Actually, we need even more resolution.

[Jim Kasson]

True colour sensors (either MS or Scanning backs) never present any aliasing although the pixels are huge and the lens out resolves the sensor.

Take a look at the Betterlight Super 6K rendition of the ISO 12233 target rosette here: http://blog.kasson.com/?p=4802

Look at the horizontal lines around the 7. (Nyquist is about 5.5) They diverge as you go from left to right when the target is converging. That's aliasing. It occurs because the lens is resolving at high MTF beyond the Nyquist frequency of the sensor. So it does happen. On the other hand, ISO 12233 is designed to find things like that, and you'd be hard pressed to ever discover the effect in a natural image scene. I have seen moire in BL images with window screens in them.

Note the admirable lack of false color; that's the beauty of the BL back, and MS backs as well, as you point out.

So this is merely a quibble with your point.

Jim

[Theodoros]

Take a look at the Betterlight Super 6K rendition of the ISO 12233 target rosette here: http://blog.kasson.com/?p=4802

Look at the horizontal lines around the 7. (Nyquist is about 5.5) They diverge as you go from left to right when the target is converging. That's aliasing. It occurs because the lens is resolving at high MTF beyond the Nyquist frequency of the sensor. So it does happen. On the other hand, ISO 12233 is designed to find things like that, and you'd be hard pressed to ever discover the effect in a natural image scene. I have seen moire in BL images with window screens in them.

Note the admirable lack of false color; that's the beauty of the BL back, and MS backs as well, as you point out.

So this is merely a quibble with your point.
 

Jim

I use an Imacon 528c at 16x and its totally moire free, I thought it would be the same with scanning backs but obviously forgot that sampling there is tri-linear... 

[Jim Kasson]

I use an Imacon 528c at 16x and its totally moire free, I thought it would be the same with scanning backs but obviously forgot that sampling there is tri-linear... 

It actually does the equivalent of three shots.

Jim

[ErikKaffehr]

Hi Jim,

Thanks for contributing to the thread.

I would say that colour aliasing is a major problem that is caused by the Bayer pattern while monochrome moiré and aliasing are lesser obvious artefacts. On the other hand I feel the monochrome aliasing also creates false detail, that may be seen as texture. That is part of the reason I use the feather shots as a sample, it illustrates the issue well.

I guess that we will live with the Bayer pattern for a long time. The other approaches are not that practical. Right now those are multishot, scanning backs and Foveon type sensors. Foveons have problems with noise and colour interpretation, as far as I understand. Multishot and scanning backs can have problems with things that move.

My understanding is that the best way of getting rid of aliasing (colour or not) is to reduce the pixel size. Increasing the fill factor would also help, I am pretty sure. Making the pixels smaller reduces DR at the pixel level, but I would say that the loss is probably acceptable with say 3 micron pixels and present levels of readout noise.

Best regards
Erik

Take a look at the Betterlight Super 6K rendition of the ISO 12233 target rosette here: http://blog.kasson.com/?p=4802

Look at the horizontal lines around the 7. (Nyquist is about 5.5) They diverge as you go from left to right when the target is converging. That's aliasing. It occurs because the lens is resolving at high MTF beyond the Nyquist frequency of the sensor. So it does happen. On the other hand, ISO 12233 is designed to find things like that, and you'd be hard pressed to ever discover the effect in a natural image scene. I have seen moire in BL images with window screens in them.

Note the admirable lack of false color; that's the beauty of the BL back, and MS backs as well, as you point out.

So this is merely a quibble with your point.

Jim

[Theodoros]

Hi Jim,

Thanks for contributing to the thread.

I would say that colour aliasing is a major problem that is caused by the Bayer pattern while monochrome moiré and aliasing are lesser obvious artefacts. On the other hand I feel the monochrome aliasing also creates false detail, that may be seen as texture. That is part of the reason I use the feather shots as a sample, it illustrates the issue well.

I guess that we will live with the Bayer pattern for a long time. The other approaches are not that practical. Right now those are multishot, scanning backs and Foveon type sensors. Foveons have problems with noise and colour interpretation, as far as I understand. Multishot and scanning backs can have problems with things that move.

My understanding is that the best way of getting rid of aliasing (colour or not) is to reduce the pixel size. Increasing the fill factor would also help, I am pretty sure. Making the pixels smaller reduces DR at the pixel level, but I would say that the loss is probably acceptable with say 3 micron pixels and present levels of readout noise.

Best regards
Erik

Wouldn't smaller pixels increase cross-talking between them and thus increase colour aliasing Erik? (additionally to noise per area increase and the DR reduction)... Moire doesn't seem to be a problem that occurs often with pixels of 6microns, (I don't see the owners of those sensors complaining at all for moire),  it seems to me that 6microns is good enough for a modern sensor with no AA filter, I am curious to see how things will develop with CMOS sensors for MF from here on... I expect that there will be no more CCD sensors here after and I am really curious to see a comparison between Leica's new 37.5mp CMOS sensor (6 microns) with respect to Sony's 50mp one.

[Jim Kasson]

I would say that colour aliasing is a major problem that is caused by the Bayer pattern while monochrome moiré and aliasing are lesser obvious artifacts. On the other hand I feel the monochrome aliasing also creates false detail, that may be seen as texture.

I agree on both points. The luminance aliasing produced by mono. scanning, and MS cameras is far less objectionable than in-your-face false color, and completely invisible most of the time.

My understanding is that the best way of getting rid of aliasing (colour or not) is to reduce the pixel size. Increasing the fill factor would also help, I am pretty sure. Making the pixels smaller reduces DR at the pixel level, but I would say that the loss is probably acceptable with say 3 micron pixels and present levels of readout noise.

Making the pixels smaller doesn't affect the DR per unit area materially if the dimmest signals of interest must have SNRs of at least 3 stops, as I personally find the lower limit for what I consider to be a quality image. At that level, photon noise dominates, and RN is hardly a contributor at all, unless there is a pattern to the RN. Remember that noise adds in quadrature.  I think, from my simulations, that 2 um spacing would be fine for a FF sensor, and maybe a lot less. We won't see that for quite a while, though.

With respect to MS cameras, why not bring back color wheels? You'd have a mono camera that would be versatile, and a color one that would be limited. You'd be able to use any filter set you wanted, for any color rendering desired. There could be a cottage industry developing filter sets. Photographers could dye their own glass, just like they used to mix up their own developer.

Jim

[ynp]

With respect to MS cameras, why not bring back color wheels? You'd have a mono camera that would be versatile, and a color one that would be limited. You'd be able to use any filter set you wanted, for any color rendering desired. There could be a cottage industry developing filter sets. Photographers could dye their own glass, just like they used to mix up their own developer.

Jim

Jim,

Very interesting idea. Getting back to XIXth century.

If I , say, have a P1 Monochrom back or Leica Monochrom and want to shoot a painting through the filters, is there a Software to automatically mix the files? And have a reliable color management?

Yevgeny

[Jim Kasson]

If I , say, have a P1 Monochrom back or Leica Monochrom and want to shoot a painting through the filters, is there a Software to automatically mix the files? And have a reliable color management?

I imagine that any camera profiling software should work, providing the filter spectra aren't too weird.

Jim

[ynp]

I imagine that any camera profiling software should work, providing the filter spectra aren't too weird.

Jim

Thank you for the explanation.
Maybe the past is my future. ...

[Theodoros]

Jim,

Very interesting idea. Getting back to XIXth century.

If I , say, have a P1 Monochrom back or Leica Monochrom and want to shoot a painting through the filters, is there a Software to automatically mix the files? And have a reliable color management?

Yevgeny

Hi Yevgeny,
I believe people that are keen to Astrophotography are advanced on the matter... Never the less, It all comes down on how to get rid of BP at the end... it's causing all short of problems.

[ynp]

One of the forum members contacted me offline and directed me to the Sinar' s technology: CTM, and I found an interesting quote:

CTM exclusively works with the Sinarback eVolution75H, 86H and eXact. The standard infrared filter needs to be replaced by a clear glass filter or these digitalbacks can be ordered with clear glass filters (552.45.02X). CTM is a multi-shot application because capturing one-shot images is showing a permanent large color deviation and an obvious lower color resolution. There are two high quality color filters (blue and yellow) integrated in the Sinar CTM Slider mounted in front of the lens like a Sinar LC Shutter 100. CaptureFlow RePro SW automatically provides two multi-shots (4-shot blue and 4-shot yellow).

Edit: the extract was taken from a Capture Integration file.

[ynp]

Hi Theodoros,

Thanks. I am not tech savvy at all and struggle with the tech language.  I do not understand a lot of things on digital even in my own language. I will have to google for Astro photography.

Last year I had a problem with a shooting of a collage on fine silk with a lot of small 3-dimentional elements and newspaper clippings. It was mounted on a wall of a barn in Provence and I had no MS back with me.
I tried my Leica s2 on it, with a shift lens first, than made a number of captures with the idea to stitch them. I looked at the files  at the hotel and saw a lot of artifacts. I went to a local photographer and hired him to shoot the collage on his old 5 by 7 film camera, scanned the film on our Leaf flatbed and there were only minor color and falloff corrections needed.
Just a story to share.

[Theodoros]

Hi Theodoros,

Thanks. I am not tech savvy at all and struggle with the tech language.  I do not understand a lot of things on digital even in my own language. I will have to google for Astro photography.

Last year I had a problem with a shooting of a collage on fine silk with a lot of small 3-dimentional elements and newspaper clippings. It was mounted on a wall of a barn in Provence and I had no MS back with me.
I tried my Leica s2 on it, with a shift lens first, than made a number of captures with the idea to stitch them. I looked at the files  at the hotel and saw a lot of artifacts. I went to a local photographer and hired him to shoot the collage on his old 5 by 7 film camera, scanned the film on our Leaf flatbed and there were only minor color and falloff corrections needed.
Just a story to share.

There are certainly a lot of advantages (some disadvantages too) in using film depending on the case... Certainly the major disadvantage of digital is the fact that captures are not in colour but an interpolated result and the associated equipment (Bayer pattern etc) that is involved... One that shoots MS like you, (especially one that uses such a capable back as the one you have) surely has understand the issues... Unfortunately we'll have to wait until single shot captures are also in true colour before we can get rid of artefacts... One more thing to mention is Sinar's work on profiles (which you stated above), it seems that they are ahead in working on the matter, they seem to care about accurate colour reproduction as their major market and they target people or organisations that concentrate in painting reproduction... Their profiling methods look far more advanced than "competition"...

[BJL]

What I meant is that indeed parts of the Toledo picture are OOF. This is not a problem and did not preclude that picture to be chosen for photokina.

We are not really disagreeing there, since I (like Erik) just stated the limitation to scenes where OOF foreground is not a problem.  Though frankly ,"Toledo" is a poor example: the OOF "foreground" is about 80% of the image, and as soon as I enlarge anywhere close to "400MP", it is very disappointing to hunt almost in vain for something truly sharp. I suspect that its selection was I more about demonstrating a technological possibility.

Also, about Epson's making these printers proving that 400MP is needed; I can see another reason:
- cameras exist giving files of about 10,328 pixels on the long edge, and somewhat more is probably coming soon.
- owners of such printers might well want sometimes to print such files with 10,328 pixels across the width of the roll, so needing about that many pixels across the roll.
- owners might also want at other times to make far larger panoramic  prints, with the short edge of the image oriented across the roll.
And voila: 10,328 on the short edge is needed for the printer, even if not for any print.

[jerome_m]

Also, about Epson's making these printers proving that 400MP is needed; I can see another reason:
- cameras exist giving files of about 10,328 pixels on the long edge, and somewhat more is probably coming soon.
- owners of such printers might well want sometimes to print such files with 10,328 pixels across the width of the roll, so needing about that many pixels across the roll.
- owners might also want at other times to make far larger panoramic  prints, with the short edge of the image oriented across the roll.
And voila: 10,328 on the short edge is needed for the printer, even if not for any print.

You cannot possibly be serious: nobody in their right mind would buy a 60" (150cm) wide printer to print images which would fit in a 40" (120cm) printer sideways, since the second printer is half the price and a lot less floor space.

It is quite simple really: to take full advantage of a 60" (150cm) printer, one will need images measuring 18000 pixels on their short side when printing at 300 dpi. And: yes, people do print images which measure 60" (150cm) on their short side. Large prints do exist, they are made and sold daily.

[Isaac]

Who was it that said "if you can't make it good, make it big!" ?

anon. “Of course, you know the adage, if you can’t make it good, make it big. If you can’t make it big, make it red. So we do like big red photographs.”

[BJL]

You cannot possibly be serious: nobody in their right mind would buy a 60" (150cm) wide printer to print images which would fit in a 40" (120cm) printer sideways, since the second printer is half the price and a lot less floor space.

If some one (or some printing shop) wants to do both huge prints (60" on the short edge) and less huge ones (a mere 60" on the long side), it makes sense to get one printer that can handle both tasks, rather than having to pay for and make space for two huge printers.

[jerome_m]

If some one (or some printing shop) wants to do both huge prints (60" on the short edge) and less huge ones (a mere 60" on the long side), it makes sense to get one printer that can handle both tasks, rather than having to pay for and make space for two huge printers.

You are aware than one can use the smaller paper rolls in the larger printers, right?

[Jim Kasson]

If some one (or some printing shop) wants to do both huge prints (60" on the short edge) and less huge ones (a mere 60" on the long side), it makes sense to get one printer that can handle both tasks, rather than having to pay for and make space for two huge printers.

Right you are. Not to mention that you'll spend more on ink for a printer than you'll ever spend on the printer itself. In a commercial environment, you'll spend much, much more. So the added cost of a 60" printer over a 44" one is a drop in the bucket, and a wise investment if you've got the room, even if you'll put 44" rolls in it most of the time.

Jim

[jerome_m]

Right you are. Not to mention that you'll spend more on ink for a printer than you'll ever spend on the printer itself. In a commercial environment, you'll spend much, much more. So the added cost of a 60" printer over a 44" one is a drop in the bucket, and a wise investment if you've got the room, even if you'll put 44" rolls in it most of the time.

You are aware than one can use the smaller paper rolls in the larger printers, right?

Additionally: you are aware that for this kind of printers, ink costs are watched by the customers so that ink is considerably cheaper per liter than for your typical desktop printer?