What is the flange?

[igor_jarm]

Hi,

 

I have a FD lens that I want to use on my EOS digital camera. I have a small

workshop so I can make all the parts needed for the makeover. I know the

flange to film distance for the FD is 42mm and for EF 44mm. What I don't know

is what exactly is the flange on a FD lens. The inner part where the aperture

levers are, or the outer ring that looks like a female side of a bayonet?

I know next to nothing about mounting the FD lens, but it seems to me the

inner part is what actualy doesn't rotate - here I'm thinking of the things I

read about FD breech lock system that has no wear on the flange precisely

because of not rotating, but the outer ring simply looks like a flange to me.

So, which is it?

 

Thanks.

[awahlster]

The flange is the chrome ring the very outer step on a FD lens.

 

what you refer to as "outer ring that looks like a female side of a bayonet"

 

what you will have to do is move this surface 2mm towards the front of the lens to be able to mount an FD lens on an EF mount body.

 

Or you will have to sink the mating surface on the EF body 2mm towards the film plane.

 

Good luck. by the way while I have heard of this being done with one or two lenses in the past it is a VERY difficult thing you attempt.

[walter_degroot]

there is som,eone who posted here. and did the conversion

what you got was a manual lens that could never be used on a fd again.

the cost was not low either.

you run the risk of destroying the lens.

 

I realize that new eos lenses and all current lenses are pricesd as if thay were made of platinum.

what we really need is a digital FD mount camera.

[roger_kallet]

Igor,

 

Check in every now and then and tell us how you're doing.

 

Good luck.

 

Roger

[mad reilly]

I just read a big article about this. I thik it was on www.photonotes.org (If I offended the webmaster by putting up another web site please accept my apologies I won't do it again) I was thinking about this myself (big investment in lenses only to toss them later) They article mentioned that there is a few third party lens adaptors out there and that Canon even produced a few but only to a select few "pro" photographers with some serious telephoto lenses. I believe I read that the diameter of the FD lens is a bit smaller than an EF mount as well as the film plane to lens dimention. Long and short, the people who did this have had mediocre results. Any way the article had some good info. Good luck

[igor_jarm]

Thanks for the answers all is clear now.

 

I know what I will do is pretty much irreversible damage to a perfectly good lens, but I realy don't plan to buy any FD camera.

 

I successfuly took apart the mounting part of a lens and isolated the part that needs the change. The change needs some planing and precision but it realy doesn't seem that difficult.

 

My plan is simply to remove the chrome ring, mill the remainder for a bit more than 2mm and attach on it the EF bayonet. What I don't like is I will probably damage or destroy the red dot, I realy like it :)

 

The only thing that worries me a bit is I have to use the part with the aperture levers because it contains a glass element and there's not enough space for the EF bayonet. I'll probably have to mill this one too. I'll use an m42 to EOS converter and bore the 42mm hole to a larger diameter. I'll have to shorten the levers too.

 

I will post my progress as I go, but it may take a little while.

 

Thanks again.

[awahlster]

You might as well remove the levers since they will serve no purpose once you've altered the lens. Of course you will need to figure out some way to lock the aperture so that you can change it.

[pvp]

The flange, technically, is the front of the mounting ring on the camera body. The flat surface that the lens mounts against, is 42mm from the film in FD cameras.