Stretch factor changes with focus

[Devon]

When using an anamorphic adapter (like SLR Magic's 1.33x,) does the stretch factor DECREASE or INCREASE when focusing close-up?

Thanks!

[Grimor]

Usually projector 2x attachments change stretch when focusing.

I have owned only a 1.33x (optex) and the stretch differences are not noticeable.

[dhessel]

I have never used this particular lens but all of the anamorphic adapter I have used decreased as you focused closer. For example I had a Kowa 16H that was 2x at infinity and about 1.8x at min focus.

[GiM_6x]

Theoretical it should not change, the optical formula is afocal (as for every lens...).

But as with any lens, it will have an maximal angle to accept, and if the original lens exceed it (as for close-up focus or for a zoom to wide range), the image will be affected and somehow "limited" on the strech side which will diminish.

So, it depend, if a very good adapter for that lens - no changes, else if it is somehow at limit between the lens' angle and what adapter can acomodate - might afect limiting the final image who is streched.