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02-26-2010, 12:54 PM   #1
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best 50mm for K-x aps-c

so im intrested in a pentax smc-a 50mm 1.7. they go for about 100 bucks on ebay and i really like the shallow dof of fast 50s. im getting confused with all these references to crop factors and sensor types. i figured i could try a A 50mm 1.7 and if i dont like it, step up to the DA 50mm 1.4.

any suggestions. should i just bite the bullet and go straight for the da 50mm 1.4?

TIA
Jorge

02-26-2010, 01:00 PM   #2
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For a non-film shooter, crop factor shouldn't matter at all. 50mm is 50mm is 50mm.

A 50/1.7 is a good choice. very very sharp wide open, and cool color rendering. If you like the OOF stuff what you should compare also is the bokeh; the 1.4 and 1.7 are quite different. Search around in flickr for different shots from these two lenses. People say 1.4's bokeh is better, but some also say that it doesnt get good until it hits 2.8.... I've used both and I prefer the 1.4 myself even below 2.8. The 1.7 has a pretty unique bokeh though. I personally ended up trading the 1.7 and keeping my 1.4.

Personally I'd go for the A first, you can always sell it if you end up not liking all this 50mm stuff. Best is if you can get a good deal on F 50/1.7 with a broken filter ring so you can get autofocus.

The Tak, K, M, A, F, FA versions of all these 1.4 and 1.7 lenses should be optically the same.
02-26-2010, 02:40 PM   #3
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I got an A 50 f1.7 first, then decided that for me the manual focusing was more trouble than it was worth. But lots of people love it, so it's not a bad idea to get an inexpensive used copy to try out. You won't lose much if you resell it.

After that I got an FA 50 1.4, then an FA 50 1.7. I kept the FA 1.7 because I found it sharper than the 1.4 up until 2.0, and I don't really ever shoot between 1.4-1.7 anyway. Bokeh-wise, they were a little different, but I didn't have a real preference one way or another.
02-26-2010, 03:07 PM   #4
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I have just sold some of these in the marketplace and haven't put my next ad up, so count me as very biased.

I think the 50/1.7 is the best value/quality mix among 50mms. Choose the M if you want the lowest price, A if you want more convenience and F if you need autofocus. They retain their resale value well so if you don't use it or find a reason to upgrade, it won't cost you. The FA50/1.4 at current prices would make me think a lot harder about getting it outright.

02-26-2010, 06:24 PM   #5
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I have read that the M 1.4 is not as sharp as any of the other 50mm Pentax lenses.
02-27-2010, 02:08 PM   #6
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Note there is no 50mm lens in the DA series. There are K, M, A, F, FA, and D-FA 50's (the later being an f/2.8 macro), and a DA*55, but no DA50.

I concur that unless you need autofocus, the f/1.7 versions usually represent the best value- not much more expensive but very cleary better optically than the f/2 versions, much cheaper and arguably just as good as the f/1.4 versions. But if you need AF, it might take a while to track down an f/1.7 version.
02-27-2010, 02:47 PM   #7
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QuoteOriginally posted by Marc Sabatella Quote
Note there is no 50mm lens in the DA series. There are K, M, A, F, FA, and D-FA 50's (the later being an f/2.8 macro), and a DA*55, but no DA50.

I concur that unless you need autofocus, the f/1.7 versions usually represent the best value- not much more expensive but very cleary better optically than the f/2 versions, much cheaper and arguably just as good as the f/1.4 versions. But if you need AF, it might take a while to track down an f/1.7 version.
I also agree that if you don't need AF, the A50/1.7 is probably the best value. They can usually find them for $80. I think it's worth the extra $30 over the M50/1.7, although the build quality of the A isn't as good as the M.

If you want AF, I'd try picking up an F50/1.7. They usually go for a little under $200. The FA50/1.7 version is the same optically but typically sells for 25-50% more because it's (much) more rare than the F50/1.7.

Personally I prefer the 1.7 to the 1.4 since I found the 1.7 to be sharper below 2.8, espeically if you don't use a lens hood (since the 1.7 front element is more recessed than the 1.4 front element). Here's a quick comparison of the 1.4 vs 1.7 from when I owned both the FA50/1.7 and FA50/1.4.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/81528-fa50mm-f...mm-f1-7-a.html

FWIW, I actually sold both since then and now have an F50/1.7 and an A50/1.2
02-27-2010, 07:48 PM   #8
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Pretty much the same here: I owned the A 1.7/50 but replaced it with the F-series version because I got a good deal for it.
But optically they are absolutely the same. And due to the 140 focus throw manual focusing is easy. The A series absolutely represents the best value.

Still the f/1.4 lenses give smoother bokeh because of the 2 additional aperture blades.

02-27-2010, 07:57 PM   #9
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I would suggest look for the F 1.7 as it would be better value for the money now as it has AF and the manual A's are getting pretty expensive for a manual that was selling for around only $50 before.
I see F 50mm 1.7 for $150.
02-28-2010, 08:39 AM   #10
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QuoteOriginally posted by GerryL Quote
I would suggest look for the F 1.7 as it would be better value for the money now as it has AF and the manual A's are getting pretty expensive for a manual that was selling for around only $50 before.
I see F 50mm 1.7 for $150.
do you have a link???

TIA
12-05-2010, 10:48 PM   #11
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Why do you want a 50? I'm going to guess it's for it's fast aperture. If this is the case, and therefore you are looking for some nice bokeh, please look at the 1.4's more closely. You need to stop the 50 1.7 down to get good sharpness out of it, and the OOF areas quickly turn into hexagons which can be rather distracting. Yes, this 1.7 is sharper, but the overall image is more busy and distracting in my experience.

I'm going to go out on another limb and suggest you look at an autofocus lens, because frankly, manually-focusing one of these 50 1.7's can be a pain in the butt. It's certainly not impossible, but the stock screen tricks you into seeing a larger depth of field than is actually captured at apertures under 2.8, and it can get frustrating. For super low DOF, it's nice to have a computer zip to the subject's eye, instead of fumbling for it yourself while your subject loses interest.

I quite like my K55, but I have missed more shots with it than I have gotten, because people move around, stop down metering is slow, and focusing is hit or miss. The A 50 1.7 I find quite the crap shoot when it comes to focus, although metering is a breeze. I can focus the K55 much better than the 50 1.7.... but they never made an A version of the 55 .

I've been playing with an FA 50 1.4 for a few days, for over twice the price that I paid for both of those other 50's combined, but I can already tell that this one is going to be far far more useful in practice. Lens tests be damned, the 1.4 is just plain HANDY with it's auto focus, and if you stop all three of these lenses down to f2, the 1.4 beats the 1.7 and is on par with the 1.8 IMHO. The differences between lenses past f2.8 are pretty much only seen in the out of focus areas, with all the lenses being nice and sharp, but the 50mm 1.4 rendering more circular bokeh due to the 8-bladed aperture.

For f4 and beyond, the FA 50 is sharper, but the DA 40 actually beats it. The 50's are most useful (to me) for mild telephoto and portraiture, all shot under f4 (often below f2.8). This is what makes 50's special to me.

Strongly considering selling the manual primes and keeping the FA 50 1.4. It just makes life a lot easier, which is worth the price of admission to me.
12-06-2010, 12:45 AM   #12
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Best is 43mm ltd. Second best is 40mm ltd.
12-06-2010, 01:13 AM   #13
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QuoteOriginally posted by Andi Lo Quote
For a non-film shooter, crop factor shouldn't matter at all. 50mm is 50mm is 50mm.
A 50mm lens on a K-x with be equivalent to a 75mm lens on a full frame/35mm camera. I have a 50mm 1.7-M on a K-x, looks good for $50.
12-06-2010, 08:49 AM   #14
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I wish i still had the eyes for manual focus
12-06-2010, 09:33 AM   #15
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The best 50mm for pentax cameras all depends on what you're req'ts are. the more that you're willing to pay the more automatic the lens becomes. And in most cases the more expensive.

The tak and K 55/1.8 are great lenses available for around 50 USD's. You can get a helios 44M 58mm for around 25-30 it is supposedly a great lens. or you could spend more and get what is a good compromise of price and functionality (the a 50mm/1.7). Or you could get AF also. But I'm a little unsure of the 50mm focal length to start throwing a lot of money at it. For 80-100 I can get a fast lens with excellent quality and not have to deal with stop down metering.
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