Using Lens Doctor FD -> EF converter

Hi,

I recently purchased a Lens Doctor FD to EF converter, second hand. I've had some interesting issues, and was wondering if anyone could shed some light on this.

I tested the converter on my 7D with 2 lenses: Canon FD 50mm 1.4, and a Vivatar FD 200mm 3.5. The Vivatar looked great. No issues--exposure was correct, and the image was sharp, even wide-open at 3.5. However, the 50 1.4 had issues:

1. In both AV and M modes, the exposure was almost always too bright, by a lot, usually 2-3points off. That is, looking through the viewfinder the exposure meter, when in the middle, caused the picture taken to be too exposed. There was mention in a conversation between the Lens Doctor and the person I bought this from saying something about having to adjust exposure. But 2-3points seems very extreme.

2. The other problem is that pictures taken when opened 1.4-2.8 are VERY unsharp. Totally unsueable in any fashion. One could barely make out teeth when taken a portrait at this aperture. When at 4.0, the picture is pretty sharp. This is also the case when looking through Live View. The strange thing is, when looking through the viewfinder, the picture is very sharp. Perfect. Why the descrepancy between taken pictures and the viewfinder?

I doubt the glass in the converter is at fault since the pictures taken with the Vivatar lens are very sharp. Also I would expect if the glass is bad, that no picture would be sharp, even at smaller apertures. I am wondering if this has to do with some fancy electronics in the 7D adjusting based on lens information? The converter does have contacts to allow for focus confirmation, so maybe there is some incompatibility? I did try briefly taping up the contacts, and it seemed the problem was still the same. However, the test was brief, so not sure.

Also, from some brief googling, it appears that the Canon FD 50mm 1.4 is supposed to be pretty sharp. Not sure if it's only sharp > 4.0. But can it be ruled out that the lens is bad? Again, the picture looks perfect through the viewfinder. But for pictures taken at 1.4, it pretty much looks broken, not your typical "not so sharp cause of the large aperture" kind of look.

So, has anyone had these issues using FD -> EF converters?

If you're curious, the reason I'm going through so much trouble with this is because I asked my dad to give me his camera he used since I was a child (he doesn't use it anymore.) I can remember very well him and that camera--he took it everywhere that we went. I's very sentimental. I figured if I could take pictures through his lens, I'd remember him through the pictures. So, that's why I really want this to work.

Thanks for any help!

If you take a shot using the FD 50 on an FD body, how does it look?

S.Horton wrote in post #13551619
If you take a shot using the FD 50 on an FD body, how does it look?

haven't had a chance to try. probably won't for a while. i don't want to activate the camera before it's looked over by a professional. it hasn't been used in probably more than a decade, so i'm worried that something might break if i try to use it. (tell me i'm being stupid and i'll go ahead and try. It's a Canon A-1 btw.)

If it breaks, at least you'll know what to repair. If you get it cleaned and it breaks, same result. So, no risk, actually. Try it.

S.Horton wrote in post #13551985
If it breaks, at least you'll know what to repair. If you get it cleaned and it breaks, same result. So, no risk, actually. Try it.

okay cool, i will. but that would take weeks anyway (gotta get batteries, film, take shots, develop, etc.) any insight into this before trying? i understand that if the shots come out good, then we know the lens is good, and it has to be something with the converter or the camera. but well, i know i won't get to this for some time too.

Might be a silly question, but does the Lens Doctor converter adjust the apeture at all? if not, then you'd be shooting wide open regardless, so you've only got shutterspeed & ISO to control the exposure...

@OP I don't because I do not have that setup. I evaluated ownin FD glass and a converter, and concluded it wasn't worth it. The people here who helped me along will also stop by your thread, in time, and they do know.

joeseph wrote in post #13552037
Might be a silly question, but does the Lens Doctor converter adjust the apeture at all? if not, then you'd be shooting wide open regardless, so you've only got shutterspeed & ISO to control the exposure...

well, i can see the aperture blades converge when i move the aperture ring (since it's manual control on the FD lenses), and the converter has no moving parts.

also, as indicated, the picture does change when going 1.4 -> 4.0. alas, i can barely compare the oof area / bokeh on the 1.4 shots since it's soooooooo unsharp (yes, it's that bad), but as i said, the > 4.0 shots are pretty sharp.

so, i don't think the converter is stopping the aperture from changing.

edit: to clarify what i'm seeing a little, at 1.4-2.8, you can see a glowing haze around objects. kinda like if someone applied a heavy blur. it actually looks kinda cool, and could be used artistically, but pretty much unsuable in normal situations.

Xyclopx wrote in post #13552088
well, i can see the aperture blades converge when i move the aperture ring (since it's manual control on the FD lenses), and the converter has no moving parts.

I'm even more confused now, I thought FD lenses had apeture controlled by a moveable pin inside the lens mount that was controlled by the camera mechanism. Sounds like there's more to it!

joeseph wrote in post #13552182
I'm even more confused now, I thought FD lenses had apeture controlled by a moveable pin inside the lens mount that was controlled by the camera mechanism. Sounds like there's more to it!

oh right...

okay, the Lens Doctor piece has a rotating ring "LOCK<->OPEN". when you attach the FD lens to it, you move the ring to "LOCK". what that does is move the lens pin you're talking about 100% to the opposite side. when you do that, it goes from 100% max aperture -> aperture manually selected on the lens. does that make sense?

so, basically moving the pin back and forth on the lens toggles between 100% max aperture and the manual selection.

but in this case, the lens doctor adapter keeps the aperture closed up to whatever is manually selected, since the pin is always on the close position.

When using fd lenses with EOS adapters at large apertures they usually will always come out like you are describing unfortunately. They need to be stopped down before they look decent. Find a m42 mount 50mm with an EOS adapter (they work without the extra glass) and you will have sharp!

GregoryF wrote in post #13552293
When using fd lenses with EOS adapters at large apertures they usually will always come out like you are describing unfortunately. They need to be stopped down before they look decent. Find a m42 mount 50mm with an EOS adapter (they work without the extra glass) and you will have sharp!

oh really!? yes, this sounds like what i saw. hmm, any ideas why?

also, that explains the sharpness problems, but how 'bout the exposure issues?

do you happen to have links to more information about this off the top of your head? (saving me some googling time, ha ha)

edit: you know, if that's the case, i would assume the problem should go away if i take off the removeable glass pieces and use it as an extension tube. maybe i should try that then.

Xyclopx wrote in post #13552380
edit: you know, if that's the case, i would assume the problem should go away if i take off the removeable glass pieces and use it as an extension tube. maybe i should try that then.

you know that you would lose infinity focus then, right?

DreDaze wrote in post #13552984
you know that you would lose infinity focus then, right?

yes, i only meant this as a test to see if the glass in the coverter was causing the softness, which i suspected after someone mentioning that large apertures are always soft with these converters.

does anyone know why the converter would cause more softness at larger apertures? i would think if the converter causes softness, it would be the same amount, no matter the aperture. and again, the Vivitar 200mm was sharp. what's the difference with large aperture lenses?

also, i would note, this is not just being "soft." i mean, it's more like someone applied a very heavy guassian blur in photoshop. you could barely make out features like teeth on a person.

EDIT: also does anyone know why the image in the viewfinder is perfect, while pictures taken and the live view are bad?

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