[liemjerry]

Like what others mentioned.. I would say your choice of lenses K/M 1.4 are pretty much identical. Actually even 1.4 gives a bit more pleasing bokah, but the nature of 1.4, it makes wide open aperture sharpness way lower than 1.7 even the 1.4 lens is set to be 1.7~1.8ish. Between 1.4 and 1.7, you won't get too much of the boost during the night either.

From your situation, I would say, rather debating on 1.4 vs 1.7, I would.. indeed pick up a even cheaper 50mm 1.8 or 2.0 as alternative options for 1.7, and keep a cheaper 1.4.

My personal opinion is, none of those 3 are my liking really.

for compactness, price, image quality, performance, for large aperture I would go for :
Pentax-A 50/1.2
Pentax-A 50/1.4
Pentax SMC Takumar 50/1.4

Small aperture, but even more compact I would go for :
Pentax-A 50/2.0
Pentax-FA 43/1.9
Pentax SMC Takumar 55/1.8


I currently have Pentax-M 50/2.0, Be honest with you, it's way lower performer than other fifties I have owned. I would personally stay away from M version and early K versions. Early K is just K mount of SMC Takumar version with less of yellow glass element. But it would be bigger, heavier, and more expensive compare to SMC Takumar.

If you want to have nice bokeh, then the choice could be 50/1.2, 50/1.4, or 55/1.8. I found that 55/1.8 has the best bokeh even compare to any version of 50/1.4. As for Pentax-A 50/1.2, it's an unique lens. You simply will never get sharpness till your aperture goes down to F4 or beyond. But it is what it is.. It's a 1.2!! It works best on crazy smooth bokeh and when you absolutely don't need sharpness on the subject. The painting quality of 1.2 is probably strictly to artists (maybe).
Let you have the taste of 55/1.8 (which is a cheap lens BTW.. my had tiny bit trace of fungus and it's still super sharp! I picked up around $30 I believe) Using fairly wide but not widest 50 range, but makes it a 55 (even more telephoto).. It brings up the characteristic similar to medium format. There is a reason why on 645 a 80mm F2.8 although it's F2.8 it gives much better bokeh than a 135 50mm F1.4 but subject is WAY SHARPER!! Because you are in theory at F2.8 compare to F1.4!!! That's why I would say, if you want great bokeh, 50mm F1.4 vs 55mm F1.8.. I would personally pick up 55/1.8 any given day!

I use MX body, so in my opinion, appropriate lens is Pentax K, Pentax-M, could you suggest me ?

[boriscleto]

This is normally how it breaks down..

Takumar - yellow (no)
Super Takumar - yellow (8-element 50/1.4 no, 7-element 50/1.4 yes. 35/2 with 49mm filter yes. all others no)
S-M-C Takumar - yellow (50/1.4 & 35/2)
S-M-C Super Takumar -yellow (what is a S-M-C Super Takumar?)
SMC Takumar - yellow (50/1.4 & 35/2)

SMC K - not yellow

You can swap out elements just means they are design identically and glasses are identical shape. the only difference is after discovering the radioative issue, Pentax "REPLACED" the rare element to glass. No harm no foul.. Only people mentioned without the radioactive, the sharpness goes softer a tiny bit. true or not? who knows?

The non-radioactive 8-element 50/1.4 simply cost too much to produce. So it was replaced after a year in production with a new 7-element design that at the time was said to be sharper than the 8-element (probably just marketing speak). The 35/2 was completely redesigned in the late 60s (49mm filter on redesign vs 67mm filter on original). Both used Thorium oxide as a crutch to make up for having fewer elements, or different shaped elements.

For example the first 35/2



And the radioactive version



By the mid-1970s changes in environmental and safety laws made the transition to Lanthanum a necessity.

[gofour3]

I use MX body, so in my opinion, appropriate lens is Pentax K, Pentax-M, could you suggest me ?

I only shoot film and would stick with any of the K Series normal lenses. (K50/1.2, K50/1.4, K55/1.8 or K55/2) The M Series would be my next choice if size matters.

This is no advantage in using any screw-mount lenses on a MX film body, same with an A Series lens.

The K Series K50/1.4, K55/1.8 or K55/2 all have the same optics as their older Takumar brothers, but have better SMC coatings and a better minimum aperture. Also there is no M42 adapter to mess with. You can’t use the “A” setting on any A Series lens, so there is no point in spending the extra money for that feature if you are only going to use the lens on your MX film body. Also any Auto focus lens will be more clumsy to manual focus than a K Series lens.

Phil.

[glasbak]

The 35/2 was completely redesigned in the late 60s (49mm filter on redesign vs 67mm filter on original).

For example the first 35/2

I only have the older first version (67mm filter), it has a yellow dis-colorization, and a radiation meter test revealed it was radioactive.

[monochrome]

SOURCE

I suppose it is possible Asahi Pentax had a small inventory of SMC Tak elements in stock and could have used them in early production K-mounts.

[liemjerry]

I only shoot film and would stick with any of the K Series normal lenses. (K50/1.2, K50/1.4, K55/1.8 or K55/2) The M Series would be my next choice if size matters.

This is no advantage in using any screw-mount lenses on a MX film body, same with an A Series lens.

The K Series K50/1.4, K55/1.8 or K55/2 all have the same optics as their older Takumar brothers, but have better SMC coatings and a better minimum aperture. Also there is no M42 adapter to mess with. You can’t use the “A” setting on any A Series lens, so there is no point in spending the extra money for that feature if you are only going to use the lens on your MX film body. Also any Auto focus lens will be more clumsy to manual focus than a K Series lens.

Phil.

you K is Takumer taste with better recipe from SMC?

[gofour3]

you K is Takumer taste with better recipe from SMC?

The K Series has the same SMC coatings but on all glass surfaces, the Takumars had the SMC coatings on some but not all glass surfaces.

Phil.

[photodesignch]

I use MX body, so in my opinion, appropriate lens is Pentax K, Pentax-M, could you suggest me ?

It's K mount, so your choice is unlimited.. I personally would use Pentax-A lenses because I feel the A lenses are a bit better in image quality and building quality. (Better SMC as well). But If adapted, Takumars aren't all that bad. SMC Takumars are cheap, tiny, and well built!!! My less favors are M lenses and older Takumars.

If no focus ring dampening don't bother you, you can even use a FA43 limited on it. I use it all the time! best color rendering ever

[liemjerry]

thank you for all your attention, finally I was choose Pentax K 50mm f1.4 and I am happy with this lens : built quality, optic quality and also ergonomically when focusing an object.
Very nice ideas, infos from you all, many thanks

[pinholecam]

Dear Friends,

I am looking for lens for Pentax MX SLR 35mm/film and there's 3 lenses in my choice :

1. SMC Pentax K 50mm f1.4
2. SMC Pentax-M 50mm f1.4
3. SMC Pentax-M 50mm f1.7

Which are from 3 lenses above that have :

- Best sharpness almost in any aperture value
- Low Chromatic Abberations
- Low Distortion
- Good Bokeh
- Good Tonality especially for B/W Photos

Thank you for your help and I looking forward for it.

Best regards,

At a point, I had all the M and the A 50's.
Now I still have the A50s and a few others but sold off the Ms. (Silly decision really as the M are smaller and does not have a plasticky exterior (though all are metal inside as well))

- Best sharpness almost in any aperture value
>> The f1.4 matchs the f1.7 at the same f-stop. The f1.7 is little bit better on the off center at wide open, but by f4, no real difference.

- Low Chromatic Abberations
>> Nothing too bad to worry about on any of them. A slight nod to the f1.7 at wide open perhaps.

- Low Distortion
>> Nothing glaringly obvious on any of them.

- Good Bokeh
>> f1.4 for sure. The f1.7 and f2 have hexagonal apertures when stopped down by 1 stop.
Drives me nuts as its very distracting when there are OOF highlights (in hex shape)


- Good Tonality especially for B/W Photos
>> Er... Pentax in most of their SMC lenses go for high contrast.
So if high contrast and bold drawing style (Zeiss like to me) is what you want, then any of the Pentax 50s are ok.
That of course does not mean that you can't tweak to taste in PP.
I change my taste for this so often, sometimes I like the lower contrast and less spread out highlights/shadows of old uncoated lenses (non Pentax except for old pre-SMC ones), often I want the more contrast (and flare tolerant) Pentax SMC lenses.

I'd say, get the M50/1.4 for the better size.

Thats not saying that the f1.7 is not good.
In most real use, its a great lens.

With the A50/1.7









---------- Post added 07-09-2015 at 07:46 AM ----------

With the A50/1.4