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Film vs digitally optimized SK 43XL Digitar

tylerallenmohr

Active member
My apologies if this has been covered previously (I couldn't find older threads on the topic)

I recently called Fofocare in NYC to ask Jeff if they had any Digitar XL lenses in Alpa mount available. He informed me that they have the 43XL and that it is the 'film optimized' version. When I asked what the differences were, he informed me that the film version was designed to account for a film plane which is never perfectly flat. Coincidently I do intend to shoot film if I decide to pick up the lens.

I am trying to gather deeper information as to the distinctions between the versions.
 

Alkibiades

Active member
there is no film version of the 43 xl.
Apo Digitar 43 xl is one of the latest schneider lenses together with 28xl and 60 xl these 3 dont have any earlier film versions. You could take the 43 xl for film also, but there are much better- and cheper- lenses for film. The strong side of the 43 xl is the possibility to resolve high end digital sensors.
Maybe you mean the Apo Digitar xl 47 mm- this lens base indeed on Super Angulon MC 5,6-47 mm that was a film lens for all formats till 6x12 cm.
 

tylerallenmohr

Active member
there is no film version of the 43 xl.
Apo Digitar 43 xl is one of the latest schneider lenses together with 28xl and 60 xl these 3 dont have any earlier film versions. You could take the 43 xl for film also, but there are much better- and cheper- lenses for film. The strong side of the 43 xl is the possibility to resolve high end digital sensors.
Maybe you mean the Apo Digitar xl 47 mm- this lens base indeed on Super Angulon MC 5,6-47 mm that was a film lens for all formats till 6x12 cm.
Here are the 2 messages in the thread that have me confused. I will certainly have a call directly with the dealer during business hours later on, but in the meantime I'm just left scratching my head.


Screen Shot 2022-01-08 at 6.00.06 PM.png
Screen Shot 2022-01-08 at 6.00.19 PM.png
 

dchew

Well-known member
Tyler,
That doesn't make any sense, and makes me suspicious. As Alkibiades said, the 43xl was introduced later and was specifically introduced for digital sensors. You can see the "new lens" brochure here. It covers the 28, 43, 60, 100asph and 120asph. Note the 100asph was never delivered. Also, I don't know how they would optimize a lens for an unknown, non-flat surface. I can see how a lens that does not "measure up" to digital applications would be reserved for film. That's a big conjecture on my part, but it is the only thing I can think of that makes any sense.

Dave
 

rdeloe

Well-known member
I think the seller has no idea and doesn't know you have the world's best MF forum looking into this :)
I think the job of the salesperson was a lot easier back in the pre-Internet days when one didn't have to worry that people could fact check you quickly and reliably drawing on experience from people around the world!
 

tylerallenmohr

Active member
I should reiterate that the information I received is coming from Fotocare in New York City. An authorized Alpa dealer and one that has only delivered wonderful service to me in the past.

But the collective guidance and wisdom of this community is one I have a lot of trust in. I’ve come to rely on the expertise I find here on many subjects
 

dchew

Well-known member
Tyler,
It is certainly possible the dealers know something we don't that was never published. I would just make sure you get an explanation of what "optimized for film" means. Especially since there is no known history of that being the case.

Dave
 

Paul Spinnler

Active member
I bought the SK 43XL when it came out back in the the day, I think more than a decade ago, and I remember speaking to a chap at SK who told me that this is their latest and best resolving lens (pre 60XL that was) specifically optimized for the 80MPX sensors of the day. Back then I had an Aptus 12 II; I was and still am astounded at the quality of this lens considering the minimal size compared to the Rodenstocks ... so I am not sure where this "film" notion comes from. Maybe it was sold as part of a kit by Alpa back in the day with the roll-film adapter which means people think it is somehow "optimized" for film; but I really think it is not. A great lens if you can get it!
 

tylerallenmohr

Active member
After a phone call with Jeff at Fotocare it appears the lens in question is something of a one-off. A modified version of a regular 43XL that has one if the internal groups slightly adjusted to Perform better on a ‘curved’ film plane.

Believe me, I’m still a bit stumped but he stands by his product and has invited me to test it the next time I’m in town.

Since the 48XL and 60XL are also in store I may take him up on the offer and try both a film and digital shoot-out with the 3.

Thanks for the replies!
 

itsdoable

Member
Film does bulge in the middle of the holder, but I'm not sure how sensitive that is at this format, the bulge would be small, and the emulsion thickness would be relatively thick compared to the format size. But if you acquire the lens, you could measure the field curvature.
 

Makten

Well-known member
You can certainly optimize a lens for digital use, but I think the "film bulge" is a misunderstanding. The film should be perfectly flat, but a digital sensor is not "optically flat". There is always a piece of glass infront of the sensor to block IR and UV, an optional AA filter and a top layer for pure protection.
Now, if you look through this glass plate from the position of the lens exit pupil, it will appear thinner in the middle than at the corners (because the glass is at an angle). This causes field curvature, astigmatism and a bit of spherical aberration, and it gets worse the larger the exit pupil is, and the closer to the sensor it is.

People adapting Leica M lenses on Sony FF cameras have been into trouble because of this, since the Sony filter stack is much thicker than even digital Leicas. A 43 mm lens designed for medium format (or large format) film will most likely have the exit pupil close enough to the sensor that it will cause similar trouble when shot on a digital sensor. But it will also most likely not be a problem if you stop down a lot.

So, if the lens was designed for digital, it might give less good results on film, and vice versa.
 

dougpeterson

Workshop Member
You can certainly optimize a lens for digital use, but I think the "film bulge" is a misunderstanding. The film should be perfectly flat, but a digital sensor is not "optically flat". There is always a piece of glass infront of the sensor to block IR and UV, an optional AA filter and a top layer for pure protection.
Now, if you look through this glass plate from the position of the lens exit pupil, it will appear thinner in the middle than at the corners (because the glass is at an angle). This causes field curvature, astigmatism and a bit of spherical aberration, and it gets worse the larger the exit pupil is, and the closer to the sensor it is.

...

So, if the lens was designed for digital, it might give less good results on film, and vice versa.
This is correct.
 

tylerallenmohr

Active member
You can certainly optimize a lens for digital use, but I think the "film bulge" is a misunderstanding. The film should be perfectly flat, but a digital sensor is not "optically flat". There is always a piece of glass infront of the sensor to block IR and UV, an optional AA filter and a top layer for pure protection.
Now, if you look through this glass plate from the position of the lens exit pupil, it will appear thinner in the middle than at the corners (because the glass is at an angle). This causes field curvature, astigmatism and a bit of spherical aberration, and it gets worse the larger the exit pupil is, and the closer to the sensor it is.

People adapting Leica M lenses on Sony FF cameras have been into trouble because of this, since the Sony filter stack is much thicker than even digital Leicas. A 43 mm lens designed for medium format (or large format) film will most likely have the exit pupil close enough to the sensor that it will cause similar trouble when shot on a digital sensor. But it will also most likely not be a problem if you stop down a lot.

So, if the lens was designed for digital, it might give less good results on film, and vice versa.

I think this is the explanation that's closest to what I've been able to discern. Taking into account the presence (or lack) of a sensor filter with digital vs a film plane
This is correct.
🙌
This is the clearest explanation of the situation and it makes more sense now.
 
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