No 2X extender for 70-300mm L Series

[TexinAfrica]

I just found out that the Canon externders (models II or III) will work with most ranges of zooms but not the 70-300mm L series.  I assume this must be due to it's "trombone" design or some issue related to it's compace size.  Can someone elaborate?   Thanks.

[neuroanatomist]

The Canon extenders have a front element that protrudes forward, so a complatible lens must have a space between the lens mount and the rear element (i.e. the rear element must be recessed) for the lens to be compatible with the extender.  The 70-300mm L has a rear element that comes right to the lens mount. 

Canon extenders are compatible only with L-series primes of 135mm and longer, and L-series zooms starting at 70mm, with the exception of the 70-300 L.  There are 3rd party extenders (e.g. Kenko) that do not have the protruding element and are compatible with most Canon lenses.

[jalbfb]

The Canon extenders have a front element that protrudes forward, so a complatible lens must have a space between the lens mount and the rear element (i.e. the rear element must be recessed) for the lens to be compatible with the extender.  The 70-300mm L has a rear element that comes right to the lens mount. 

Canon extenders are compatible only with L-series primes of 135mm and longer, and L-series zooms starting at 70mm, with the exception of the 70-300 L.  There are 3rd party extenders (e.g. Kenko) that do not have the protruding element and are compatible with most Canon lenses.

I have the Kenko x1.4 and it works just fine with my 70-300L just as neuro stated.  It's a lot less in price as well compared to Canon extenders

[smirkypants]

Canon extenders are compatible only with L-series primes of 135mm and longer, and L-series zooms starting at 70mm, with the exception of the 70-300 L.  There are 3rd party extenders (e.g. Kenko) that do not have the protruding element and are compatible with most Canon lenses.

I hate to be a conspiracy theorist, but it seems lots of things that Canon is doing lately is to push people to buy more expensive equipment. The f8 problem keeps people from putting extenders on lower-priced f4 and f5.6 zooms, and the 70-300 won't take an extender at all.

Just, you know, sayin'...

[5dmk.iii]

Canon extenders are compatible only with L-series primes of 135mm and longer, and L-series zooms starting at 70mm, with the exception of the 70-300 L.  There are 3rd party extenders (e.g. Kenko) that do not have the protruding element and are compatible with most Canon lenses.

I hate to be a conspiracy theorist, but it seems lots of things that Canon is doing lately is to push people to buy more expensive equipment. The f8 problem keeps people from putting extenders on lower-priced f4 and f5.6 zooms, and the 70-300 won't take an extender at all.

Just, you know, sayin'...

Agree all they way. Crippling the F8 AF was very low from Canon. Push the pros who can afford it, but for the hobbyists, it's cruel....

Just as a side note:  there's a review of the 70-300L, where Mr. Farace HAS used the 2x iii with the 70-300mm albeit in MF mode and fixed to 300mm  (so that there is no love making between the 2x protruding element and rear element of the 70-300L).

http://www.shutterbug.com/content/canon-ef-70-300mm-f4-56l-usm-long-short-it

Beware though: if used in AF more or less than 300mm, you could damage the lens or the extender... so I would not recommend doing it unless you know what you are doing. In this lens, the element moves during focussing as well, so even in MF mode... be very careful !

[Mt Spokane Photography]

Canon extenders are compatible only with L-series primes of 135mm and longer, and L-series zooms starting at 70mm, with the exception of the 70-300 L.  There are 3rd party extenders (e.g. Kenko) that do not have the protruding element and are compatible with most Canon lenses.

I hate to be a conspiracy theorist, but it seems lots of things that Canon is doing lately is to push people to buy more expensive equipment. The f8 problem keeps people from putting extenders on lower-priced f4 and f5.6 zooms, and the 70-300 won't take an extender at all.

Just, you know, sayin'...

There are a lot of Canon patents for the rear lens focusing.  They are supposedly able to make a lens smaller, lighter and with improved IQ, but the Canon TC compatibility is lost.
 
Since its mostly a f/5.6 lens, A TC is not going to AF except with the older 1D series bodies. 
 
It is a compromise.  Do you want big, heavy, and more distortion, or give up TC compatibility.  I'll take losing Canon TC compatability, since I can get a Kenko.  There is no work around for the weight, size, and IQ.

[Marsu42]

I hate to be a conspiracy theorist, but it seems lots of things that Canon is doing lately is to push people to buy more expensive equipment. The f8 problem keeps people from putting extenders on lower-priced f4 and f5.6 zooms, and the 70-300 won't take an extender at all.

There are a lot of Canon patents for the rear lens focusing.  They are supposedly able to make a lens smaller, lighter and with improved IQ, but the Canon TC compatibility is lost.

We had these discussion just 1-2 weeks ago (use the search :-)) - you can get the Kenko and tape some pins to get f8 af, but it will be slow. So Canon might not have done this just for marketing purposes, but also to prevent people stating that their bodies have a crappy (f8) af. But of course, Canon wants to sell their expensive stuff, thus the 70-300L has some iq drawbacks on ff.

In general, I got the 70-300L since about one month and am extremely happy with it. It's no "shoot in the dark lens", but these have a very thin dof to begin with, but it's got a very good size-weight-iq-af-zoomfactor-buildquality-price combination.

[dr croubie]

you can get the Kenko and tape some pins to get f8 af, but it will be slow.

Actually, since I got the Kenko (Pro300 DG, there's a lot of other different versions, your experience may vary) 1.4x, I've figured out that you don't even need to tape pins.

If the lens takes canon extenders (ie like a 70-200L), then it has 10 pins.
If it has 10 pins, then the kenko converter will translate Fmm and f/ properly, ie 70-200 f/4 becomes 100-280 f/5.6.
If it has 7 pins (like my 70-300L), then the kenko is "invisible" to the camera, ie, the EXIF data still reads 300mm f/5.6, even though it's 420mm f/8 in reality.
So the camera "tries" to AF, but unless it's in very bright sunlight (even if it is), it hunts and fails a lot because the aperture is just too narrow (for my 7D at least).

But hey, seeing as I already had the 70-300L, adding an extra $100 wasn't bad for a Manual Focus 420mm f/8 IS lens on top.

[Marsu42]

you can get the Kenko and tape some pins to get f8 af, but it will be slow.

Actually, since I got the Kenko (Pro300 DG, there's a lot of other different versions, your experience may vary) 1.4x, I've figured out that you don't even need to tape pins.

Afaik, only the updated "DGX" converters need the taping hack since they modify the lens' (exif) data. But since you've got the 70-300L too: Have you used it on a crop camera? How is the iq - does it worsen so much that it's better to stay @300mm, keep the af and crop the picture?

[wickidwombat]

if you can find an older kenko DG 1.4 teleconverter that does not report aperture it will still report the lens as f5.6 to the camera and you will keep AF but i think it will slow down
the new current model DGX converters report aperture so need the f8 AF of a 1D I used the kenko DGx with my 28-300 and 1D3 for ages and it worked great so i imagine the 70-300 will be just fine too.

[briansquibb]

A 2x would make it F11. Not very useful methinks as you are talking of defraction before you start

The Tenko 1.4 is fine on the 1D4

[TexinAfrica]

I appreciate the help from all.   I'm a bit new to this process so let me clarify.  I understand the Canon TC will not work.  Several explained why.  Thanks.

However, it appears the Kenko 1.4 will work but struggles with auto focus in dim light. It will work fine on manual focus?   I would prefer to avoid taping any conductors (it's that anal engineer in me)  Thanks from lovely downtown Luanda, Angola.

[wallybarthman]

I've owned a host of teleconverters including both the DG and DGX Kenko models.

If you buy the newest models (DGX) you do not need to tape pins.  The aperture and focal length will still report correctly but the Kenko does not cause the AF to be deactivated. 

If you buy any other reporting teleconverter (Tamron SP, Kenko Teleplus Pro DG) you would need to tape pins. 

If you buy any other non-reporting teleconverter you won't need to worry about it. 

My suggestion is the buy the Kenko Teleplus Pro 300 1.4x DGX teleconverters.  No taping, but your EXIF data will be correct. 

[Marsu42]

However, it appears the Kenko 1.4 will work but struggles with auto focus in dim light. It will work fine on manual focus?

Of course mf will work fine - but personally, I'd find that tricky for wildlife and the standard viewfinder screen of my 60d which makes the dof larger than it actually is (this problem has gotten me a lot of "what did I think?" pictures).

Afaik, the problem with af and small aperture is not (only) that the little light left, but that the *phase* af gets problems while *contrast* af in live view might work fine.

the new current model DGX converters report aperture so need the f8 AF of a 1D I used the kenko DGx with my 28-300 and 1D3 for ages and it worked great so i imagine the 70-300 will be just fine too.

... and ...

If you buy the newest models (DGX) you do not need to tape pins.  The aperture and focal length will still report correctly but the Kenko does not cause the AF to be deactivated. 

@wallybarthman: Are you using a 1d body which does af @f8? Because what you're saying is the opposite of everything else I ever read of putting a 1.4x tc on a 5.6 lens and using it on a non-1d eos body!

[DianeK]

But since you've got the 70-300L too: Have you used it on a crop camera? How is the iq - does it worsen so much that it's better to stay @300mm, keep the af and crop the picture?

I find the IQ even at 300mm is very good and so I just crop instead of using an extender.  I have a 60D. The image below is a severe crop, only 1/3 the original size.
Diane