Pentax 100mm comparison, DFA 100mm f2.8 vs M 100mm f2.8

**janosh** · 03-07-2022, 10:06 AM

It would be useful to specify camera type and autofocus vs manual.

house · 03-07-2022, 12:20 PM

Originally posted by janosh

It would be useful to specify camera type and autofocus vs manual.

The camera is the K-1 and the lenses were manually focused using live view. I've added the info to the first post.
You may be interested in this post as well. Scroll down for mtf charts comparing the two lenses.

Originally posted by house

Spent half an hour shooting charts with some of my comparable, mostly vintage, lenses. The results largely match my experience from just shooting the lenses but the curves can clarify some behaviour. I've used the free mtfmapper software that was used to calibrate the Perseverance rover cameras. I've shot an A1 size chart to minimize error. MTF mapper download | SourceForge.net

Do note that these are only relevant to my particular copies of the lenses and K-1. I have made effort to avoid mistakes but it is a home setup not a proper lab.

Pdf files and the various charts can be downloaded here https://filebin.net/squipa562ph8p2qu this link will expire eventually.

I'm not focussing on wide open as that's not my main use case.

SMC Pentax-FA 50mm f1.4 vs SMC Pentax 55mm f1.8 vs SMC Pentax-DA 50mm f1.8
Interestingly the K 1.8/55mm behaves very well. The FA 1.4/50 curves look a bit odd so I wonder about misfocus. The DA shows clear signs of being optimized for apsc.

The K 1.8/55 has better CA performance than the FA 1.4/50. Note the 4 vs 1.5 in the colour key.

HD Pentax-FA 35mm f2.0 vs SMC Pentax-DA 35mm f2.4 AL
Here the DA cleans up a little bit better when stopped down.

SMC Pentax 28mm f.35 SHIFT vs SMC Pentax (K) 28mm f3.5 vs Vivitar (Komine) 28mm f2.8 MC Close Focus Wide Angle
Here the K3.5/28 shines and the 3.5/28 shift reveals why it has such peculiar performance.

F11 CA comparisons between the two K 28mm. Note that the shift graph goes to -8!

SMC Pentax-D FA 100mm 2.8 macro wr vs SMC Pentax-M 100mm f2.8 vs SMC Pentax (K) 135mm f3.5
I've previously made side by side photos that revealed much the same as below. The macro suffers from a lot more CA as well. The M 100mm is a great performer that is rarely talked about. for non macro it beats the dfa100 macro.

F8 CA comparison. Note numbers in the key, the colours aren't directly comparable. The macro has *a lot* worse CA, not that the graph goes to 4.

**mikesbike** · 03-07-2022, 08:44 PM

The M100mm might be of the same optical design as the subsequent F or FA? In that case, test reviews of the FA and DFA have shown both to be very good lenses, with wide open to be better in the DFA 100mm. Then there's the matter of WR. Some really cool macro shots can be had under drippy conditions.

steephill · 03-08-2022, 06:50 AM

Originally posted by mikesbike

The M100mm might be of the same optical design as the subsequent F or FA?

No, very different designs. The M100f2.8 isn't a macro lens and has 5 elements in 5 groups. The F and FA macros have 9 elements in 8 groups.

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03-07-2022, 10:06 AM	#16
janosh Site Supporter Join Date: Jul 2008 Location: Albuquerque, NM Posts: 243	It would be useful to specify camera type and autofocus vs manual.

03-07-2022, 12:20 PM	#17
house Pentaxian Join Date: May 2015 Photos: Albums Posts: 3,306 Original Poster	Originally posted by janosh It would be useful to specify camera type and autofocus vs manual. The camera is the K-1 and the lenses were manually focused using live view. I've added the info to the first post. You may be interested in this post as well. Scroll down for mtf charts comparing the two lenses. Originally posted by house Spent half an hour shooting charts with some of my comparable, mostly vintage, lenses. The results largely match my experience from just shooting the lenses but the curves can clarify some behaviour. I've used the free mtfmapper software that was used to calibrate the Perseverance rover cameras. I've shot an A1 size chart to minimize error. MTF mapper download \| SourceForge.net Do note that these are only relevant to my particular copies of the lenses and K-1. I have made effort to avoid mistakes but it is a home setup not a proper lab. Pdf files and the various charts can be downloaded here https://filebin.net/squipa562ph8p2qu this link will expire eventually. I'm not focussing on wide open as that's not my main use case. SMC Pentax-FA 50mm f1.4 vs SMC Pentax 55mm f1.8 vs SMC Pentax-DA 50mm f1.8 Interestingly the K 1.8/55mm behaves very well. The FA 1.4/50 curves look a bit odd so I wonder about misfocus. The DA shows clear signs of being optimized for apsc. The K 1.8/55 has better CA performance than the FA 1.4/50. Note the 4 vs 1.5 in the colour key. HD Pentax-FA 35mm f2.0 vs SMC Pentax-DA 35mm f2.4 AL Here the DA cleans up a little bit better when stopped down. SMC Pentax 28mm f.35 SHIFT vs SMC Pentax (K) 28mm f3.5 vs Vivitar (Komine) 28mm f2.8 MC Close Focus Wide Angle Here the K3.5/28 shines and the 3.5/28 shift reveals why it has such peculiar performance. F11 CA comparisons between the two K 28mm. Note that the shift graph goes to -8! SMC Pentax-D FA 100mm 2.8 macro wr vs SMC Pentax-M 100mm f2.8 vs SMC Pentax (K) 135mm f3.5 I've previously made side by side photos that revealed much the same as below. The macro suffers from a lot more CA as well. The M 100mm is a great performer that is rarely talked about. for non macro it beats the dfa100 macro. F8 CA comparison. Note numbers in the key, the colours aren't directly comparable. The macro has a lot worse CA, not that the graph goes to 4.

03-07-2022, 08:44 PM	#18
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	The M100mm might be of the same optical design as the subsequent F or FA? In that case, test reviews of the FA and DFA have shown both to be very good lenses, with wide open to be better in the DFA 100mm. Then there's the matter of WR. Some really cool macro shots can be had under drippy conditions.

03-08-2022, 06:50 AM	#19
steephill Pentaxian Join Date: Nov 2018 Photos: Gallery Posts: 586	Originally posted by mikesbike The M100mm might be of the same optical design as the subsequent F or FA? No, very different designs. The M100f2.8 isn't a macro lens and has 5 elements in 5 groups. The F and FA macros have 9 elements in 8 groups.