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09-06-2019, 02:43 PM - 6 Likes   #1
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My 100mm lenses: Do my M lenses hold up to the modern DFA's ?

The DFA 100mm macro WR came as a free bonus when I purchased my K1ii with the kit lens 28-105. For many years I own the M100/4 macro and M100/2.8 and I was curious these could hold position against the newest glass. The weather was OK for some shooting, a bit blurry sun produced lots of light without harsh shadows. I took some pictures from 3 meters and some macroshots nearby at 1:2 magnification (closest possible M100/4). White balance put on "daylight", 400 ISO and manual focussing.

My test scene this time:
Focussing point were the two fruits on the statue.

Center sharpness at F5.6:
All primes perform rather equally, kit lens is a little bit softer.

Same shot (F5.6), right border at 200% with higher contrasts:
The DFA 2.8 and M 2.8 show the best sharpness, the M 2.8 frings a little bit more, but nothing to worry about.
Th M macro shows some softness at the border, the kit lens is clean but less sharp.

Same shot, right upper corner at F5.6 200%:
The M100/2.8 wins here, followed by the DFA2.8, the M100/4 and the kit lens wich is the softest also here.

The two brightest lenses wide open compared:
Amazing how good the 40+ years old M lens holds up to the DFA for center sharpness. The M is a tad softer and shows a little more glowing. These are 200% crops (!).

Same shot (wide open) a little bit off-center in harsh area:
Here the M lens shows its characteristic purple fringing like most lenses of the M-era do wide open. Sharpness still is very good.

And finally some macro-shots as close as possible for the M100/4 lens (1:2):
Both lenses perform for center sharpness very similar. Visible in OOF-highlights are the rounded blades of the DFA and the hexadiagonals of the M.

Even expanded at 200% there is very little between the modern DFA and the old M100/4. The design of this M lens goes back to the M42 Takumar era 50 years ago or so.
My lens does not suffer haze or separation, it still has very clean glass in it.

  • All three primes are very good, and outperform the DFA 28-100 kit lens.
  • With both macro lenses you can shoot stellar macroshots. There is very little in between them.
  • I did not check things like curvature etc.. But I used both macro lenses for DSLR-scanning and the results were prestine on both.
  • The M-lenses are a little less contrasty, I can see this in the diagrams. Easy correctable in post btw.
  • The M100/2.8 always was a very nice companion of mine, als on film days I shoot wonderful pictures with it. Light, compact and decent sharp portrait lens.
  • The two M-lenses perform very well on digital full frame.

Last edited by Henrico; 09-07-2019 at 03:14 AM.
09-06-2019, 03:07 PM - 1 Like   #2
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Why zoom at 200 % ? 100% is the maximum you should use for any purposes with a digital capture.

Could the lack of contrast be down to lack of a hood for example ? Or just the coatings are not working as well.

I love using old K and M series lenses (I have a few !!). The coatings are not going to be as good as modern lenses, but optically they deliver the goods. One of the major advantage of the Pentax system in my book.
09-06-2019, 04:08 PM   #3
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I too am curious, why 200%? Doing so is an upsample with three out of four pixels being extrapolated (best guess) data. This may be useful is if one's monitor has dot pitch finer than what can be discerned with human vision at reasonable viewing distance, but otherwise not so much.

I'm glad you are satisfied with the performance of all three primes. The M 100/2.8 is sort of a cult classic and the other two both share excellent reputations.

09-06-2019, 04:19 PM   #4
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Thanks for the comparison. That looks like a lot of work ! In my opinion it's a toss-up between the DFA 100 and the M100 macro. I would say the DFA slightly pulls ahead of the M100 Macro, because of its consistency. Many lenses have a sweet spot, but the DFA seems to outperform, or match all the other lenses with the 2 f-stops that you used in this test. It would have been interesting if you include F4 and F8, since the sweet-spot for most lenses is F8 and the F4 on some lenses outshine the F2.8 seting by a large margin. I have the DFA and I always thought it would be hard to find a Macro lens with that type of performance.

09-06-2019, 05:25 PM   #5
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Love post like this, thank you a lot for the work you have done.

Image from the older M macro looks not bad at all but DFA100wr seems to be the clear winner to me which is a no surprise. its consistency is outstanding.
I mostly use my DFA100 for night cityscape. I almost forget it is a macro lens. Your post helps remind me that and it makes me love the lens even more.
Off-topic: Anyone like the DFA100 macro, check out the 50 Macro too. You will probably like it as well. (I used to have FA50 f2.8.)

Last edited by tokyoscape; 09-06-2019 at 05:31 PM.
09-06-2019, 05:30 PM   #6
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I have the DFA 100mm WR lens, and love it. Great design. Its look and feel is much like a Limited. I am happy to have WR for shooting closeups under drippy conditions.

I also have long had an older Sigma EX 105mm AF macro lens. I've always liked it and retain it now mainly for having an aperture ring, which is necessary on certain models of my film bodies.
09-06-2019, 05:37 PM   #7
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Thank you for the comparison. I found this interesting because I have owned all of the primes above and will purchase the zoom when and if I go to K-1 (still using K-3). I had 2 M2.8, 1 M4, and 1 A2.8 (non macro). I decided to sell them all and replace with DFA 100wr thinking it would be a good replacement in 1 unit. I gained a stop (2.8) in macro + 1:1 magnification (w/o ext. tubes) + WR. I gave up manual aperture control and the buttery smooth manual focus. It was a good choice for me in the end, very satisfied with DFA. The M and A 100mm were excellent.

09-06-2019, 06:18 PM   #8
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Nice comparison. While the older M's are nice, gotta give it to the DFA. Pulls ahead just that little extra in contrast and sharpness out of the box, and like the rounded blades on this lens.
09-06-2019, 07:49 PM   #9
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To me the DFA is clearly sharper. Even if it wasn't better control of the aberrations is worth the price of admission.
09-07-2019, 12:14 AM   #10
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100/2.8 M = my favorite lens
So yeah you got a point
09-07-2019, 12:32 AM   #11

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Macro lenses are always optically gerat. DFA adds new coating, sealing, af. No aperture ring, af is often pointless for macro.
09-07-2019, 02:18 AM   #12
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The M and A are very good.
But the DFA is great - one of the jewels in the Pentax crown.

Thanks for doing the tests - I'm happy with my choice.
09-07-2019, 03:37 AM   #13
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Shots at F4 and F8

I choose F5.6 shots because it is middle of the road. Below the shots taken at F4 and F8 at 100% . Same place same time.

N.B. All focussing was done with live view 16x on K1ii.

Owning a DFA 100 macro there is no rational reason to buy the M lenses of coarse. The DFA has the best IQ, is WR, is AF, well build and last but not least 1:1.

The M's are affordable for their look & feel and perform very good on 36 MP full frame also. That was what I was curious about...

IQ-wise in 40 years there's not that much changed. It were no cheap lenses that days either.

I will keep my M's anyway, I still like using them for fun. They look nice on my white K-01.

Shots at F4:
No kit lens here, that starts at F5.6. The M macro is wide open and clearly softer. The DFA100/2.8 and M100/2.8 are very similar.

Shots at F8:
The kit lens stays behind, the other three are top notch.

09-07-2019, 05:45 AM   #14
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The M 100mm seems to roar back at f4 and f8 due to the contrast ? The DFA 28mm-105mm trails again in sharpness and resolution.

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