Sigma tele converter question.

The large Nikon lenses also have their own dedicated converters (dedicated because some of the converters have ‘male’ sections which fit inside the lens barrel and so will not work with other lenses), but a converter decreases the amount of light reaching the focal plane (be it film or a chip) so it would also hinder the workings of the auto focus magikery.
Buy a big aperatured telephoto lens (500mm f2.8 + your smiling bankmanager, anyone?) or stand closer.

Flood.™

Even in the bygone years before thr birth of autofocus lenses, converters could only be used in bright daylight according to their manufacturers instructions.There are a few very expensive Canon lenses sold with their own converter. otherwise, i would fully garee on the previous comments.

You could always stand closer, you know…;)

Flood.™

Thanks everyone,

I tried my old converter at Farnborough, where you need the extra reach but it was very difficult to manual focus such a heavy lens at speed.

In the end I gave up.

Thanks for saving me from another unwanted peice of kit.

Septic.

I took this with the converter, a bit too grainy for my taste.

Well, isn’t it time for a “Mark II” then Damien 😀 . I tried one and the AF went fast an aqurate. Just back from CPS as my 100-400 broke down (again). When I said I was going for a Mk II, although I wanted something with a 1.66 8 Mb sensor, I was told that it was wise to wait for the Photokina next month. So I hope it is a 45AF 8 or 10 m “5D” or so. BW Roger

I have used the “tape” option on my Canon 500m with the 1.4 and 2.0 extender. It works reasoably with the 1.4 but with thee 2.0 the AF went complete gaga. Now I only use extenders while the lens is on a tripod and on MF.

BW Roger

The 500 will be around 800mm equivalent on the D100. so a 1600mm F12.6 lens is going to take some holding. How bright is the place you’re going?

Gareths answer mentions the haze etc too. Good point.

no, it won’t autofocus. I’ve got a D100 and the 50-500 lens as well as the sigma 1.4x EX converter. It works nicely on a tripod for birding for example, exposure metering still works but you have to focus manually.

Not really a problem in that sort of situation, the chances of an accurate AF on the thing you want with that focal length are pretty low (500×1.4, plus 1.5 ‘digital crop’ = 1050mm equivalent). Much better to set up a shot and wait for the subject to be where you want it.

Some folk talk of taping over a contact on the converter to prevent the lens passing its maximum aperture (f6.3 at the long end) to the camera. This is supposed to fool the camera into attempting to AF in bright light. Never tried it, since I cannot imagine it being fast enough to be of any use.

As for using it on aircraft? Not tried it really, if your subject is so far away that you need a 1000mm+ lens (equivalent) I’d be giving up, it would need to be a very clean, clear day with no heat haze or atmospheric pollution to get much usable. It really would be a case for finding a better (closer) location.

For wildlife (small creatures at medium distances) the converter works quite nicely, despite the lack of AF.

Is that through the range? Constant?
It might be that f4 is too dark for the 50mm end of the lens, y’see, or that 500mm is too much for the converter. What magnification is the converter – if that puts the aperature rating up into the f5.6-f8 range then it could be that.
I could also be talking out of the top of my bush hat too, though. Its been a while…

Flood.™

f4

Septic.

What is the aperature range at its widest?
Vaguely remember that if the aperatures are too small (f5.6-f8-ish) then the camera cannot cope.

Flood.™