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Old Sep 6, 2007, 4:13 PM   #1
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So I've been using my SMC-A-50mm f1.7 manual focus lens a lot lately. Really love it, super sharp. Hate even thinking about parting with it, but an upgrade to the newer and auto focus FA 50mm f1.4 for a small cost.

I know a couple people here just "upgraded" to the FA 50mm lens.

Someone reassure me that the new FA 50 will be as sharp as my old 50.

Thanks

Fred
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Old Sep 6, 2007, 4:34 PM   #2
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I just received my FA 50mm f1.4 and must say that it may not be sharper than my M 50mm f1.7 but the bokeh is better and I have a much higher rate of in-focus images thanks to the AF.

Ira
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Old Sep 6, 2007, 7:08 PM   #3
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Hi Fred,

All the f1.7s are generally a little bit sharper wide open than the f1.4s, but as Ira mentioned, AF can make a significant difference regarding percentage of in focus shots with razor thin DOF lenses, so you might get better overall results.

The FA 50 f1.4 also can possibly exhibit some focusing anomalies in artificial light as opposed to sunlight, but IMO, it's worth the tradeoff. It seems that all the DSLRs have this problem to some extent with very fast lenses, and it's being addressed in new models with "fast lens" AF sensors, so this might become a thing of the past with future Pentax DSLRs. Mine doesn't do it (as far as I can tell) with either the DS or the K10, but I've seen some comments from very discerning shooters, so I guess it's possible.

Scott
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Old Sep 8, 2007, 9:06 PM   #4
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Thanks for the comment Ira and Scott.

Fred
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Old Sep 9, 2007, 2:20 AM   #5
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I have both and i use the a 1.7 most the time as i love the focus feel, has no ca wide open and is sharp wide open. I use the FA 1.4 when i need the AF and it works so well at f4 with the Pentax 360 flash or even on board flash to give extremely sharp pics. To be honest i would not sell either as both have different strengths and uses. I also have a M50 1.7 i use on a film camera.

Tony
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Old Sep 9, 2007, 4:46 AM   #6
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TC3 wrote:
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I have both and i use the a 1.7 most the time as i love the focus feel, has no ca wide open and is sharp wide open. I use the FA 1.4 when i need the AF and it works so well at f4 with the Pentax 360 flash or even on board flash to give extremely sharp pics. To be honest i would not sell either as both have different strengths and uses. I also have a M50 1.7 i use on a film camera.

Tony
I have the F50mmF1.7 (same optics as the M version ) after selling off my FA50mmF1.4 . Before that I did some test. The difference was so subtle that I could hardly tell them apart. I like the 1.7 older look. I do not collect lens otherwise I would have kept the FA.
F4 is the sweet spot for both as it has reached 95% of the sharpness already. All F1.4& 1.7 are great.

Daniel
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Old Sep 9, 2007, 9:28 AM   #7
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I just got hold of a M 50mm f1.4 and as far as I can tell, it shows a little more CA and flare wide open than my A f1.7

Do note that this is minimal, and only noticable if you "pixel peep".

Sharpness wide open is very good with both lenses, and incredible at f4.

I would only differentiate the two by easy of use, and then I'd say M < A < FA. And that's probably why their prices are in that order aswell...

I'll do a more extensive test this evening and post the results in this forum.

Tom
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Old Sep 29, 2007, 1:39 PM   #8
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I just registered for this group and did a quick search. So far have been unable to locate any specific information pertaining to the following:


Is anyone using the Pentax SMC-A-50mm f1.7 (or the 1.4, for that matter) with a K10D? How do the two marry? Is it a good union?


Am hoping someone on this thread can pick me up and provide some insights.


Thanks in advance,



1freek





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Old Sep 29, 2007, 3:07 PM   #9
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1freek wrote:
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I just registered for this group and did a quick search. So far have been unable to locate any specific information pertaining to the following:


Is anyone using the Pentax SMC-A-50mm f1.7 (or the 1.4, for that matter) with a K10D? How do the two marry? Is it a good union?


Am hoping someone on this thread can pick me up and provide some insights.


Thanks in advance,



1freek




I occassionly use my 50 f1.7 on my K10D. Works very well, and due to the K10D having a better viewfinder than my DL2, I can focus it spot on as well.



Used with an autofocus 2x converter, it makes a sharp 100mm "almost" macro lens.



Dal
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Old Sep 29, 2007, 3:33 PM   #10
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The differences normally should be subtle and might depend on the individual lens. I did a test some time ago and my FA 1.4 was clearly sharper than my F 1.7, which wasn't good at all wide open. Stopped down a bit the difference was gone.

But can someone please explain to me why you should compare the two lenses wide open. IMO it is more relevant to compare them both at f1.7, and then consider the f1.4 as an extra bonus with the faster lens. Most people seem to se it the other way, but I've never understood why.

Kjell
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