Stupid stacked tele question

[nakey]

Tamron Adaptall 52A 70-210 F3.8-4 + Tamron Adaptall 01F 2x Teleconverter + some cheap no-name brand 2x PK Teleconverter that looks like the Kenko MC4 = ???

840mm F16? or did i get my maths wrong?

EDIT: The Adaptall lens does 1:2. The Adaptall Teleconverter makes it 1:1. Adding the PK teleconverter? 2:1???

[Lowell Goudge]

maths are all correct

the question is, image quality and light.

remember most lenses are not at their best wide open, and F16 is awfully small apature before you begin to stop down.

If I had to bet, I would guess that a 2x crop using only the tamron TC would be better than stacking both.

[nakey]

Originally Posted by Lowell Goudge

maths are all correct

the question is, image quality and light.

remember most lenses are not at their best wide open, and F16 is awfully small apature before you begin to stop down.

If I had to bet, I would guess that a 2x crop using only the tamron TC would be better than stacking both.

Yeah, i don't see myself using all three together, tbh. just a "what happens if i..." moment. i did buy the Adaptall TC to get 1:1 macro, but i bought the PK teleconverter for Tammy 70-300 + TC shits and giggles(didn't have a wonderful night beforehand, thought a little LBA shopping would do wonders for the soul).

Still, it couldn't hurt trying that for a moon shot :P