Using two Canon EF 1.4X entenders

[skinkfoot]

Does anyone here use two 1.4X extenders? If so, can you tape one set of pins and say focus at f8 on a canon ef 400 L f5.6? 

Right now I use a 5d mk iii and I find it quite capable with the extender taped .  I guess I am thinking, when the new firmware comes in the spring, can I feasibly have a 800 f8(f11 reality)? I understand that the image may degrade, and it will be slower, but I was wondering if anyone with 1d series has tried this?

[neuroanatomist]

AFAIK, only the TC closest to the lens 'reports' so after the firmware update there should be no need to tape pins.  Not sure about physical compatibility - I know a MkII 1.4x and 2x can be stacked, but the MkIII versions cannot.

[photo212]

two 1.4X will NOT fit together. the front element stick proud of the case, and the back element has no recessed cavity for it to fit.

http://www.adorama.com/CA14XAF3U.html?gclid=CI_WmcqPtbUCFYk7Mgod_n4AfQ

A 1.4X and 2X will fit together, but really cuts the image quality down.

Even if you managed to get two 1.4X to fit together, why? a 2X is the same thing.

[wickidwombat]

you can stack a kenko on the back of a canon
however with some lenses my 5Dmk3 doesnt like this
5Dmk2 has no problem with it

[ferdi]

Can you put an extension tube between the extenders?

[AlanF]

The 5D III will take a Kenko and my 100-400, but it seizes up or doesn't work with the 300 series II. If you want a x2, the native 2XTC will be much better than two 1.4s.

For amusement, I tried the Canon 1.4 TC with my old Sigma 10-20 f/4, which is equivalent to the EF-S but does not stick out at the back. Without the extender, it produces a circle filling about 2/3rds of the full frame of the 5D III. With the extender, it cover full frame to be a 14-28 f/5.6, and correctly reporting the aperture etc.

[rs]

The 5D III will take a Kenko and my 100-400, but it seizes up or doesn't work with the 300 series II. If you want a x2, the native 2XTC will be much better than two 1.4s.

For amusement, I tried the Canon 1.4 TC with my old Sigma 10-20 f/4, which is equivalent to the EF-S but does not stick out at the back. Without the extender, it produces a circle filling about 2/3rds of the full frame of the 5D III. With the extender, it cover full frame to be a 14-28 f/5.6, and correctly reporting the aperture etc.

If Canon made a 1.6x TC which is physically capable of mounting EF-S lenses (nothing poking out into the lens) and somehow make that compromised design optically sound, it would help ease the migration from crop to FF for many users. The 10-22/3.5-4.5 would be quite nice to use on FF as the 16-35/5.6-7.2 lens it effectively is.

Returning to the discussion here, the 2x TC is superior to stacking two 1.4x TC's.

As for AF, its phase detection and there are reasons why small apertures don't work other than software limits in firmware. f8 is really pushing things to their optical limits, and f11 is taking it too far. Split-image focus screens allow you to see what PDAF sees. Google "split-image blackout" for further info.

In summary, don't bother. Use the upcoming firmware update and a single 1.4x TC, and crop from there if you really need more reach. You'll retain AF and will no doubt get better optical quality than using too much extension on that lens.

[scrappydog]

The 5D III will take a Kenko and my 100-400, but it seizes up or doesn't work with the 300 series II.

I can do this with my 5DII but not my 60D.  CR member bchernicoff used a Kenko 1.4x and a Canon 1.4x II together with his 400/2.8, and they worked fine with his 5DIII.

EDIT:
He used the Kenko 1.4x with the Canon 2x II.

[neuroanatomist]

Does anyone here use two 1.4X extenders? If so, can you tape one set of pins and say focus at f8 on a canon ef 400 L f5.6? 

Right now I use a 5d mk iii and I find it quite capable with the extender taped .  I guess I am thinking, when the new firmware comes in the spring, can I feasibly have a 800 f8(f11 reality)?

I've used the 2xII with a 100-400L for 800mm f/11, on a 7D and 5DII.  Focusing was difficult even on a tripod.  Optical quality was not great, contrast was very low.  Stacked 1.4x TCs would be worse.

I've used the 1.4xIII with the 100-400 on the 1D X, AF worked, and optically the results were quite decent.

[photo212]

Can you put an extension tube between the extenders?

you probably can, but extension tubes are mainly for macro work. they will also provide some magnification, too. The big problem with them for general use is that infinity is no longer infinity. You are limited in focusing to the subject depending on the focal length and tube size.

[Lnguyen1203]

Does anyone here use two 1.4X extenders? If so, can you tape one set of pins and say focus at f8 on a canon ef 400 L f5.6? 

Right now I use a 5d mk iii and I find it quite capable with the extender taped .  I guess I am thinking, when the new firmware comes in the spring, can I feasibly have a 800 f8(f11 reality)? I understand that the image may degrade, and it will be slower, but I was wondering if anyone with 1d series has tried this?

If you use two extenders, the max aperture would be f11, no matter what the camera says.  The 1DX does not AF at f11 when I tried to use the combo: 500f4 II, Kenko 1.4x, extension tube, 2x III.  Swapping the order of the Kenko and the canon 2x gives me an error.

[East Wind Photography]

You can use tubes with extenders but you will not focus to infinity anymore and it's possible the AF will not function.  you will may have to manual focus or use live view focus.

Can you put an extension tube between the extenders?

[skinkfoot]

I often use  a 12mm extension  tube so that I can shorten the minimum focus, on the 400 5.6 it brings me down from 12 ft to around 9 ft.  this is a great working distance for odonata and feeder birds. 

I was thinking 5d mkiii-extender-extension tube-taped extender. hopefully giving me 800mm f8(f11).  with min distance of 9 feet , max of around 35 feet.

Right now the 400 f5.6 with taped extender gives decent performance auto focusing at f8, I was just curious about how good the firmware update was on the 1dx.

[rs]

Right now the 400 f5.6 with taped extender gives decent performance auto focusing at f8, I was just curious about how good the firmware update was on the 1dx.

I can't imagine it working - the firmware update is only a software workaround, pretty much equivalent of taping the pins on the TC - the hardware limits are still there. At f11 you are right up there at the physical limit of phase detect AF. The light coming in from the lens is theoretically too parallel for the left phase and right phase to be able to see anything. The AF sensors should get no light hitting them, just like a split-image focus screen goes black at smaller apertures.

Neuro - you said you've tried your 100-400 with a 2x TC:

I've used the 2xII with a 100-400L for 800mm f/11, on a 7D and 5DII.  Focusing was difficult even on a tripod.  Optical quality was not great, contrast was very low.  Stacked 1.4x TCs would be worse.

When you say focusing was difficult, do you mean manual focusing was difficult, or AF was difficult?

Skinfoot - just use a single 1.4x TC and crop the rest. AF will be verging on usable, and optically it will be superior to stacked TC's.

[skinkfoot]

Thank You rs that is what I wanted to know.