or not, but it does not control shutter release. None of this surprises me though - this is always how manual lenses have worked for me. So I'm wondering if the D600 just has better capabilities in this regard.


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gustafson

Senior Member
Last edited:

Fred Kingston

Senior Member
This has been a good exercise...

I just double checked... I don't have to hold the Back Button to get the focus... just turn the focus ring... and the green dot lights...

Focus trap is different... I turn the focus ring until I get the dot, then press the shutter... Focus trap is when you hold the shutter while turning the focus ring, and when the camera achieves focus, the shutter automatically fires...

Which menu option causes the camera to NOT fire unless focus is achieved????
 

gustafson

Senior Member
Ok, we're on the same page then I got the impression you were able to focus trap with your AI lens.

On the D7100, for AF-C and AF-S, you can select the priority to Focus or Release. (AF-C would be the one to set if you're back button focusing). However, as far as I know, autofocus features (AF-C, AF-S, back button AF, etc.) are only active when CPU AF lenses are mounted. For manual lenses, the only help you get is the focus confirmation dot to let you know if the single focus point is in focus.


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gustafson

Senior Member
Is there a way to post some of these "off" photos so we can see what ISO/Shutter the camera is choosing on them as well? It would help troubleshoot other possible issues as well.

Here's a link to some of the problem pics. The photos that appear to be taken by a 70-210 f/4 @ 145mm were in fact taken with a modified TC-16a fitted with a 200 f/4 Q.C or 100 f/2.8 E or some other manual focus lens (I don't own a 70-210 f/4 and my D7100 has never had one mounted on it). Thank you for review and comments.

https://www.flickr.com/gp/89411942@N04/Z389m3
 

gustafson

Senior Member
I may have missed it with all the other questions but.....What exposure mode are you using? Spot, Center weighted or Matrix?

Generally Matrix, unless I'm doing moon shots, where I use Spot. I did have a recent episode where I forgot to switch back to Matrix from Spot and got squirly results on the venerable 35 f1.8 DX, and have learned to watch the metering mode ever since


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