New D7100 owner, think i've got autofocus problem. :-(

johncook

Senior Member
Hi guys,

got the D7100 used recently. I think I have a copy with an autofocus issue. I shoot RAW, AF-C and AF-S with the full 51 focus points available.

I select the focus box I want to focus on (normally place over the eye) and then take the photo.

This technique has served me well for 4 yrs on my D7000 then D700.

I've used my 24-70 2.8 and 50mm 1.4. Shooting wide open and stopped down to f5.

I've done back to back tests with the same lenses on my D700 in the same conditions. The D700 is sharp each time.

I'm worried its the camera because 1-2 in 10 shots on the D7100 will be sharp and in focus. The others will be slighty off. I'm pretty experienced so am confident its not user technique (I'm know its a jump to 24 MP but even shooting at 1/1000th sec in good daylight at 70mm handheld should be sharp!)


I'll try some tripod shots to be sure its not me but I'm pretty sure it the camera.

bought the camera off ebay, used (3800 actuations)and excellent condition. But If it needs to go to Nikon i'll pay a hefty sum. I've contacted the seller re the issue, will see what he says.

disappointing because its a great camera. If I cant focus sharp and consistent with it, I wont end up using it.
 

J-see

Senior Member
Did you fine-tune the focus for your lens? It's possible with some minor adjustments, she performs better.

More megapixels require a higher shutter but unless you're tumbling down the stairs, 1/1000s at 70mm should deliver a sharp shot.
 

johncook

Senior Member
i'll have a play with the fine adjustments. I played around with it ranging from +10 to -10, but didn't see consistent results.

I'll try with camera on tripod with focus on something like a ruler and see tonight

really hope I can fix it with something like fine tuning.


would firmware update help? think that's not been updated.
 

J-see

Senior Member
i'll have a play with the fine adjustments. I played around with it ranging from +10 to -10, but didn't see consistent results.

I'll try with camera on tripod with focus on something like a ruler and see tonight

really hope I can fix it with something like fine tuning.


would firmware update help? think that's not been updated.

If the lens is out of focus firmware likely won't help but it never harms to have the latest firmware.

I struggled with the focus of some lenses and always solved the issue by fine-tuning the AF. On the one cam they can perform well but on the other they need a + or - adjustment.

Here's a post about a quick and easy method:

http://nikonites.com/tutorials/27824-simple-auto-focus-calibration-dslrs-adjustable-settings.html

I'd first try that and see if it solves the issue.

Also, when shooting d51 with a narrow DoF, if the sensor picks one of the outer pixels to focus at, the center of the shot might look out of focus. But likely it is simply a matter of tuning.
 
Af fine tune is critical with the D7100.....if you are on AF-s you need to lock it on the centre point ..use that to focus ..eye or whatever and then re frame ....

Simple AF tune is just to place an extending tape on the floor with a pencil at right angles at 16 inches then shoot from ioe uabout 10 ft away using the pencil to focus on ...you will soom see on your computer if the 16 inch mark is the centre of your focus ..depth
 

johncook

Senior Member
I've done a lot of testing the last few days and given myself a headache with it all!!

I did a reset on the camera and it seems to be ok.

I still think its a bit soft with the 50mm 1.4G but with the 24-70 it seems to be sharp and in focus throughout the zoom range.

happy days again!
 

johncook

Senior Member
the 1.4G is sharp wide open (on its focus point) on my D700, so not sure why its a little soft on the D7100.

these were in my test shots though.

I've shot some normal photos where its been sharp on focus (generally focus on eye)
 

Felisek

Senior Member
D7100 has much smaller pixels (about 3.9 μm vs. about 8.5 μm), so it is more demanding on the lens. You need a super sharp lens to match the pixel density in D7100.
 
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