TCON 17 front/back filter thread.

[Warman]

I have a TCON-17 teleconverter and as most of you know it does not have a front filter thread, however i recently bought a skylight filter and i can attach it to the 58mm converter and attach the 58-55 step down ring and TCON 17.
What are the optical disadvantages of using the filter before the tele? Does anyone do it like i describe or is it totaly useless done like that?

[dbump]

I believe the disadvantage is potential vignetting. By putting the filter in between the two, you're moving the teleconverter further from the camera, effectively shrinking its aperture, relative to the lens. Not by much, but it may be enough, given the close tolerances.
It's easy enough to test!

[Warman]

Heum, i see. I only use it at full zoom and having tried it at that setting i didnt notice any vignetting so i guess im ok. Thanks for the info.

[dbump]

No problem!
I've heard that there is a more serious concern with using a polarizer between an adapter tube and a converter lens--the polarizer isn't designed for that kind of weight, and might separate at the rotating section, dropping your nice lens. You didn't mention a polarizer, but thought I'd throw that out there.

[Warman]

Glad that you did because i was assuming the same for the polarizer and am considering getting one. BTW, what about close up filters stacked toguether? like a +1,+2 and +4 to get +7? Not to use with the tcon of course.

[dbump]

Re: the polarizer, I think it can be done safely if you always support the lens with one hand--but I don't know that I'm dextrous enough to do that AND shoot
I haven't played around with macro filters yet (on the list), but I believe they're designed with stacking in mind.
Do you have a set yet? Like them?

[Warman]

I dont have yet, there is a hama set of 3 filters (+1,+2,+4) for sale at about 50 euros but that might be a little expensive i dont know. I was considering waiting to get a hoya +10.