Nikon AF performance with teleconverters

StewartR

StewartR

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Does anyone know what the specifications are that describe whether or not Nikon bodies can autofocus with teleconverters fitted?

In Canon-land, it's very simple. Every EOS body will be able to AF if the effective maximum aperture is f/5.6 or better; and 1D-class bodies will be able to AF if the effective maximum aperture is f/8 or better. This information is published by Canon.

In Nikon-land, however, I haven't been able to find any published official specifications. I believe that the f/5.6 restriction also applies generally to Nikon bodies, but I can't prove it. And I haven't been able to find out whether any Nikon bodies can do better than that (and if so, which ones).

Can anybody help?
 
Stewart, I have a Sigma 170-500 (editted!) which is f/6.3 at the long end. I've just tried it with a Teleplus 1.5x teleconverter on a D70 and a D200 - both AFed well despite the light giving me 1/4s @ f/6.3 (an effective aperture of around f/10, I think). I tried it at 2 distances, 10 feet (low contrast - leaves against leaves) and 30 feet (again, low contrast, brown trellis against old red brick).

HTH.

(BTW, some Nikkor zooms cannot use Nikon's telecons but you know that already!)
 
The closet it comes to setting a limit in the D200 manual is this "–1 – +19 EV (ISO 100 at 20 °C/68 °F)". No mention of minimum apertures (or should that be maximum minimum apertures?). Like I said, they work at f/6.3 with a 1.5x telecon!
 
PsiFox,

That's an excellent table, but sadly it doesn't tell the whole story! As far as I know, someone please correct me on this, but not all AF-S lenses can use a teleconverter; one such lens is the 24-70 f2.8 AF-S.

I don't think there is a logical trend with this, and the complex acronym that Nikon employs is hard enough to decipher yet alone to match lens type with a TC!
 
Best bet when matching telecons to Nikkor lenses is to read the lens manual...
 
Wail said:
PsiFox,

That's an excellent table, but sadly it doesn't tell the whole story! As far as I know, someone please correct me on this, but not all AF-S lenses can use a teleconverter; one such lens is the 24-70 f2.8 AF-S.

I don't think there is a logical trend with this, and the complex acronym that Nikon employs is hard enough to decipher yet alone to match lens type with a TC!
Click to expand...
Try

for AF

http://nikonusa.com/pdf/manuals/lenses/TC/AFTeleconverter.pdf

for MF


http://nikonusa.com/pdf/manuals/lenses/TC/MFTeleconverter.pdf

source
http://support.nikontech.com/cgi-bi...GV4dD10ZWxlIGNvbnZlcnRlcg**&p_li=&p_topview=1
 
StewartR said:
In Canon-land, it's very simple. Every EOS body will be able to AF if the effective maximum aperture is f/5.6 or better; and 1D-class bodies will be able to AF if the effective maximum aperture is f/8 or better. This information is published by Canon.


Can anybody help?
Click to expand...


I don't 100% understand this, surely it depends on available light whether anything can af or not at a particular aperture, granted the better quality body's will have keaner af, but to say all body's will af at f/5.6 or better :thinking:...are they saying af just shuts down at f/6 whether there is enough light or not, and f/9 on 1D class body's.
Maybe that's why there isn't a definitive spec, its just not as simple as that Canon statement suggests..:shrug:.
Regardless, I wouldn't expect Nikon to be any different to Canon, although choosing the right converter to get the best results from a particular lens may be more complicated than it is in Canon land.
 
Nod said:
Best bet when matching telecons to Nikkor lenses is to read the lens manual...
Click to expand...
PsiFox said:
Try

for AF

http://nikonusa.com/pdf/manuals/lenses/TC/AFTeleconverter.pdf
Click to expand...
Well that's interesting. What both of you (and the Nikon chart) are implicitly saying is that the ability to AF does not depend on which camera you're using - so there is no Nikon equivalent of the enhanced AF performance which Canon 1D-series camera deliver. It also seems that the effective maximum aperture needs to be f/5.6 or better across the entire range.

(Nod reports AF at f/6.3, but that's with a 3rd-party TC which might not be reporting its presence to the camera properly.)
 
joxby said:
...are they saying af just shuts down at f/6 whether there is enough light or not, and f/9 on 1D class body's.
Maybe that's why there isn't a definitive spec, its just not as simple as that Canon statement suggests..:shrug:
Click to expand...
That's it exactly. Canon bodies will refuse to try to autofocus if the lens/extender combo has a maximum aperture smaller than f/5.6 (or f/8 on the 1D). With some 3rd-party TCs It is possible to fool them by taping up some of the pins on the contact, so that the camera doesn't know there's a TC fitted.

Presumably Canon have a reason for making it work like this, but I don't know what. I'd have thought it would be better to at least let the camera try to AF, though I guess that could lead to some frustration amongst less-experienced users. And it does cut down on the confusion that reigns in Nikon-land!

But the interesting aspect is that AF will definitely work at f/8 on some Canon bodies, and (so far as we can tell) it won't on any Nikons. Can that really be true?
 
I can't find any reference to af shut down at any aperture with any Nikon af-s teleconverter, if its too dark, it will just hunt, afaik, at what aperture it hunts will depend on......AVAILABLE LIGHT, body and lens, you'd have to try them to find out.
That's really kinda odd, the af shuts down even if there is enough light....:suspect:.....whatever, maybe in some conditions, Nikon will get an af where a Canon body is prevented from getting an af, can't imagine that's a regular occurrence, but :shrug:
Y'know what, it doesn't sound right, what about long exposures ? with an average Canon body, you can only shoot the moon at f5.6 when using a teleconverter...wtf ?


:thinking:

StewartR said:
But the interesting aspect is that AF will definitely work at f/8 on some Canon bodies, and (so far as we can tell) it won't on any Nikons. Can that really be true?
Click to expand...

AF will only work at f/8 on some Canon body's if there is enough light.

*edit* assuming there is no af shutdown on Nikon af-s body/teleconverter combo's, I just shot my 80-200 f/2.8 @ 200mm with a cheapy x2 teleconverter, it af'ed perfectly on my next door neighbours tree/sky, ok the iso was 800 and shutter speed was 1/30th......but the app was f/14 :).
 
joxby said:
*edit* assuming there is no af shutdown on Nikon af-s body/teleconverter combo's, I just shot my 80-200 f/2.8 @ 200mm with a cheapy x2 teleconverter, it af'ed perfectly on my next door neighbours tree/sky, ok the iso was 800 and shutter speed was 1/30th......but the app was f/14 :).
Click to expand...
That's irrelevant. The lens is f/2.8 and the TC makes it f/5.6. The aperture at which you actually take the shot doesn't matter because the lens focuses whilst wide open and then stops down for the shot. It's the "wide open" aperture that matters - in your case it was f/5.6
 
*smacks head*
God, I don't actually know how to replicate shooting with a teleconverter at a wide open f/8 then, I don't have anything slower than 2.8, and I'm buggered if I can work out how to stop down the lens manually, without an f stop error.
Maybe I should shoot more often with this camera...

:bonk:
 
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