[wallyb]

K or M? I suspect you'll get the 1st that becomes available that matches what you believe would be a bargain price point - this is how I ended up with my 1.2's

This guy knows me very well...

But, I am leaning towards the M version just because of having the 135/3.5 M and 75-150/4 M, which are superb lenses... plus with the recommendation of the 50/1.7, well... it's all starting to fall into place I was going to get rid of my 55/1.8 m42 if I got the K version, though.

[keyser]

I think most of the important points have been covered already. I can second the opinion that the M50 1.4 is by no mean cheap feeling.

It's not as sharp as the 1.7 until stopped down past f/2 BUT the images it renders are beautiful in tone and contrast. Couple that with low light performance and you've got a winner. It's my go-to lens for this reason.

The only real negative is the 1.4 can exhibit 'funky' bokeh and smooth bokeh in equal measure. I think there's a thread about this on the board somewhere. It's never ruined any shots but it's worth concidering.

[PentHassyKon]

This guy knows me very well...

wallyb - someone who asks about getting more 50's is definitely someone who has LBA.
And.....

if you have LBA, it becomes a matter of getting the most lens for your money
so you can buy more lenses (what the heck is the plural of lens?)

BTW, if you are truly an LBA'er then you need to keep an M42 lens around
This means you must get the K and the TAK

[Just1MoreDave]

this is only an observation, but I have always found the M series lenses don't have the same consistancy and feel of K series lenses, mostly the aperture clicks and focusing collar drag just aren't the same,

the impression is that the M series "feel" cheap.

I know it is not scientific but .........

I know from experience that the feel of the aperture ring can be greatly improved by removing it, cleaning any grit or crud, lightly regreasing it and reassembly. I have an S-M-C Takumar 55/2, K55/1.8 and M50/1.7 in front of me right now, and I notice that the M50/1.7 has no shielding to reduce the possibility of dirt getting in there in the first place. The Takumar's distance scale is a separate piece that fits over the gap between aperture ring and lens body. The K55/1.8 has a raised rib on its distance scale that might do the same job but looks less effective.

The M50/1.7 aperture and focusing rings are also thinner, not really a big shock but that does affect how they feel. The M50/2 definitely has a "consumer-grade" feel to it.

one of the advantages with the M series however, even though I call M series the "mini series" is that most of the lenses use 49mm filters, so you only buy one set and they work on everything. this was done at the expense of speed in the longer lenses.

The 52mm K series always seems a little off to me because of this. Many Takumars also use the 49mm size, and it continues to be used on modern primes.

[B Grace]

Georgweb's post of the lens diagrams do indeed show some differences but they are pretty minor. It's possible the edges of the elements changed slight over the years to streamline assembly. The big revision appears to be made to the third element with the M-series and that may have been due to reducing the size of the barrel or maybe they tried to leverage their SMC coatings and made that element easier to produce. The cemented surfaces are very similar. These lenses are very close to being the same.

[Lowell Goudge]

I have the Pentax M 50mm 1.4 and it certainly doesn't feel cheap. The focus ring is smooth and well-dampened. The aperture clicks are tight and defined. Nothing loose here.

It was really an impression I had when comparing the SMC 105mm F2.8 to the SMC-M 100mm F2.8. the M 100 just didn't feel right.

The only other M series lens I have is the SMC-M 100F4 macro, but it is the same as the SMC, and SMC tak so there is not much difference in feel

[georgweb]

Georgweb's post of the lens diagrams do indeed show some differences but they are pretty minor. It's possible the edges of the elements changed slight over the years to streamline assembly. The big revision appears to be made to the third element with the M-series and that may have been due to reducing the size of the barrel or maybe they tried to leverage their SMC coatings and made that element easier to produce. The cemented surfaces are very similar. These lenses are very close to being the same.

That's what I thought with many lenses gauging the lens schemes.

Turned out it is not true. Very different behaviour with lenses that almost look the same from their optical lens scheme.

Here's a nice intro I find, History of fast 35mm film optic lenses

[stevebrot]

...The 50/f1.7 and 50/f1.8 (and f2.0) was the same throughout production (6:5's both of them)...

Huh?

• M,A,F,FA 50/1.7 6 elements/5 groups
• Pentax never made a 50/1.8, though the K 55/1.8 and K 55/2 both have 6 elements/5 groups
• M,A 50/2 5 elements/5 groups

The M and A 50/2 lenses are sort of the poor step children of the Pentax fast 50 line-up. Both optical performance and price were a step down from their faster f/1.4 and f/1.7 siblings.

Steve

[stevebrot]

The 52mm K series always seems a little off to me because of this. Many Takumars also use the 49mm size, and it continues to be used on modern primes.

I agree with your observation regarding filter size. On the other hand, all of my non-Pentax 50s take 52mm filters and caps, so I am a happy camper even though.

Steve

[Pentaxor]

I see that there's a lot of love for the 55/1.8. I tend to agree on that.

[Douglas_of_Sweden]

Huh?

• M,A,F,FA 50/1.7 6 elements/5 groups
• Pentax never made a 50/1.8, though the K 55/1.8 and K 55/2 both have 6 elements/5 groups
• M,A 50/2 5 elements/5 groups

The M and A 50/2 lenses are sort of the poor step children of the Pentax fast 50 line-up. Both optical performance and price were a step down from their faster f/1.4 and f/1.7 siblings.

Steve

Typo, meant the 55/1.8 and 2.0 of course. Edited.

[stevebrot]

Typo, meant the 55/1.8 and 2.0 of course. Edited.

Thought so

Steve

[wallyb]

Just for anyone keeping track, I ended up going with the M 50/1.4 and the K 55/1.8, in great part due to the helpful replies here. I'm actually still looking for the K55 at the moment, I will be sure to pick up the next reasonably-priced one in the marketplace.

Thanks all!

[axl]

Great choice, Wally!
I never owned 50/1.4 but then it's not my prefered focal length. But had F50/1.7, it was great lens... until I got K55/1.8. This gem blew my socks off! I ended up selling F50 despite it's fast AF and kept the K55 as my primary portrait lens. I recently acquired hood to match the FOV on my K10D. It's hood from Tak 85/1.9 and step ring 52-58. I love this more and more, hope you'll get yours soon!

BR
Peter

[keyser]

Great choice with the 50mm 1.4. You'll be glad of the low light performance and narrow depth of field pretty soon I think!

I don't see the K55 around very much, the Tak version seems to come up more often. Good look in your search though.