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07-15-2009, 03:27 AM   #16
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Thanks. You are fantastic.

07-15-2009, 03:35 AM   #17
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Phil, you've got twenty K series lenses! So you're the one who got them all!

I can't fault your logic Phil as I have the K 200/2.5. The fact is price will almost always be a major factor is determining what people buy. In reality all the Pentax fast 200mm lenses are very good. I'm sure bigowl will be pleased with whichever model he finally opts for.

Tom G

Last edited by 8540tomg; 10-23-2009 at 05:29 AM. Reason: typo
07-15-2009, 06:30 AM   #18
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QuoteOriginally posted by GLXLR Quote
Does the * designation magically make the A* better optically? Not really. From what I have seen though, they look roughly similar.

f/2.5 f/2.8... ehh... 1/3 a stop at best, not a big deal. If you can find a deal for either of em, i would go ahead and just pick it up.
The A* has the ED glass. Does it make it 2x better than the K? I doubt it.
07-15-2009, 07:45 AM   #19
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I could be wrong on this, so feel free to correct me, but I recall reading at some point low dispersion glass doesnít make a significant difference in IQ until 300mm. Iíll probably get flamed for writing this one but the images Iíve seen from these two lenses appear to bear this out. This is hardly scientific and merely an observation based on what I have seen. The important point is both the A* 200/2.8 and K 200/2.5 are excellent lenses. You canít go wrong with either so if you can find one, buy the one that suits your needs and budget.

Tom G

07-15-2009, 08:51 AM   #20
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QuoteQuote:
Does the * designation magically make the A* better optically? Not really. From what I have seen though, they look roughly similar.

f/2.5 f/2.8... ehh... 1/3 a stop at best, not a big deal. If you can find a deal for either of em, i would go ahead and just pick it up.

The speed difference of f2.5 compared to f2.8 is bigger than you think, look at the
hype Pentax generated about the K50/1.2 when it was released in 1975. The world’s fastest lens and so on. It’s only f0.2 faster than the K50/1.4, yet it cost more than double. I have both of those 50mm lenses and they are totally different beasts, is one better than the other? Nope they are just different.
07-15-2009, 12:03 PM   #21
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QuoteOriginally posted by gofour3 Quote
The speed difference of f2.5 compared to f2.8 is bigger than you think, look at the
hype Pentax generated about the K50/1.2 when it was released in 1975. The worldís fastest lens and so on. Itís only f0.2 faster than the K50/1.4, yet it cost more than double. I have both of those 50mm lenses and they are totally different beasts, is one better than the other? Nope they are just different.
The difference from f/1.2 to 1.4 is 1/2 f-stop. The differnce between f/2.5 and 2.8 is only 1/3 f-stop, which is often considered to be within tolerable expsoure variations.

Ben
07-15-2009, 12:43 PM   #22
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I agree the speed difference of these two sets of lenses do not seem like much on paper or when you are using them, but they were a big deal in marketing and cost. Look at the price a K50/1.2 will fetch compared to a 1.4 and the status symbol it holds.
07-15-2009, 01:21 PM   #23
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QuoteOriginally posted by gofour3 Quote
I agree the speed difference of these two sets of lenses do not seem like much on paper or when you are using them, but they were a big deal in marketing and cost. Look at the price a K50/1.2 will fetch compared to a 1.4 and the status symbol it holds.
I was unclear in my reply. Indeed I find the 1/2 f-stop difference for the 50s quite noticeable and as such the 50/1.2 quite useful at times - and with APS-C sensors you can never have enough aperture to limit the depth of field. But the 2.5 versus 2.8 really lies within the acceptable exposure error range and I find that quite insignificant - but that's my personal view...

Ben

07-21-2009, 05:55 AM   #24
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QuoteOriginally posted by Blue Quote
A* lens are not auto focus nor are they weather sealed. Weather sealing is a DA* thing.




Edit: They both have 6-6 optical formula and both take 77mm threaded filters. However, the K has a minimum focus distance of 2 meters and the A* has 1.8 meter. The K weighs 950 grams while the A* weighs 850. The A* has ED glass. The A* is more likely to cost double or triple the price of a K.

Pentax Telephoto Prime Lenses
Duh - my bad!! I meant the DA*, not the A*. It was a bad day for me...
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