2x, 1.4x extenders

CarlEvans

CarlEvans

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I'm using a 100-400mm L-series IS lens on a canon 500D body and I'm really struggling to find a decent extender.
I've looked at canon extenders and with my lens AF is "impossible" according to there chart of compatible lenses.
I've also looked at kenko which do offer a AF function with there extenders but apparently do not work with the 500D body (according to there website)
I'm just wondering if anyone has any experiance with this who could give me some advice. Thanks in advance :)
 
Isn't the issue that unless you have a 1D body the camera can't auto-focus above f/5.6, while the 1D can use AF at f/8?

A 1.4x extender adds 1-stop (f/5.6 up to f/8), 2x adds 2-stops (up to f/10?), so AF won't work regardless of the extender used?
 
Thorburn said:
Isn't the issue that unless you have a 1D body the camera can't auto-focus above f/5.6, while the 1D can use AF at f/8?
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This is true. However some people are claiming that the new Kenko 1.4x will allow AF with a 100-400 - LINK. But if it don't work blame them, not me.
 
hollis_f said:
This is true. However some people are claiming that the new Kenko 1.4x will allow AF with a 100-400 - LINK. But if it don't work blame them, not me.
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Looks like they're using the 5D Mk3 which uses the same or similar AF system as the 1D though, aren't they? Did see that it's getting official f/8 AF support next year.
 
Aside from the potential AF issues, another thing worth noting is that the 100-400 isn't the best lens to be sticking extenders onto in the first place. The fact that you want to use an extender implies that you want to reach further than full zoom. The 100-400 is not quite as sharp at the long end as the 400 prime. Therefore, an extender will only multiply that softness and will add-in some other aberrations into the bargain. Couple that to the loss of one or two F-stops and it may be a waste of time? Before going to the bother of finding an extender which may or may not work with your set-up, it might be worth considering if the results are likely to be what you seek in the first place. There is no substitute for getting a bit closer to your subject.;)
 
Reviews state that an IS lens will bring your F stop down 1 after its increased with a 2x extender allowing the AF to work. Some extenders have 3 contact points which tell the lens an extender has been fitted, by covering these 3 contacts with tape it apparently works fine and does not reduce your F stop. I have a friend trying it tonight who will let me know.
Was hoping someone uses a 100-400 with an extender that can provide some feedback.
 
CarlEvans said:
Reviews state that an IS lens will bring your F stop down 1 after its increased with a 2x extender allowing the AF to work.
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Nope. IS has no effect at all on the aperture of a lens (which is the all-important factor for AF).

CarlEvans said:
Was hoping someone uses a 100-400 with an extender that can provide some feedback.
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I've tried using a 100-400 with various TCs, with the taped-pins when needed. It has never worked properly.

If it did work, do you not think that the 'Birds' forum would be full of images taken with such a combination. Birders are forever struggling for focal length. If a cheap, workable solution existed then they'd be all over it like a rash. They're not because such a solution doesn't exist.
 
Having an IS lens might let you hold the lens steady for 1-stop extra in terms of time, but it won't affect the reduction in size of the aperture - that will still be 1-stop for a 1.4x and 2-stops for a 2x AFAIK.
 
This is my understanding of how things work:
Reporting TCs: A TC-compatible lens (e.g. 400/5.6) detects the presence of a TC through the extra contacts and reports the correct f-stop for the combination to the camera.

Non-reporting TCs, or taped TCs, or TCs with non-TC-compatible lenses: The lens does not detect the TC and just reports its own f-stop. AF may still work, because the camera doesn't know about the true f-stop, and tries to AF even if the combination is outside the specs.

Kenko DGX: Unlike the above TCs, the DGX manipulates the communication between the lens and the body so that the f-stop is always reported correctly for the combination, and so that AF is retained even if the combination is above f/5.6. From your and others observations that f/8 is reported but AF still works, my guess is that wide-open f-stop and used f-stop is reported separately and the camera looks at the wide-open f-stop to determine if it should try to AF.

Personally unless you have fantastic light conditions a 2X TC on either of your lenses won't produce great results. Canon limit autofocus to f5.6 for all but there 1D series camera's, and it also depends on the compatibility of the lens with the TC as only certain lenses work.

TCs are really designed for the faster prime lenses not zooms because the optics can handle the drop off in image quality and hit on the auto focusing, but you can use a zoom and TC but be aware you'll need decent light conditions to get anything worth while image wise
 
pete.rush said:
This is my understanding of how things work:
Reporting TCs: A TC-compatible lens (e.g. 400/5.6) detects the presence of a TC through the extra contacts and reports the correct f-stop for the combination to the camera.

Non-reporting TCs, or taped TCs, or TCs with non-TC-compatible lenses: The lens does not detect the TC and just reports its own f-stop. AF may still work, because the camera doesn't know about the true f-stop, and tries to AF even if the combination is outside the specs.

Kenko DGX: Unlike the above TCs, the DGX manipulates the communication between the lens and the body so that the f-stop is always reported correctly for the combination, and so that AF is retained even if the combination is above f/5.6. From your and others observations that f/8 is reported but AF still works, my guess is that wide-open f-stop and used f-stop is reported separately and the camera looks at the wide-open f-stop to determine if it should try to AF.

Personally unless you have fantastic light conditions a 2X TC on either of your lenses won't produce great results. Canon limit autofocus to f5.6 for all but there 1D series camera's, and it also depends on the compatibility of the lens with the TC as only certain lenses work.

TCs are really designed for the faster prime lenses not zooms because the optics can handle the drop off in image quality and hit on the auto focusing, but you can use a zoom and TC but be aware you'll need decent light conditions to get anything worth while image wise
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Thanks a lot for this!
 
hollis_f said:
Nope. IS has no effect at all on the aperture of a lens (which is the all-important factor for AF).

I've tried using a 100-400 with various TCs, with the taped-pins when needed. It has never worked properly.

If it did work, do you not think that the 'Birds' forum would be full of images taken with such a combination. Birders are forever struggling for focal length. If a cheap, workable solution existed then they'd be all over it like a rash. They're not because such a solution doesn't exist.
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"Do I not think that the 'birds' forum would be full of images taken with such combination"

Ummmm I simply asked if anyone had any experience with my particular lens and a TC where AF works as everyone has there own experience. Never mentioned anything about 'birding' although that is what I would be wanting it for :) I'm simply researching my options until I can afford a 600 or 800mm :) thanks a lot for the input guys.
 
FourRingCircus said:
Aside from the potential AF issues, another thing worth noting is that the 100-400 isn't the best lens to be sticking extenders onto in the first place. The fact that you want to use an extender implies that you want to reach further than full zoom. The 100-400 is not quite as sharp at the long end as the 400 prime. Therefore, an extender will only multiply that softness and will add-in some other aberrations into the bargain. Couple that to the loss of one or two F-stops and it may be a waste of time? Before going to the bother of finding an extender which may or may not work with your set-up, it might be worth considering if the results are likely to be what you seek in the first place. There is no substitute for getting a bit closer to your subject.;)
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I agree and advice very much taken on board, cheers!
 
CarlEvans said:
"Do I not think that the 'birds' forum would be full of images taken with such combination"

Ummmm I simply asked if anyone had any experience with my particular lens and a TC where AF works as everyone has there own experience. Never mentioned anything about 'birding' although that is what I would be wanting it for :) I'm simply researching my options until I can afford a 600 or 800mm :) thanks a lot for the input guys.
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Sorry, I wasn't trying to get at you. It's just that there are a vocal minority who will try to persuade you that the 100-400 with a 1.4x TC is a viable combination. The lack of images in the 'Birds' forum taken with that combination is a good indication that it isn't a viable combination for that purpose. I'm merely trying to save you from wasting money finding out that it isn't.
 
CarlEvans said:
I agree and advice very much taken on board, cheers!
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You're welcome.:thumbs:

BTW, I'm one of those birders with the 100-400 and the 1.4x & 2x TC's in my arsenal. I never use a TC with that lens, and in fact, I never use that particular lens specifically for birding at all.

HTH;)
 
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