| Author: | | Junior Member Registered: July, 2017 Posts: 38 | | Lens Review Date: May 14, 2020 | I can recommend this lens: Yes |
Price: $25.00
| Rating: 9 |
| Pros: | Inexpensive, very sharp, low CA | | Cons: | None | | Sharpness: 9
Aberrations: 8
Value: 10
Camera Used: Pentax K-3II
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I have been using this lens strictly for astrophotography. For that purpose it is one of the best lenses I have. When it is stopped down to f/4, it is very sharp and the CA is low. Here is an astrophoto taken with it (tracking by Astrotracer):
 | | | | | | | Forum Member Registered: November, 2018 Posts: 96
2 users found this helpful
| | Lens Review Date: October 3, 2019 | I can recommend this lens: Yes |
Price: N/A
| Rating: N/A |
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 | | | | | Junior Member Registered: June, 2013 Location: Utrecht Posts: 31
1 user found this helpful
| | Lens Review Date: September 9, 2019 | I can recommend this lens: Yes |
Price: $80.00
| Rating: 10 |
| Pros: | Light, compact, sharp and contrasty, super sharp stopped down | | Cons: | Some purple fringing, easy removable | | Sharpness: 9
Aberrations: 8
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K1ii, K-01 and film
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I bought this long time ago for fl 100,- ( no euro's that time) and it was my most used short tele / portrait on film. This lens also shines on digital. Always use a hood to avoid flaire. This lens is well build, light weight, decent sharp already wide open (though little contrast), has superb color reproduction and at from F4 - F8 nice contrast. I compared this with the DFA 100 macro 2.8, you can find it here: https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/392245-my-...dern-dfas.html
The DFA is sharper wide open, frings less and produces more contrast. But the difference is minor.
If you can grab it for little, you won't be disappointed. It's not a macro b.t.w.. If you own it for portraits, you can save the money buying a DFA for that purpose.
Digital on K-01:
Scanned older color negative:
 | | | | | Forum Member Registered: May, 2018 Location: NYC Posts: 77
4 users found this helpful
| | Lens Review Date: November 11, 2018 | I can recommend this lens: Yes |
Price: N/A
| Rating: 9 |
| Pros: | colors, bokeh, focal length, rendering | | Cons: | none for the price | | Sharpness: 9
Aberrations: 8
Bokeh: 9
Handling: 9
Value: 10
Camera Used: Sony A7III
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I did not list the price as I picked this up at a yard sale for $20 and that would skew the prices.
I got this a few years back not knowing what it was - I did not have a camera at the time to use it on.
I thought it looked like a good lens and it had the original case and caps so I picked it up with the idea of using it some time in the future.
I was finally able to try it this year when I got the Sony A7III.
I used the K&F Concepts PK-NEX adapter and was amazed at the results of this lens right away.
In fact this was the lens that got me into seriously considering other vintage manual lenses to use with the A7III (now I have mild LBA).
The 100mmm length is actually quite handy once you figure out where you need to be to get an effective shot.
Not surprisingly, its like having a slightly longer 85mm and shorter 135mm with a combination of what those two focal lengths offer - the DOF of the 85mm for portraits and the reach of the 135mm.
Colors are rendered very nicely, images are sharp and low light images are good (at least they are with the A7III which is an excellent low light camera).
Bokeh is pretty easy too - it is smooth and pleasing.
Great lens!
Here are a couple of shots I first took with this lens:
 | | | | | | | Veteran Member Registered: March, 2013 Location: Montreal Posts: 495
3 users found this helpful
| | Lens Review Date: October 23, 2018 | I can recommend this lens: Yes |
Price: N/A
| Rating: 10 |
| Pros: | IQ in general, Sharpness, colors, small and light | | Cons: | Can cause LBA? | | Sharpness: 10
Aberrations: 8
Bokeh: 8
Handling: 9
Value: 10
Camera Used: MX, K10D, K20D, K-5II, K-1
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Ok, so this lens kind of changed everything for me. Found at a garage sale, and not putting in my price here because it was unrealistically low. I knew nothing about this lens, but for less than the price of a pint, hard to resist.
I have used this lens mainly with digital, though excellent with film too. On digital it seemed a world above my M50/1.7 and M28/2.8. Not sure what the magic of this lens might be - great combo of sharpness and color? Compact easy handling? Someone had mentioned using all auto-focus lenses other than this - because somehow this particular lens seems to focus automatically anyway?!? Ok, not quite, but....
Ok, who knows what it is, but if I'm unhappy with photos I'm taking, I put on the M100/2.8 and my day gets better. Not sure why.
Yes there's some PF, and sometimes colors seem too bright and too strong? But...
And then I think this caused a bit of LBA... Could other lenses change my day the way this one can?
Yikes, hadn't meant to write a new-agey review! Will add more sometime...
| | | | | New Member Registered: June, 2017 Posts: 3 | | Lens Review Date: June 16, 2017 | I can recommend this lens: Yes |
Price: $100.00
| Rating: 9 |
| Pros: | Nice bokeh and usability | | Cons: | none really | | Sharpness: 9
Aberrations: 8
Bokeh: 9
Handling: 10
Value: 10
Camera Used: Samsung NX1
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I'm using this on a Samsung NX1 with the official NX to PK adapter. Fully manual, but works great. Great lens for outdoor portraits and landscapes. Photos come out sharp enough and very adjustable in lightroom. I also have the 135mm, but prefer using this 100mm more. Photos edited to taste in Lightroom.
  | | | | | Site Supporter Registered: October, 2008 Location: Vancouver, Canada Posts: 6,637
3 users found this helpful
| | Lens Review Date: February 18, 2017 | I can recommend this lens: Yes |
Price: $134.00
| Rating: 8 |
| Pros: | Well built and good handling. | | Cons: | Could be sharper, minimum aperture of f/22 | | Camera Used: Pentax film bodies (K1000, KM, KX, K2, K2DMD, ME, MX, LX, Super A, P50)
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The M100/2.8 was released in 1977 and was a direct “miniaturized” replacement for the K105/2.8. The M100/2.8 was in production until 1984, when it was replaced by the A100/2.8.
Optics:
Typical “M” series optics compared to the “K “series lens it replaced. Pretty good, but nothing outstanding at any aperture.
Focal Range:
100mm is a nice focal length on FF for portrait or short telephoto work. Though it’s sad with the release of the M100/2.8 Pentax stopped producing a 105mm option for the first time since the late 1950’s.
Build:
Excellent all metal build in a smaller size & weight than its K Series predecessor.
Usage/Handling:
Excellent handling for an “M” series lens, mostly due to it being a short telephoto. The M100/2.8 also has a great distance scale and is easy to manual focus or adjust the aperture. Very nice compact telephoto lens to travel with.
The M100/2.8 uses a 49mm round plastic clip-on hood labelled: “SMC PENTAX 1:2 85mm 1:2.8-4 100mm”. This detachable lens hood will offer better protection than the smaller built-in hood on the A100/2.8. The M100/2.8 also had a dedicated hard lens case which also held the hood or you can use the shorter Pentax soft lens case from that period.
Speed:
F2.8 is an average speed for a telephoto lens in the 100mm to 135mm focal range. The 85mm lenses tended to be faster and of course more expensive. The 100mm/105mm lenses were the slower more affordable portrait option.
The M100/2.8 vs my other similar FL short telephoto primes:
I also own the K105/2.8 which is sharper at every aperture compared to the M100/2.8. The M100/2.8 is as well built & handles the same as the K105/2.8 and has a slightly better minimum focusing distance of 1 meter compared to 1.2 meters for the K105/2.8. The K105/2.8 has a better minimum aperture of f/32 than the M100/2.8’s f/22. I rated my K105/2.8 a 9.5 and the M100/2.8 gets an 8.5.
Summary:
Overall the M100/2.8 is an excellent short telephoto/portrait lens that is perfect for travelling due to its smaller size. But it’s not in the same league as its older brother the K105/2.8
Price:
I bought the M100/2.8 off eBay. It was in excellent + condition and came with the lens hood.
Sample shots taken with the M100/2.8. Photos are medium resolution scans from original slides.
Camera: KM Film: Fuji Velvia 50 ISO: 50
Camera: ME Film: Fuji Provia 100F ISO: 100
 | | | | | Forum Member Registered: January, 2015 Posts: 71 | | Lens Review Date: February 9, 2017 | I can recommend this lens: Yes |
Price: N/A
| Rating: 9 |
| Pros: | Sharp wide open, small & light, nice bokeh | | Cons: | Mega PF | | Sharpness: 10
Aberrations: 6
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K-5, K-50
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I bought my copy at a bargain price because it is stuck wide open and has a scratch on the front element but otherwise clean and good mechanically (hence no price listed to throw off the average). I used to own the "A" version and can confirm that sharpness improves as you stop down, but the real draw here is that IQ is very very good wide open at f/2.8. I have some pixel peeping tendencies and while f/8 is certainly sharper, I cannot in good faith knock the wide open IQ at all. This is especially true if you consider the diminutive size, ease of MF, buttery bokeh and price/value.
I use this M lens exclusively in Av mode on the K-5/K-50 since it won't stop down anyway.
Purple fringing.....if you shoot a tree against a bright sky at f/2.8 you may find that entire branches turn purple. It is borderline comical in some situations, but still easy to remove in PP. You can spend a bunch more and get a modern lens with similar specs that doesn't exhibit PF, but personally I'll suffer through a few mouse clicks on my keepers to get where I need to be.
I recently took some test shots comparing this lens to the Kiron 105mm f/2.8 Macro (mint copy). At portrait distances this SMC-M 100mm f/2.8 is noticeably sharper, easier to focus, and has smoother bokeh. Interestingly, the Kiron seemed to have a shallower DOF at the subject yet did not blur the background as smoothly. All comparisons were made wide open at f/2.8.
This lens can produce pro-quality (or close, at least) portraits and won't break the bank.
| | | | | New Member Registered: September, 2016 Posts: 3
2 users found this helpful
| | Lens Review Date: October 30, 2016 | I can recommend this lens: Yes |
Price: $50.00
| Rating: 10 |
| Pros: | Quality through and through | | Cons: | Can't think of any | | Sharpness: 10
Aberrations: 9
Bokeh: 8
Handling: 10
Value: 10
Camera Used: K-30
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Metering and auto white balance is spot on with my K-30, which isn't to take for granted with legacy lenses. No need to dial in any + or - EV.
So much fun to shoot with this lens, so small for this focal length, yet so well constructed. Focuses like a dream and focus throw is not too long which makes for fast shooting even though it is a manual lens. Focuses close enough that it's even usable indoors in spite of the long focal length.
Still sharp enough wide open but with some very slight PF in harshly lit areas. Immaculate image quality stopped down from F4 onwards. Great contrast and rendering. Very nice out of focus areas. Faultless prime. Price I paid for an excellent copy is laughable. Some lenses you know you will never get rid of, and this is one of those for sure.
Downscaled original sample + 100% crop, shot at F5.6 if I remember correctly. Impressed with the sharpness which can be seen in the rendering of the window frame, where the finely corrugated stone border is resolved without any issues.
  | | | | | New Member Registered: June, 2013 Posts: 18
2 users found this helpful
| | Lens Review Date: October 6, 2016 | I can recommend this lens: Yes |
Price: $50.00
| Rating: 10 |
| Pros: | Great image quality in small package | | Cons: | I wish it has more aperture blades. | | Sharpness: 10
Aberrations: 9
Bokeh: 10
Handling: 10
Value: 10
Camera Used: Sony a7
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This is my main portrait lens on my a7. My copy is in great condition, like new, the glass was incredibly clean and cosmetically in perfect condition. The focus grease was a bit dry, so I relubed it and now it really is a joy to use. The lens is very small, with is a big plus.
I was astonished when I saw the first portraits. I didn't expect such a great image quality. At f2.8 is very sharp, but not excessively sharp, and contrast was a bit flat. But microcontrast is at a very good level at this point. It vignettes a bit. Very good for portraits. At f2.8 it has a bit of purple fringing, but not so much! When stopped down it becomes great. At f5.6 sharpness in incredibly high, and focusing at infinity gives excellent sharpness across the frame on a FF camera. Very impressive. Bokeh is very beautiful and smooth at all apertures and seems to resist flare very well.
The six aperture blades make a smi-circular shape until f5.6, but I really wish it had more of them. 8 blades would be perfect.
I recommend this lens!
| | | | | Veteran Member Registered: July, 2014 Location: Nagoya Posts: 577
2 users found this helpful
| | Lens Review Date: July 31, 2016 | I can recommend this lens: Yes |
Price: $180.00
| Rating: 10 |
| Pros: | Sharpness/clarity, size, build, handling | | Cons: | None worth mentioning | |
Sharp and contrasty pictures from f2.8, compact, classic M series quality, ideal for portraits, flowers and longer street shooting (I use it for street with black and white film a lot, and it really shines).
Even for £100 in Exc+ condition I think it's a bargain. Definitely recommended. Get a cheap 49mm tele hood for best results.
K1000, Fomapan 100, f4:
 | | | | | New Member Registered: June, 2015 Posts: 1
1 user found this helpful
| | Lens Review Date: July 5, 2015 | I can recommend this lens: Yes |
Price: $80.00
| Rating: 10 |
| Pros: | Value, Sharpness, IQ | | Cons: | Contrast | | Sharpness: 9
Aberrations: 9
Bokeh: 9
Handling: 8
Value: 10
Camera Used: NEX-5R
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Outstanding lens for the value. If you can snag this for under $100, you'd be hard pressed to find a better option at a similar price (but that's true for most of the M-series'). Around $175-ish the max for what I would pay for this lens.
Build quality is excellent, as is form factor.
Bokeh is quite good, and the 100mm is not too large on a APS-C that still makes for a very affordable portrait lens. Sharpness can actually be a bit too much for a portrait lens stopped down, but is wonderful wide open.
The only down side is I almost always have to PP the color and contrast (but that's true for most legacy lenses).
Bottom line is this is one of the best values out there.   | | | | | New Member Registered: March, 2014 Posts: 1
1 user found this helpful
| | Lens Review Date: January 14, 2015 | I can recommend this lens: Yes |
Price: N/A
| Rating: 9 |
| Pros: | Excellent sharpness across the frame stopped down | | Cons: | | | Sharpness: 9
Aberrations: 9
Handling: 9
Camera Used: Sony A7
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The SMC Pentax-M 100mm f/2.8 is a very good M prime. Very compact for a 100mm, smooth focusing and solid construction.
The lens is usable from f/2.8, but stopping down to f/4 boosts the contrast and sharpness noticeably, even in the center. From f/5.6 the lens is very sharp all the way to the full frame corners. CA is very low.
All in all, an excellent performer
| | | | | New Member Registered: March, 2009 Location: Copenhagen Posts: 10
4 users found this helpful
| | Lens Review Date: January 12, 2015 | I can recommend this lens: Yes |
Price: $90.00
| Rating: 9 |
| Pros: | Small, light, well built, sharp, nice bokeh, cheap | | Cons: | Purple fringing at full aperture against the light, a bit long for portraits on digital camera | | Sharpness: 9
Aberrations: 7
Bokeh: 10
Handling: 10
Value: 10
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Despite this lens doesn't have automatic aperture (for those using it on a digital body) I have given it a 10 for handling due to the fact that it's diminutive size combined with light weight and the buttery-smooth focus ring makes the handling exquisite and for me I like to use it on 2.8 due to the great bokeh for portraiture, so I havn't really missed the "A"-setting. Suprisingly I havn't been able to find many images online taken with this lens so I have attached some images that I have shot with a K5 - making it a 150 mm effectively but still with the size of a 50 mm standard lens! This lens though, is abit challenged from purple fringing when shooting against strong light. This lens is a very inspiring little gem! Enough words, I will let the images will speak for themselves 
   
  
 | | | | | New Member Registered: December, 2014 Posts: 2 | | Lens Review Date: December 8, 2014 | I can recommend this lens: Yes |
Price: $120.00
| Rating: 9 |
| Pros: | IQ, Solid build, small, light | | Cons: | purple fringing | | Sharpness: 10
Aberrations: 8
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K200D
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I own this lens for more than 3 years now and it is still my favourite one. It is build like a tank, fun to use. I love the imagy quality and the colours of this lens. If you have the chance do not hesitate to buy a copy. I think it is a bit underestimated beside the 85mm f2 but it is almost as good, but for a much better price.
The only thing you have to be aware that this lens, as many of the old ones, does not tolerate when the light comes directly to teh lens. In this case you will get solid purple fringing. All the other cases it is an excellent choice.
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