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Wednesday, January 7, 2009

Canon 200mm f1.8 lens

My new camera lens is a World fastest telelens, Canon EF 200mm f1.8L.
Here is some information:
This lens has best difraction limited optical quality I have seen.
Lens is used in SuperWASP project, actually eight of them:
The model I bought is electronically focused, so there is no mechanical link between lenses and
focusin ring. After lots of thinking I ended up to modify the lens for the astro work.
Opening up and messing with electronic and mechanic of the expencive lens was not a
easy decision, but it was the only way to use it with my new astrocamera, QHY9.
  • removing the original Canon bajonet
  • cutting off all the wires between the lens and the bajonet
  • soldering an extencion cord between the lens and the bajonet
  • attachment of the M42 ,75mm thread to the lens end
Aftger the modification I can use any EOS Canon body to powering up and adjust the lens
Images of the modification:

Original wires are cutted and extencions soldered in.
Canon bajonet with cutted wires. Extencion cords are soldered to the bajonet. M42 ,75mm thread is attached to lens end.
Allmost ready assembly.
As you can see from the images I used the lenses filter holder as a route for the cords.
(The canon holder is too small for 2" astronomical filters.)
After final image I wrap some aluminium foil around the lens end to
prevent any light leaks. The foil was then attached with
Black tape around it.
After the modification the lens can be controlled with any unexpencive EOS body.
I build a power source for the EOS body, so there is
no need for the batterys.


Unknown said...

Really great to see an experiment,
i have also 200mm1.8lens in dead condition,i wants to repair it, can you suggest me any one good repairer?
i need your help please help me for repair the same.
pravin indrekar

J-P Metsavainio said...

Hi Pravin,

I'm sorry, I don't know any names for repairer.
I think, you should contact to a local, official, Canon service.


Nathan Kugland said...

Birger Engineering ( makes a Canon EF lens interface that powers the focus motors of this lens without having to do surgery. About $1k and works great.

J-P Metsavainio said...


It's way too expensive for my purpose though. (My "surgery" for the lens, is reversible.)