[JeffJS]

I keep thinking about the 300 f4. Makes a 510 ~f5.8, yes?

Then I see the old Tamron SP 300mm f2.8 on eekbay for $500 and go hrm... (I have the SP 2x and the SP 1.4x, along with the SP 180mm f2.5). I used to rent that lens and got some stunning images with it...

Something like that. I would love to have the 180. I wanted a 300 f2.8 until I watched a FA*300 f2.8 blow right past any comfort zone of mine to $3500 (and that may have been cheap, I don't know).

[geekette]

Well I said "the best" because I figured any teleconverter would be under $100 lol.. Used to seeing them for like $30.

So which is the best one under $100? lol..

[jstevewhite]

Well I said "the best" because I figured any teleconverter would be under $100 lol.. Used to seeing them for like $30.

So which is the best one under $100? lol..

Well, that's a crapshoot. Rule of thumb goes 7 element 2x==good, 4 element 2x==bad.

I'd check ebay for one of the Tamron SP 2x; they weren't too bad. There are some Vivitar series one Macro Teleconverters that are pretty decent (but only sell for less than $100 occasionally). Or, go to your local used camera store and ask to see their TC junk bin, then go through the K mount ones until you find one that doesn't suck

It's worth noting that it can depend on the lens that's attached. I had an old Kenko POS for my Canon that was absolutely stellar with my 200mm f2.8, but was really terrible with anything else. And a Vivitar S1 Macro TC that was excellent with my Tamron 90, but terrible for long telephotos.

In other words, once you get outside the ones mentioned, you're just guessing. Most, though, will be crap.

[selar]

I have a Kenko 1.5x SHQ convertor thats very good, you can get that for a bit over $100, has the advantage of working with SDM as well. However, it doesnt modify the aperture, so you may have to use exposure compensation.

[Marc Sabatella]

Well I said "the best" because I figured any teleconverter would be under $100 lol.. Used to seeing them for like $30.

So which is the best one under $100? lol..

See my previous post; it's just that much more true now.

But if you really are just interesting in using it as a telescope and not taking pictures, then any TC will do fine - the viewfinder image isn't big enough to show much image degradation. Or get one of the "telescope" type lenses, which also aren't that good, but not so bad you'd necessarily be able to tell just looking through the viewfinder.