Mamiya 28mm vs Cambo 24mm lens

[Don Libby]

This is in response to a request of a comparison of the two lens.

Both images were taken last night as I was testing/getting used to my loaner Cambo RS1000 from Capture Integration.

Cambo RS1000 P45+ and 24mm lens image shot on tripod.

Phase One 645 P45+ and Mamiya 28mm lens hand held.

No processing done what you see is what I got.

That's all from me as I need to help Sandy pack for the North Rim tomorrow.

Cheers!

don

 

[Guy Mancuso]

28mm some softness in the corners as expected but a magenta cast in the 24mm center

 

[Don Libby]

a magenta cast in the 24mm center

Guy - spotted that right off. Call me weird but I just don't like shooting with a center filter.

don

 

[Guy Mancuso]

Yea don't like them either. If was going back to this which i still may i would avoid lenses that need it . With stitching mostly use a longer lens anyway. I think the 35mm is a good stitching lens and even longer on some things like landscapes

 

[Graham Mitchell]

Sorry, I don't get it. Are we supposed to be able to judge lens quality from these tiny JPEGs?

 

[David K]

I'm sure a crop of the corners will confirm what appears to be some softness from the Mamiya 28. I do wonder though how relevant that corner sharpness is when stitching. I'm guessing that much if not all of the softness would be cropped out with normal overlapping technique and the two end shots could be arbitrarily cropped to eliminate that as well. Interesting to me is that non-use of the center filter yields a color cast. I expected vignetting due to fall off but not a cast. Anyway, thanks for posting this, I find it interesting stuff.

 

[Don Libby]

I'm sure a crop of the corners will confirm what appears to be some softness from the Mamiya 28. I do wonder though how relevant that corner sharpness is when stitching. I'm guessing that much if not all of the softness would be cropped out with normal overlapping technique and the two end shots could be arbitrarily cropped to eliminate that as well. Interesting to me is that non-use of the center filter yields a color cast. I expected vignetting due to fall off but not a cast. Anyway, thanks for posting this, I find it interesting stuff.

David - the image taken with the 24 was taken using the center filter. I'd agree that the 28 shows some fall off but by no means is it unusable.

don

 

[Bob]

What happens with these lenses if one applies a c1 lens cast profile?
thanks
-bob

 

[David K]

What happens with these lenses if one applies a c1 lens cast profile?
thanks
-bob

Pretty sure this is the question I want to ask also. If you shot with the 24mm and used the center filter what's up with the magenta color cast. I've read comments about color casts from tiltint/shifting (with certain backs) but didn't realize this could be a problem with a plain vanilla straight on shot. To each their own, but I wouldn't be happy having to deal with that...

 

[Jack]

I shot with the 24+CF on my Horseman with P45+, and had no notable color shift. I even added 10mm of rise, just to confirm image circle and not got that degree of color shift. Something weird is up here?

Don, are you processing these in C1? You're now using a P45+, and not a P30+, right?

 

[ericstaud]

I shot with the 24+CF on my Horseman with P45+, and had no notable color shift. I even added 10mm of rise, just to confirm image circle and not got that degree of color shift. Something weird is up here?

Don, are you processing these in C1? You're now using a P45+, and not a P30+, right?

Jack, I dare you to show us an image with a phase back and the 24mm Digitar without lens cast.

 

[ericstaud]

Pretty sure this is the question I want to ask also. If you shot with the 24mm and used the center filter what's up with the magenta color cast. I've read comments about color casts from tiltint/shifting (with certain backs) but didn't realize this could be a problem with a plain vanilla straight on shot. To each their own, but I wouldn't be happy having to deal with that...

The center filter does nothing to affect lens cast, only light falloff.

Both the Kodak and Dalsa chips used in the Phase/Hassy and Leaf/Sinar backs will produce non-uniform color when used with wide symmetrical lenses or with shifts and tilts. All these chips are calibrated to deliver uniform color response on a camera with a mirror box between the sensor and the lens. When you use a view camera, plate camera, or a tilt/shift setup, all bets are off. You run into this with the Schneider Digitar series from the 24 up to about 60mm, and also with a camera like the GX680 with swings and tilts. Each MFDB company has its own software to remove the casts. With a plate camera like the Alpa/Cambo/Sinar/etc you pretty much need to shoot a reference image using the white plexi with every shot. The color casts move around the image with a change of shift, focus, f-stop, or with swings and tilts. The images below are uncorrected from the 24XL and the 28HR on my P45+. I have seen this amount of color cast on 2 P45+ backs and 3 P45 backs, it is perfectly normal and easily corrected 100% every time. The 33MP dalsa sensor will show less color cast than this, but will still need to be corrected in software.

 

[thsinar]

The colour cast is a sensor issue, not a lens one: in any case, such shots have to be corrected with a "white shading" (or call it "gain file" or "lens cast profile").

Best regards,
Thierry

Pretty sure this is the question I want to ask also. If you shot with the 24mm and used the center filter what's up with the magenta color cast. I've read comments about color casts from tiltint/shifting (with certain backs) but didn't realize this could be a problem with a plain vanilla straight on shot. To each their own, but I wouldn't be happy having to deal with that...

 

[thsinar]

I can absolutely confirm Eric's words. Also that the Kodak sensors are more prone to this than the Dalsa, though you still need to correct the cast as well.

To convince yourself: take a shot of a uniform light grey paper and check it out.

Thierry

The center filter does nothing to affect lens cast, only light falloff.

Both the Kodak and Dalsa chips used in the Phase/Hassy and Leaf/Sinar backs will produce non-uniform color when used with wide symmetrical lenses or with shifts and tilts. All these chips are calibrated to deliver uniform color response on a camera with a mirror box between the sensor and the lens. When you use a view camera, plate camera, or a tilt/shift setup, all bets are off. You run into this with the Schneider Digitar series from the 24 up to about 60mm, and also with a camera like the GX680 with swings and tilts. Each MFDB company has its own software to remove the casts. With a plate camera like the Alpa/Cambo/Sinar/etc you pretty much need to shoot a reference image using the white plexi with every shot. The color casts move around the image with a change of shift, focus, f-stop, or with swings and tilts. The images below are uncorrected from the 24XL and the 28HR on my P45+. I have seen this amount of color cast on 2 P45+ backs and 3 P45 backs, it is perfectly normal and easily corrected 100% every time. The 33MP dalsa sensor will show less color cast than this, but will still need to be corrected in software.

 

[Jack]

Jack, I dare you to show us an image with a phase back and the 24mm Digitar without lens cast.

I should have clarified what I meant by notable, and perhaps a better adjective would have been detrimental...

For the veracity of the thread however, I will post the challenged example... A test image of the 24 digitar in front of my P45+ on a Horseman with about 10mm of rise cranked in. There is some color shift in the sky and some in the foreground, but IMO not as "notable" as Don's samples. The same shot done zeroed shows "no notable" color shift in the sky, but still has a tad in the foreground:

 

[thsinar]

Jack,

this can vary from sensor to sensor, but ALL sensors have this "issue" (issue between brackets, because it isn't really an issue with "white references" applied to the files). It is inherent to the sensor, more with Kodak sensors (like the P45) but also with Dalsa sensors.

Your example DOES show to me some notable CC: measure the difference in RGB values and you will have at least 3 to 5 points difference in magenta to green. And it becomes visible to our eyes with a difference of 3/4 points. Call it "notable" or "detrimental", the result is the same: it is visible for our eyes.

If you shoot now on a UNIFORM GREY background, with your very same settings, you would notice it even more.

Also and a very important remark: you magenta cast in the center is in a very bright part (3/4+ tones): the darker you get, the more you will have a cast. In the 1/4 tones the CC can carry up to 10 points easily, thus even more notable/visible.

That's only sharing my experience and knowledge about this "issue", not to start a war on which sensor is better. And as said, this isn't really an issue.

best regards,
Thierry

I should have clarified what I meant by notable, and perhaps a better adjective would have been detrimental...

For the veracity of the thread however, I will post the challenged example... A test image of the 24 digitar in front of my P45+ on a Horseman with about 10mm of rise cranked in. There is some color shift in the sky and some in the foreground, but IMO not as "notable" as Don's samples. The same shot done zeroed shows "no notable" color shift in the sky, but still has a tad in the foreground:

 

[ericstaud]

I should have clarified what I meant by notable, and perhaps a better adjective would have been detrimental...

For the veracity of the thread however, I will post the challenged example... A test image of the 24 digitar in front of my P45+ on a Horseman with about 10mm of rise cranked in. There is some color shift in the sky and some in the foreground, but IMO not as "notable" as Don's samples. The same shot done zeroed shows "no notable" color shift in the sky, but still has a tad in the foreground:

That looks really good Jack. Detrimental sounds like the perfect word, the color shift is there, but no one is going to care. Figuring out a way to deal with your back and it's very subtle color shifts is tricky. If you decide not to shoot the plexi for every shot, then you won't be able to correct an image where the shift becomes too much based on the subject matter.

The 22MP Dalsa sensor has similar, but even more subtle color casts. I worked with one for months without figuring out the color problems ( I did often look around the room to try to find the source on the color shift in the lighting). Once the 33MP backs came out I really had to learn a lot more about color uniformity on these sensors and now can easily see color casts in my images made with the Aptus 22. The image below was made with the 22MP sensor. The color shifts are not detrimental, but are definitely there.

Another source of color shifting on these backs is from the IR filter itself, which can create a Red/Cyan shift. Even if Dalsa or Kodak came out with a sensor that eliminated the magenta/green casts, the IR filter shift would still require corrective measures on lenses like the 24, and with other lenses using large shifts. Many here know that Leica picked a very light IR blocking filter to avoid the red/cyan shift with their wide lenses. The result was a camera that would often shift black textiles to a purple tint.

I'm not trying to turn anyone off these cameras or backs. I use one for all my work, and feel that the quality or the images and the flexibility of the systems are worth having to deal with the non-uniformity in the color. I am rather shocked that I have never met anyone who owns or is testing a system like this that has gotten a good tutorial from their dealer about the color uniformity of their back, the causes, and the solutions.

 

[Jack]

Well FWIW, I carry the sheet of CI plexi with me if I use my P45+ on anything other than the AFD3 body for that very reason. IF one is going to use any MFDB in conjunction with a shift/wide-angle camera, I think it needs to become part of their standard workflow.

 

[David K]

I've learned something new here and appreciate those that have posted and shared their knowledge.

 

[Jeff Turner]

I too very much appreciate all of the expert advise/experiences regarding MFDB as I am starting the process of evaluation of the addition of one to my equipment.
Cheers and thanks to all who contribute!!!!!