F8 autofocusing ability for different Nikon cameras: A friend and I have both noticed that our D7100s autofocus much more reliably at F8 -- when using an F5.6 maximum aperture lens...

pmackd Loc: Alameda CA

A friend and I have both noticed that our D7100s autofocus much more reliably at F8 -- when using an F5.6 maximum aperture lens with a 1.4X TC -- than either a D610 or a D750. I am not sure why this is. He thinks it's no AA vs. AA. Has anyone with a D800, D800E or D810 made a similar comparison? Or even better, has anyone compared a D800 (no AA) with a D800E or D810 to see, using the same F8 limited lens and teleconverter combo, which autofocuses better?

DaveO Loc: Northeast CT

May help:

http://masteryournikon.com/2015/01/18/will-a-nikon-autofocus-at-an-aperture-of-less-than-f5-6/

DaveO Loc: Northeast CT

The Nikon Teleconverter Compatibility chart has this not at the bottom:

Autofocus is available only with cameras that offer f/8 support. These include the D4/D4S, Df, D800/D800E, D810/D810A, D600/ D610, D750, D7100 and D7200. For cameras that do not support f/8, teleconverers can be used without autofocus.

pmackd Loc: Alameda CA

DaveO wrote:

The Nikon Teleconverter Compatibility chart has this not at the bottom:

Autofocus is available only with cameras that offer f/8 support. These include the D4/D4S, Df, D800/D800E, D810/D810A, D600/ D610, D750, D7100 and D7200. For cameras that do not support f/8, teleconverers can be used without autofocus.

This may be so but there is a world of difference in performance among these cameras and even depending on which lens is used. I'm especially interested in what D8XX owners have to report since I don't own one of these and haven't tested any.

Nikon isn't telling the full story.

DaveO Loc: Northeast CT

:thumbup:

Steve Perry Loc: Sylvania, Ohio

A couple things to consider - you may have already thought of these but i wanted to toss them out there:

1. The AF sensors are not on the imaging sensor (they are at the bottom of the mirror box) so AA vs non-AA shouldn't make any difference with regular AF (maybe a little with Live View, but not that I've ever noticed).

2. Not all AF sensors in your camera are the same. Believe it or not, only the center AF sensor in the 800/e and the D7100 is compatible with F8 (the surrounding ones are "5.6 and up to but not quite F8" ). So, if you have your D800/e set to something other than the center sensor and the D7100 is set to center, it will likely focus more reliably. I think the D810 & D750 have 11 F/8 compatible sensors and the D610 has 7 - but they are around the center.

Note that this doesn't mean you can't get an AF lock with one of the other sensors with an effective F8 lens, it just means the center will be more reliable.

pmackd Loc: Alameda CA

Steve Perry wrote:

A couple things to consider - you may have already... (show quote)

Thanks for all this. I knew about your point #1 which is why I've benn arguing with my friend. Leaves me puzzled though why the D610 and D750 cannot autofocus at F8 as well as the D7100. We only use center focus point when using a TC so the number of compatible points is not relevant for our tests.

lamiaceae Loc: San Luis Obispo County, CA

pmackd wrote:

A friend and I have both noticed that our D7100s autofocus much more reliably at F8 -- when using an F5.6 maximum aperture lens with a 1.4X TC -- than either a D610 or a D750. I am not sure why this is. He thinks it's no AA vs. AA. Has anyone with a D800, D800E or D810 made a similar comparison? Or even better, has anyone compared a D800 (no AA) with a D800E or D810 to see, using the same F8 limited lens and teleconverter combo, which autofocuses better?

OK, I'm totally lost here, not being a Nikon owner I have no idea what f-8 specifically has to do with AF? As far as I know, on my Pentax cameras, if I set the older lenses to "A" it will AE or AF at any stop depending on if one is talking about a A-series or F-series lens. These and all other lenses work at any f-stop, f/1.2 to f/32 to some extent. Pentax DA and FA lenses are all electronic with no physical click stops. I know this question was about Nikon, but it does not "click" with my general photo knowledge. With any DSLR camera or lens if there is not enough light at any f-stop the system may not AF or AE.

DaveO Loc: Northeast CT

Steve Perry wrote:

A couple things to consider - you may have already... (show quote)

So you think you know a little about Nikon autofocus modes?? Learn a little more: http://www.youtube.com/watch?v=_N_bzhJAKms

Saw it on Youtube, fine job along with others and your wildlife shots. Great to have more help here, welcome! :lol: :lol:

The Villages Loc: The Villages, Florida

Steve Perry: Welcome to the Forum. I have viewed your YouTube videos with interest.

MtnMan Loc: ID

lamiaceae wrote:

OK, I'm totally lost here, not being a Nikon owner... (show quote)

DSLRs focus at the minimum f-stop for the zoom setting. The lens closes down to higher f-stops when you press the release.

Steve Perry Loc: Sylvania, Ohio

pmackd wrote:

Thanks for all this. I knew about your point #1 which is why I've benn arguing with my friend. Leaves me puzzled though why the D610 and D750 cannot autofocus at F8 as well as the D7100. We only use center focus point when using a TC so the number of compatible points is not relevant for our tests.

Hmm.. I'll take another stab (no promises :) )

Did you do an AF fine tune on the lenses + TC with all the cameras in question?

The lens needs its own AF fine tune setting and the lens + TC will need yet another (the lens +TC is treated like a separate lens by the camera).

Beyond that it's a head scratcher for sure.

INshooter Loc: Indiana

Steve Perry wrote:

A couple things to consider - you may have already... (show quote)

I just downloaded your ebook on wildlife photography last night. So, I am now looking forward to your input here on the forum!

MtnMan Loc: ID

INshooter wrote:

I just downloaded your ebook on wildlife photography last night. So, I am now looking forward to your input here on the forum!

Me too. It looks fabulous!

I appreciated the discussion on back button focus. There are many advocates on UHH but none have provided as good an explanation as to why. The key is setting the camera to AF-C.

I still do not see why BBF is superior to using AF-C and the AF/AE lock when you want to lock it in. It might be a coordination thing.

He uses release priority with BBF. I use focus priority.

I suppose it is worth trying again. He does note that when you first try it you may not like it. So far I have only reached that stage.

imagemeister Loc: mid east Florida

pmackd wrote:

A friend and I have both noticed that our D7100s autofocus much more reliably at F8 -- when using an F5.6 maximum aperture lens with a 1.4X TC -- than either a D610 or a D750. I am not sure why this is. He thinks it's no AA vs. AA. Has anyone with a D800, D800E or D810 made a similar comparison? Or even better, has anyone compared a D800 (no AA) with a D800E or D810 to see, using the same F8 limited lens and teleconverter combo, which autofocuses better?

Here is MY theory - FWIW .......The crop frame camera will have a longer time to AF because of the smaller mirror moving faster than the full frame mirror - this gives the crop frame a longer AF dwell time between shots ( as in a multiframe sequence).