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01-03-2011, 07:04 PM   #1
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Fast Fifty & Teleconverter - doable?

Can anyone tell me how a fast 50 (maybe and A 50/1.4 or 1.7) might stand up to being teleconverted with the A 1.4x teleconverter. Was wondering if such a combination might suffice for the (very) occasional shot at 70mm-ish. Don't think I need to drop five bills on the DA70 (as much as I might like to). Thanks in advance.

01-03-2011, 07:43 PM   #2
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QuoteOriginally posted by amalongi Quote
Don't think I need to drop five bills on the DA70 (as much as I might like to). Thanks in advance.
The TC should work, but you lose a stop, right?

If you are already looking at old lenses and TCs you might also want to consider an old 85mm ish lens. I quite like the screwmount 80mm lens I've been playing with. Overall it's no DA 70 as far as ease-of-use is concerned, but it was about 1/4 the price.
01-04-2011, 04:07 AM   #3
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Yeah, I know. I have a couple of K-mount lenses (including a beautiful K55/1.8 that my daughter is using) but I have to admit to being lazy. I much prefer the ease of use of the A lenses over the K/M lenses. I enjoy manual focusing - using the green button not so much.
01-04-2011, 09:49 AM   #4
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I have the M50/1.7 and I can tell you it held up quite well on the Vivitar 2X Macro-Teleconverter, so i would think the 1.4X would also be fine.

01-04-2011, 09:59 AM   #5
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on my "TO DO" list is an 85mm shootout.

I would compare my Vivitar 85F1.4 with my super takumar 85F1.9 and both my super tak 8 element 50mmF1.4 and SMC (K) 50mmF1.4 while using the 1.7x AF TC.

This gives me 4 real options at 85mm, the 50mm's would be effectively be F2.5 but it makes for an interesting discussion point in terms of a portrait lens.

the real interesting point iis whether either of the 50's with a TC and wide open are sharper at F2.5 than the two 85's,
01-04-2011, 10:21 AM   #6
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The teleconverter will make you lose 1.5 stops I believe. I would think that the image quality would be acceptable but not extremely good. I tried a vivitar 2x teleconverter not the macro focusing one and it was somewhat soft.
01-04-2011, 10:30 AM   #7
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QuoteOriginally posted by epqwerty Quote
The teleconverter will make you lose 1.5 stops I believe. I would think that the image quality would be acceptable but not extremely good. I tried a vivitar 2x teleconverter not the macro focusing one and it was somewhat soft.
Note that while you loose 1.5 stops with the 1.7x TC the pentax SMC-F 1.7x AF converter is an exceptionally fine teleconverter.

It will only really amplify the flaws of the lens itself. The problem is, many F1.4 lenses are a little soft wide open. Maybe however, this is not a problem as some people want a portrait lens to be a little soft wide open. the question is, at what point do the lenses perform equally, that is where a shoot out would be useful
01-04-2011, 11:20 AM   #8
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I'll kind of go against the grain here:

To me, a fast 50 was what original teleconverters were originally made for. A bit of extra reach when needed, acceptable light loss because of fast lens, and historically inexpensive.

Put a TC on a 200 and ehhhh.....at least you get the shot. But on 50, the results can be quite good, especially when you look at the balance sheet of your modified FL and the cost of a new lens.

01-04-2011, 04:48 PM   #9
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One more guy here who's been fumbling with a variety of fast fifties and 2x teleconverters. Compared to an old 105/2.8 Vivitar/Tokina lens, the results were on par, pretty much throughout my testing (including f/1.2 fifties). Mind you this was all done with 2x t-cons. That 105 Viv/Tok lens was decent, but nothing compared to the one-grand-and-rising class.

Conclusion: You just can't emulate a fast 70 - 110 lens. If you look at pics as well as test data from that class of lenses, you realize that this seems to be the best focal length to get the best possible results in terms of even performance throughout the aperture range. Referring amongst some very good Pentax lenses to: Zeiss ZF (ZE) Makro-Planar T* 100mm f/2 (on Canon EOS) - Lab Test / Review - Analysis. You just can't emulate it.

Workarounds:
- Plugging the 50 on the t-con and don't care :-) I did it and it gives you a decent mid-tele.
Exceptions:
- A 3x macro t-con on an already good near distance 50 (not what you asked for I know).
- A longish 50 lens like a 58/2 Helios. Get excellent exposures and crop the hell out of the pic :_)
- An 80ish enlarger lens. Slow, but you have a cheap 85mm :-)

Good luck,
Georg
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