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04-18-2021, 02:09 AM - 2 Likes   #1
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Pentax 100mm comparison, DFA 100mm f2.8 vs M 100mm f2.8

I've done a quick test comparing the smc Pentax DFA 100mm f2.8 Macro WR with the smc Pentax M 100mm f2.8. This quick unscientific test compares the lenses at long distance because that is my primary use case. I may add more examples later.

First off physical appearance:



The smc Pentax M 100mm f2.8 is on the left in all samples below. All samples have been processed with identical Rawtherapee settings (capture sharpening, embedded colour profile, auto match curve). White balance was set to auto. Right click (or similar) and open image in new tab to inspect at 1:1

Comparison of colour and rendering stopped down (f16)


Resolution and fine detail at f2.8:


Resolution and fine detail at f8:


Against sun and branches at f2.8:


Against sun and branches at f5.6:


Overview against sun and branches (note tripod shifting on soft ground so above against sun images aren't perfectly comparable)


Interestingly the resolution is pretty much the same. For live view focusing at infinity the dfa 100 macro is understandably difficult. Tiny movements of the rather loose focus ring will change focus by quite a lot. In that respect the M 100mm f2.8 is better suited for tripod use at near infinity distances.


Last edited by house; 04-18-2021 at 02:21 AM.
04-18-2021, 06:04 AM   #2
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One interesting think with the M 100mm f2.8 is how the colours change as you stop down. Blues become more saturated. The DFA 100mm has more consistent colours across apertures
04-18-2021, 06:40 AM   #3
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Try the same test with a red subject...
04-18-2021, 07:24 AM   #4
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QuoteOriginally posted by house Quote
One interesting think with the M 100mm f2.8 is how the colours change as you stop down. Blues become more saturated. The DFA 100mm has more consistent colours across apertures
Although the M100/2.8 is capable of high resolution (SMC Pentax-M 100mm F2.8 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database), its contrast tends to be lower than in lenses designed for current tastes, especially wide open. That may be the effect you are seeing.

04-18-2021, 02:12 PM   #5
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I've owned many 100/2.8 macro lenses. As good as they are, nothing beats the D-FA100/F2.8 WR Macro. It is fabulous, hands down. Ricoh/Pentax needs to make a 200mm version of this lens. The Irix 150 macro is great but too much CA for my like.
04-18-2021, 05:51 PM   #6
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Interesting.
04-18-2021, 09:11 PM   #7
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Yeah. A new 200mm macro.
04-18-2021, 11:15 PM   #8
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QuoteOriginally posted by Andrea K Quote
Try the same test with a red subject...
I think I will add some more tests at some point. Will add red if I come across a suitable subject.

04-19-2021, 05:50 AM   #9
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It is interesting for PF comparisons (and for size). However, note that trees make very bad subjects for sharpness and focus evaluation, too many chances of missed focus, moving branches, etc.
04-19-2021, 08:04 AM   #10
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QuoteOriginally posted by house Quote
I think I will add some more tests at some point. Will add red if I come across a suitable subject.
I wrote "red subject" because the DFA MACRO 100mm has some problems with magenta:


This is a SOOC shot, the fluorescent red was just like that in the viewfinder but not in reality... so I'm just curious of other samples.
04-19-2021, 09:19 AM   #11
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QuoteOriginally posted by bdery Quote
It is interesting for PF comparisons (and for size). However, note that trees make very bad subjects for sharpness and focus evaluation, too many chances of missed focus, moving branches, etc.
That's true. I did photograph some particularly stationary objects (buildings) but I missed focus with the DFA! Was a bit careless and short on time but it was also surprisingly difficult to live view manual af with the DFA100.

As mention I'll perhaps add to this post later. I'm doing this as an evaluation what lens to bring when I get to move about a bit more again. I got a pristine DFA100 cheaply so decided to buy it to see how it does. Was longing for AF for my private 100mm shots. Catching running kids with 100mm manual focus turned out a bit frustrating. Doable but demanding utmost concentration and patience.

I was rather surprised not to see any major IQ difference stopped down a bit also that the M100 improves pf way better than the dfa when stopping down. The M 100 may well turn out to be the better lens for tripod work near infinity. Not what I expected even if I've always found the M100 results very good. The M can turn very strange and magenta all over if it caches the sun the wrong way which is an issue.
04-19-2021, 04:46 PM   #12
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QuoteOriginally posted by david94903 Quote
I've owned many 100/2.8 macro lenses. As good as they are, nothing beats the D-FA100/F2.8 WR Macro. It is fabulous, hands down. Ricoh/Pentax needs to make a 200mm version of this lens. The Irix 150 macro is great but too much CA for my like.
Until you manually focus it. Then the focusing action of the A100/2.8 Macro will have you looking at the D FA WR variant in disgust
04-19-2021, 11:30 PM   #13
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I don't shoot macro but isn't it fine at close distance? The focus ring is a bit loose but at least you have good throw. At infinity though it's fiddly to say the least.
04-20-2021, 06:45 AM   #14
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QuoteOriginally posted by house Quote
Was longing for AF for my private 100mm shots. Catching running kids with 100mm manual focus turned out a bit frustrating. Doable but demanding utmost concentration and patience.
Macro lenses, even with AF, will still struggle a bit with moving subjects. The focus throw is long and AF is slow in general terms.

QuoteOriginally posted by house Quote
I was rather surprised not to see any major IQ difference stopped down
I'm not surprised. You're comparing optically excellent lenses (true macro are always excellent) in ideal conditions, i.e. stepped down. Essentially you're demonstrating the age-old expression "F8 and be there" To see differences, stress the lenses more by shooting wide open, or in difficult light (which you did, and it showed a dramatic difference in PF).
04-29-2021, 02:54 AM   #15
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this is really interesting thanks folks

My wife bought me a mint 100 f2.8 M as a birthday gift a few years ago. Its a lovely thing but I dont use it that often as its an odd focal length on APSC

Had the new macro on my hit list for a while but found M100 with extension tubes to be pretty darned good, and the macro price has got a bit high of late - now I wont worry - but I will pull out the M100 and go play at the weekend
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