Anyone have experience with high quality half-frame or smaller digitization?

loccdor · Mar 24, 2025

Just curious what challenges you might run into when digitizing film smaller than 35mm full frame. I'm using a Pentax K-1 and am going to be trying out high resolution film on half-frame. I think I've selected a camera with a good, sharp lens; Olympus Pen D. I'll try using Adox Scala/HR-50 so the film definitely won't be the limiting factor. Might try slow Fuji slide for color. I like the idea of being able to buy expensive film for it due to the economy of its picture size.

I bought a few extension tubes for the Pentax K-1 as the 50mm macro lens only goes to 1:1. Half-frame would need what, something like 1.5:1?. Depth of field will be smaller, not sure how much that will be a problem. Been scanning full-frame at f/8, maybe I'll need to go down to f/5.6 for half-frame for diffraction? I can get about 4800 good dpi at 1:1 on this setup.

Would be great to hear your thoughts.

koraks · Mar 24, 2025

loccdor said:
Half-frame would need what, something like 1.5:1?

Your Pentax K1 is full frame, no? Then you'd need around 2:1 magnification. It's 'half frame', after all - not '2/3 frame' or thereabouts.

loccdor said:
I can get about 4800 good dpi at 1:1 on this setup.

That would surprise me, to be honest. That would effectively mean no losses in capture.

Anyway, yes, extension tube might be the easiest way with acceptable image quality and low cost. You'll be working beyond the magnification that the lens is optimized for, so there will be some losses and artifacts; notably purple fringing and the like tend to play up more noticeably. You may be able to correct this satisfactorily in digital post. What aperture will be ideal depends on the tradeoff between curvature of the focal plane vs. diffraction vs. film flatness vs. depth of field. Just try it out & see, and try to do the best job at keeping the film flat and parallel to the sensor.

Keep in mind that diffraction during capture will also be more of a concern given the shorter lens on the Pen D. Not sure what you're after, but it's generally hard to beat a bigger format by optimizing optics etc. on a smaller format. If you like the idea of 72 frames to a roll, then fine. If you're in it to save a few pennies without sacrificing quality, I doubt you're really going to be satisfied in the end. YMMV and all that.

xkaes · Mar 24, 2025

I digitize smaller negatives down to Minox using a Sony a900 (full-frame) without any problem. I use lenses designed for that format on a bellows. A 50mm macro is OK, but for 1/2 frame I use a 35mm f4.5 Tominon process/macro lens I usually shoot at f8-11 with flash to compensate for any film curvature -- even though the formats are small and I hold them in enlarger negative carriers.

I'd start with what you have -- seems like you have all you need -- and see if you like the results.

What is your light source?

loccdor · Mar 24, 2025

Thanks Koraks. Yes, K-1 is full frame. 36mm at 1:1 I thought would be 1.5:1 for 24mm longest side. But I think that would also be a bit off due to the change in aspect ratio from 2x3 to 3x4, losing some of the image area to the blank space. No matter, I'm sure a few tubes can get us in the ballpark and the lens will do the rest.

It's a combination of factors why I'm trying it out, I already know I like how half-frame looks but I'm curious how far it can be pushed before running into some technical limit.

Xkaes, do you find the film curvature to be more of a problem on the sub-full-frame formats? On my film holder the sprocket portion seems to help a lot with 35mm flatness vs 120. I can't consistently get 120 flat unless I use glass. It would seem like f/11 on a very small format might be erasing some detail.

xkaes · Mar 24, 2025

I assume that the issue of flatness is less as the format gets smaller, but maybe not. In any event, as magnification increases the DOF decreases so the need to stop down increases. I haven't run any tests, but with a digital camera it's easy to run test at each f-stop and compare the results. I mainly use f8-11 because that's what my light source (electronic flash) produces. There are times I use ND filters -- that's the only way I can control the flash -- to avoid smaller f-stops.

BrandonAvery · Mar 25, 2025

Depth of field and diffraction may be challenges; careful testing helps!

runswithsizzers · Mar 25, 2025

koraks said:
Your Pentax K1 is full frame, no? Then you'd need around 2:1 magnification. It's 'half frame', after all - not '2/3 frame' or thereabouts.

loccdor said:
Yes, K-1 is full frame. 36mm at 1:1 I thought would be 1.5:1 for 24mm longest side. But I think that would also be a bit off due to the change in aspect ratio from 2x3 to 3x4, losing some of the image area to the blank space.

As @loccdor suggests, calculating the magnification is somewhat complicated because the half-frame and full-frame dimensions are not the same shape. If the Pentax K1 sensor is 36mm x 24mm, and the Olympus Pen F negative frames are 24mm x 18mm, then enlarging the long dimension of the negative to fill the long dimension of the sensor requires (36mm / 24mm =) 1.5x or 150% magnification. Because 1.5 times the short edge of the negative = 27mm, which wont fit on the short edge of the sensor (24mm), then some of the negative would be cropped.

Enlarging the short edge of the negative to fill the short edge of the sensor requires (24mm / 18mm =) 1.33x or 133% magnification. At 1.33x, the long edge of the negative will be about 32mm, so will not fill the full width of the sensor (36mm). This will mean loosing some of the potential pixels your sensor is capable of.

It would be possible to get more pixels from your gear if -- at 1.5x -- you can take one digital image of one side of the half-frame negative, then reposition the negative and take a second image from the other side. The two digital images can then be combined ("stitched") to form a single image without cropping the negative. This may or may not be practical, depending on how your camera and/or negative holder are set up -- and it may or may not be worth the extra time and effort, but it is something to consider

loccdor · Mar 25, 2025

Thanks for those numbers regarding magnification. That makes sense.

I don't think I would ever stitch half-frame, it's something I've tried a few times on medium format using ANR glass, but only when I have a really exceptional detailed shot with high quality in film and technique (i.e. not very often), it's rather time consuming.

Anyways, for half frame my hunch is that the half frame camera's lens will be the main optical limit here when digitizing the whole frame. Hope I'm wrong!

MattKing · Mar 25, 2025

It may be worthwhile to digitize two frames at a time using what works for you with regular full frame 35mm.

Les Sarile · Mar 30, 2025

loccdor said:
Just curious what challenges you might run into when digitizing film smaller than 35mm full frame. I'm using a Pentax K-1 and am going to be trying out high resolution film on half-frame. I think I've selected a camera with a good, sharp lens; Olympus Pen D. I'll try using Adox Scala/HR-50 so the film definitely won't be the limiting factor. Might try slow Fuji slide for color. I like the idea of being able to buy expensive film for it due to the economy of its picture size.

I bought a few extension tubes for the Pentax K-1 as the 50mm macro lens only goes to 1:1. Half-frame would need what, something like 1.5:1?. Depth of field will be smaller, not sure how much that will be a problem. Been scanning full-frame at f/8, maybe I'll need to go down to f/5.6 for half-frame for diffraction? I can get about 4800 good dpi at 1:1 on this setup.

Would be great to hear your thoughts.

Bought super cheap on local listing - SMC Pentax-M 50mm F4 macro lens, and I was noticing just how sharp the results I was getting from it. I was curious just how much can it resolve. So I tested it using Kodak Techpan @ ISO25 developed in Kodak Tehnidol at all apertures and scanned it using DSLRs 14.6MP K20D, 36MP D800 and my Coolscan 4000dpi as well as optical magnification. The Pentax K-1 you're using also has the same pixel count as the D800 and the Adox may be comparable to the Kodak Techpan.

Full target at bottom left and 100% crops from the DSLRs and Coolscan above it. Since the D800 is the equivalent of about 5200dpi, it results in larger crop compared to the 4000dpi from my Coolscan.

As you can see from the optical magnification crop on the right, clearly the lens can capture far more detail onto this film then can be resolved by these methods I used. I don't know how the Olympus Pen D will compare.

Resolution testing my SMC Pentax-M 50mm F4 macro lens by Les DMess, on Flickr

Of course this was done under very controlled conditions using high res test target intended to out resolve the system being tested. At this point I'm not even sure if my cheap lens was the weak link!

Although I have a couple of half frame cameras like the Olympus Pen FT and Konica Auto-Reflex, I have not tested them in this manner.

grain elevator · Mar 30, 2025

If you do run into lens limitations, you should probably invert it, if it's a lens optimised for magnifications less than 1:1. That' very inconvenient of course and I guess it will be good enough.

loccdor · Mar 30, 2025

Les Sarile said:
Bought super cheap on local listing - SMC Pentax-M 50mm F4 macro lens, and I was noticing just how sharp the results I was getting from it. I was curious just how much can it resolve. So I tested it using Kodak Techpan @ ISO25 developed in Kodak Tehnidol at all apertures and scanned it using DSLRs 14.6MP K20D, 36MP D800 and my Coolscan 4000dpi as well as optical magnification. The Pentax K-1 you're using also has the same pixel count as the D800 and the Adox may be comparable to the Kodak Techpan.

Full target at bottom left and 100% crops from the DSLRs and Coolscan above it. Since the D800 is the equivalent of about 5200dpi, it results in larger crop compared to the 4000dpi from my Coolscan.

As you can see from the optical magnification crop on the right, clearly the lens can capture far more detail onto this film then can be resolved by these methods I used. I don't know how the Olympus Pen D will compare.

Thanks, good to see those results!

I was able to put the first half-roll (transferred mid-way from another camera) through the Pen D. I used Delta 400 @ 800, which was not ideal for a resolution test, and digitized the frames as doubles since my extension tubes are not here yet. But things look promising, even at a wide open aperture, sharpness of the in focus plane is outresolving my digitization system. I'm excited to try the Scala 50 out with in and the tubes.

As a side note, I really love the handling of the Pen D! It fits so well in the hand, and has the controls positioned so well, that I can shoot and advance it one-handed using my thumb. Never had a camera where I was able to do that before! Plus, the 0.8 meter minimum focus distance happens to be the exact length of my outstretched arm, so not having a rangefinder is really no problem! I like it much better than I thought I would.

Les Sarile · Mar 30, 2025

loccdor said:
Thanks, good to see those results!

I was able to put the first half-roll (transferred mid-way from another camera) through the Pen D. I used Delta 400 @ 800, which was not ideal for a resolution test, and digitized the frames as doubles since my extension tubes are not here yet. But things look promising, even at a wide open aperture, sharpness of the in focus plane is outresolving my digitization system. I'm excited to try the Scala 50 out with in and the tubes.

As a side note, I really love the handling of the Pen D! It fits so well in the hand, and has the controls positioned so well, that I can shoot and advance it one-handed using my thumb. Never had a camera where I was able to do that before! Plus, the 0.8 meter minimum focus distance happens to be the exact length of my outstretched arm, so not having a rangefinder is really no problem! I like it much better than I thought I would.

Welcome!

Would also be interested in seeing your results if you're willing to share.

loccdor · Mar 31, 2025

Les Sarile said:
Would also be interested in seeing your results

I'll post the Scala 50 results with extension tubes in a couple weeks. In the mean time, here's a 7x7mm crop of the Delta 400 at 800, at 1:1 without using the tubes, with the Pen D set to f/5.6 and 1/500.

Grainy due to the film and 1-2 stops overexposure, but I can see more potential detail from the lens hiding there.

grain elevator · Mar 31, 2025

loccdor said:
I'll post the Scala 50 results with extension tubes in a couple weeks. In the mean time, here's a 7x7mm crop of the Delta 400 at 800, at 1:1 without using the tubes, with the Pen D set to f/5.6 and 1/500.

Grainy due to the film and 1-2 stops overexposure, but I can see more potential detail from the lens hiding there.

View attachment 395183

Hell yeah, looks amazing! I suppose this sharpness must come from near the centre of the negative? Even so that's really impressive.

loccdor · Mar 31, 2025

grain elevator said:
sharpness must come from near the centre of the negative?

Yes that one is in the center. Here's one from the edge (and it's only 5mm wide and at f/2.8!). Focus was just guessed with arm length so there's also room for improvement there. Amazed with Olympus.

xkaes · Mar 31, 2025

No problem making huge prints even with fast film.

Les Sarile · Tuesday at 11:14 AM

loccdor said:
I'll post the Scala 50 results with extension tubes in a couple weeks. In the mean time, here's a 7x7mm crop of the Delta 400 at 800, at 1:1 without using the tubes, with the Pen D set to f/5.6 and 1/500.

Grainy due to the film and 1-2 stops overexposure, but I can see more potential detail from the lens hiding there.

View attachment 395183

Very cool!
I missed out on Agfa Scala being processed through DR5. Is this similar?

Disconnekt · Tuesday at 8:14 PM

One (not so cheap at ~$400 new) option is getting a "ultra macro" lens like the Lowa 60mm f2.8 that can go to 2:1 (https://www.venuslens.net/product/laowa-60mm-f2/)

braxus · 2025-04-07T00:27:44-0400

I used my Primefilm XAs scanner set to full rez 10000 dpi, which of course works out to half of that for half frame. In this case it works because half frame isn't all that detailed.

Anyone have experience with high quality half-frame or smaller digitization?

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Anyone have experience with high quality half-frame or smaller digitization?

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