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12-16-2010, 05:58 AM   #1
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Super-Multi-Coated Takumar (M42) vs. Pentax-M (K-mount)

Hi,

I have about 3 Super-Multi-Coated Takumar lenses (55/1.8, 29/3.5 and 135/3.5) and recently got a SMC Pentax-M 50 1.7 which I like a lot. The coating looks a bit different on the M compared to the Tak's and I was wondering if there is a significant difference in optics quality between these two categories? . Thanks

12-16-2010, 06:26 AM   #2
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SMC vs Takumar

I'm no expert but I believe that the SMC coatings are continually improved. Each glass surface loses some light to reflection. The better the coating the less the loss. Try say 10 elements with 7% loss each element vs 2.4% per element. The more elements the more losses. Resulting in a fainter image and loss of contract to internal scatter. That is one reason why simpler lenses such as the DA40 F2.8 - SMC-M 40/F2.8 produce such good images and get such high scores in the lens reviews on this site. (smaller and less elements)

Back to the coatings
Comparing my SMC-M 28mm F2.8 with Takumar Bayonet 28mm F2.8 .
The Pentax has a blue-crimson back reflection. The Takumar a pink-violet tone.
Checking the reflection of a room light shows the reflection to be brighter with the Takumar (coating is poorer compared with SMC). Secondly the front element of the Takumar is noticibly larger, strange considering they are both F2.8.


Last edited by Postumus; 12-16-2010 at 06:27 AM. Reason: Typo
12-16-2010, 12:09 PM   #3
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Thanks Postumus, I agree with your approach and appreciate your feedback. However both my Takumars and the M's I was referring to, are Super Multi Coated. My question was more related on how exactly did the coating improve (I it did at all) from one to the other. I heard something about the number of layers being higher on M's compared to Tak's. Also, is it true that M's are better performers in terms of image quality?
12-16-2010, 12:35 PM   #4
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QuoteOriginally posted by BogdanMF Quote
Thanks Postumus, I agree with your approach and appreciate your feedback. However both my Takumars and the M's I was referring to, are Super Multi Coated. My question was more related on how exactly did the coating improve (I it did at all) from one to the other. I heard something about the number of layers being higher on M's compared to Tak's. Also, is it true that M's are better performers in terms of image quality?
Some advertising at the time referred to lenses labeled "SMC" as having an improved version of the Super-Multi-Coated process. It doesn't look a lot different. I think they were trying to reassure customers that it was at least just as good, while trying to shorten the name.

When comparing the M lenses to M42 Takumars, you can't say they're all better or all worse. A couple of lenses were unchanged, such as the 100mm f4 macro. At 28mm, they designed two new lenses for the K series, then had three different designs for the M series, and even produced a fourth variation with a design for the A series.

12-16-2010, 01:42 PM   #5
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Just to give some short examples to complete the picture. I've heard that S-M-C Tak 135/3.5 is basically identical to SMC Pentax-M 135/3.5 however the latter is more compact than the former. My second example would be S-M-C Tak 55/1.8 against SMC Pentax-M 50/1.7, I've heard that M's are actually sharper than the Tak's and have more layers. Third and last, S-M-C Tak 28/3.5 against SMC Pentax-M 28/3.5. The word is that M's are sharper at this aperture but don't know for sure, also it looks more compact that the Tak.
12-16-2010, 03:53 PM   #6
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Sort of on the subject....

As a matter of interest, and probably well known amongst Takumar officionados, here is an extract from a Takumar lenses brochure (May 1968). This is for Super Takumars - pre SMC:

'Takumar lenses are custom coated, depending upon their maximum aperture and the number of elements they contain. For this reason certain lenses in the Asahi Pentax System receive a purple coating, some have a coating which is amber in colour, and others employ a combination of purple and amber'.

Presumably they kept this going with extra colours through SMC to K and to M and beyond.

An interesting advert in the back of the brochure includes the fact (?) that
336 lenses will fit the Asahi Pentax Spotmatic but that there are only 22 genuine Takumar lenses designed specifically for it. In other words don't even consider the other 314

Phil
12-16-2010, 05:26 PM   #7
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QuoteOriginally posted by BogdanMF Quote
Just to give some short examples to complete the picture. I've heard that S-M-C Tak 135/3.5 is basically identical to SMC Pentax-M 135/3.5 however the latter is more compact than the former. My second example would be S-M-C Tak 55/1.8 against SMC Pentax-M 50/1.7, I've heard that M's are actually sharper than the Tak's and have more layers. Third and last, S-M-C Tak 28/3.5 against SMC Pentax-M 28/3.5. The word is that M's are sharper at this aperture but don't know for sure, also it looks more compact that the Tak.
The S-M-C Tak 135/3.5 is the same as the SMC Pentax K-mount version. This version has 4 elements and that always seemed the mark of a cheap 135. There are a lot of Takumar examples but the SMC Pentax version is not that common. The Pentax-M is a different design and you might see 20 of these for every SMC Pentax. I like the Pentax-M version because it's small, it has a hood, it has 8 aperture blades and it's pretty good. The performance differences are pretty small here.

I think of the S-M-C Tak 55/1.8 as a portrait lens and the Pentax-M 50mm f1.7 for sharpness. That's how I use them, though I haven't actually tested to see if it's true. Pentax used to recommend the 50/1.7 lenses over 50/1.4 for copying documents, because they had a flatter field as well. That suggests the 50/1.7 is also good on extension tubes.

I don't think any of the 28/3.5s are terrible. The SMC Pentax 28mm f3.5 has an excellent reputation. It's really big for such a slow lens, though. They are all different optical formulas. I thought the M version was pretty good too. I found some faster 28mm lenses that are more useful to me. They might not be as good wide-open, but at f3.5, they're stopped down and very competitive with the f3.5 lenses.

It's not too costly to just buy all these lenses and test or shoot to compare them yourself.
12-16-2010, 06:45 PM   #8
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QuoteOriginally posted by just1moredave Quote
it's not too costly to just buy all these lenses and test or shoot to compare them yourself.
STOP!


it's okay

12-16-2010, 09:03 PM   #9
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...I must admit....
That I suffer from assigmatism BUT!................

commments taken with a smile.......
thx all and sundry...
12-17-2010, 02:07 AM   #10
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QuoteOriginally posted by Just1MoreDave Quote
The S-M-C Tak 135/3.5 is the same as the SMC Pentax K-mount version. This version has 4 elements and that always seemed the mark of a cheap 135. There are a lot of Takumar examples but the SMC Pentax version is not that common. The Pentax-M is a different design and you might see 20 of these for every SMC Pentax. I like the Pentax-M version because it's small, it has a hood, it has 8 aperture blades and it's pretty good. The performance differences are pretty small here.

I think of the S-M-C Tak 55/1.8 as a portrait lens and the Pentax-M 50mm f1.7 for sharpness. That's how I use them, though I haven't actually tested to see if it's true. Pentax used to recommend the 50/1.7 lenses over 50/1.4 for copying documents, because they had a flatter field as well. That suggests the 50/1.7 is also good on extension tubes.

I don't think any of the 28/3.5s are terrible. The SMC Pentax 28mm f3.5 has an excellent reputation. It's really big for such a slow lens, though. They are all different optical formulas. I thought the M version was pretty good too. I found some faster 28mm lenses that are more useful to me. They might not be as good wide-open, but at f3.5, they're stopped down and very competitive with the f3.5 lenses.

It's not too costly to just buy all these lenses and test or shoot to compare them yourself.
I've noticed that too about the M135/3.5, it looks more compact but it's a 5 element design compared to the S-M-C Tak which is a 4 element design. The SMC-K version looks pretty much the same as the S-M-C Tak except for some cosmetic issues.

I now have both S-M-C Tak 55/1.8 and M50/1.7 but so far cannot confirm any significant difference. The guy that sold me the M said that it's better coated than the Tak and I can somewhat confirm this on a more empirical level, it looks like the front element reflects lesser light than my Tak.

I cannot say anything about the S-M-C Tak 29/3.5 except that it's sharp, however I've heard someone saying that SMCK 29/3.5 was actually an upgrade of the original S-M-C Tak and gets generally better reviews compared to both Tak and M versions.

I just remembered very important aspect about the Tak coating process, that it's radioactive. Pentax used thoriated lenses for this series. Does anyone know if this has been kept throughout the later SMCK and M series?
12-17-2010, 05:11 AM   #11
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Almost all Takumars are not radioactive.
Only the following are:

Part No. Model
43931 1:2/35mm Super-Takumar
43932 1:2/35mm Super-Multi-Coated TAKUMAR
37800 1:1.4/50mm Super-Takumar
37801 1:1.4/50mm Super-Takumar
37802 1:1.4/50mm Super-Takumar
37902 1:1.4/50mm Super-Multi-Coated TAKUMAR
37982 1:1.4/50mm SMC TAKUMAR
12-17-2010, 09:29 AM   #12
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QuoteOriginally posted by blende8 Quote
Almost all Takumars are not radioactive.
Only the following are:

Part No. Model
43931 1:2/35mm Super-Takumar
43932 1:2/35mm Super-Multi-Coated TAKUMAR
37800 1:1.4/50mm Super-Takumar
37801 1:1.4/50mm Super-Takumar
37802 1:1.4/50mm Super-Takumar
37902 1:1.4/50mm Super-Multi-Coated TAKUMAR
37982 1:1.4/50mm SMC TAKUMAR
There are some more. Don't feel like putting pulling togeather the part numbers, but the Super-Takumar, Super-Multi-Coated Takumar, and SMC Takmar 55mm f1.8 lenses are as well. The Super-Multi-Coated Macro Takumar 50mm f4 is also, but hardly at all (compared to the others).
12-17-2010, 11:00 AM   #13
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Ok, if you count the very low activity lenses also, there may be more, but the stronger ones, the ones that yellow, are those mentioned in the list.

It has been proposed, that the stronger radioactivity in certain lenses is not due to the wanted Thorium spices, but some other, unwanted, radioactive contamination. Possible ...
12-17-2010, 04:18 PM   #14
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QuoteOriginally posted by blende8 Quote
Ok, if you count the very low activity lenses also, there may be more, but the stronger ones, the ones that yellow, are those mentioned in the list.
The 55mm lenses are most certainly susceptible to the yellowing, and are as, if not more radioactive than the 50mm's, based on several people's tests I've seen posted around the internet. I do not think the Macro is (it is only minimally radioactive). We should also add the S-M-C 85/1.8. Here's the best listing with actual data:

Radioactivity of old manual lenses::Manual Focus Lenses
12-17-2010, 04:32 PM   #15
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If yellowing is the only concern with radioactive lenses then I'm not concerned. it can be fixed easily.
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