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08-03-2011, 09:16 AM   #1
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Help with choosing a lens - looking at 50mm f1.4

Hi all,

I have been advised that a 50mm f1.4 lens would be great to have, as it lets in much more light than the two zoom lenses that came with my Pentax K-r.

So I'm looking to buy one, and it looks like you can get a second-hand 50mm f1.4 on eBay for around 100.

What should I be looking at/for? Some of those lenses are Ashai, some are Pentax, some Takumar, some say they have no autofocus, some say "M KA", others "PK-PKA-KR".

What should I be looking for so I get a lens that will work with my K-r and has autofocus? How do you know if you're buying a second-hand lens that's in a good condition?

Many thanks for any suggestions!

08-03-2011, 09:30 AM - 1 Like   #2
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Most of the lenses you mentioned are manual focus lenses that will have varying degrees of automation or lack of depending on the type, although they can pretty much all be used on your K-r.

If you want an auto focus lens currently the only option for a 50mm 1.4 (I believe) is the Pentax FA shown here: Pentax-FA 50mm F1.4 Reviews - FA Prime Lenses - Pentax Lens Reviews & Complete Lens Database

It averages around 270 dollars on the used market but is also available new.

If you'd like to learn more about how to use manual focus lenses on your K-r go here: https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...ml#post1140022

Note that depending on your desired application there may be more suitable options than 50mm, as the size of the sensor used in Pentax DSLR's is one where a lens in the 28-35mm range might be considered more of a 'normal' counterpart to a 50mm from the film era.

An inexpensive option with relatively good low light capabilities would be the newer DA 35mm 2.4 lens. https://www.pentaxforums.com/lensreviews/SMC-Pentax-DA-L-35mm-F2.4-AL.html
08-03-2011, 09:36 AM - 1 Like   #3
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to be quick :

You can get a 50/1.4 or 50/1.7, both are so great whatever the mount. But don't take a 50/2 not great as the 2 before, and around the same price thougt.

You can find the F50/1.7 or the FA/1.4 or FA50/1.7 (F or FA mean they have AF) for around 100-250€ so, according to current change market 90-220.

You can find the "A" version (No AF, but aperture setting can be done by the body) 50/1.7 for 50-120€ so according to current change market 40-110

You can find the "A" version 50/1.4 for 70-150€, 90-130.

or the K or M version (No AF, and Aperture must be set on the lense, the body will display "F--" in aperture value) both great 50/1.7 and 50/1.4 for 50-100€ or 40-90.


I have the A50/1.7 which is very good lense, very bright, quite cheap and easily available on ebay or website like it.
08-03-2011, 09:38 AM - 1 Like   #4
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To judge second-hand lenses: https://www.pentaxforums.com/forums/pentax-lens-articles/59245-pawnshop-lense...ers-guide.html

The Pentax AF candidates are the F50 and FA50, both f/1.4. Optics are the same; the F50 is rarer and costlier. US$150 is a good price for the FA50. The newest model is DA*55/1.4 and it's EXPENSIVE!

All the other Pentax Fast Fiftys are manual focus: K, M, and A are in Pentax PK bayonet mount; Asahi Takumar are all M42 screwmount. AF Fast Fiftys from other makers exist, but I haven't used them, can't discuss them, and AFAIK none is better than the FA50/1.4. That one is a must-have!

If you can forego AF, manual-focus Fast Fiftys are cheaper and fun. I use Catch-In-Focus; CIF is the non-rich-person's AF. But if you *need* AF, grab a FA50/1.4. Good luck!

08-03-2011, 01:38 PM   #5
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Thanks so much for all your replies, much appreciated and VERY helpful! Those of you that have manual/non-AF lenses: is it a huge pain in the butt not having AF?

And is the difference in picture quality/light/brightness really that big? I have asked the same question on a Pentax UK forum, and some of them say I should just increase exposure with my current lens (which is f3.5-5.6). Would that produce the same result in terms of brightness/bokeh/sharpness?

Thanks so much!
08-03-2011, 02:11 PM - 1 Like   #6
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MF is fine once you get used to it. But it suits those who don't have to photograph fast moving subjects. I wouldn't be without my AF lenses in a wedding or catwalk shoot.

Knowing your current lenses well will enable you to get the most out of them. So assuming you have the kit 18-55 lens, it is a reasonably sharp lens if used at f/8. Set any 'faster' (like f/4) and you may be disappointed with the results. Hence, a 'fast fifty' such as the FA 50/1.4 is a very good choice for low light and thin depth of field photography (great for portraits for example). It's probably the best value lens for that purpose but there are many other choices such as the Pentax FA 43 limited or FA 77 limited, which are even more highly acclaimed for all the aspects you were interested in.
08-03-2011, 02:26 PM   #7
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As Ash said, manual focus is nothing to fear. AF was only invented about 30 years ago, yet folks before then (including myself) managed to capture action shots.

Using a fast lens like a 50/1.4 is NOT like boosting ISO on a slow lens. Yes, both let you shoot fast-moving subjects, and in lower light. But raising ISO adds some noise to the picture. And a wide-aperture lens lets you control what is and isn't in focus: the infamous DOF (depth of field). I consider my FA50/1.4 as my gotta-get-the-picture! lens. I use other (cheaper) manual-focus Fast Fifty's when I'm not in a hurry, but when I still want the artistic DOF control. And with my delaminating eyeballs, I depend on CIF which I mentioned above.

Confession: I now own about 50 Fifty's, each with different qualities. Others here have many more.
08-03-2011, 03:52 PM   #8
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I think that in general, for a fast-aperture lens, the autofocus part of things is not as useful as you would think. Plus a 1.4 is really fun to manually focus.

The A 50 1.4 is often available for about 100 dollars, and it would be my pick for price performance king.

08-03-2011, 04:46 PM   #9
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I'll add what I say in other 50/1.4 threads: We don't use such a lens wide-open in order to have edge-to-edge sharpness, but to grab light and action, and to exercise creative DOF control. An AF or A-type 50/1.4 is great to use stopped-down when composing -- the wide-open image is nicely bright -- then hit the shutter and it stops-down to the desired aperture. At f/1.4 it lets in over 5x as much light as an f/3.5 lens. Your eye will notice the difference.
08-04-2011, 04:32 AM   #10
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QuoteOriginally posted by RioRico Quote
...At f/1.4 it lets in over 5x as much light as an f/3.5 lens. Your eye will notice the difference.
Thanks so much for that - that's what I thought too. I'll see what I can find on eBay and will let you know how I get on! Thanks so much for all the great advice!
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