[gofour3]

When you say "blown away" what are you comparing it to? A kit lens? Or another 50mm? I don't have an apples-to-apples comparison for you, but I will in a week. I have a K 55mm/1.8 on the way, and I have two M 50/1.7s and an A 50/2. These I have had for almost two decades, though only know really using on DSLR and comparing critically. I also have a K 50/4 Macro on the way.



This is what I am finding as I grow my 50(-ish, counting the 55) collection.

Between the two M50/1.7s I have no difference. Between the M 50/1.7 and the A 50/2, I see no difference, just like what m42man just said - I see nothing special in the M 50/1.7 and I have two copies I've tried. It's good, very good. But no different vs. a 2 except the f-stop. But based on "buzz" I am really excited to see what the 55/1.8 does and the 50/4. From what I can extrapolate the 55/1.8 should be much more interesting than the 50/1.7.

As to metering, I find my A 50/2 and M50/1.7s meter exactly the same in AV for the A and stop-down with the M. I have run some tests on that at every f-stop. Maybe there is something peculiar about the 55/1.8? Anyway, I am going to do some head-to-head comparisons in about a week.

I am betting what I will eventually do is get an A 50/1.4, and keep that and the K 50/4 macro, sell the others. I bet I will keep the 55/1.8 for novelty value. That is my bet now; we'll see how it plays out in a month's time and lots of tests.

I feel that way, too. I bet in a year or two I will spring for one and be overjoyed.

You will like the K50/4, it’s the sharpest lens in the K series. I also recommend getting the #3 Pentax Auto Extension tube for 1:1 magnification.

Another lens to consider is the K55/2, it has the same optics as the K55/1.8 and is just 1/3 of a stop slower. People seem to avoid this lens like the plague for some reason, it’s actually very good.

Phil.

[m42man]

have you tried using a good hood inorder to improve contrast? it makes a world of difference.

Adam, I haven't tried that yet (mind you I was shooting away from the sun in the instance I was referring to), though actually I've always been very pleased with the M50/1.7's performance shooting AT the sun (at least in the days of film).

BUT, what I have tried just now is to re-examine the offending photos, and it occurred to me that the Pentax is over-exposing relative to its rivals. So, I applied -1EV in Pentax PhotoLab, with the result that perceived contrast (and sharpness) improved significantly! Also, as you might imagine, colour improved, though it's still a bit cool. (Actually, -1EV was overdoing it a bit, as it's now slightly underexposed relative to the others.)

The above just shows how VERY important it is to get consistent exposure when testing and comparing lenses, even if you have to perform corrections in PP.

So, my apologies to the M50/1.7!

[paperbag846]

One of the things I find so amazing about the K55 is that it just does not flare unless you point it right at the sun... even though I should really be using a hood with it, I find I don't need to.

In direct comparison, the A 28 2.8 flares BADLY. It's out of control. It might be the focal length (i.e., the A 28 is pulling in light from the sides), but I think it has to be more than just that.

Both lenses are sharp, but OOF really shines on the K 55 1.8. And colours on the K55 are really nice. The 28 A looks desaturated (which can be nice too, but in my opinion, I would prefer to desaturate in post, rather not have much of an option). The K55 is not exactly 100% accurate with colours, but it is very warm and is perfect for skin tones and indoor settings. I find my kit lens and 28mm better with outdoor, strong contrast colours.

Thanks again... I'm slowly learning how each lens has it's own purpose outside of focal length and aperture... and how to build an efficient toolbox. Cheers, everyone!

What I learned from the digital processing of sound is - you can take something away no problem, but you can't add it in. I'd rather have all the contrast and colour in the world, to play with. But I shoot RAW... JPEG would be a completely different story.

[aleonx3]

I happen to have all three A28 2.8, A50 1.7 and K55 1.8. I like the A lenses since I can use aperture priority. However, I have not done any really comparison among the three lenses. And I have not find any bad about them such as the "flare" problem as stated by other users; it is just that I haven't done thorough testing on my copies yet.

[dragonfly]

The shape of the diaphragm on the 55mm is not a hexagon when stopped down one or two stops. Each blade has a wave shape, and it doesn't become a hexagon until F5.

[Oro]

What's your camera model? The k20d has a documented problem metering with manual glass as you move the fstop from f4.

I have used it on an ist D and ist DS. I have had no problem at all at any f-stop. I have not used a newer model yet.

You will like the K50/4, it’s the sharpest lens in the K series. I also recommend getting the #3 Pentax Auto Extension tube for 1:1 magnification.

Thanks, Phil. I was thinking of that accessory already. I guess I may get it sooner rather than later.

[RioRico]

My pile of 50's has grown ominously and deserves a shootout, but I haven't (and probably won't) rigorously test the lot. Each is taken out in its turn, and used, and cherished for its own character. The Pentaxi include:

FA50/1.4, M50/1.7, M50/2, MacTak 50/4 (1:1), Tak 55/1.8, SupTak 55/2

What I notice is: the FA/1.4 is fast. The MacTak is super-sharp. The others have subtle differences. The f/2's don't get used enough. I don't know (or care) how they all render color because I always diddle with WB, temp, etc; or I torture the colors, or convert to B&W, or whatever. I'll just say that the FA/1.4 and MacTak *are* special, and the M50/1.7 and Tak 55/1.8 *feel* special.

So someday Real Soon Now I'll gather these up with all the others and do a perfunctory 3-shots test. I doubt I'll be tempted to throw any away. I *am* on the lookout for some other f/1.4's, whether Nikkor, Olympus, Yashica, whatever. They can join this crowd:

Meyer - Oreston 50/1.8, Domiplan 50/2.8, Primotar-E 50/3.5
Yashinon DX 50/1.7; Zeiss Jena 50/2.8; Industar-50/3.5
a nameless plastic Japanese 50/2 that equals the M50/2
Chinon 55/1.7; Porst Color Reflex 55/2.8; Helios-44 58/2

Of those, the Oreston and Industar and Helios *seem* special. But more research is needed. Can I get a grant?

[stevebrot]

I own a ton of "fast 50s", including both the K 55/1.8 and the A 50/1.7. No question, no doubts, the K55/1.8 is the better of the two. The ONLY aspects where the A 50/1.7 presents an advantage is in the convenience of use and size/weight.

Having said that, I would balance my comment by saying that the A 50/1.7 is worth having in its own right. It is a decent lens optically. I just would not trade my K 55/1.8 for one


Steve

[pdxbmw]

I have or have had the 1.7 in A and M, while owning the K55 at the same time. The K55 and the SMC Tak 55 seem to be the same thing optically to me. I kept the Tak and sold the K, I regret it know, but so be it. The 1.7's and the K/SMC Tak 55 both pop wonderfully. I didn't notice a real difference between all four, except the increase in plastic on the A.

Patrick

[paperbag846]

I have or have had the 1.7 in A and M, while owning the K55 at the same time. The K55 and the SMC Tak 55 seem to be the same thing optically to me. I kept the Tak and sold the K, I regret it know, but so be it. The 1.7's and the K/SMC Tak 55 both pop wonderfully. I didn't notice a real difference between all four, except the increase in plastic on the A.

Patrick

I now own both, and to be honest, I am having some trouble telling them apart, other than the slight FOV difference. I see a small difference in speed between 1.7 and 1.8 but that is likely a placebo effect.

The A compatibility with my k20d makes me want to sell the K, but I think the K is sharper wide open. It might be true that the K would serve as a better portrait lens (of course I really should look for something longer for a true portrait lens... but the reason I am deliberating selling the K55 is the lack of funds ). I am worried that I will be relinquishing a cool collectible... I feel as if the K55 is much rarer than the A50 1.7.

Any final thoughts? I'm not so concerned about colour because I tend to be heavy on the PP, but bokeh rendering has been discribed as "busy" by many?

[oxidized]

I only own the 50mm1.7, however I am very happy with it. Extremely sharp from 2.0 on and very convenient (Amount). The only potential drawback (though now i am just being picky) is that the bokeh isnt super outstanding. I hear its much better on the 50mm1.4, which I dont own...

[paperbag846]

While I think it may be a silly decision... I think I will keep both.

After shooting a bunch of quasi tests I have found...

A) At smaller apertures, the lenses are almost identical.
B) The K55 is more "realistic" with colour, the A50 is more saturated.
C) The A50 shows more fringing wide open.
D) The K55 looks "smoother" wide open in OOF areas (JUST A BIT).
E) The K55 in-focus areas are sharper wide open.

In other words, the K55 seems to perform better wide open, but that advantage quickly dissipates as you close down.

Therefore, I think that the A50 is really ideal for most shooting conditions, especially considering the convenience of Av, Tv, and more reliable metering.

However I think it would be good to think of the K55 as a good poor-man's portrait lens, and would be the better pick when I can set up my shot and want max aperture.

Thanks for the advice everyone. I think that it helped me notice the subtle differences between the lenses. For the prices they go for, WOW these are good deals.

[paperbag846]

A basic comparison of the SMC A 50mm 1.7 and SMC K 55mm 1.8 wide open:

I notice smoother OOF areas with the 55mm, and that the 55mm actually renders colder than the SMC A! Not particularly important for RAW shooters... but I struggle to find real differences between the lenses. To be honest, I feel that in focus areas look near-identical... it's the OOF areas that are different.

[paperbag846]

Now for a comparison at f4, where things get a little ugly in the OOF areas for the SMC A 1.7 vs. the 55m K 1.8.

I think I like the colour of the SMC A better than the K, but the rendering of the SMC K better. Is it weird that I think two super-similar lenses have their own purposes?

[m42man]

Very interesting comparison photos, paperbag. For my money, I think I prefer the 50/1.7, assuming it's the one at the bottom.

At f4, it seems to have much nicer colour and bokeh, also it has a touch of the elusive "3d effect" (no doubt helped by the bokeh).

Amazing really, because from my own experiences with the 50/1.7, and from the reputation of the 55/1.8, I would have expected quite the reverse!