Lens tubes operation and effect

Fotal · Expire: 2013-08-21

These questions are really about offsetting the lens from the camera body but much in the way a lens tube does it. I've never tried tubes myself even though I got some M42 ones but I'm still waiting on a M42->EOS adapter I have ordered.

To my understanding tubes are used to basically turn an ordinary lens into a semi macro lens.

My logic tells me that you would also loose infinity focus at the same time but by how much? Is it possible to tell how far a lens will focus depending on the tube used?

Also, are there any other effects that will emerge when offsetting the lens from the camera body?

It's only fair that I tell you the real reason for this question.
I'm thinking on using old (read cheap) Canon FD-mount lenses with a
no glass FD to EF adapter for some close focus or "macro" work.

What do you think? Bad idea?

Richard_D · Joined: 21 Oct 2007 Posts: 2378 Location: Faversham Kent UK

There's a recent thread on using M42 lenses on a Nikon in which Rick gives the formula for calculating maximun focus when lenses are mounted beyond the normal register difference.

Fotal · Expire: 2013-08-21

thanks Richard!

Also, I found this a table related to EF lenses:

http://bobatkins.com/photography/eosfaq/closeup.htm

While the macro work would be fine I had hoped for a better focus distance.