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01-19-2009, 03:23 PM   #1
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Manual 20mm lenses - any good?

Has anyone got one of these lenses?

SMC Pentax 20mm F4
SMC Pentax-M 20mm F4

I saw that they are sold for about EUR 300 ...
Are they that good? Can anyone post some shots taken with one of them?

Thanks!

PS: The M 20/4 gets 'only' 8.50 at the lens reviews section

01-19-2009, 03:48 PM   #2
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QuoteOriginally posted by Noisychip Quote
Has anyone got one of these lenses?

SMC Pentax 20mm F4
SMC Pentax-M 20mm F4

I saw that they are sold for about EUR 300 ...
Are they that good? Can anyone post some shots taken with one of them?

Thanks!

PS: The M 20/4 gets 'only' 8.50 at the lens reviews section


I used to own the M 20 f/4, until it was stolen

It's absolutely wonderful. Better than my 12-24 at 20mm, better than my 16-50 was also.












This lens showed me in spades how great SMC coating is.


.
01-20-2009, 02:07 AM   #3
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jsherman999,

thanks a lot for posting these. Great shot, very nice colors, contrast and sharpness. Would you buy one in my case for the price (above)?

EDIT: Do you remember what apertures these shots were taken at (roughly)?
01-20-2009, 04:42 AM   #4
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The M 20/4 is indeed a great lens. I'm convinced it is (basically) the same optical formula as the DA 21 limited, which has exactly the same dimensions. While it is not AF, you can just turn the focus ring to the hyperfocal distance using the distance scale and snap away, never worrying about manual focusing at all. I eventually sold mine (at a loss), but I think I spent $275 or so on it. You can pick up a used DA 21 for not much more than $300 though, so if you only shoot digital that may be a better bet.

01-20-2009, 01:35 PM   #5
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Hm, looks like those lenses are a good option. However, I'm still thinking that it might be a bit too much for a 20+ years old, used lens ...

And I'm still unsure whether a 21 or 20mm prime will beat a decent zoom that significantly to make it worth it.

Anyway, thanks a lot for your shots and opinions!
01-20-2009, 01:44 PM   #6
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Maybe you can try the Vivitar 20mm f/3.8 (Kiron made). I've just bought myself one for the enormous sum of... EUR 15 (roughly US$ 20). I think it performs better on FF (I'm going to buy a Canon 5D just for the FF sensor) but if you want I can compare it with 20mm on the Pentax 18-55mm kit lens (version 1).
01-20-2009, 01:45 PM   #7
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through my own experimentation...

the true benefit of these older 20mm lenses is in the fact that they (should) offer superb quality corner to corner on FILM (ie, "full frame")

the DA21 beats both of these hands down on APS-C, because its faster and smaller, the benefit of the older glass is lost.

as to why they cost so much still, i havent a clue.
01-20-2009, 01:45 PM   #8
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QuoteOriginally posted by Finn Quote
The M 20/4 is indeed a great lens. I'm convinced it is (basically) the same optical formula as the DA 21 limited, which has exactly the same dimensions. While it is not AF, you can just turn the focus ring to the hyperfocal distance using the distance scale and snap away, never worrying about manual focusing at all. I eventually sold mine (at a loss), but I think I spent $275 or so on it. You can pick up a used DA 21 for not much more than $300 though, so if you only shoot digital that may be a better bet.
it is most definitely not the same optical forumula

01-20-2009, 01:47 PM   #9
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QuoteOriginally posted by Noisychip Quote
jsherman999,

thanks a lot for posting these. Great shot, very nice colors, contrast and sharpness. Would you buy one in my case for the price (above)?

EDIT: Do you remember what apertures these shots were taken at (roughly)?

I'm sure those were all f/8, & I was probably shooting hyperfocal at the time.

I don't know if I'd spend $300 for the M 20 f/4, although I could probably come
veryclose to talking myself into it.

I paid $170 shipped from a forum member, but that was an exceptional deal, I now see.

If I could be guaranteed that the DA 21 could give me the same sharpness/
color/contrast as the M 20 f/4, I'd buy one in a heartbeat - it's just that I hear
various grumblings about the DA 21's performance.

I loved my M 20 f4 and still pine for it, and am still watchng for a good deal on
it or the A 20 f/2.8.



.
01-20-2009, 01:54 PM   #10
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QuoteOriginally posted by Asahiflex Quote
Maybe you can try the Vivitar 20mm f/3.8 (Kiron made). I've just bought myself one for the enormous sum of... EUR 15 (roughly US$ 20). I think it performs better on FF (I'm going to buy a Canon 5D just for the FF sensor) but if you want I can compare it with 20mm on the Pentax 18-55mm kit lens (version 1).
Is it K mount or M42? Do you have one? (It's not in your sig...)

I'm quite sure it'll beat the kit lens, but how about a 'better" WA zoom as the 16-45? Is there much of a difference?
01-20-2009, 01:59 PM   #11
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QuoteOriginally posted by Noisychip Quote
Is it K mount or M42? Do you have one? (It's not in your sig...)
It's M42 but as far as usability goes, it works the same as any M lens (strictly manual). Yes, I have one but I have bought it only one hour ago I'll take some shots for you though.

QuoteQuote:
I'm quite sure it'll beat the kit lens, but how about a 'better" WA zoom as the 16-45? Is there much of a difference?
Way back then there were not many pixel peepers. I'm not too sure that a MF 20mm is better than a modern zoom like the 16-45. After all, the 16-45 is optimized for the APS-C format, with better coatings, etc.
01-20-2009, 02:54 PM   #12
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Well, here's the comparison with the kit lens (18-55mm version 1) with the Vivitar 20mm f/3.8, both at f/8:

SMC Pentax-DA 18-55mm @ 20mm f/8:


Vivitar 20mm f/3.8 @ f/8:


Conclusion: the 20mm Vivitar is not so good at the corners (aberrations). The Kit lens has a better contrast too. But then the Vivitar is FF, the Kit lens isn't.

The Vivitar on the K20D:



01-20-2009, 03:18 PM   #13
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QuoteOriginally posted by Noisychip Quote
And I'm still unsure whether a 21 or 20mm prime will beat a decent zoom that significantly to make it worth it.
I've never used a 20, but have borrowed and shot with the 21. It's nice, although distortion is surprisingly noticeable shooting architecture. What wold make me consider it - and I *am* considering it - is size. I normally carry three primes - short normal (28), long normal (40), and telephoto (100). I'd love to be able to carry a true wide as well for occasional use. But any zoom - even the kit - that includes that focal length is so much bigger than either the 20 or 21 that I'd probably have to leave the 28 & 40 at home to take the zoom. And experience has taught me I'm usually happier with the 28 & 40 than with the 18-55. So i want wide, but I want it small (and yes, I'm also looking forward to checking out the DA15/4, should it actually be released any time soon).
01-20-2009, 05:20 PM   #14
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QuoteOriginally posted by Asahiflex Quote
Well, here's the comparison with the kit lens (18-55mm version 1) with the Vivitar 20mm f/3.8, both at f/8:

Conclusion: the 20mm Vivitar is not so good at the corners (aberrations). The Kit lens has a better contrast too. But then the Vivitar is FF, the Kit lens isn't.
These shots are not bad at all for a 15 € lens, wow! But you are right, the kit lens looks better concerning the colors at least.

But I would certainly buy one of these Vivitars if I could find one for cheap
01-20-2009, 08:18 PM   #15
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W. T. F.

.


It's things like this that make me think a strange synchronicity actually lies
beneath the random chaos that is the universe...

This fall I was shooting with a bag of 4 lenses, one of which was the M 20 f/4.
I left it on a bench open & unattended for a few minutes in a crowded area, and
when I got home, my 20 was missing. Figured I was stupid and got it stolen.

This afternoon I was going through some stored clothes I'm going to throw away
or donate, and out of an old hoodie sweatshirt pocket rolled:



Apparently, I had put the lens into a pocket when changing lenses, and not
back into the bag. It's so small I guess I didn't notice, even when I took the
hoodie off.

I feel like I just found $200 in an old pair of jeans.

Sorry for the momentary thread hijack, but here are some indoor "glad to
see you again" shots:

(wide-open)




And Gooshin is right, it's not the same optical formula as the DA 21ltd - 8 elements
in 8 groups (M 20) vs. 8 elements in 5 groups.

But my M 20 f/4 is sharper than the DA 12-24 & 16-50 at 20mm, so I doubt
that the DA 21ltd is noticeably sharper than the M - it's just 5mm shorter and
10 grams lighter, and AF. (It could be far better, I just haven't seen evidence so.)

I also remember seeing a post listing original MSRP for a couple Pentax lenses,
including the M 20 f4, and they had it at $900 something. I'll look for that post,
but can anyone confirm or deny that figure? Seems pretty high for a retail
price in the 70's.


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