[darkymir]

Hello,
I currently own K-5 and 18-55 kit and old mf A 70-200/4. I'm planing to get a fast mf 50 mm with nice bokeh for portrets. I can chose between M 50/1.4, M or A 50/1.7 and K 55/1.8. My main doubts are between the 50/1.4 and the 55/1.8. I don't have the opportunity to test them, so i'll be thankful for the opinion of people who have used both. Samples also may be very helpful.

The 50/1.7 (i can get bot M or A version) is a little bit cheaper, so how much the other two surpass it?

[microlight]

They are all optically superb (I have all three), but the A50/1.7 is the one I'd go for, as with the A setting, your camera will work in all modes, it will just be the focus that is manual. With the two K lenses, you will be restricted to manual mode and using the green button to meter.

The A50/1.7 however isn't built to quite the same standards as the M or K lenses; the aperture ring is plastic, for example. A relatively common issue with this lens is that a small welded part inside the aperture ring can come adrift with time which can result in the aperture ring jamming in position, whether that's A or not. It can be fixed but it's fiddly. So I'd advise finding out whether there's any problem with the aperture ring before you buy. If you don't mind manual/green button then I'd go for the M50/1.4; great construction quality, and smaller and just over half a stop faster than the K55/1.8 which I think was a K-mount modification of the SMC Takumar 55/1.8 from the Spotmatic era.

[Dlanor Sekao]

My K55 1.8 is One Unbelievably sharp and capable lens ! Since I own so many 50's I have tested them against each other repeatedly......the SMC-K is the last I would ever part with.
microlight is right about the plastic aperture ring becoming unwelded (plastic Weld) as I have two different A lenses that I had to repair.
Not to change your ideas as far as what to get......don't discount the Ricoh Rikenon series either. The XR and P series are just as capable as any of the Pentax line.
In the Rikenon Line I also suggest the Rikenon P 50mm 1.4.......One Fantastic lens.
As long as you stick with the Pentax line there really aren't any lenses that are bad.....every one is quite Good and your not going to notice a lot of difference until you really start getting technical , pixel Peeking , or do large prints. Even the Very common 50mm 2.0 "A" lens is very good and can be had for a Song and Dance.....I sell them for $10-$20.......try it....... You will see what I mean.
Do Yourself a favor and read through the PF Lens Reviews......there is ALOT of Info there.

[Cuthbert]

I would recommend a K 50mm f1.4, not a M.

The K with Thorium glass is IMO superior...besides that I consider the K55mm f1.8 better than the M/A 50mm f1.7.

Also, I just shoot a film with the Rikenon 50mm f1.4 but I feel it's better than the M50mm f1.4, the bokeh is a little busy but I like it.







I took these with a XR2S, Fuji 200 and a polarising filter.

[darkymir]

Thank you for your opinions and for the samples.
I'll keep in mind about plastic ring of the A 50 mm.
Unfortunately i'm limited whit lens variety i can chose from, so no Rikenons around me.
I'm glad i had such quick response, but keep on posting

[surfar]

I have most of the niftys mentioned so far, all are good.However the price of the DA 50 f1.8 isn't too large and it works on the K1 as well, a good future investment.

[GUB]

I have F, A, M 50mm 1.7s - A, M, K, s-m-c and a 7 and an 8 element sup tak 50mm 1.4. The A 50 1.7 is my go to technical lens and the sup tak 50 1.4s are my art lens. They seem to have more Monet in them than all the others (and my K50 1.4 is a dog - model variation?)!!. I also have a stack off 55mms but they undeservably live in the shadow of the 50s (Too many lenses too little time). It is funny but I find myself reaching for the older lenses with less coatings - it is almost like the coatings cost you something.

[ChristianRock]

I don't think you can go wrong with any of them... I have the M 50 1.7 (amazing, very sharp and contrasty from wide open), the F 50 1.7 (similar to the M, my copy isn't quite as sharp as my M but it's still amazing, and AF is very handy), the Rikenon P 50 1.4 (probably the best of all 50s I have had), the Rikenon XR 50 1.4 (not quite as good as the P version, soft wide open), and the K 55 f2 (basically the same lens as the 55 1.8, but this version only opens up to f2 - also amazing). I have had the Auto Sears 50 1.7 (great lens, same as Rikenon XR 50 1.7) and the Auto Sears 50 f2 (also a great lens, possibly the sharpest of them all when stopped down - but the focus ring was just too short).

They are all a little bit different... but I don't know how you can go wrong with any of them. I would say this - If you plan on shooting wide open, get the M 50 1.7 (usually under $50) or the F 50 1.7 (usually under $130). Though I have to say that my Rikenon P 50 1.4 is also sharp from wide open and 1.4 is 1.4! Now, if you plan to usually stop down, I would say the K 55 1.8's rendering stopped down is just divine, but I have also seen great things from the little plastic DA 50 1.8.

Rikenon P 50 1.4 wide open:


Rikenon P 50 1.4 @f2.8 (notice the bokeh stays good stopped down - that is one advantage of the 50 1.4 designs, the bokeh usually stays nice at most apertures)


M 50 1.7 wide open:


I didn't use the Sears 50 1.7 wide open much... I think this was @f2.8


K 55 f2 wide open:


K 55 f2 @f5.6 if I recall correctly:

[mgvh]

I have: K50 f4 Macro, M50 f1.7, A50 f1.7, DA 50 f1.8, Mamiya/Sekor 55mm f1.4, Super Tak 55 f1.8
Each has their own appeal and different strength, but I think the two 55mm lenses (which are both M42 mount) would be the last I would let go. I find it easy to shoot with M42 in A mode, and those two just seem to give me the most attractive results most consistently.

[stevebrot]

Also, I just shoot a film with the Rikenon 50mm f1.4 but I feel it's better than the M50mm f1.4, the bokeh is a little busy but I like it.

Funny you should mention the "busy" bokeh. I have a couple copies of the fairly common XR Rikenon 50/2. For some reason the lens has mythic stature in regards to sharpness and to be sure, both of my copies are crazy sharp. OTOH, the XR 50/2 has the most nervous bokeh of any lens on my shelf. FWIW, my Rikenon P 50/2 is the same way. Family characteristic?


Steve

[stevebrot]

I forgot to mention...for the OP...of the lenses you listed with image quality followed by build being the major criteria, my vote goes with the K 55/1.8 followed by the M 50/1.7. If convenience is more important than build, the A 50/1.7 would be my choice...assuming you never want to use it on extension tubes or bellows or any other situation where you need a working aperture ring. The aperture ring on my copy still works, but it is extremely sketchy. After almost a decade of fielding questions on this site I am of the opinion that there is no question whether the aperture ring on an A 50/1.7 will fail. The only question is whether it will happen in such a way that allows you to get it back in the "A" position.


Steve

[reh321]

I would recommend a K 50mm f1.4, not a M.

The K with Thorium glass is IMO superior...besides that I consider the K55mm f1.8 better than the M/A 50mm f1.7.

The "M" line {and the following "A" line} came about because Pentax wanted to reduce the "heft" of lenses;
the lenses are shorter than the corresponding "K" and preceding "Super Takumar" lines, use narrower plastic rings instead of the heavy-weight metal people were used to, and they also used a different glass.
Even though these lenses are over thirty years old, they feel "modern".

Pictured below are the three 50mm prime lenses I happen to own.
My understanding is that the "K" line basically updated the "Super Tak" line to the then-new K-mount, so if I had a "K" 50mm lens, it would be roughly the same size as the "Super Tak", longer and perhaps 50% heavier than the more modern lenses.




On the far left is a "Super Tak" 50mm f/1.4 that I bought recently on eBay. The price was good, and I was in the process of buying several M42 lenses just in case the Aperture Control malady hit my K-30, but I don't have much actual experience with it.

In the middle is the "M" 50mm f/2 which was kitted with my ME SE when I bought it in 1979. My sense is that it isn't quite as sharp as the A 50 f/1.7, but I haven't actually tested it. The ME SE ended up in the dump after it got damp at Niagara Falls, but I kept this lens to backup the A 50 f/1.7 ... and I've kept it ever since. I have to admit that I've basically ignored it all these years, so I can't really provide much of a "reference" for it.

On the far right is the "A" 50mm f/1.7 which was kitted with my Super Program when I bought it in 1984. The aperture ring tended to stick between f/8 and f/5.6, but the lens provided reliable service to me for eleven years {I had only two lenses, this one and a Vivitar zoom telephoto, so this one was on the camera most of the time}, so I would have to say that it more than passes the build-quality test. When I came back to Pentax by purchasing a K-30 last year, this was the first old lens I tried on the K-30; I was very pleasantly surprised by the sharpness of the pictures.

[Cuthbert]

Funny you should mention the "busy" bokeh. I have a couple copies of the fairly common XR Rikenon 50/2. For some reason the lens has mythic stature in regards to sharpness and to be sure, both of my copies are crazy sharp. OTOH, the XR 50/2 has the most nervous bokeh of any lens on my shelf. FWIW, my Rikenon P 50/2 is the same way. Family characteristic?


Steve

These will go in the bokeh thread, but I think I can also post them here:















I find this bokeh almost Soviet like, but an Helios would be more smoother I assume. Sharpness is good but not over the top, for the colours I shot with a polarising filter that helps a lot and I also need to test the lens with some serious film...in general I like this lens even if it's not the number 1 of my list in the 50/1.4 area (that honour is for the CZJ Pancolar, the Nikon 58mm 1.4 and the SMC Takumar), out of curiosity who made it?

It's definitely not a Pentax lens, building quality is good but not up to the Pentax standard.

[stevebrot]

The "M" line {and the following "A" line} came about because Pentax wanted to reduce the "heft" of lenses;
the lenses are shorter than the corresponding "K" and preceding "Super Takumar" lines, use narrower plastic rings instead of the heavy-weight metal people were used to, and they also used a different glass.

Not wanting to directly contradict you, but I am unaware of any move to plastic parts for the M-series lenses. As with the K-series, all-metal build was characteristic of the line. Use of plastic came with the A-series and even then was not done with all lenses in the line.


Steve

[ChristianRock]

Funny you should mention the "busy" bokeh. I have a couple copies of the fairly common XR Rikenon 50/2. For some reason the lens has mythic stature in regards to sharpness and to be sure, both of my copies are crazy sharp. OTOH, the XR 50/2 has the most nervous bokeh of any lens on my shelf. FWIW, my Rikenon P 50/2 is the same way. Family characteristic?


Steve

The Rikenon XR 50 1.4 I have wins the "weirdest bokeh ever" award in my opinon and mine has a broken iris, so it's permanently stuck wide open now...



However once it was stopped down to f2, it was great. It only did that wide open.

Anyway. Good thing I got the Rikenon P 50 1.4 to use in its place. The newer P version, I can tell, is a different optical design - much better at wider apertures, and the bokeh remains pretty much sane even wide open. Here it's wide open, in this type of picture the XR would have gone a bit nuts in the out of focus area, but the P does a really good job I think.


At some point I want to get a Rikenon P 50 1.7 just to see if it is better wide open than the older XR (and its Auto Sears counterpart). The XR was just ok but the Pentax 50 1.7 design had it beat pretty good wide open.