1.4x and 2x Extenders

Just a question of clarification, if I may.

I find it odd that neither of these extenders is listed as compatiable with the 70-200 f/4L IS lens. It seems to be compatiable with all the others. Surely, this isn't a typo or a miss on Canon's part in its propaganda.

Can someone just clarify this for me and tell me they won't work? I have to believe some of you guys have tried it.

Thanks!

WilsonFlyer wrote in post #12020340
Just a question of clarification, if I may.

I find it odd that neither of these extenders is listed as compatiable with the 70-200 f/4L IS lens. It seems to be compatiable with all the others. Surely, this isn't a typo or a miss on Canon's part in its propaganda.

Can someone just clarify this for me and tell me they won't work? I have to believe some of you guys have tried it.

Thanks!

I hope so I just ordered the 2x III for my 70-200L

WilsonFlyer wrote in post #12020340
Just a question of clarification, if I may.

I find it odd that neither of these extenders is listed as compatiable with the 70-200 f/4L IS lens. It seems to be compatiable with all the others. Surely, this isn't a typo or a miss on Canon's part in its propaganda.

Can someone just clarify this for me and tell me they won't work? I have to believe some of you guys have tried it.

Thanks!

Can you post the exact quote from Canon your speaking of ?

I had the 70-200 F4 IS and the only 3rd party extender that would NOT work was the 1st batch release from Kenko of their DGX version. Kenko has since made revisions and they work properly now on this lens and 3 other Canon EF lenses that were initially in-compatible.

Regards,

http://www.bhphotovide​o.com …arts/canon2xExt​ender.html

Interesting B&H says that. Sounds like you guys know it will work too.

Here's what I saw, for what it's worth...

http://usa.canon.com …f_1_4x_iii#Spec​ifications

The 2*TC is not officially listed as compatible with any lens which has a maximum aperture smaller than f2.8. This is because when added the 2*TC reduces the minimum aperture of the lens by 2 stops and if the minimum aperture of the lens is smaller than f5.6 the lens won't auto focus on any canon camera body outside of the 1D and 7D*.
Furthermore canon only officially make the teleconverters to both fit and be used with a select range of lenses (based on optical construction and performance) there are some that can physically fit teleconverters without problems (eg canon MPE fits both 1.4TC and 2*TC) though sometimes these might have other problems (eg the noted minimum aperture AF problem). Note also that the Canon teleconverters have a physical protrusion from the front so on many lenses the restriction on fitting isn't just a recommendation, but a physical limitation.

The list from B&H is including lenses that can physically fit the teleconverters - note how some have apertures smaller than f2.8 for the 2*TC.

* only in liveview mode - in regular viewfinder mode it will still lose auto focus.

Overread wrote in post #12020777
The 2*TC is not officially listed as compatible with any lens which has a maximum aperture smaller than f2.8. This is because when added the 2*TC reduces the minimum aperture of the lens by 2 stops and if the minimum aperture of the lens is smaller than f5.6 the lens won't auto focus on any canon camera body outside of the 1D and 7D*.
Furthermore canon only officially make the teleconverters to both fit and be used with a select range of lenses (based on optical construction and performance) there are some that can physically fit teleconverters without problems (eg canon MPE fits both 1.4TC and 2*TC) though sometimes these might have other problems (eg the noted minimum aperture AF problem). Note also that the Canon teleconverters have a physical protrusion from the front so on many lenses the restriction on fitting isn't just a recommendation, but a physical limitation.

The list from B&H is including lenses that can physically fit the teleconverters - note how some have apertures smaller than f2.8 for the 2*TC.

* only in liveview mode - in regular viewfinder mode it will still lose auto focus.

OK. Now I feel even stupider than I thought. So, if I'm hearing you right, an f/4 will effectively become an f/6 and will not have autofocus capabilities? That would be a deal-breaker for me. Just rying to make sure I understand.

FWIW, I'd be using this with a 60D or 600D. Wish I could see a 7D in my future but it just ain't happnin' right now.

In losing 2 stops of light it becomes a 140-400mm f8 lens and will on the 60D and 600D lose auto focus. Furthermore there are tricks whereby you tape the pins on the TC so that the camera's AF section can't "read" the TC being attached. However even when doing so the limitation on AF is present because AF speed and accuracy (even in good light) takes a noticeable hit and it will hunt and be a lot slower than normal.

So it comes at a cost - image quality also takes a hit, but from what I've read the f4 versions have a very respectable image quality.

You could use a 1.4TC without problems (it takes you to an f5.6 lens which will retain AF) for more range if you need it. Otherwise I'd start saving for either a 400mm f5.6/100-400mm/300mm f4 or save and swap the 70-200mm f4 for the 70-200mm f2.8 IS L M2 (and add the 2*TC)

Overread wrote in post #12020777
7D*.
* only in liveview mode - in regular viewfinder mode it will still lose auto focus.

Am I reading this right?

nikmar08 wrote in post #12020926
Am I reading this right?

Yes the 7D can retain auto focus up to f8 when used in live view mode because its using a different kind of AF (contrast detection), From what I understand it is slower than the regular mode used in viewfinder focusing.

When used through the viewfinder, as normal, the 7D uses phase detection AF which only retains AF up to f5.6 - it is however a far faster AF mode


(note with regard to the custom AF controls in the 7D whilst these certainly apply to the phase detect AF mode (in viewfinder AF) I'm unsure if they also apply to the contrast detect AF used in live view mode (the fact that this mode has its own 3 options for AF control suggests that the custom mode AF control is not in operation with this mode - but I'm not certain of this fact).

^^ Yes there are limitations in liveview AF comapred with viewfinder AF, I can't recall them from the top of my head.

Also a Wikipedia quote from another thread "Furthermore, as the autofocus system does not calculate whether the subject is in front focus or back focus, focus tracking is not feasible" probably means the loss of AI Servo capability, not sure will have to try over the weekend.

Overread wrote in post #12020777
The 2*TC is not officially listed as compatible with any lens which has a maximum aperture smaller than f2.8.

Despite AF not working, Canon does officially list 2x TCs as compatible even with the 400mm F/5.6, it simply mentions that it will be MF only.

The Canon 1.4x TC is MF only on this 100-400L.....I was bummed........

jjackflash wrote in post #12020562
http://www.bhphotovide​o.com …arts/canon2xExt​ender.html

The above B&H data is for a 2X extender and correct.

WilsonFlyer wrote in post #12020688
Interesting B&H says that. Sounds like you guys know it will work too.

Here's what I saw, for what it's worth...

http://usa.canon.com …f_1_4x_iii#Spec​ifications

This Canon data is correct for the 1.4 extender.

---------------


Using the 2X on a fixed F4 lens will put you at F8.0 and using a crop body it will not AF. Some folks have used live view and contrast detect & had AF perform but IMO i would rather use MF versus this method.

Regards,

Silverfox1 wrote in post #12021090
The above B&H data is for a 2X extender and correct.

This Canon data is correct for the 1.4 extender.

---------------


Using the 2X on a fixed F4 lens will put you at F8.0 and using a crop body it will not AF. Some folks have used live view and contrast detect & had AF perform but IMO i would rather use MF versus this method.

Regards,

FYI... The 2x data on the Canon site appears to be exactly the same specifications as to the lenses officially supported (as the 1.4).

http://www.usa.canon.c​om …_ef_2x_iii#Spec​ifications