enygy Loc: LI, NY

I have seen comments that DSLRs may have trouble autofocusing with slow lenses or lenses with teleconverters attached bringing the F number above 6 or 8 etc...

I have also seen it mentioned that the higher the F number of the lens, the fewer sensors will work in AF mode and these will be closer to the center.

Questions -
Will the camera refuse to even try to focus with a lens above its rated F number or will it just have difficulty focusing in lower light conditions?

If I am shooting in bright light, are these concerns moot anyway?

Will the camera automatically cut out sensors on the periphery of the array as I switch to a slower lens?

Do the lens/teleconverter combination communicate with the camera to come up with the combined F number? I think the answer must be yes.

BTW I have a D610.

Thanks!

imagemeister Loc: mid east Florida

answers:

1. Most but not all will try to AF - depends on the exact body and the exact lighting conditions and the exact contrast of the subject. Low light, low contrast = more trouble.

2.not necessarily - again, it depends on several things.

3.not sure - again it depends on the exact camera model - IMO.

4.the answer is mostly yes - but maybe no with third party converters ....

.. I am speaking mostly in generalities here as I am not a Nikon expert..

..

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You might find this page from Nikon Canada useful:

http://cdn-5.nikon-cdn.com/Assets/Common-Assets/Images/Teleconverter-Compatibility/EN_Comp_chart.html

F8 support is available with the D610, so that means that if you use a lens that has a maximum aperture of F5.6 without a TC, it will become an F8 lens when you use a 1.4X TC. If you want to use a lens with a 2X TC, then the max aperture cannot be smaller than F4.

The D610 has 7 sensors that can focus at F8.

http://imaging.nikon.com/lineup/dslr/d610/features03.htm

But don't try to use a teleconverter - which is intended for medium to long telephoto lenses, or 70-200 or longer tele zooms, with a superzoom lens that goes from 28-300 or from 18-400 or whatever - TCs are not designed for that kind of lens, and even if you were to get it to mechanically connect without lens element collision (possible when you use the shorter focal lengths of a super zoom), the image quality will be fair to awful and you can forget about being able to autofocus.

Regarding your questionssss:

1. Your D610 will work, but AF performance will be compromised.
2. Even in bright light, AF performance will not be as crisp with a TC as it is without one.
3. Your D610 won't cut out sensors. The less sensitive sensors will just not have enough light to focus.
4. If you use a Nikon TC with a Nikon lens, yes. Otherwise - it depends.

jackpinoh Loc: Kettering, OH 45419

Have you checked your camera manual? Nikon manuals will tell you how many AF points are reliably available as a function of maximum aperture (lens max aperture + TC stop penalty).

enygy Loc: LI, NY

Thanks imagemeister, helpful answers.

enygy Loc: LI, NY

Helpful answers Gene and I appreciate the links. Great to see it right from the source!
Thanks.

enygy Loc: LI, NY

Thanks Jack. Good suggestion and though I couldn't find that section when I looked earlier it doesn't mean it's not there. I will take another look.