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03-24-2011, 10:59 PM   #1
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K50 1.4 or A50 1.7 ?

The A50 1.7 was my first 50mm, and I love it. I now have a chance at getting the K50 1.4 and was wondering if it is worth getting and replacing my A50 1.7.

I did research and am still confused. The K-series has its reputation of being excellent glass all-around, and I assumed them to be greater than their M/A/Takumar counterparts (which got me into this). The reviews here (and other forums) of the K50 are positive, as expected, but the A50's are just as positive and don't really compare them. I checked Takinami's lens tests, and the A50 seems to be sharper than the K50 overall. People glow about the K50 1.2 (and the K-series in general) and, assuming all K's were created equally nicely, I'm guessing the K50 1.4 performs at about the same level. I also read that the K and M versions of the 1.4 share the same optical formula, inferior to the one used in the A and FA version. From the time spent on this forum, it seemed to me that people found the K and M variants of Pentax lenses in general optically superior to A and FA variants. Are the 50's exceptions to this "rule"?

I can't find enough info to make a conclusion. Anyone have experiences/knowledge with these lenses to help me out? The A50 1.7 has been my only 50mm and I don't have many lenses to compare to--does the K50 1.4 have awesome qualities that would be worth buying/replacing the A50 1.7?

I'm losing sleep over this!

The "A" features of the A50 1.7 are nice, but I wouldn't miss them. They are not a factor in this decision.

03-24-2011, 11:14 PM   #2
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The K50mm should be a bit sharper, but I'd say the difference is negligible at best. I wouldn't worry about upgrading unless you want to step things up to an A 50mm F1.2. Alternatively, you could look for an FA 50mm F1.7, which IMO is the sharpest non-macro Pentax 50.

QuoteOriginally posted by MobiusOne Quote
The K-series has its reputation of being excellent glass all-around, and I assumed them to be greater than their M/A/Takumar counterparts
When the K-series first came out, there were no "star" or "pro" lens series. There weren't really any budget or compact lenses, either, so overall quality was high.

Most K lenses are optically identical to corresponding screwmount SMC Takumar lenses (the 50mm being a prime example), and many M lenses are also based on the same optical forumlas, their main distinctive feature being a streamlined barrel design. It wasn't until the A series that Pentax started playing around with plastic and new optical formuals to create true budget lenses. Thus, more variety in IQ surfaced. You'll notice that while the A 50/1.2 and /1.4 (I think) have metal barrels, the /1.7 and /2 have plastic ones. The IQ degrades similarly

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03-25-2011, 01:46 AM   #3
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or a cheaper K50f1.2 (cheaper than A50f1.2)

I compared K50f1.2 @f1.4 with FA50f1.4 and M50f1.4. The K50f1.2 is a bit sharper at f1.4, which is a click down.

My M50f1.7 and A50f1.7, @f1.7 and @f1.8 have a bit larger/thicker DOF than the 50f1.4 at half click down. I use my A50f1.7 for light weight and daily/overall use, but FA50f1.4 is for multi purpose kids/action/travel use.
03-25-2011, 05:23 AM   #4
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Thanks for the info, guys! I guess this was my knee-jerk reflex to the possibility of me landing a K lens, which I always thought to be impossible given the availability and increased prices.

Based on this, I'm teetering towards not getting the K 50/1.4. Sounds like the "upgrade" between the A 50/1.7 and K 50/1.4 is marginal at best and saving the money waiting for a good deal on a A or K 50/1.2. If its optically identical to the corresponding takumar, am I better off getting the takumar to save money (assuming that Takumars tend to go cheaper)?

Heck, I should probably just stick with the A50 1.7, shouldn't I? Versatile for everyday use. But the K has 8 blades of bokeh goodness! And possibly better color rendition? The A 50 is satisfactory, but the possibility of better? Argh, LBA

Speaking of which, I want to throw in a third lens into this: the K55/1.8. The general consensus seems to be that this thing is ridiculously sharp and was wondering if this is worth possibly replacing the A 50/1.7.

03-25-2011, 05:40 AM   #5
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I have neither K50 1.4 nor A50 1.7 but I do have M50 1.7 and FA50 1.4

It is nice thing to have automatic metering (at least if you shoot with DSLR). Other than that I could say that both M50 1.7 and FA50 1.4 give excellent photos both on K10D and K-7. Actually it seems that the resolution of both lenses is at least as good (or better) than K-7 sensor resolution of 14 Mpixels.
03-25-2011, 05:49 AM   #6
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I had both of them, although for very brief period and not at the same time. IQ wise, I'd say K50/1.4 is better. It has nicer OOF, and more pleasing contrast and colours (to my eye). One huge disatvantage of K series is the green button metering. K-7 is reprted to be better than K10/20 but the exposure errors are still there. Ideally, have both
03-25-2011, 05:50 AM   #7
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The A 50mm 1.7 is a very sharp lens--I tend to agree with Takinami's test. The K50 1.4 is sharp wide open (unlike the M, A and FA versions of the 50mm 1.4), and has a nicer bokeh than the A 50mm 1.7 (which is also pretty sharp wide open). K55 1.8's bokeh is also more pleasing than that of A 50mm 1.7. Otherwise, frankly, talking in terms of sharpness about A50 1.7, K50 1.4, K55 1.8 is splitting hairs. Other aspects--color, for instance--are more important. The A50 1.7 has a kind of brownish cast and warmer colors. I prefer the colors of the K's.
03-25-2011, 06:15 AM   #8
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Just keep the A50f1.7, go and get the K55f1.8 and/or A50f1.4. The f1.4 delivers beautiful bokeh and commonly available for cheap. A50f1.2 or K50f1.2 is almost ten times fold. At f1.2 I consider it is for a special case from time to time. My use of 50s is mostly at 1.8, but whenever I grab the f1.4, somehow, I stick with f1.4 and find cases that I can use at f1.4 ;-)

03-25-2011, 09:09 AM - 1 Like   #9
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These are my answers to suit my needs. There isn't a "best" answer for all users unless all users have identical needs. Take them as you will.

I like to buy, try and sell lenses, so I currently own or have owned at some time the following normal lenses, beginning in 1977.
K50/1.4, Super-Tak 50/1.4, SMC Tak 50/1.4, M50/1.4, M50/1.7, FA50/1.4, A50/1.4, K50/1.2, M50/2.0, SMC Tak 55/1.8, K55/1.8, Auto-Tak 55/1.8
Generally speaking, across the range, ALL Pentax normal lenses produce excellent reuslts in general photography. They excel at certain specific tasks, which vary by maximum aperture. These are my observations:
  • Pentax f/1.7 normal lenses were instentionally designed to offer a comparatively flat field and sharpness across the field, and to be used for flat work (photographing text subjects on a copy stand when that was how printing negatives were made).
  • Pentax f/1.4 normal lenses were intentionally designed to offer more pleasing bokeh than f/1.7's. As a consequence they tend to lose sharpness at the corners at large apertures.
  • Pentax f/1.2 lenses were intentionally designed to be the penultimate normal lenses, sharp at almost any aperture, with potentially the finest bokeh simultaneously.
  • Pentax f/1.8 lenses were intentionally designed as a great compromise between flat field and pleasing bokeh.
  • Pentax f/2.0 lenses are the smae optical formula as the f/1.4's (I thnk) [EDIT: Axl in the post following corrects this to f/1.7] but were intentionally crippled by adding internal baffles so that maximum aperture is limited to f/2.0. They were marketed as budget lenses, but they still produce great images at middle and smaller apertures.
Larger max-aperture lenses are easier to focus in low light and can capture a sharp image with less ambient light than their smaller max brethren, if that is important to you.

Optical sharpness distinctions between these lenses are rarely apparent to me when producing prints in sizes smaller than 8x10. By f/8, sharpness distinctions between these lenses largely disappear altogehter. For those of us who don't make a living selling gallery-sized prints of our photographs the lens choice is somwewhat irrelevant.

The big differences are aesthetic - and subjective.

The coatings formula used on these lenses changed over time, so that color rendering from one optical-formula-identical lens series to the next has also changed (Super Tak >> SMC Tak >> K >> M - and even within the series), and color rendering may become a decisive factor.

The construction philosophy and materials evolved over time, so that Takumar lenses are pleasing to use to some, but overly heavy to others. "A" lenses, though having the electrical contacts to make metering efficient in newer cameras, may have plastic components that aesthetes (like me) don't care for.

There really isn't a right answer other than the answer that suits your needs and desires.

Personally I enjoy using K cameras and Takumar and K lenses because I like the way the experience of taking a photograph feels and sounds with that equipment. Sometimes M cameras and lenses are small enough that my large hands and fingers aren't comfortable with them. If I lose some tiny bit of photographic perfection (which I doubt) by making K film and manual-metered digital my choice, that's my compromise.

For my K10D (soon enough to become a K-5) I use the FA50/1.4 for my AF normal lens (we'll forgo that debate over whether the FA35/2 is the "New Normal" for a crop-sensor DSLR), so I really don't need the A50/1.4, but I would buy an FA50/1.7 if I came across one).

Last edited by monochrome; 03-25-2011 at 01:05 PM.
03-25-2011, 10:24 AM   #10
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Couple of things as reaction to above:
There are 3 families of Pentax 50s:
1 - the big guns - this includes all f1.2 and 50mm f1.4 lenses and FA43/1.9
2 - the standard issue lenses - this includes 50/1.7, 55/1.8 and 55/2 lenses
3 - the starters - here ar 50/2 lenses

Group one has 7 elements in 6 groups and between 8 and 9 aperture blades. The general consensus is there are slight tweaks to the formula between 1.2 and 1.4 lenses and FA43. All of these lenses produce great OOF and have marked difference between corners and center sharpness untill around f2.8

Group 2 has one element less at the back of the lens and they all have 6 nlades. There are slight tweaks between the 50 and 55mm versions but the basic layout is the same. As mentioned, these lenses produce flatter field and as result slightly more even sharpness across the field on larger apertures. The 55/2 is optically identical to 55/1.8 but has internal ring that restricts the f stop wide open to f2. In general these lenses are well regarded workhorses and many say they are above Canikon's slower 50s in all aspects of IQ. The OOF rendering on these lenses is good but not as smooth as in group one and stopped down the 6 bladed aperture shows in hexagonal highlights.

Group 3 keeps 6 blades but replacet the cemented doublet found in groups 1 and 2 by single element. As result layout is 5-5. This group only contains M50/2 and A50/2. According to many these are the worst Pentax 50s but still very capable lenses, comparable to other brands' 50/1.8s and souch.

I can't comment on group 3 as I never owned those lenses. From group 2 I had K55/1.8, A50/1.7 and F50/1.7. Main difference is in coatings and/or used glass. K55 is very warm, F50 quite cold and A50 was somewhere in between. All three were really great little lenses.

From group one I owned/tried K50/1.2, K50/1.4, FA50/1.4 and FA43. Again biggest differences is in colour reproduction and contrast. FA43 is warmes and most contrasty, followed by FA50 and Ks, K50/1.2 is very PF resistant (at leat my copy was). 43 has bussiest OOF wide open but by f2.8 these are pretty much indistinguishable IMO.

So what to pick? Generally speking people consider the ladder this way:
1 - K/A50 f1.2
2 - FA43
3 - K/A/F 50/1.4
4 - F/FA50 f1.7
5 - M/FA 50 f1.4
6 - K55/1.8
7 - M/A50/1.7
8 - K55/2
9 - M/A 50/2

Many say A50/1.4 is the best f1.4 Pentax 50. And F/FA50/1.7 have nearly cult following. And the f1.2 versions are pretty much untouchables even if some owners of FA43 would argue

Good luck choosing, sorry if I confused you

Regards
03-25-2011, 11:36 AM   #11
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Whoa, we need to rename this thread "The Complete Guide to Pentax 50s"! Thank you all so much!

All of this information is exactly what I wanted and more, especially from monochrome and axl. You did the opposite of confusing me. During the entire day, I deliberated over whether the K50/1.4 would be worth getting on this rare opportunity for me. This info definitely eased my mind in justifying the purchase and whether I'm getting bang for my buck or not.

By the way, where would you place the SMC/Super Takumar 50/1.4 on that ladder?
03-25-2011, 01:14 PM   #12
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QuoteOriginally posted by MobiusOne Quote
. . .

By the way, where would you place the SMC/Super Takumar 50/1.4 on that ladder?
Heh - are you going to enforce a no-fly zone when the revolt starts later in this thread?

First, Axl's response is much more technically correct and organizes your choices by actual characteristics of the lenses. My response drives to personal preferences. (While I read Takinami and the comments on Stan's, those rankings are academic to me. I like what I like why I like it.

I'd also suggest you review some of the Lens Club Threads here such as Takumar Club, The 50's Association, K,M,A,FA Clubs. Each thread has many examples taken with normals.

Of the lenses I listed before I still have:

Auto-Takumar 55/1.8 - goes with my "K," so not dispensable
K50/1.4 (1977) - goes with my KX, my college graduation present

Super- Takumar 50/1.4
S-M-C Takumar 50/1.4
SMC 55/1.8
FA50/1.4

If forced to choose one of these and dispose of the rest I would keep the S-M-C for all the subjective reasons I described above.
If forced to choose one lens from the entire list of available Pentax normals I would choose the 43/1.9.

Last edited by monochrome; 03-25-2011 at 02:03 PM.
03-25-2011, 02:22 PM   #13
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Very nice Axl.

The review section does not explain the 50s as good.
QuoteOriginally posted by MobiusOne Quote
we need to rename this thread "The Complete Guide to Pentax 50s"!
I am in for this idea.

Across the lines T/K/M/A/F/FA and may be DA* too?
03-25-2011, 04:00 PM   #14
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QuoteOriginally posted by MobiusOne Quote
During the entire day, I deliberated over whether the K50/1.4 would be worth getting on this rare opportunity for me. This info definitely eased my mind in justifying the purchase and whether I'm getting bang for my buck or not.

By the way, where would you place the SMC/Super Takumar 50/1.4 on that ladder?
I'm glad I could help.
Personally I'd get K50/1.4 any time I could afford it again. I only sold it (along with it's big brother K50/1.2) becaouse I got in real dire straits with cash flow and decided with new baby and no split scree the FA43 will have to do... For now anyway but speaking about bang for your buck, you'll get plenty, as long as you can live with green button metering

Regarding Taks, well I'm not too big on them (mainly because I'm not keen on M42>K adapters and most Taks were small which equals relatively slow) but from my understanding SMC Takumars should be the same as K series, S-M-C use different coatings and super taks and taks obviously don't sport SMC. Also there is an early version with 8 elements, very sought after and highly valued (if seller and bidders know what they are dealing with ). And then there are other 50ish Takumars but I really don't know much about them, so I'll leave that for others (perhaps Asahiflex would shed a light on this matter)
03-25-2011, 04:08 PM   #15
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QuoteOriginally posted by hoanpham Quote
Very nice Axl.

The review section does not explain the 50s as good.

I am in for this idea.

Across the lines T/K/M/A/F/FA and may be DA* too?
Thanks,

The DA* is different beast alltogether, at least in K land. It has 9 elements in 8 groups, sorted 3+1+doublet+3. Pretty much unlike anything else in this range, and one more (and differently placed) than FA*85 (which is meant to replace). Problem is that unlike Photozone.de or dpreview.com, I wouldn't consider DA*55 to be normal lens. So called normal lenses or nifty 50s as we sometimes fondle them were designed to produce certain FOV on 135 format. DA* wasn't it was designed to act as specialized portrait lens on APSC format, providing different FOV on this (native to it) format than older 50/55 were supposed on 135 (native to them) format. For this reason I wouldn't compare DA* to older 50ish lenses but rather to 70-85mm portrait lenses of film era...
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