Well…yes, yes they are. I bought one a few days ago from Amazon (clicked through on Adam Carolla) for s’s and g’s. It arrived well packaged as usual today and I had to try it out. I chose the Opteka brand for a few reasons.
The only way however that I could test it under the exact same settings was this method. Which I must say I am quite proud of for coming up with. Please excuse the mess of camera equipment behind it I was playing around earlier. This image shows the camera with the following setup: Lens, M42 to FD adapter FD to EOS adapter By stacking these like such I was able to get the same effect as using an FD lens on the EOS camera but I was still able to do this: I used an M42 to EOS adapter (something that if you don’t own go purchase one now) and attached the lens directly to the camera. Without the need for any correcting optics like the FD to EOS adapter contains. The lens I used is an SMC Pentax Takumar 85 1.8. A lens that is so renowned for its construction, sharpness and overall quality that it still sells today (almost 40 years after production) for more than I paid for my Canon EOS 85mm 1.8 brand new by $100. A simply wonderful lens it is, well until you use the correcting adapter on it that is… Here are the two images from those two setups. Unfortunately the settings cannot be 100% perfect, because the correcting adapter kills 1 stop of light coming through and ads a 1.27x crop factor. But I made things as close as possible. Both times stopping down the lens for more clarity and sharpness. The photo on the left of my rediculously awesome lamp is using the lens with only the M42 adapter, the right image of my fantastically wonderful lamp uses the M42, FD, EOS combination. Please click the pictures for a full res. You can see the huge crop factor and what that does, combined with the crop sensor cameras that I and most people use makes many lenses way too tight. Also buying that f/1.4 lens isn’t so special now when the fastest your camera reads it at is f/2. Not to mention look at the insane chromatic abberation on photo with the correcting optic. This is something I probable wont use all that often truth be told. For $30 I don’t feel as if I lost anything, but I really don’t feel like I gained anything either.