[ddb]

Secondly, use a neutral grey card. You can buy one on line

check!

great! I can not thank you enough! I saved everything. I have a dual apple cinema 27 I think I should be fine. These have a grey screen cover glass, sort of rings the bell now that you mentioned grey cards.

I assume this was painted by someone who worked with oil primarily but hustled somewhere along a summer riviera back in old times to make a buck with painting quick pastels. He started ambitiously but was rushed to finish maybe the sunset, maybe time to get some dinner, god knows! He was likely a victim of metamerism too. Nevertheless, he managed to sell it to "someone", the original framework was mahogany. I think he painted this with 3000K and something afternoon backlight that is my guess to go. obviously, I have no clue.

I'll continue with my project in a few days when my missing stuff arrives.

Hope this sheds some light on it

---

Last edited by ddb; 08-05-2018 at 03:51 AM.

[Schraubstock]

grey screen cover glass,

Thanks for the reply.
Is this the sort of grey glass they sold many years ago which clips on to the front of the screen to make colours more vivid ?
If so please dispatch it into the rubbish bin. (Trashcan I think you call them in your part of the world)

They have no place for post processing photographs nor calibrating the monitor !

[ddb]

Thanks for the reply.
Is this the sort of grey glass they sold many years ago which clips on to the front of the screen to make colours more vivid ?
If so please dispatch it into the rubbish bin. (Trashcan I think you call them in your part of the world)

They have no place for post processing photographs nor calibrating the monitor !

I think I saw those at my doctor's. Mine screen shield is not removable and the glass is part of apple cinema. I am certain it is polarized because I cannot wear my polarized sunglasses in front of it, that's why is sort of grey when removed with suction grips, I believe. I used my Nvidia tool to calibrate my monitors and apple monitors looks about right compared to my phones and tablets which are also polarized I assume.
apple monitors do have a slightly colder tone and are more contrasty than my nonapple monitors.


The grey card and your clues definitely explain my color temp issues. the card is arriving tomorrow! I always complained about everything being too warm I blamed lenses and nonsense but didn't realize I always shoot between 5p and sunset and color temp change really fast during the late afternoon. 20 min just before the sunset makes a whole lot of difference, by the time I shoot, ambient temperature already changed! , also, I use my lens paper wipes for my white reference, apparently is not the best practice


tomorrow is a very new day for me and thanks to you! from now one Ill bring the grey reference with me and put it in the crop area whenever I can.

still, for the photos like the one below the problems will persist I figure. took this one today, with sony-nex3 and Konica 40/1.8 using noncustom environment calculated (k) white balance and darktable sony nex preset that ignores the lens. warm part of the shot is about right and ok, but front grass is too cold it was not like this in my eyes, the foreground grass was warmer, the only way to deal with these problems is to retouch front grass digitally I assume.

first things first, tomorrow the grey card. thank you again!

[Schraubstock]

glass is part of apple cinema

Interesting discussion.
I have no experience with Apple computers or Apple monitors and it could very well be that your monitor is not optimal for true colour work, rather it is optimised for consumers who love over-saturated and contrasty pictures. There is market for these as in general the average consumer is demanding those over-saturated colours they see every day in advertising and on their smartphones, and this grey front panel or whatever it is facilitates this. So I cant comment.

In my work it is important to be able to produce colour correct images. To achieve this I work with an EIZO Coloredge CG2420, a monitor with an inbuilt calibrator, which when once initially correctly calibrated, will automatically re-calibrate the monitor automatically every 8 weeks. Usually during an off period.

The last image you supplied is under exposed and has a distinct yellow cast. I see this very often with pictures posted here, particularly those images which were taken during sun rise and sundown before the so-called blue hour.

There is a huge difference between a true warm sun set rendering and the look that is achieved by adding a bit of extra warmth by adding a bit more yellow. And often people do not know when to stop. It makes the picture look like as if a clear yellow blanket was thrown over the picture. When you do this everything in the picture is overpowered with this yellow cast, even parts of the image which should not be affected by the natural warmth of the ambient light. When you then add to this underexposure you finish up with a bad picture.

I have corrected your picture (as much as an 18bit JPG would allow) by importing it into a program called Oloneo PhotEngine. This has a colour picker (pipette) allowing you to hone in on a very small neutral grey part in the image. In most picture you will find one of those. In your picture this was easy. The moment you click on this grey spot it changes everything. And there is, in almost all cases if not all, no arguing that the photo is now correct. Note how the grass in the foreground has changed because a yellow cast always makes green more green. This could be a problem with some folk if they like this fat green in which case they have to go into the green channel and tickle the green a little. But don't forget some people cannot see certain colour correctly and they will argue with you that broccoli isn't green.

As to the grey card you must make sure that the card is actually part of the picture you are taking. Portrait photographers in fact will ask the model to hold the card for the pilot photo. This photo will then be discarded once the correction details are noted or stored as a preset for all others which were taken under these conditions.

Cheers

P.S.
1) You have dust on the sensor
2) The sky is not optimal which is always a problem when working on 8bit images. In RAW this will not be a problem.

---

Last edited by Schraubstock; 10-27-2018 at 10:51 PM.

[pentasonic49]

There is a world of difference between a true macro lens and a zoom lens with "macro" printed on it. Don't be fooled, the zoom lenses are not suitable.

[ddb]

Interesting discussion.
I have no experience with Apple computers or Apple monitors and it could very well be that your monitor is not optimal for true colour work, rather it is optimised for consumers who love over-saturated and contrasty pictures. There is market for these as in general the average consumer is demanding those over-saturated colours they see every day in advertising and on their smartphones, and this grey front panel or whatever it is facilitates this. So I cant comment.

In my work it is important to be able to produce colour correct images. To achieve this I work with an EIZO Coloredge CG2420, a monitor with an inbuilt calibrator, which when once initially correctly calibrated, will automatically re-calibrate the monitor automatically every 8 weeks. Usually during an off period.

The last image you supplied is under exposed and has a distinct yellow cast. I see this very often with pictures posted here, particularly those images which were taken during sun rise and sundown before the so-called blue hour.

There is a huge difference between a true warm sun set rendering and the look that is achieved by adding a bit of extra warmth by adding a bit more yellow. And often people do not know when to stop. It makes the picture look like as if a clear yellow blanket was thrown over the picture. When you do this everything in the picture is overpowered with this yellow cast, even parts of the image which should not be affected by the natural warmth of the ambient light. When you then add to this underexposure you finish up with a bad picture.

I have corrected your picture (as much as an 18bit JPG would allow) by importing it into a program called Oloneo PhotEngine. This has a colour picker (pipette) allowing you to hone in on a very small neutral grey part in the image. In most picture you will find one of those. In your picture this was easy. The moment you click on this grey spot it changes everything. And there is, in almost all cases if not all, no arguing that the photo is now correct. Note how the grass in the foreground has changed because a yellow cast always makes green more green. This could be a problem with some folk if they like this fat green in which case they have to go into the green channel and tickle the green a little. But don't forget some people cannot see certain colour correctly and they will argue with you that broccoli isn't green.

As to the grey card you must make sure that the card is actually part of the picture you are taking. Portrait photographers in fact will ask the model to hold the card for the pilot photo. This photo will then be discarded once the correction details are noted or stored as a preset for all others which were taken under these conditions.

Cheers

P.S.
1) You have dust on the sensor
2) The sky is not optimal which is always a problem when working on 8bit images. In RAW this will not be a problem.

Hi and thank you again!,

Yes, I am a dirty man, my lenses have no covers, many need to be taken apart and cleaned. i usually bring an old tamrac bag of dusty primes and switch like every two min for angle and depth practice. the place is dusty as hell.

This was my first lens today so it should look a bit be cleaner.


I just came home and gotta take a fast nap soon. I got the grey cloth
and I used in the corner for reference. half of the grey is lit half is shadow
so is the photo. the original photo was totally yellow as usual..


https://imgur.com/a/iTlTOEn

Here is how I see things but maybe I am wrong.

foreground grass is too cold and needs to be referenced to cold grey
background is too warm and needs to be referenced to warm grey

I stacked two layers added alpha to layer and erased the top too warm lake top with the eraser and flattened both images to one and cropped it.
used a program called darktable and gimp from software center in ubuntu 18

is what I did about right? I know it could be done better and in raw. I bought a software called luminar i didn't start to use it yet. I am kind of reluctant to move back to windows, but I will start using it when I have a decent photo to show. I can not thank you enough for your help!

ps: i am working on an old Eizo will trade it for an iMac that collects dust and takes space on my desk, on apple cinema every grass looks like astroturf , red is screaming blacks are too black. its ok for watching movies and I guess is a good 2nd reference because every phone is screaming colors nowadays.

1. attachment. spot grey taken from grey shade area
2 attachment spot grey taken from grey sunlit area
3. stacked 1 and 2 erased top of photo 1 and used photo 2 for upper part of flattened merged photo



---------- Post added 08-09-18 at 02:43 AM ----------

There is a world of difference between a true macro lens and a zoom lens with "macro" printed on it. Don't be fooled, the zoom lenses are not suitable.

I am sure you are right about that I there is one, 50 mm with the life-size adapter I think is Minolta rokkor x. I am not sure if I need lifesize but sound about ok. I still have to wait a few days for the auction to finish.


I have several macro zooms but no macro primes. Thank you for the hint!

[Schraubstock]

Thanks for posting.

The dirt I thought looks more like dust (crap ?) on the sensor. Dirt on lenses usually do not show up so much, if at all, and then only at very small iris openings.

I don't think you are not using the grey card correctly. The card should be placed such as to be free of reflection. If shadow falls on to it this should not matter but reflection does. In the sample image you provided, when I click the hand held card on different parts it reacts differently. This should not be the case. In this particular picture you can't place the grey card in front in the grass, it would disappear. Take a stick, ram it into the ground a few metres away from the camera and hang the card up on it. If the card is not in focus it should not matter.

Finally, I just discovered the pics are shot with a Sony camera. I have never used a Sony camera and I do not know how it would compare with Pentax gear.

[pentasonic49]

Your Rokkor 50mm is a macro lens, you won't need the 1:1 adaptor unless the paintings are miniatures. As already mentioned, a proper macro lens has minimum distortion and has a flat field, an advantage when photographing a flat painting. For best results using a tripod, you need to have the camera in line with the centre of the subject and exactly square, so the corners of the picture are the same distance. As for the aperture to use, most lenses give their best resolutions at two to three stops smaller than maximum. Manual focussing is best with macro, and it would be a good idea to take three shots with very small changes of focus and choose the best when highly magnified on a computer screen. Bracketing the exposures is also recommended.

[ddb]

Your Rokkor 50mm is a macro lens, you won't need the 1:1 adaptor unless the paintings are miniatures. As already mentioned, a proper macro lens has minimum distortion and has a flat field, an advantage when photographing a flat painting. For best results using a tripod, you need to have the camera in line with the center of the subject and exactly square, so the corners of the picture are the same distance. As for the aperture to use, most lenses give their best resolutions at two to three stops smaller than maximum. Manual focussing is best with macro, and it would be a good idea to take three shots with very small changes of focus and choose the best when highly magnified on a computer screen. Bracketing the exposures is also recommended.

great, thank you! I'll be waiting for that 50mm lens and clean it inside and outside before I use it. today, I am experimenting with slave flashes and led lights. I need some reflection and will have to lower exposure time to find a good color balance


I set up the rig with diffused and polarized led light, but the color composition changes because it misses reflection of waxy, shiny pastels. can't fix it with grey balance, will need some reflection, reflected sun or flash.


I have a clamp that has 90 degrees 1-4 /20 mounts, It is clamped to motorized standing desk and I used a paracord and torpedo fishing sinker clamped to the lens hod just to make sure the lens falls 26mm off-diagonal cross, I guess I am good, camera is leveled, so is laminate on the floor, I 've got these:

https://www.amazon.com/SoftTouch-Leveling-Glides-Straight-Furniture/dp/B001W...PXZZ4KRC9TAY55


hope, I will get to to the good-enough point by the time macro lens arrives, maybe its an overkill but it sure is fun.

---------- Post added 08-09-18 at 07:10 PM ----------

Thanks for posting.

The dirt I thought looks more like dust (crap ?) on the sensor. Dirt on lenses usually do not show up so much, if at all, and then only at very small iris openings.

I don't think you are not using the grey card correctly. The card should be placed such as to be free of reflection. If a shadow falls on to it this should not matter but reflection does. In the sample image, you provided when I click the handheld the card on different parts it reacts differently. This should not be the case. In this particular picture, you can't place the grey card in front of the grass, it would disappear. Take a stick, ram it into the ground a few meters away from the camera and hang the card up on it. If the card is not in focus it should not matter.

Finally, I just discovered the pics are shot with a Sony camera. I have never used a Sony camera and I do not know how it would compare with Pentax gear.

yes, the lens is specked with two black markings I just got 40/1.8 it this week I couldn't take it apart yet. it's a nice lens, will bother and remove the crap it with a drop of peroxide and ethanol. i think is a dried fungus or a metal chip stuck to the inner group.


I like my Pentax-m set of manuals a lot so I was looking for a Kmount mirrorless digital camera with tilt-up led screen and at least 24mp Exmor sensor. maybe Pentax maybe something else. they all have Sony sensors nowadays. i dont need any frils just a good focus peaking tool and a neat durable housing. I don't take shots of things that don't want to wait. I don't like viewfinders I shoot from the crotch, I dont care about TTL, nothing but iso and some exposure bracket takes just in case. I take my sd card out so often i could use a second sd or micro sd slot with a hot swap

i review my raws instantly using my otg card reader, my huawei phone handles raws without any hesitation, i dont use tilt up screen for anything else but live preview and evf ok.



I don't like zoom lenses and I don't want to haul a dolly with miniature cape Canaveral ramp rig. I like to be as invisible as I can. I wanted a Pentax but it looks like is going to be Sony A7


I appreciate your help a lot it shortened my learning process a lot.

[bkpix]

Don't lose sight of the question, what is your ultimate use of the photos?

If, for example, you plan to publish a book that uses photographs of the paintings as illustration, you probably want the photos to be very accurate. That means color management, a good flat field lens with no distortion, and careful, even lighting without glare. A tripod.

On the other hand, if you just want an insurance inventory, you don't need any of that. Your phone or a point and shoot will do, hand held.

I'm in the middle. I shoot photos of my own work for submission to galleries. I want the photo reproductions to be accurate in the sense that they convey what the original art work is about. I'm not terribly worried about exact color matching, slight distortion, or pixel-shift resolution. These images will be looked at on a computer screen, often for no more than a few seconds, and then they have had their moment of glory. So long as they are attractive, they don't need technical perfection.

Given that, I often shoot outside on a cloudy day. If I can keep my shadow out of the frame I'll lay the work flat on the ground. Rather than a gray card, I use exposure compensation to get the whites to be the right value of white. The histogram is your friend. Hand held is fine for this. If I've keystoned the image too much, there is PP software for that. Color balance can be tweaked a little warmer in PP if the light is too cool.

If the outside light isn't cooperating, or it's raining, I set up two matched flashes at 45 degrees on each side of the picture, which is clipped to a drawing board that's propped up on a chair. This works well so long as I don't have an uneven reflective surface to deal with. Polarizing filters can help, but aren't perfect. This has encouraged me to make more work with a smooth matte finish.

My main advice is, don't overthink the project.

[ddb]

Don't lose sight of the question, what is your ultimate use of the photos?

If, for example, you plan to publish a book that uses photographs of the paintings as illustration, you probably want the photos to be very accurate. That means color management, a good flat field lens with no distortion, and careful, even lighting without glare. A tripod.

On the other hand, if you just want an insurance inventory, you don't need any of that. Your phone or a point and shoot will do, hand held.

I'm in the middle. I shoot photos of my own work for submission to galleries. I want the photo reproductions to be accurate in the sense that they convey what the original art work is about. I'm not terribly worried about exact color matching, slight distortion, or pixel-shift resolution. These images will be looked at on a computer screen, often for no more than a few seconds, and then they have had their moment of glory. So long as they are attractive, they don't need technical perfection.

Given that, I often shoot outside on a cloudy day. If I can keep my shadow out of the frame I'll lay the work flat on the ground. Rather than a gray card, I use exposure compensation to get the whites to be the right value of white. The histogram is your friend. Hand held is fine for this. If I've keystoned the image too much, there is PP software for that. Color balance can be tweaked a little warmer in PP if the light is too cool.

If the outside light isn't cooperating, or it's raining, I set up two matched flashes at 45 degrees on each side of the picture, which is clipped to a drawing board that's propped up on a chair. This works well so long as I don't have an uneven reflective surface to deal with. Polarizing filters can help, but aren't perfect. This has encouraged me to make more work with a smooth matte finish.

My main advice is, don't overthink the project.

I think you are right just about everything and I will end up using two radio-controlled or optically triggered flashes attached to a stretched imperial size wood board with levelers on the back side, so I will be able to hang it lay it on the floor. the lens is of secondary importance but worthy of consideration.

We are moving overseas again, so I would like to have a solid backup. When I am done cataloging, I would like to give this setup to my niece who is a young painter and sticks to digitizers because she can not "show her paper to anyone" she is not old enough to understand the importance of exclusivity.

She is my niece and it is to an extent a legacy issue too I have a bit of a hard time leaving a "good enough for my insurance" job behind me

[ddb]

Don't lose sight of the question, what is your ultimate use of the photos?

If, for example, you plan to publish a book that uses photographs of the paintings as illustration, you probably want the photos to be very accurate. That means color management, a good flat field lens with no distortion, and careful, even lighting without glare. A tripod.

On the other hand, if you just want an insurance inventory, you don't need any of that. Your phone or a point and shoot will do, hand held.

I'm in the middle. I shoot photos of my own work for submission to galleries. I want the photo reproductions to be accurate in the sense that they convey what the original art work is about. I'm not terribly worried about exact color matching, slight distortion, or pixel-shift resolution. These images will be looked at on a computer screen, often for no more than a few seconds, and then they have had their moment of glory. So long as they are attractive, they don't need technical perfection.



Given that, I often shoot outside on a cloudy day. If I can keep my shadow out of the frame I'll lay the work flat on the ground. Rather than a gray card, I use exposure compensation to get the whites to be the right value of white. The histogram is your friend. Hand held is fine for this. If I've keystoned the image too much, there is PP software for that. Color balance can be tweaked a little warmer in PP if the light is too cool.

If the outside light isn't cooperating, or it's raining, I set up two matched flashes at 45 degrees on each side of the picture, which is clipped to a drawing board that's propped up on a chair. This works well so long as I don't have an uneven reflective surface to deal with. Polarizing filters can help, but aren't perfect. This has encouraged me to make more work with a smooth matte finish.

My main advice is, don't overthink the project.

thank you again, Bob, I ended up shooting straight on the easel in the middle of the room, attached two optical slave flashes at the ends of a tripod boom (around 45 deg), shot raw in exp brackets of 3 and created an HDR afterward, sharpened a bit, denoised, adjust the exposure and colors, and exported as 16 bit png.


I used my phone angle tool to align easel (20 deg) and cam, the laser pointer on the camera is good enough to verify alignment, everything looks good now. HDR is very forgiving. I borrowed a sigma 50 macro, but macro zooms, nifty fifty 35 and 28mm primes on auto worked just fine there is no details on paintings that would make a difference

I even tried to shoot at iso 400 and higher and managed to denoise and colorcorrect to totally ok. so i guess i could do handheld np when outside.

[pxt]

When I try take shots of painting in museum without flash I miss a lot polarise filter. A lot of reflection was from windows. I will be suggested bulp plus material to make difusor to more control lighting painting if look still for another solution.

[ddb]

When I try take shots of painting in a museum without flash I miss a lot polarise filter. A lot of reflection was from windows. I will be suggested bulp plus material to make difusor to more control lighting painting if look still for another solution.

I kind of got to the bottom of it lately. If you have reflection problems in public museums:


1. get a pancake lens with few glass elements only, to preserve colors - sharpness is secondary. A pentax-m 40mm or Konica 40/1.8 will do it. Shoot wide open or one stop down.

2. Get two radio triggered flashes to overcome external lights. 1st flash bounce one off the floor and 2nd one off the ceiling. if the ceiling is too high to use, put a Garry Fong dome on a top flash, mini flashes with swiwel and 2x AA batteries will handle it, i use minis at 1/8 of power or less depends on exposure times available


using ISO 3200 is pretty safe for oil assuming a modern sensor. i can do handheld np even when absolutely dark. angles, temperature and noise are usually an easy fix in post processing.