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Morgan_Moore

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« Reply #40 on: October 30, 2007, 02:30:44 pm »

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That will happen if you boost contrast either globally with curves/levels or locally with large-radius USM. Either will intensify the visibility of any skin blemishes.
[a href=\"index.php?act=findpost&pid=149611\"][{POST_SNAPBACK}][/a]

Of course.

My opinion/thesis is that there is somthing about european skin and its translucence that cameras 'see throught it' (in the same way that xrays do)

Or are over sensitive in one channel (blue? nearlyUV?) in a way that just darkens those areas dissproportianaly to the rest of the image

So to get a real look you neet to sandwich two conversions - that skin and the rest - which is a stupidly long process

In my B+W days I was taught that tungsten was more flattering for the yellow light smoothed skin and blue filters were for 'hard men' portraits because the red imperfections went darker and brought more contrast to the image

Some one needs to test what happens if one shoots under the different sources and newtralises the image back with a grey card

S
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Sam Morgan Moore Bristol UK

Natasa Stojsic

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« Reply #41 on: October 30, 2007, 07:52:17 pm »

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I have seen this on twenty year old non smoking non starved models

I even got eyebags on a six year old kid recently

I believe the cameras exagerate the effect - it is there - but really shows with digital

It seems like a 2% darkening in the skin colour of the model equates to a 10% darkening in the file

S

ps this is a very european phenomenon - I photographed an agrentinian with gold skin and couldnt even find anywhere to retouch
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Is this the reason why most photographers say LEAF is usually better when it comes to skin tones?
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Morgan_Moore

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« Reply #42 on: October 31, 2007, 01:24:20 am »

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Is this the reason why most photographers say LEAF is usually better when it comes to skin tones?
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I dont know - maybe

I think the old myths - imacon is yellow - eyelike is flat - ect where often based around quick demos on canned camera 'looks' in early software

But the phenomonon is there (IMO) for both phase and sinar which are kodak and dalsa if I am not wrong

So it aint one chip and not the other

The eye/brain processor is of course running some pretty complex conversions so maybe the cameras just provide a more objective view of what people actually look like

S
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Sam Morgan Moore Bristol UK

amsp

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« Reply #43 on: October 31, 2007, 06:12:07 am »

I find that people seem to forget that digital is just that; DIGITAL. It is not supposed to look great straight out of the camera if you are shooting RAW. It's just collecting the data so you can decide what you want the photo to look like in post. It always cracks me up when people say things like: "Leaf has better skin tones" or "this or that camera has the best colors". What they should be saying is: "I like the colors I get with the files from this camera at default settings with this RAW developer".  Having shot a RAW file you still have the work ahead of you equivalent of choosing a film before the shot back in the days. Nothing has changed, just reversed. And you have more control over the final look today. Now more than ever the photographer is creating the image, not your gear. JMHO.
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Anders_HK

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« Reply #44 on: October 31, 2007, 07:18:54 am »

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Having shot a RAW file you still have the work ahead of you equivalent of choosing a film before the shot back in the days. Nothing has changed, just reversed. And you have more control over the final look today. Now more than ever the photographer is creating the image, not your gear. JMHO.
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Getting off subject, but need to state my view;

The photographer had choice with film too - gear did not dictate, but it was much EASIER (not to mentiond CHEAPER), just choose film before you shot. Now requires more involvement from all, not only professionals who were part of printing process before with film, but also us amateurs who were not.

Film nowadays is more difficult than even five years ago when I got serious into photography and slides; finding film, processing, making it DIGITAL.  

Regards
Anders
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Morgan_Moore

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« Reply #45 on: October 31, 2007, 09:34:51 am »

On the IR/UV thing

While profiles and 'looks' can help I dont think they can be the answer - they only perform transforms on data they have

An extreme example to demonstrate the point.

If a digital camera were blind to red then no profile or transform could correct that

Because red would be black and black would be black

No mathematic al transform (which is what profiles/looks are) could know which black areas were supposed to be red and which black areas supposed to be black

Extrapolate this theory and you are lead to the use of phisical filters at some point in the capture process to create an image that is percived correctly by the eye before or after conversion

Being that red skin areas go dark that would demonstrate an insensitivity to red so it would appear that using a (mild) red filter (which cuts other colous but red)  could be the solution

This would have of course to be used in conjunction with a grey card or white reference to remove a blatant hue from the image

Is this filter exactly what used to be known as a 'warm up' filter in the 'old days'

S
« Last Edit: October 31, 2007, 09:41:00 am by Morgan_Moore »
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Sam Morgan Moore Bristol UK

eronald

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« Reply #46 on: October 31, 2007, 10:27:48 am »

Morgan,

 Here is what I think at the moment:

1. If a sensor is blind to some color, you cannot put it back into the images.
2. If a sensor is too strongly sensitive to a color, you can scale back that color in the imagery mathematically ,provided it can discriminate it.
3. If a sensor is under-sensitive to a color you can intensify it mathematically, provided again that you can discriminate it.

 The discrimination bit depends on the Bayer filters which are set in front of the actual photosites.

 As an example, take the Leica M8 and its IR sensitivity. Here case (2) applies.  but a look at the curves for the Kodak sensor used in the Leica M8 shows that they are getting collinear in the IR region and so IR cannot be *easily* discriminated from red. So it's easier to just kill the IR physically with a filter. I think this argument may carry over to the digital backs with similar Kodak sensors (Phase, Hassy) although they already have a stronger IR filter in front of *all* the Bayer filters.

 i would agree that it's possible that some color-hue filters over the lens might also help with discrimination between visible colors. And also bring the sensor back into its linear region. In particular a blue (cooling) filter used under incandescent light should help bring up the blue channel and get rid of blue channel noise visible when the blue channel is low and other channels are strong.

 Maybe some experiments would be in order here ?

Edmund

Quote
On the IR/UV thing

While profiles and 'looks' can help I dont think they can be the answer - they only perform transforms on data they have

An extreme example to demonstrate the point.

If a digital camera were blind to red then no profile or transform could correct that

Because red would be black and black would be black

No mathematic al transform (which is what profiles/looks are) could know which black areas were supposed to be red and which black areas supposed to be black

Extrapolate this theory and you are lead to the use of phisical filters at some point in the capture process to create an image that is percived correctly by the eye before or after conversion

Being that red skin areas go dark that would demonstrate an insensitivity to red so it would appear that using a (mild) red filter (which cuts other colous but red)  could be the solution

This would have of course to be used in conjunction with a grey card or white reference to remove a blatant hue from the image

Is this filter exactly what used to be known as a 'warm up' filter in the 'old days'

S
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« Last Edit: October 31, 2007, 10:28:34 am by eronald »
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Morgan_Moore

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« Reply #47 on: October 31, 2007, 01:01:57 pm »

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Morgan,

 Here is what I think at the moment:

1. If a sensor is blind to some color, you cannot put it back into the images.
2. If a sensor is too strongly sensitive to a color, you can scale back that color in the imagery mathematically ,provided it can discriminate it.
3. If a sensor is under-sensitive to a color you can intensify it mathematically, provided again that you can discriminate it.

 The discrimination bit depends on the Bayer filters which are set in front of the actual photosites.

 As an example, take the Leica M8 and its IR sensitivity. Here case (2) applies.  but a look at the curves for the Kodak sensor used in the Leica M8 shows that they are getting collinear in the IR region and so IR cannot be *easily* discriminated from red. So it's easier to just kill the IR physically with a filter. I think this argument may carry over to the digital backs with similar Kodak sensors (Phase, Hassy) although they already have a stronger IR filter in front of *all* the Bayer filters.

 i would agree that it's possible that some color-hue filters over the lens might also help with discrimination between visible colors. And also bring the sensor back into its linear region. In particular a blue (cooling) filter used under incandescent light should help bring up the blue channel and get rid of blue channel noise visible when the blue channel is low and other channels are strong.

 Maybe some experiments would be in order here ?

Edmund
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I hate to say it, because I like a good virtual punch up, but I think we are in complete agreement

A guess is that this is particularly a high ISO situation because nowadays the sensors who have originall been specced ISOs at 25-50 are being pushed by market forces and software into being used a up to an eight times the sensitiviy to thier original design, one would not be suprised if 'linearity loss' was one of the compromises of the ISO race

hope you enjoying the P45 - now you can 'experiment' as much as you want rather than hypothesize


S
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Don Libby

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« Reply #48 on: October 31, 2007, 03:06:05 pm »

Edmund

Getting back to the Mamiya ZD screen Phase One combo....

How is that working out for you?

I've got a P30+ and am currently using the cheesy Phase screen overlay but would use this combo if it works.

don

eronald

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« Reply #49 on: October 31, 2007, 06:09:19 pm »

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Edmund

Getting back to the Mamiya ZD screen Phase One combo....

How is that working out for you?

I've got a P30+ and am currently using the cheesy Phase screen overlay but would use this combo if it works.

don
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No complaints so far, but I haven't done any checking yet as to the exactness of the borders.
However, of course, the ZD back and the P45 have very similar sizes, the P30, NOT !!!!

Bill Maxwell can scribe lines on any screen as well.

Edmund
« Last Edit: October 31, 2007, 06:11:03 pm by eronald »
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EricWHiss

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« Reply #50 on: October 31, 2007, 06:41:49 pm »

Ok if we can't get good correction with profiles then we need:

1) UV filter to stop veins under skin from showing
2)  IR filter to keep red blotches off skin.

What would be awesome is to get a flat piece with both coatings that we could stick over our sensors - what's that place that's taking off the IR and AA filters from the DSLR sensors MAXMAX? Maybe they could do it?
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marcmccalmont

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« Reply #51 on: October 31, 2007, 08:05:28 pm »

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Ok if we can't get good correction with profiles then we need:

1) UV filter to stop veins under skin from showing
2)  IR filter to keep red blotches off skin.

What would be awesome is to get a flat piece with both coatings that we could stick over our sensors - what's that place that's taking off the IR and AA filters from the DSLR sensors MAXMAX? Maybe they could do it?
[{POST_SNAPBACK}][/a]

[a href=\"http://maxmax.com/aXNiteFilters.htm]http://maxmax.com/aXNiteFilters.htm[/url]
Look at the cc1 and cc2 filters they can be mounted on the lens
Marc
« Last Edit: October 31, 2007, 08:07:01 pm by marcmccalmont »
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Morgan_Moore

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« Reply #52 on: November 01, 2007, 12:56:24 am »

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Ok if we can't get good correction with profiles then we need:

1) UV filter to stop veins under skin from showing
2)  IR filter to keep red blotches off skin.

What would be awesome is to get a flat piece with both coatings that we could stick over our sensors - what's that place that's taking off the IR and AA filters from the DSLR sensors MAXMAX? Maybe they could do it?
[a href=\"index.php?act=findpost&pid=149900\"][{POST_SNAPBACK}][/a]

I have already bought an UV/IR cut filter and it doesnt work*

My guess is that one that really worked would have a significant ND effect too

I am sure the makers compromise in thier designs

A really strong UV/IR cut filter may affect ISO and there not be a percieved market for such in this ISO obsessed age

But in a studio with a lot of light I coulc live with my back at 12 ISO

S

*correct this affect
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Sam Morgan Moore Bristol UK

eronald

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« Reply #53 on: November 01, 2007, 01:05:06 am »

Quote
Ok if we can't get good correction with profiles then we need:

1) UV filter to stop veins under skin from showing
2)  IR filter to keep red blotches off skin.

What would be awesome is to get a flat piece with both coatings that we could stick over our sensors - what's that place that's taking off the IR and AA filters from the DSLR sensors MAXMAX? Maybe they could do it?
[a href=\"index.php?act=findpost&pid=149900\"][{POST_SNAPBACK}][/a]

Actually, I think good profiles can be made for the P30+ and P45+. The previous models had a different less strong IR filter, I believe, so one would need to shoot with a 486 (IR,UV cut) , maybe and then reprofile to get rid of any IR effects.

One of the problems is that people in the US hate magenta in faces, but I've looked hard at people's faces and some magenta is really often there (burst blood vessels etc). This means that a profile that is pleasing -rather than realistic- needs to be edited. My profiles are in fact heavily edited.

BTW, some of the older Phase profiles are seriously bad (spiky), but I have recomputed versions that are much smoother. In particular for the P25.

Edmund
« Last Edit: November 01, 2007, 01:05:28 am by eronald »
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eronald

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« Reply #54 on: November 17, 2007, 06:44:13 am »

I am still using Mammy  -the P45+, AFDII- as a walkbout camera, while I get used ti the controls. For street and walkabout photography, the 800 and 400 Iso settings seem perfectly usable, apart from some striation issues which I have reported to Phase via the dealer and hope to get solved.

Focus with the Mamiya is good, setting the camera to spot metering or going to manual exposure is sometimes a necessity to avoid over-exposure.

The screen on the Phase back seems its weakest point.

At the risk of repeating myself, I would like to say that I really like the Mamiya "look" with this back.

Edmund
« Last Edit: November 17, 2007, 06:48:24 am by eronald »
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