Artwork photography under exposed - please help

[PeterHun]

Hello,

I have a problem here, and I really hope someone will be able to help, as it drives me crazy.

I am taking pictures of large posters for a website.

I built a vacuum table (holding the artworks nicely flat even in vertical position), I have 2 strong light sources 45 degrees from both sides, and i bought a color checker passport.

The camera is a Canon 550D with kit lens (EFs 18-55mm IS)

I set the white balance and the exposure with the grey card of the color checker:

-For white balance I take a photo with the grey card, and set the white balance manually.
-For exposure, I set the camera's light meter to zero while pointing it to the center of the grey card, with the light meter on SPOT mode.

Of course I do this with the same light environment what I use for the artworks.

After shooting, I use the color checker to color correct the photo.

Still the final result seems quite under exposed.

For testing reasons i made a scan of one of the posters (with a flatbed scanner) - the result looks great, and the colors are also seems to be right.

Comparing the photos i take and the scan, the photo is MUCH MORE dark.

I was trying to get as close as I can to the scanned version by adding exposure manually in photoshop (of course I am shooting in RAW).

The result is close - but still I feel the scan looks better.

But my main question: W

>>>>What is the reason that my photos areunder exposed?<<<<

When I add some exposure (+1.3), the result is somewhat satisfying, but I would like to have as accurate colors and exposure level as I can, without manually editing the photos - using only the judgement of my eyes.

Please give advice, what can cause the problem?


Thank you!

Ps.: a friend of mine just told me, maybe it is the exposure compensation in my camera - I am shooting in manual mode where is no exposure compensation, but just to make it sure i set it on ZERO and made a test shot - the result is the same, under exposed image.

Please see the test shots and the scan below:

 

[Derrel]

My first thought was that you had the camera set to minus exposure compensation. The answer is to add the +1.3 or +1.7 in Camera so if you were actually exposing the poster more, rather than less. Slow down the shutter speed would be my advice.

 

[PeterHun]

My first thought was that you had the camera set to minus exposure compensation. The answer is to add the +1.3 or +1.7 in Camera so if you were actually exposing the poster more, rather than less. Slow down the shutter speed would be my advice.

Hi Derrel,

Thank you very much for your reply. Yes I was thinking about the same - but as I wrote it in my post, I try NOT to relay on my eyes and "guessing" the right exposure. Instead I would like to have as correct exposure and colors as I can by using the right settings and the right devices.

Also to be honest it makes me to feel very uncomfortable that there is something in this process what I obviously don't understand.

I need to photograph hundreds of posters - and I would like to understand what I am doing, instead of making the shooting again after 2 weeks

Thank you!

 

[Designer]

-For exposure, I set the camera's light meter to zero while pointing it to the center of the grey card, with the light meter on SPOT mode.

Why not set the exposure by exposing for the poster?

A grey card is not going to be the same reflectance as the art work.

Furthermore, you should need only one WB reference shot for the whole session.

 

[Derrel]

I would stop using spot mode… If there is even the slightest bit of reflection on the gray card's surface, sport mode will tend toward under exposure. At my old studio job we began and ended each day with a gray card shot and it is extremely important to avoid all and I mean all diffuse highlight on the surface of the gray card.

I would suggest that you move away from spot metering immediately and switch to center weighted, and for the exposure, I would suggest that you get the meter reading off of the particular poster. After shooting your poster, then look at the in camera histogram and get the exposure correct at the time of shooting, and in that way your post processing will be negligible .

 

[Derrel]

A good, and generous exposure should be good for most posters. I would not expect more than 4/10 of an f-stop in variation between The vast majority of movie posters. If for example you expose at F8 at 1/4 second at ISO 125 for one movie poster, that same exposure should be good under the same lights for almost any poster. For whatever reason your camera is giving you an under exposed image. When you must Add 1.3 exposure values in post processing then you know that your in-camera exposure was insufficient.

 

[The_Traveler]

Peter,

There is no such thing as the 'right' exposure but only what looks good and correct to your eyes in those light conditions.
One unknown factor is the scan software; how is it handling the contrast and placement of the tone curves of the poster.
It looks to me that the photo (1.3) is slightly 'flatter' than the scan and the highlights are slightly brighter.
It wold be interesting to look at the tone curves of the two images to see how they compare.
My guess is that the mid tone curve peak of the photo will be not so high and wider than the scan.
(IM slender experience, scans seem to build contrast).

 

[Original katomi]

Hi another view.
If I were doing your shoot here is my thoughts
Meter in three places on the poster
The yellow, the red and the blue/black then average the readings for a test shot.
From there adjust and re shoot. Once I had the settings correct I would switch to manual and “ lock” the settings in for that poster. Hope this helps

 

[Designer]

Or, knowing my camera has a bodacious dynamic range, and I can even increase it if I want to, I'd just meter the poster, shoot, and check the histogram. I might even set the WB to "auto", considering that I would be using the same lights all day.

What is the end use of these photographs? Are you going to print new posters from your photographs? Or are you posting them on the internet? Is this project for recording and archiving the posters? The end use may help you decide how to do this project.

 

[ac12]

I would use an incident meter to get the base exposure.
Then shoot a gray scale to fine tune the exposure.

The gray scale will tell you visually, if you are exposing to get all the steps in the scale, or if you are bias to one side or the other.​

 

[Derrel]

This should be really easy work. If your lights are either constant or flash at the same power, once you determine more or less the right exposure,you should be able to know, within 1/2 of a stop, the right exposure for any poster that you happen to put on the vacuum board easel. For example let's say you have two flash units or two LED lights of the same power. Once you determine the correct exposure,you should be able to shoot at that exposure for poster after poster after poster.

As I mentioned above in my former studio job we used long roll cameras shooting 35mm film from a motorized gigantic camera that weighed over 50 pounds...at the start and end of each day of shooting,we shot a slate and color checker, and it was extremely important to avoid any and I mean _any _difuse highlight on the gray card. Because our proofs were machine printed,we had to be extremely exacting in how the light was allowed to hit the very slightly reflective surface of the gray card. You mentioned that you were using spot metering which measures a very specific and small area of the gray card. My suggestion is not to use spot metering, but to use a much larger-area metering pattern.

It is also possible that you have the tone curve in the camera set to low or to Auto. The_Traveler mentioned the curve implementation, which has a huge effect on the way the final image looks. If your tone curveis too flat, your images will look muddy.

I used to do a pretty fair amount of copy stand work back in the 1980s, and I used to light at 45° with two studio strobes and I shot hundreds and hundreds of slides that were to be used for presentation, a decade before the era of the PowerPoint presentation. The key is to establish the correct exposure, and then it is a simple matter of assembly line shooting. If you are having difficulty,and it seems that you are,then you should definitely try to get a better system implemented.

Again, I think your problem really is with the spot metering and the gray card,but it is possible that there are other issues, such as the tone curve that the camera is set to apply, and of course possibly some other issue that we are not aware of.

 

[The_Traveler]

scantips.com - Brightness/Contrast controls vs. histogram

 

[Derrel]

I reread your original post. You mentioned that you are shooting in raw.The way A raw image looks is very highly-dependent upon the image software that creates the JPEG from the data. For example when you import a bunch of raw images in Lightroom and apply a really bad profile, The images will look really bad. Most software programs these days allow you to choose the profile that will be applied to raw data "upon import"... after having carefully re-read your original post, I would suggest that the camera created JPEG images probably will look better than raw images which have been imported with a poor match of settings for the data captured.