tele-extenders

[normsmith]

If this question has been addressed please direct me to the thread. If not, My EOS 10D doesnt autofocus of my with the 300 F:4L IS when I use the Canon 2X extender. The lens works well with the 1.4. I notice that the max aperture with the 2X is f:8. and with the 1.4X it seems to be 5.6.


Was I mistaken in thinking that the 1.6 "magnification" factor of the 10D doesn't apply to the aperture?

Norm

[CyberDyneSystems]

The 1.6X has NO effect on lens aperture.

But the 2X converter does. Autofocus will not function on most EOS bodies if the Aperture is less than 7 ( I think its 7? )

Chances are you can get the 10D to autofocus with the 2X extender if you try the tape trick. f/8 in bright light,. it should work. Perhaps not perfectly.

give me a second,. let me see if I can find the tape trick....

[CyberDyneSystems]

http://www.fredmiranda.com/TipsPage/

Here it is :)

[chris maddock]

One thing - If applying the tape to the extender just results in the lens hunting, try applying it to the lens instead.

I found that a taped 1.4x extender worked a treat with my 100-400/f5.6 and D30, but that my 70-200/f4 wouldn't focus at all with the extender. Taking the tape off the extender resulted in the 70-200 working as well with the extender as without it. So I put the tape on the 100-400 instead and both lenses worked with the extender.

KRs
Chris

[normsmith]

Thanks. Does this technique affect the exposure calculation?

[chris maddock]

normsmith wrote:
Thanks. Does this technique affect the exposure calculation?

Nope - the final exposure is calculated at the point of the shutter release.
That is how some third-party manufacturers get away with producing f6.3 or slower lenses. The lens tells the camera it's f5.6, so the autofocus will work, but reverts to telling it (and using) the correct aperture at the point of exposure.

KRs
Chris

[normsmith]

Thanks, I'll give that a try.

Norm

[defordphoto]

normsmith wrote:
Thanks, I'll give that a try.

Norm

I just bought the 1.4TC and coupled it with my 100-400L. With those contacts taped, it auto focuses just fine:

http://racefamily.racinglines.com/MiscPhotos/img_7603_std.jpg

Dontchya think? ;)

[normsmith]

About all I can say is "WOW"

[NILOLIGIST]

RFMSports,

Great shot!! But then all of your shots are great. Now, compared to the natural light that was present when you took this shot, how much ligth did you lose? You do lose 1 stop, is that correct?

I want to get the TC but I am very concerned with the loss of light. But I plan on getting the 70-200L 2.8 so I guess I can use it with that.

NiL,

[Deadlus]

to CyberDyneSystems,

Just a quick question, do you still have your Sigma 50-500? and have you tried it with a 2X extender?

Thanks in advance

Deadlus

[CyberDyneSystems]

I have tried the 2X with the 50-500mm,.. er,.. it sort of works.... :(

...and YES! I still have that lens! I can't see me parting with it.

Obviously Autofocus is out the window,. in Fact the 500mm's f/6.4 is allready a little high for autofocus on most bodies,. thus the Sigma "fools" the camera into thinking it is an f/5.6!

At 1000mm,. the images are not to clear. In perfect circumstances with the right lighting and a very steady tripod it is usable... but I don't recomend this combo unless you are desperate for a 1000mm shot.

You can check out the Eagles in my gallery to see how tough it can be,.. this was about 300 meters away with a breeze,. this is why everything is so blurry.

http://cyberdynesytemsimaging.fotopic.net/show_collection.php?id=21229&offset=13

On the other hand,. the Sigma 1.4 converter works pretty well with it. Again you loose the Autofocus. I will try the tape trick on it,. but I am sure there will need to be plenty of sunshine for that to work!

[defordphoto]

Nil: I didn't test it to see. But if that's what it's supposed to lose then that's what it lost. I don't too much into 'testing' stuff. I just get out there and shoot and if I get great shots then it really doesn't matter what I've 'lost' anyway does it?

The windsurfers is the only thing I have used it on so far and it was super bright and sunny, but that's what I bought it for and it did a great job on that.

I'll post more photos this weekend I think. I have about 1,800 windsurfer shots and I also shot the SprintBoats this past weekend and we did 2500-plus there, so I have a bit a work to do to get these galleries online!

I LOVE IT! :D

[CyberDyneSystems]

The pure math f/5.6 X 1.4 = 7.84.... my guess is that means an f/stop of f/8?

[defordphoto]

CyberDyneSystems wrote:
The pure math f/5.6 X 1.4 = 7.84.... my guess is that means an f/stop of f/8?

Works for me. With the contacts taped I don't think that the EXIF is correct either, but that's okay too. Little sacrifices I can definitely live with. I saw some bird photos in a similar thread over at Fred Miranda's that are superb!

[pwagner]

Thanks Chris! That's exactly what I wanted to hear regarding the 100-400 and the 1.4x II. That explains how the Sigma 50-500 retains AF at the 500 end. Also, as always, thanks to RFM for in-the-field demonstration of the combination. Mmmmm.... 400mm * 1.4 * 1.6 = 896mm.

[Deadlus]

CyberDyneSystems wrote:
I have tried the 2X with the 50-500mm,.. er,.. it sort of works.... :(

...and YES! I still have that lens! I can't see me parting with it.

Obviously Autofocus is out the window,. in Fact the 500mm's f/6.4 is allready a little high for autofocus on most bodies,. thus the Sigma "fools" the camera into thinking it is an f/5.6!

At 1000mm,. the images are not to clear. In perfect circumstances with the right lighting and a very steady tripod it is usable... but I don't recomend this combo unless you are desperate for a 1000mm shot.

You can check out the Eagles in my gallery to see how tough it can be,.. this was about 300 meters away with a breeze,. this is why everything is so blurry.

http://cyberdynesytemsimaging.fotopic.net/show_collection.php?id=21229&offset=13

On the other hand,. the Sigma 1.4 converter works pretty well with it. Again you loose the Autofocus. I will try the tape trick on it,. but I am sure there will need to be plenty of sunshine for that to work!


Thanks alot - i just bough a Sigma 50-500 and was thinking of getting a converter.
But im gona try it out awile and see how mutch need ill have 800+.
Btw great photos i love them,

Thanks again

Best regards

Deadlus