1.4/50 vs. 1.7/50 vs. 1.8/55

reh321 · 07-13-2016, 07:13 PM

Originally posted by stevebrot

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.

Oh, I don't want to be disagreeable.

What I do know for certain is the following:

(1) All the "Super Taks" I have feel like solid metal {I've said the 300mm might be a better club or hammer than anything else},
while my "M" 50 f/2 and "A" 50 f/1.7 have extremely similar feel to them, and feel "modern" {like "DA" line, for example} to me

(2) The "M" 50 f/2 weighs 156g while the "A" 50 f/1.7 weighs 164g {extra glass for extra fraction of f-stop would explain this}

Based on feel, I had thought that current construction methods began with the "M" lenses and hadn't changed much since then
{although the "F" and "FA" lines have always seemed to me to be of lesser quality} BUT what I actually know is very limited,
as I noted above .... one could equally postulate that both my "M" f/2 and "A" f/1.7 are largely metal, they added more, too much,
plastic for the "F" and "FA", and eventually found a reasonable compromise with more experience.
{and, of course, there many other permutations would fit my limited facts}

Cuthbert · 07-14-2016, 12:12 AM

Originally posted by reh321

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".

You and Stevebrot are both right: the M is better than the A but K and Tak are much better built.

The K50mm f1.4 and the latest SMC Takumar 1.4 (with rubber ring) are the same optically , but the K is bigger, it takes 52mm filter and of course the diameter of the K mount i much wider than the old M42 mm, giving the impression that for instance a Spotmatic F with Tak is a smaller camera that a KM with K 50mm f1.4.

A 50mm f1.7 and 28mm f2.8 feels loose and cheap, but on the other side my A 35-210mm zoom feels very solid, I never handled the A 50mm f1.2 but the 1.4 again feels loosier than the M that is not to the standard of the K50mm 1.4.

These are my 2 cents, I have all these 50mm primes and if I had to keep a single one of course it would be the K50mm f1.2, followed by the K.

**gofour3** · 07-14-2016, 08:59 AM

Originally posted by reh321

What I do know for certain is the following:

(1) All the "Super Taks" I have feel like solid metal {I've said the 300mm might be a better club or hammer than anything else},
while my "M" 50 f/2 and "A" 50 f/1.7 have extremely similar feel to them, and feel "modern" {like "DA" line, for example} to me

(2) The "M" 50 f/2 weighs 156g while the "A" 50 f/1.7 weighs 164g {extra glass for extra fraction of f-stop would explain this}

I have the M50/1.7 and the A50/1.7, the "M" version weighs 20 grams more than the "A". That's more plastic in the A50/1.7 and explains the doggy aperture ring assembly, which is the worst I've seen on a Pentax lens.

I feel these two 50mm lenses are too small for a "normal/standard" prime on a full frame body, I like the extra heft of a "K" series lens any day. For me the K55/1.8 is a better choice over the two 50/1.7 lenses.

Phil.

darkymir · 07-15-2016, 12:58 PM - **1 Like**

Thank you all for replaying to my question. Today i've bought the 50/1.4 Pentax-M. This is my first fast lens and i'm very pleased with the results.

Cuthbert · 07-15-2016, 01:07 PM

Originally posted by darkymir

Thank you all for replaying to my question. Today i've bought the 50/1.4 Pentax-M. This is my first fast lens and i'm very pleased with the results.

Yes the M50mm f1.4 is a nice lens, size is its main advantage, especially on small Pentax cameras.

**Kerrowdown** · 07-15-2016, 01:24 PM

Originally posted by microlight

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

Whilst this is all correct... remember with A series lenses once set to the A position on the aperture scale, I've never found a reason to move them again.

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07-13-2016, 07:13 PM	#16
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,181	Originally posted by stevebrot 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. Oh, I don't want to be disagreeable. What I do know for certain is the following: (1) All the "Super Taks" I have feel like solid metal {I've said the 300mm might be a better club or hammer than anything else}, while my "M" 50 f/2 and "A" 50 f/1.7 have extremely similar feel to them, and feel "modern" {like "DA" line, for example} to me (2) The "M" 50 f/2 weighs 156g while the "A" 50 f/1.7 weighs 164g {extra glass for extra fraction of f-stop would explain this} Based on feel, I had thought that current construction methods began with the "M" lenses and hadn't changed much since then {although the "F" and "FA" lines have always seemed to me to be of lesser quality} BUT what I actually know is very limited, as I noted above .... one could equally postulate that both my "M" f/2 and "A" f/1.7 are largely metal, they added more, too much, plastic for the "F" and "FA", and eventually found a reasonable compromise with more experience. {and, of course, there many other permutations would fit my limited facts}

07-14-2016, 12:12 AM	#17
Cuthbert Veteran Member Join Date: Nov 2013 Photos: Gallery Posts: 1,740	Originally posted by reh321 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". You and Stevebrot are both right: the M is better than the A but K and Tak are much better built. The K50mm f1.4 and the latest SMC Takumar 1.4 (with rubber ring) are the same optically , but the K is bigger, it takes 52mm filter and of course the diameter of the K mount i much wider than the old M42 mm, giving the impression that for instance a Spotmatic F with Tak is a smaller camera that a KM with K 50mm f1.4. A 50mm f1.7 and 28mm f2.8 feels loose and cheap, but on the other side my A 35-210mm zoom feels very solid, I never handled the A 50mm f1.2 but the 1.4 again feels loosier than the M that is not to the standard of the K50mm 1.4. These are my 2 cents, I have all these 50mm primes and if I had to keep a single one of course it would be the K50mm f1.2, followed by the K.

07-14-2016, 08:59 AM	#18
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,092	Originally posted by reh321 What I do know for certain is the following: (1) All the "Super Taks" I have feel like solid metal {I've said the 300mm might be a better club or hammer than anything else}, while my "M" 50 f/2 and "A" 50 f/1.7 have extremely similar feel to them, and feel "modern" {like "DA" line, for example} to me (2) The "M" 50 f/2 weighs 156g while the "A" 50 f/1.7 weighs 164g {extra glass for extra fraction of f-stop would explain this} I have the M50/1.7 and the A50/1.7, the "M" version weighs 20 grams more than the "A". That's more plastic in the A50/1.7 and explains the doggy aperture ring assembly, which is the worst I've seen on a Pentax lens. I feel these two 50mm lenses are too small for a "normal/standard" prime on a full frame body, I like the extra heft of a "K" series lens any day. For me the K55/1.8 is a better choice over the two 50/1.7 lenses. Phil.

07-15-2016, 12:58 PM - 1 Like	#19
darkymir New Member Join Date: Dec 2015 Posts: 5 Original Poster	Thank you all for replaying to my question. Today i've bought the 50/1.4 Pentax-M. This is my first fast lens and i'm very pleased with the results.

07-15-2016, 01:07 PM	#20
Cuthbert Veteran Member Join Date: Nov 2013 Photos: Gallery Posts: 1,740	Originally posted by darkymir Thank you all for replaying to my question. Today i've bought the 50/1.4 Pentax-M. This is my first fast lens and i'm very pleased with the results. Yes the M50mm f1.4 is a nice lens, size is its main advantage, especially on small Pentax cameras.

07-15-2016, 01:24 PM	#21
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,835	Originally posted by microlight 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 Whilst this is all correct... remember with A series lenses once set to the A position on the aperture scale, I've never found a reason to move them again.