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Thinnest FD to EOS adapter?
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PostPosted: Wed Apr 26, 2023 5:14 pm    Post subject: Thinnest FD to EOS adapter? Reply with quote

I really want to use some FD lenses on a APSC Canon and I know that with the glassless adapters I'll loose focus beyond more or less 3m for a 50mm lens. (Still enough for portrait)
The thinner the adapter, the further I'll remain able to focus, so my question is has anyone maybe already done the testing and is able to tell which is the thinnest adapter available? I've been looking but they really all look the same.
The lenses I intend to use go from 55 to 300mm.
Thanks guys.


PostPosted: Wed Apr 26, 2023 8:15 pm    Post subject: Reply with quote

The problem is the design of the FD mount. It's a breech bayonet, or in other words, the bayonet is on the camera, and the lens has a sleeve that locks onto the bayonet. So it's not just a matter of the shorter registration distance of the FD mount relative to the EOS mount. The mechanics get in the way.
Bottom line: your best option is some sort of conversion. See: The Lens Doctor.. DIY may be an option, depending on the lens. A partial disasembly of the FD mount, leaving the inner part on which you attach eg a M42 to EOS adapter could suffice.


PostPosted: Thu Apr 27, 2023 6:42 am    Post subject: Reply with quote

Phalbert, when I checked my glassless FD to EOS adapter on my 5D today, these were my results (from subject to sensor plane):

With a zoom lens focal length at 55mm and f/4.5, maximum focus distance was about 48cm.
With a 55mm prime lens at f/2.8, maximum focus distance was about 36cm.
Zoom lens at 300mm and f/4.5, distance was about 7.5m.
300mm prime lens at f/6.9, distance was also about 7.5m.

The lenses I used are all properly calibrated for infinity focus, so I'm not sure why there's a difference between the zoom and prime lenses at 55mm..?

My adapter is a made in China no-name and it's the only one I've tried. The adapter is 15.7mm thick - including the mount bayonets / lugs.


#1


PostPosted: Thu Apr 27, 2023 7:16 am    Post subject: Reply with quote

55 wrote:
Phalbert, when I checked my glassless FD to EOS adapter on my 5D today, these were my results (from subject to sensor plane):

With a zoom lens focal length at 55mm and f/4.5, maximum focus distance was about 48cm.
With a 55mm prime lens at f/2.8, maximum focus distance was about 36cm.
Zoom lens at 300mm and f/4.5, distance was about 7.5m.
300mm prime lens at f/6.9, distance was also about 7.5m.

If those distances are roughly right the OP's ~3m MFD for a 50mm must have been with the lens held directly against the cameras mount!
Not so usable for portraits Rolling Eyes


PostPosted: Thu Apr 27, 2023 11:11 am    Post subject: Reply with quote

55 wrote:
Phalbert, when I checked my glassless FD to EOS adapter on my 5D today, these were my results (from subject to sensor plane):

With a zoom lens focal length at 55mm and f/4.5, maximum focus distance was about 48cm.
With a 55mm prime lens at f/2.8, maximum focus distance was about 36cm.
Zoom lens at 300mm and f/4.5, distance was about 7.5m.
300mm prime lens at f/6.9, distance was also about 7.5m.

The lenses I used are all properly calibrated for infinity focus, so I'm not sure why there's a difference between the zoom and prime lenses at 55mm..?

My adapter is a made in China no-name and it's the only one I've tried. The adapter is 15.7mm thick - including the mount bayonets / lugs.


#1

Remove the FD mount from the adapter and fix it to a thin M42->EF adapter may be the trick.


PostPosted: Thu Apr 27, 2023 6:35 pm    Post subject: Reply with quote

ah, the age-old question.
you might gain a millimetre or two by building your own adapter, by using a very thin adapter like Nikon F -> EOS and filing it off so that FD lenses and their extending parts fit flat against it. if this is at all possible.
Canon themselves came up with nothing better than a glass adapter with 1.26x extension factor and corresponding light loss. it is well reputed, as opposed to all other glass adapters, but very expensive today, rare, and still contains glass, i.e. SOME quality loss.
if anything better existed, we would know about it by now (for two decades, FD lenses were very cheap, and EOS SLRs were THE standard, so everybody tried to save on 85/1.2s and 24/1.4s, but with no general luck.


PostPosted: Fri Apr 28, 2023 8:06 am    Post subject: Reply with quote

Thanks everybody. This is all very wise and - bad news. Kathala, you sumarized it perfectly.
Somehow I had figured the max distance for a 55mm would be 3m. Can't remember how but I was wrong. 7,5m for a 300 is not worth it either. I think I just wasted a few bucks on a cheap adapter.
There is the edmika conversion, but it's not really cheap for a not-so-great/rare lens. (too much for me)
There is this too:
https://fdtoef.com/shop/
Any experience / feedback on that conversion?
Thanks.


PostPosted: Fri Apr 28, 2023 9:16 am    Post subject: Reply with quote

I think prices of $100-150 for a conversion are getting close to what you would expect to pay for a used APS-C mirrorless camera that would solve these problems for a lot of lenses, without modifying them.

For longer lenses you would probably want a viewfinder (instead of just the screen for focusing/composing) and IBIS - that might get more expensive.


PostPosted: Fri Apr 28, 2023 9:30 pm    Post subject: Reply with quote

Phalbert wrote:
Thanks everybody. This is all very wise and - bad news. Kathala, you sumarized it perfectly.
Somehow I had figured the max distance for a 55mm would be 3m. Can't remember how but I was wrong. 7,5m for a 300 is not worth it either. I think I just wasted a few bucks on a cheap adapter.
There is the edmika conversion, but it's not really cheap for a not-so-great/rare lens. (too much for me)
There is this too:
https://fdtoef.com/shop/
Any experience / feedback on that conversion?
Thanks.


Is it worth buying only one of those fully reversible fdtoef.com kits to try on several lenses?


PostPosted: Sat Apr 29, 2023 12:29 pm    Post subject: Reply with quote

They can / do differ from lens to lens and I see they are just as expensive as edmika's.

MartinV, yes there are other ways. Thank you.


PostPosted: Fri May 05, 2023 11:00 am    Post subject: Reply with quote

this might be a slightly religious statement, but with FD lenses become ever more valuable, and alternatives/workarounds becoming ever easier - do your (future) self a favour and just buy an EVIL camera. in ~2oo8, someone butchered a 24/1.4 and bragged on fora how he saved himself a grand in difference to the price of the EF version. fifteen years later, he'll have lost many times more with his butchered lens: an original costs 5-1ok by now.

and at the same time: 161 USD today is more than twice the price of a lens like the 5o/1.4. the money will be wasted, even if the conversion is reversible. if you just want "a cheap lens", buy something chinese. otherwise, again, an EVIL and a standard adapter.


PostPosted: Fri May 05, 2023 7:02 pm    Post subject: Reply with quote

Kathala, please explain the evil camera, evil lens thing. My culture doesn't reach that far. 🤷â€â™‚ï¸


PostPosted: Fri May 05, 2023 7:14 pm    Post subject: Reply with quote

EVIL camera http://camera-wiki.org/wiki/EVIL