FFD question - Rollei Vintage lens

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doubleshot1

New member
HI, i'm in the market for a 50mm with a wide aperture for my 7D.

Whilst browsing ebay i spotted a Rollei 50mm 1.8 which seems to fit the bill nicely, however, unlike most vintage lenses from the pics it seems the adapter it uses doesn't seem to add any length to the lens which i imagine would mean i can 'keep' the 1.8 aperture rather than it being increased by a stop or so. I guess this is the first point i ask anyone to clarify for me if poss ;)

Second it is down to the FFD, i can't find any info on the lens and wonder id it would be compatible with my 7D or would it give me problems focusing?

Here's the link:

http://www.ebay.co.uk/itm/110797764607?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The adapter is belive, is already atached to the lens in the pics.

Ian
 
Not sure where you heard about "most" vintage lens adapters, but the truth is, unless you're using one with actual glass in it (which, if you are, you probably shouldn't be using a lens in that mount), you're not going to be losing aperture. Any M42 or Nikon F mount lens should be pretty safe. See, with those lenses compared to Canon EF, the normal distance from the original film plane and the lens was greater than the distance between the Canon EF sensor/film plane and lenses, so when you add an adapter that adds length, you're just bringing it back to normal. And if you DID go M42, you could get either the Super-Takumar 50 1.4, the SMC Takumar 50 1.4, and some others notably cheaper than you could get that Rollei.
 
thanks for the reply. Well, i figured that bearing in mind that aperture is directly influenced by focal length i understoof that by adding an adapter (which by design sometimes requires it to be sandwiched between body and and lens) i would lose a stop or two. Wheras if the original mount on the lens is small enough to allow for the adapter to be encased around its circumfernece, i wouldn't lose any stops.....

I guess firstly i would have to find out what the intended FDD was on the Rollei lens right?
 
It's 44.6mm there is no optical element so there is no light loss.

I think you need to do a little reading up on the subject.

Good Luck!

Dave
 
David W. Jones said:
It's 44.6mm there is no optical element so there is no light loss.

I think you need to do a little reading up on the subject.

Good Luck!

Dave
Click to expand...

Dave, thank you for the info i appreciate it but there isn't a need for condacending remarks is there? I hope to one day be as knowledgeable so I too that i can share my insight with others, and when that does happen i'll try not to forget that once, I too was in need of help and guidance.

Regards

Ian
 
Condescending remarks?

I gave you the information you asked about, suggested that you do a little reading on the subject, and wished you good luck.
 
doubleshot1 said:
thanks for the reply. Well, i figured that bearing in mind that aperture is directly influenced by focal length i understoof that by adding an adapter (which by design sometimes requires it to be sandwiched between body and and lens) i would lose a stop or two. Wheras if the original mount on the lens is small enough to allow for the adapter to be encased around its circumfernece, i wouldn't lose any stops.....

I guess firstly i would have to find out what the intended FDD was on the Rollei lens right?
Click to expand...

Maybe, maybe not; the thing is, as long as your adapter is glassless, you aren't altering the focal length, and therefore aren't losing aperture stops.

If your lens was designed for a camera mount with a farther infinity focusing distance than the camera mount you're adapting it for, you're in luck: you can almost certainly obtain an inexpensive, glassless adapter that will put in the necessary distance, and allow you to focus to infinity, and maintain the focal length & aperture opening. For this reason, people often look at M42 & Nikon F mount lenses; you can adapt them to just about any modern SLR. Same goes for Pentax K-mount and M39 and some others, but they're slightly less common.

If your lens was designed for a camera mount with a closer infinity focusing distance than the camera mount you're adapting it for, you have two options: lose infinity focus, and maintain the same focal length & aperture opening, or use an adapter with glass in it and gain infinity focus, but alter the focal length and lose some aperture.

If it's the latter, it's frankly just best not to use that lens with your camera. Canon FD, Hexanon, and Rokkor-mount lenses are well-known for requiring glass (and thereby losing quality & aperture) on Canon EF cameras.

(You also have a third option of actually modifying the lens to fit properly on the new mount, but in most cases that's costly, damaging, and time-consuming, and not worth the time or expense. People sometimes do it anyway on rare, exceptional lenses, or because the lens & modification is still cheaper than buying a lens of that focal length/speed in a more friendly mount. This seems to have been the case with the lens you linked to in your first post, but I'd say unless you're strongly attached to using Rollei glass, you can get better options for cheaper.)

Yet another option is to just get a camera with a very close infinity focusing distance, like NEX or MFT cameras. You can easily adapt just about any manual focus lens to these.
 
doubleshot1 said:
thanks for the reply. Well, i figured that bearing in mind that aperture is directly influenced by focal length i understoof that by adding an adapter (which by design sometimes requires it to be sandwiched between body and and lens) i would lose a stop or two. Wheras if the original mount on the lens is small enough to allow for the adapter to be encased around its circumfernece, i wouldn't lose any stops.....

I guess firstly i would have to find out what the intended FDD was on the Rollei lens right?
Click to expand...

An M42 lens is used at 45.5mm distance from film.

Canon is shorter than that, the adapter makes up the distance to set the lens at 44.2mm, as it was originally used. That is not increasing the distance, it is setting the correct distance.

Aperture is aperture, focal length is focal length. f/x is aperture ratio not aperture. 50mm f/2 has a 25mm lens aperture.

If you mounted it at Canon distance, you would be -decreasing- the distance from the image plane. And you probably wouldn't be able to focus the lens, since it'd be stuck beyond infinity. close focus would likely become infinity or close to it.
 
Just an FYI, don't remove the lens from the adapter carelessly, the aperture stop down pin needs to be pressed in with a finger before you crank it down all the way. Also, since the flange distance on Rollei QBM lenses are so short, sometimes the adapters aren't thin enough
 
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