Life Size Adapter for Canon Macro Lens

I have a Canon macro lens (FD 50 mm 1:3.5 SSC), and it came with

this little "Life Size Adapter" attached to it. It comes off, and

appears to be little more than a big hollow tube. Anyway, I did some

research online and can't find ANY information on what this thing is

or does. (I'm mainly trying to figure out if maybe the fact that

it's just a hollow tube means it may be missing parts). Using it on

my AE-1 while attached to the lens hasn't revealed anything to me

yet.

 

Any ideas?

This "life size adapter" is what is otherwise known as an extension tube -- that is, it extends the distance between the lens and the film plane, in effect focusing closer.

 

The FD 50mm macro will focus to one-half life size. Meaning that at its closest focusing distance, it can produce a full-frame image of something that is twice the size of the 35mm film frame (which is about 1" x 1.5", so 2X is 2" x 3"). A 25mm extension tube, such as the "life size adapter," will take it down to a 1:1 ratio; it can focus on a subject that is 1" x 1.5", same as the film frame.

 

Bottom line: leave this thing OFF your lens most of the time. Just use the lens alone. If you find that you want to focus even closer on a subject than the lens alone will permit, THEN attach the tube between the lens and the camera body.

Thanks David!

 

I *thought* it might just be a fancy term for 'Extension Tube'....

In my MF days I had successively the 50/3.5 FL, FD-SSC, and nFD macros, and each of them came with a 25mm extension tube - which was perfectly useable with other lenses as well. I think by the time the nFD came along they had given up printing LIFE SIZE ADAPTER on the tube. The FL version had one distinctive feature that justified the name: it rotated the lens top-to-bottom, revealing new focus/ratio and aperture scales that allowed for the extra extension given by the adapter. Neat.

I suspect that the maximum aperture linkage in the FD version would make that very expensive if not impossible to do. The FL version only had the one stop down lever to link with.

The Life Size Adapter is an extension tube designed to give the early model 50mm a 1 to 1 capability. Newer models of the macro came with a tube that linked with the camera aperture so you can use full open aperture metering. Mine is also the oldie like yours. The optics didn't change,just the tube... You can upgrade at modest cost, if you wish,by seeking and buying the following item if you can find it: Canon extension tube FD-25U. It will have a spring loaded lever inside to do the work in connecting the lens to the camera's mechanism. If you never get up real close to your subject,then forget it and use the lens without. Some of the Carl Shipman out of print but findable books on Canons explain all.