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02-22-2011, 01:48 PM   #1
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Best K Mount Manual Tele-Converter?

I'm looking on KEH at the Vivitar manual tele-converters for K mount Pentax and I can't decide which one to go for. They have them from $4 on up. I do have a couple of Vivitar M42 ones ones and they're pretty decent for tele-converters. I am thinking maybe that's what I'll get in K mount.

I basically want it as an add on for my old manual Vivitar 75-300MM K mount zoom lens. Anyone know if the old Vivitar K mount ones are okay and if so which is the better option in those a 2X or a 3X? I'm looking to go as cheaply as possible, and the more modern digital tele-converters are definitely out of my range. I do want semi-decent, but I also need it fairly inexpensively too! Money is very tight right now.

I'm not much up on tele-converters so I thought I'd ask, see if someone might have a suggestion of an inexpensive one I should be looking for.

Thanks!

02-22-2011, 02:37 PM   #2
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I don't think you can beat the Pentax TCs. They're not cheap but they're worth the premium as far as I'm concerned.
02-22-2011, 03:30 PM   #3
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I don't think that a 2x-3x TC's are the best option no matter how cheap they are. they just degrade the image so much that it's not worth spending on them. if I were you, I would stay as low as possible and personally would vouch for a 1.4x TC. the cheapest one that is atleast good enough is the Pro-Optic brand. I think it's a knock-off of the Tamron AF TC version.
02-22-2011, 11:24 PM   #4
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A TC that's matched to a specific lens is one thing. A TC that's meant for *any* lens is something else, usually not good. You might try multitudes of TC with multitudes of lenses to find a matching set.

This assumes that image quality is important to you. A cheap TC on a cheap 400mm tube is fine for surveillance, blackmail, planning crimes, etc -- anywhere content is more important than quality. For instance, I could stack my two-each 2x and 3x TC's on my Rubinar 1000/10 mirror to give me a 10000/100 lens combo that's great for peering at... something way over there, I dunno what yet. Oh yeah, Area 51! Y'all can't get close enough with anything less.

More seriously: As mentioned, if IQ is important, don't go beyond 1.4x. With most greater TC's, you'd do better just to shoot with what you have, and crop.

02-22-2011, 11:53 PM   #5
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I'm guessing your 75-300 is somewhere around f/5.6 at the long end? Another disadvantage of a 2x teleconverter is that you lose 2 stops of light, which can make for a very dim viewfinder with slower lenses.
02-23-2011, 12:25 PM   #6
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The Kenko MC7 2x seems to me to be the best 2x tc of old. They are slightly pricier than others, but well worth the additional money. On some lenses the Kenko is markedly better than the mediocre Pentax K6T2, which on the other hand goes particularily well with the old Pentax K 300/4 lens.

The very best TCs are, in my optinion, the Pentax-A TCs, namely the 1.4x-L and 2x-L, followed by the 1.4x-S and 2x-S modells. The S-modells can be found considerably cheaper, than the L-modells, which are less versatile anyway.

Ben
02-23-2011, 12:38 PM   #7
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this has me thinking, I have the vivitar 2x-22 and 3x-22 teleconverters, a Takumar A teleconverter, and tamron and soligor M42 2x teleconverters.

I really ought to take my super tak 50F1.4 (version 1) and do some comparative testing. It may be enlightening.
02-23-2011, 12:42 PM   #8
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QuoteOriginally posted by RioRico Quote
More seriously: As mentioned, if IQ is important, don't go beyond 1.4x. With most greater TC's, you'd do better just to shoot with what you have, and crop.
not that it is relevant to MF teleconverters, but the sigma 2x (for very special and limiteed nimber of sigma and pentax fast long lenses is excellent. So is the SMC-F 1.7x AF converter.

02-23-2011, 01:48 PM   #9
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I have a Kiron 7-element 2x TC which is very good if used with a good lens. But as always with teleconverters crap lenses will produce twice as crappy images with it
02-23-2011, 01:55 PM   #10
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2x Macro Focusing TC (vivitar) PK/A mount.

02-23-2011, 02:02 PM   #11
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Here's a shot by a Canon L 2.8/300mm (converted from FD to PK) wide open combined with the aforementioned Kiron 7-element TC. Shot with K200D and very minimal pp added.


02-23-2011, 03:25 PM   #12
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QuoteOriginally posted by RioRico Quote
With most greater TC's, you'd do better just to shoot with what you have, and crop.
eversince camera makers started producing cameras with over 6MP resolution, the TC's seem to lose their value.
02-25-2011, 09:29 AM   #13
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You all have given me a lot to think about. Thanks!
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