| Author: | | Senior Member Registered: October, 2006 Location: Masachusetts Posts: 243 | | Review Date: January 21, 2007 | Recommended
| Rating: 8 |
| Pros: | Small, light, sharp | | Cons: | Corners soft wide open | |
This is a light and reasonably sharp and contrasty lens, I used it a lot with the MX cameras and Kodachrome. No noticeable vignetting, although I never did a formal test. I do believe that the corners are a bit soft wide open, but that clears up if you stop it down a step or two.
Great for throwing in a lightweight bag, works with all the old film cameras and the new digitals. It's really only a moderate wide on the reduced sensors of the new cameras, but for small groups it works quite well.
| | | | | | | Inactive Account Registered: February, 2007 Location: Italy Posts: 2
1 user found this helpful
| | Review Date: February 17, 2007 | Recommended
| Rating: 9 |
| Pros: | sharp, sharp, sharp even wide open, not too much vignetting, low distortion, light weight | | Cons: | still has distortion | |
This lens has a very good color rendition and gave me great sunset landscapes on the seaside; to be a 20mm lens it has low distortion, but it STILL retain a few...
So, using it now on my Pentax K110d instead of the 18-55, I get only a marginal distortion reduction.
Vignetting is low and resolution and contrast are HIGH.
| | | | | Veteran Member Registered: February, 2007 Location: Auckland Posts: 452 | | Review Date: June 26, 2007 | Recommended
| Rating: 9 |
| Pros: | Sharp, high res, build quality and compact | | Cons: | marginally soft wide open, slow | |
Love this lens, great morning, afternoon and night shots with this little beauty. Big difference in resolution compared to the kit lens at the wide end but you'd expect that from a prime. Corner to corner sharpness is fantastic stopped down.
| | | | | Veteran Member Registered: February, 2007 Location: Phoenix Posts: 1,056
1 user found this helpful
| | Review Date: January 18, 2008 | Recommended | Price: $275.00
| Rating: 8 |
| Pros: | very compact, short focus throw | | Cons: | speed, a little soft wide open | |
This lens is almost the spitting image of the DA 21mm f/3.2 -- with the same tradeoffs that all small lenses have, namely speed and some degree of image quality. It is very sharp stopped down a little, and it is a breeze to focus. A little push of one finger on the focus ring will do it. It is also very, very tiny, just 5mm (the depth of a filter) longer than the DA 21mm. The flipside is that it is slow at only f/4, and ultra-wide angles invariably have suboptimal image quality out toward the edges.
If you only shoot digital, the DA 21mm is probably a better bet because it is autofocus and not much more expensive (at present). But if you shoot film too, this is a great one to have in your bag. Of course, autofocus isn't usually a necessity for a 20mm lens -- there is so much depth of field that focus errors are uncommon.
I like having lenses I can share between digital and film, so the M 20mm is perfect.
| | | | | | | Senior Member Registered: January, 2008 Location: Bondi, Australia Posts: 206 | | Review Date: January 29, 2008 | Not Recommended | Price: $65.00
| Rating: 7 |
| Pros: | compact, solid construction | | Cons: | soft wide open, 20 f/2.8 leaves it for dead | |
I had been looking for this lens second hand for over 10 years, finally found one with a bit of easily removed fungus, hence the idiotically cheap price . When tested side by side with the 20 f/2.8 , the 2.8 was so much better that I sold the f/4 immediately !
| | | | | Veteran Member Registered: April, 2007 Location: Lisbon Posts: 683 | | | | | Site Supporter Registered: September, 2006 Location: Pennsylvania Posts: 1,449 | | Review Date: June 5, 2008 | Recommended
| Rating: 10 |
| Pros: | Sharpness, contrast and color and size | | Cons: | None. But it is manual. | |
This SMC Pentax M 20mm/4 lens has no trouble bridging the transition from film to digital. It responds on a DSLR sensor with excellent output. Resolution is very good to excellent, better on the DSLR as the corners tend to remain sharp whereas with film they can go a little soft with some vignetting visable through at least 5.6 on film. Those problems have not reared their heads on the K10D.
Color is just ever so slightly cool of neutral with intense and outstanding color saturation and exceptional contrast.
The coatings on this lens are "classic Pentax". Personally, I'm not sure color and contrast can get any better on any lens.
The lens is quite small, around the size of a DA40 LTD.
I use it in manual mode due to the fact that there is no A setting for this lens.
They are farily expensive even used but the output on a DSLR is wonderful.
Distortions are well controlled on the sensor and well within normal limits on film. A nice lens if you can get one.
I rate this lens this high due to the fact that it delivers the output needed. I do not ever shoot wide open, so some may find the open ap a wee bit soft. But at 5.6, 8, and 11 the lens is absolutely stellar.
| | | | | Veteran Member Registered: December, 2007 Posts: 8,237
3 users found this helpful
| | Review Date: October 17, 2008 | Recommended
| Rating: 9 |
| Pros: | Very sharp, incredible color and contrast | | Cons: | none | |
This lens floors me - very sharp, and the colors are so rich and deep. I get a big smile on my face every time I go out with it - I have the 16-50 and the 12-24, and this is sharper than both at 20mm. A joy to use.
New photo, after finding my 'stolen' M20!
 | | | | | Veteran Member Registered: December, 2007 Location: Prague Posts: 1,199 | | Review Date: November 20, 2009 | Recommended | Price: $400.00
| Rating: 8 |
| Pros: | compact size, sharpness and contrast, flare resistance | | Cons: | pentagonal aperture, vignetting when using filters on K-1 | | Sharpness: 8
Aberrations: 9
Bokeh: 7
Handling: 8
Value: 9
Camera Used: K-5, K-1
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I bought this lens mainly to use it reversed for macro. It does this job well, but pentagonal aperture is a bit distracting sometimes in the bokeh.
I found that on K-5 it is a great performer as a wide prime for landsapes but I haven't compared it to DA21 yet. But it is much much better than 18-55 of course.
On K-1 I cannot use the polarizer with this lens - it vignettes too much. The extreme corner performance on K-1 is IMO very bad until f16.
| | | | | Senior Member Registered: March, 2008 Posts: 282
1 user found this helpful
| | Review Date: January 26, 2010 | Recommended
| Rating: 9 |
| Pros: | Color and contrast, size, price | | Cons: | still a little bit of distortion | |
This is one of my favourites, a great little lens. I bought it instead of the DA 21 for a far better price and wasn't dissappointed. It has become my main prime lens on vacation trips (on the K10D).
It produces great colors for landscapes. Sharpness isn't extremely high but fine at f8. Prints at 45 x 30 cm look great. Neither vignetting nor CA noticable to me; good flare control (without hood, that is).
The lens is well built and very handy by its size. Beeing a manual lens doesn't matter much to me for a wide-angle. Once figured out, the exposure setting can be kept almost until dawn :-)
Samples: http://www.flickr.com/photos/chip_de/tags/smcm204/ | | | | | Veteran Member Registered: October, 2008 Location: Albuquerque NM Posts: 9,830 | | Review Date: May 2, 2010 | Recommended | Price: $300.00
| Rating: 8 |
| Pros: | Tiny; Great FOV on film; Color, sharp especially on digital | | Cons: | Hard to focus in low light, Soft corners on film wide open | |
I bought this lens primarily to get ultrawide coverage on film. It did not disappoint. It is terrific for film outdoors, where you can stop it past wide open, and where focus is easy. It is tiny--about like one of the smaller DA ltd lenses. The colors are Pentax perfect, especially on film, and the FOV on film is magnificent. On film corners melt away a bit wide open, but down a stop or two, there are no complaints.
However, I am not one of those who would recommend this over the DA21 for digital. This lens now costs $300-400 for a copy showing some wear, and $500 for a "like new" example. If you are using this only for digital, there is no significant advantage I can see in buying this lens over the DA21, and there are many disadvantages. The lack of autofocus and autoexposure is a majory inconvenience. In addition, the F:4 maximum aperture is not all that easy to focus indoors. Even comparing manual focus to manual focus, the half stop of brightness on the DA21 is huge. With the low light capabilities of the newer DSLR bodies, the ability to focus a lens with this field of view indoors quickly is a major consideration.
I already had the DA21, and many other ways to zoom to this focal length on APS-c even before this purchase, but this lens gives me what I needed. This lens on an MX body is about as compact as carrying a wide angle zoom that will reach its film FOV.
Here are some fun examples from my first roll with this lens shot at a local farmers market. (The film is Fuji 160S)
And on the K10d wide open:
 | | | | | New Member Registered: July, 2008 Location: Murcia - Spain Posts: 12 | | Review Date: May 23, 2010 | Recommended | Price: $360.00
| Rating: 9 |
| Pros: | Sharpness, color rendition, low vignetting and small size and rugged construction | | Cons: | None | |
LX
F11
1/125
Fuji Sensia 100
Tripod
EPSON PERFECTION V300 PHOTO
| | | | | New Member Registered: October, 2007 Location: Toronto Posts: 4
3 users found this helpful
| | Review Date: May 28, 2010 | Recommended | Price: $200.00
| Rating: 8 |
| Pros: | Very Sharp, Short Minimum Focus Distance, Nice Colour | | Cons: | Slow at f4 | |
This was my second copy of this lens. For whatever reason, I sold the first one, and then bought another, but I was very upset when I bought this lens, because the aperture lever broke. Someone took it out so that it could be used on the Canon bodies, and it was GLUED back when it was sold to me. In any case, I have neglected this lens for more than a year until I started using it on the Digital Rebel 550D (this lens does not work on full frame Canon cameras).
I wish I had used this lens sooner. Such a small and lightweight lens is perfect match for the also petite Digital Rebel. I love the fact that anything after 2 meters is consider infinity, so that's where the focus usually stays. When used on non-full frame cameras, corner sharpness issues can be neglected.
The 20mm f4 is very sharp and contrasty. It's now my favourite lens!
Pentax K10D & 20mm f4 at f4:
Canon 20D IR Converted & 20mm f4:
Canon Digital Rebel 550D & 20mm f4:
 | | | | | Veteran Member Registered: February, 2009 Location: Perth, Western Australia Posts: 2,576
2 users found this helpful
| | Review Date: December 16, 2010 | Recommended
| Rating: 9 |
| Pros: | size, handling, optical performance | | Cons: | wide open performance | |
I purchased this lens intending to use it for both digital and film cameras, however I was not too sure how it would compare to my existing Pentax-M 28mm f/3.5, which is already very good in terms of sharpness, both on film and digital.
However as soon as I mounted the M20 to a film body, I was in love with the size and handling of the lens. It really is tiny - comparable to some of the small modern limited lenses.
On film the field of view is fantastic. Extremely wide, but I was surprised by how practical it is in use. I had some reservations that this lens would be special purpose only, but really it is very practical in much the same way as the excellent DA15 limited is on digital.
The M20 continues to be a solid performer on digital. I did find that sharpness wide open at f/4 was a bit lacking, however there is quite a dramatic improvement from f/5.6 onwards. Perhaps this is the compromise that the lens designers had to make in order to keep the lens so tiny? In my mind, it is worth it! Even though I have listed this point in the cons list, I would consider it almost a non issue.
Another point that is relevant on both film and digital is that the M20 appears to be relatively resistant to flare when compared to some of my other M series lenses. This is a rather useful attribute, as with such a wide lens it is likely that you will have the sun close by for at least some shots. Keep in mind however that I am comparing it against other M series lenses, not modern DA lenses.
On digital the M20 will act like any other K or M lens - this means stop down metering and using manual mode. However in my opinion this is less of a hassle compared to other K and M series lenses of a longer focal length. Don't let it hold you back from using this lens.
One thing about the M20 on digital is that in my mind it is a bit of a strange focal length. Wide but not really wide (I would consider wide on digital 18mm and shorter). Of course this is not the lenses fault, Just something to think about.
On that note, I really do encourage the more adventurous DSLR user to try this lens out on film. I'm sure you will be impressed as it really does come into it's own. Paired with an MX body, you end up with a very compact kit.
In conclusion, I would rate the M20/4 as a 9 on film and an 8 on digital. Here I am rating it as a 9 due to the surprisingly practical nature and excellent optical performance on the 35mm film format.
I have attached a couple of shots taken with scanned Kodak Ektar 100 film. No complaints with contrast, colour or resolution here... I will endeavour to return at some point with some digital images for comparison.
 | | | | | Veteran Member Registered: December, 2007 Location: Vancouver, British Columbia Posts: 336
5 users found this helpful
| | Review Date: December 20, 2010 | Recommended
| Rating: 9 |
| Pros: | lovely IQ, good build, compact | | Cons: | currently expensive, not all that wide on digital | |
I got this lens very inexpensively - very lucky yard sale find (along with a bunch of other Pentax gear). So I won't say exactly how much it cost 
Anyway, I only ever had a chance to run it through its paces with one roll of film (long expired generic KodakMax 400) and also took a few digital test shots.
I must say, on my Pentax ME, it had a certain indefinable quality and produced fantastic shots. I would call it ‘cinematic’ – kind of bold yet mysterious. I never experienced any perspective distortion, which is great considering just how wide this little prime is. The colors and contrast were always punchy and nice, and the sharpness was also excellent to my eye. It was a joy to compose with and to manually focus on the Pentax ME. Together, they made for such a nice little compact package. And the couple of images I got with this lens on digital (my Pentax K-x) also looked nice.
Unfortunately, I was silly enough to sell it, right here on the forum marketplace. Part of me wishes I hadn't. I hope the new owner holds on to it for quite a bit longer.
The reason I sold was I thought that a Sigma 10-20 would be a better and more practical choice for DSLRs. I believed f4 to be a bit too slow and the lack of AF and zoom to be downsides. In reality, for my style of shooting, the lightweight nature or this lens and its image quality outweigh those considerations by far. Oh well, live and learn I guess. Definitely, I'd say the images I got from the Sigma were much more prosaic and less 'cinematic', much less “wow” factor.
Here are a few sample shots from that one roll of cheap expired film on my Pentax ME:
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