Modified Canon 10-22mm lens

jgoetz4

Good Evening Folks,
After a lengthy discussion with the Bud Wieser sextuplets, :roflI decided to modify my Canon 10-22mm lens so I could use it on my 5D. Now, I know a lot of you are thinking, why take a $600 lens and risk damaging it ? Well, to be quite honest, it's not that much of a risk if you know what you're doing :wink If your wife or girlfriend calls you "all thumbs", then please do not read the rest of this thread. Basically, using a hacksaw with a new blade, set the lens to 22mm (avoid getting any shavings on the glass), keep the lens on a slight angle so that the shavings fall on the floor, and slowly cut the extended part off, while watching the contacts. Now, I know you can remove the ef-s mount & replace it with an ef mount after removing a few screws and performing a few desolder/resolder connections, if you happen to have an extra ef mount lying around. In my case, I didn't, that's why I cut the extended part off and attached my Kenko 1.4x. With the Kenko, the lens' rear element actually touches the tc at about 11mm (no problem), so now you have (basically) a 16-31mm ff lens with no vignetting. I don't believe this will work with a Canon tc due to the extended front element. I shot a few test pictures earlier tonight using my 5D, and they looked very good. I'd like to get a damaged 3rd party tc and remove the elements to see if that restores the full 10-22mm range. The tc "trick" also worked on my Tamron 17-50 2.8 (24-70 4.0) with out any vignetting or loss of image quality. I will post pictures in the next few days, work permitting :thumb
Thanks for reading and have a good evening
Jim...

Robinivich

That's pretty crazy!! Keep us posted on how it goes! I suspect the lack of extreme vignetting is more an effect of the teleconverter than it is the lens itself, but it'll be neat to find out at any rate.

I can't help but wondering what a tech would say if you ever had to send it in for maintenance

jgoetz4

Robinivich wrote:

That's pretty crazy!! Keep us posted on how it goes! I suspect the lack of extreme vignetting is more an effect of the teleconverter than it is the lens itself, but it'll be neat to find out at any rate.

I can't help but wondering what a tech would say if you ever had to send it in for maintenance

Good Evening,
I am a former Electronics Tech with over 10 yrs experience in that business He or she would probably think this must have been done during the "bad economy" years I wouldn't recommend this procedure to anyone who doesn't have at least common sense. It really is not that difficult. I remember reading an article on the net last year about an individual who modified an 18-55 ef-s for a 1Ds. He did the same thing. Cut off the extended part and used a 'blank" extender with no vignetting.
Have a good evening
Jim...

TaDa

jgoetz4 wrote:

Good Evening,
I am a former Electronics Tech with over 10 yrs experience in that business He or she would probably think this must have been done during the "bad economy" years I wouldn't recommend this procedure to anyone who doesn't have at least common sense. It really is not that difficult. I remember reading an article on the net last year about an individual who modified an 18-55 ef-s for a 1Ds. He did the same thing. Cut off the extended part and used a 'blank" extender with no vignetting.
Have a good evening
Jim...

Just curious why you didn't just get a 17-40? More reach in trade off for the extra mm. Oh, and no shrapnel of course

cabinetbuff

pictures or it didn't happen!

jgoetz4

Good Evening Folks,
Here is a shot from earlier tonight of a friends' house (sorry for the vertical view :cry) I was 19' (measured) from the back of the house. The house itself is about 55' long. Quite impressive, not only for the wide angle view, but also for the 3200 iso (check the exif)
Have a good evening
Jim...

jgoetz4

TaDa wrote:

Just curious why you didn't just get a 17-40? More reach in trade off for the extra mm. Oh, and no shrapnel of course

Good Evening,
Why spend the extra $550 (+-) when you don't have to
Have a good evening
Jim...

ziggy53

Teleconverters are made for telephoto lenses and using a teleconverter on a standard or wide-angle lens will produce unusual distortions as well as very soft corners and, in most cases, CA as well. If you crop to an 8x10 it will help the image dramatically by eliminating the extreme corners.

Of course at smaller image sizes it may not matter too much and it is a cheap way to get the wide effect (if you already have a compatible teleconverter, of course).

jgoetz4

ziggy53 wrote:

Teleconverters are made for telephoto lenses and using a teleconverter on a standard or wide-angle lens will produce unusual distortions as well as very soft corners and, in most cases, CA as well. If you crop to an 8x10 it will help the image dramatically by eliminating the extreme corners.

Of course at smaller image sizes it may not matter too much and it is a cheap way to get the wide effect (if you already have a compatible teleconverter, of course).

Morning Ziggy,
I am using the tc as a 'temporary' adapter until I can find another one, preferably one with damaged elements that I can remove, and use that one with the 10-22, and also, my 17-50 2.8. The 17-50 (24-70 4.0 using the tc) does have some barrel distortion at the wide end, but that's about the only issue so far. I'll be posting more pics later this week from both lenses.
Have a good morning
Jim...

Blurmore

That is some fiercely wack angle of view. You GO lenz haxor!

ziggy53

jgoetz4 wrote:

Morning Ziggy,
I am using the tc as a 'temporary' adapter until I can find another one, preferably one with damaged elements that I can remove, and use that one with the 10-22, and also, my 17-50 2.8. The 17-50 (24-70 4.0 using the tc) does have some barrel distortion at the wide end, but that's about the only issue so far. I'll be posting more pics later this week from both lenses.
Have a good morning
Jim...

Hey Jim,

If you remove the optical elements from a teleconverter it will become an extension tube. You will lose the ability to infinity focus and any lens mounted on it will become a close focus lens. Since zoom lenses are not especially well suited for close focus, especially not short zooms, the applications will be rather limited.

I can mention that while Canon EF-S lenses are not terribly well suited to your technique of using the teleconverter, other manufacturer "crop" lenses work somewhat better because they don't use the short back focus of the EF-S designs.

The reason is that of convergence. The EF-S 10-22mm lens has a much sharper convergence angle than, for instance, the Sigma 10-20mm "crop" lens. Teleconverters are designed for lenses with a very moderate convergence angle and the Sigma 10-20mm is a closer match to the optical design of a teleconverter. It's not perfect by any means, just better.

That's why your Tamron 17-50mm is working because it too has a "normal" back focus and convergence angle.

Yes, I 've been experimenting for quite a while now:

http://www.dgrin.com/showpost.php?p=700589&postcount=7

ziggy53 wrote:

...

I am able to mount the Sigma 10-20mm f/4-5.6 EX DC HSM on the Canon 1D MKII and pull a pretty nice 8 x 10 from the center (with some post-processing work in the extreme corners.) The equivalent of a 13mm rectilinear lens is just amazingly wide.

While I had also tried a 1.4x teleconverter with the Sigma wide zoom I was not satisfied with the results.

jgoetz4

ziggy53 wrote:

Hey Jim,

If you remove the optical elements from a teleconverter it will become an extension tube. You will lose the ability to infinity focus and any lens mounted on it will become a close focus lens. Since zoom lenses are not especially well suited for close focus, especially not short zooms, the applications will be rather limited.

I can mention that while Canon EF-S lenses are not terribly well suited to your technique of using the teleconverter, other manufacturer "crop" lenses work somewhat better because they don't use the short back focus of the EF-S designs.

The reason is that of convergence. The EF-S 10-22mm lens has a much sharper convergence angle than, for instance, the Sigma 10-20mm "crop" lens. Teleconverters are designed for lenses with a very moderate convergence angle and the Sigma 10-20mm is a closer match to the optical design of a teleconverter. It's not perfect by any means, just better.

That's why your Tamron 17-50mm is working because it too has a "normal" back focus and convergence angle.

Yes, I 've been experimenting for quite a while now:

http://www.dgrin.com/showpost.php?p=700589&postcount=7



While I had also tried a 1.4x teleconverter with the Sigma wide zoom I was not satisfied with the results.

Morning Ziggy,
Thank you for the informative explanation I know if I remove the elements from the tc, I have an extension tube, but still was considering the optical effect. As it is now, the lens starts at 12mm and not 10. I found an old Sigma 100-300mm lens (no, not the 4.0 version ) that I might take and remove the ef mount, and use that directly on the 10-22. I was playing around with a few test shots last night, and the sharpness at 22mm, wide open is unbelievable. I'll try and post one of them later. Thanks again for your help
Have a good morning
Jim...