Olympus Pen F Lens Performance Analysis

r_a_feldman

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loccdor said:
The 25mm f/4 has poor corner sharpness that I think has to do with flatness of field - I'd like to know if there's ever an aperture where the corners become okay. Can improve shots where only the central subject is important though.
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Attached are three color images of a mowed grass field shot with my Olympus 25mm f4 on a 40MP Fujifilm X-E5. They have been processed in GIMP with the Edge Filter using a technique described in DP Review by Roger Cicala of Lensrentals that can give you a rapid idea of a lens' quality. The edge detect filter acts like focus peaking on a digital camera, so the whiter areas are in sharper focus.

As you can see, the lower corners are darker (less sharp) than the center at all three apertures. The corners are best at f16, but overall the image is not as bright (sharp) as at f8.

Also attached for comparison are images taken with the new Fujinon 23mm f2.8 WR kit lens wide open at f2.8. All images have been resized from 7728 x 5152 pixels to 1500 x 1000 pixels to bring the file size under the 2MB Photrio upload limit.
 

Attachments

  • SM_25mmF4_Edges_20250829.JPG
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  • SM_25mmF8_Edges_20250829.JPG
    1.7 MB · Views: 31
  • SM_25mmF16_Edges_20250829.JPG
    1.7 MB · Views: 27
  • SM_23mmF2-8_Edges_20250829.JPG
    1.7 MB · Views: 26
  • SM_23mmF2-8_20250829.JPG
    1.2 MB · Views: 41
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loccdor

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Thank you @r_a_feldman ! I managed to finish a full roll of slide film with the new (to me) Pen FV and 25mm f/2.8 lens today. I'll develop it soon.
 

alanrockwood

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Actually, half frame only requires about 1.4x more magnification than full frame to cover 8x10.

Theoretically it should be 1.333x more because half frame "should" be 18x24mm. However, the frame is closer to 17mm than 18mm on the short side, so it works out to be about 1.4x times more magnification than full frame.

However, half frame looses less of the image than does full frame when cropping to fit 8x10 because the aspect ratio of half frame is closer to 8x10 aspect ratio than is the aspect ratio of full frame.
 
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loccdor

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And to make things even more confusing, the lens factor is 1.44x
 

xkaes

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Guillaume Zuili said:
Having seen some Dario Moriyama mural prints shot with Pen cameras i can assure you that 11x14 is not the limit...
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A lot depends on your technique, the lens (of course) & how it is used, as well as the film & how it is exposed and developed. I've made 2x3 foot prints from my Pens that I think are great.
 

Paul Howell

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Way better than anything I ever got, but I only shot a few rolls. My Pen F is in deep storage, next time I'm at my unit retrieving my Miranda EE and lens I will pull out the Pen. If in good shape I will shoot a roll of Tmax 100 and develop in MCM 100, turn my enlarger to shoot to the floor and see if I can anything larger than 11X14.
 
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loccdor

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@Paul Howell Cool microscope setup. I've seen a few modified medical camera Pen F's being sold. They must have made very few of the long telephotos, they never pop up anywhere.
 

Paul Howell

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I have not looked for an Pen gear for a long time, maybe 25 years, but always seemed that the long primes and zooms were scare, Stephen Grady writes on his web sit that the 35 2.8 pancake prime is very rare as well.
 
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loccdor

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Huh, so they were calling it "single frame". I can see why that didn't stick.
 

MattKing

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loccdor said:
Huh, so they were calling it "single frame". I can see why that didn't stick.
Click to expand...

What we refer to as "half frame" is, of course, the same image area as a single frame in the motion picture film world, where 35mm film came from in the first place.
 

r_a_feldman

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MattKing said:
What we refer to as "half frame" is, of course, the same image area as a single frame in the motion picture film world, where 35mm film came from in the first place.
Click to expand...

And the 24mm x 36mm negative size was at one time called “double frame”.
 
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loccdor

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@MattKing Ah okay! For some reason I had that in my mind as Super 35, wasn't familiar with that terminology.
 
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loccdor

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Well, my Pen FV arrived with a badly busted film advance and overlapping frames. On a roll of 72 shots, the space taken up by photographs only made it to the half-way point and the rest was blank.

However, there were a few non-overlapped shots on the roll. I got to see how the G.Zuiko Auto-W 25mm f/2.8 lens did before I returned it. Its wide-open sharpness is good, lovely out of focus areas, and snappy when stopped down to f/5.6. This confirms the findings of that lens in the 1969 test.

First two wide open:





f/5.6:



Great lens. Sorry I had to return it.

After that, I received an Olympus Pen F, which arrived with the mirror jammed in the up position and unable to fire or advance. Of course, the seller blamed me for the problem, both times.

Oh well, third time's a charm as they say...
 
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