why do colors look different?

[treesprite]

What makes color look different in two pictures taken one right after the other? I can't very well gauge color change with pictures if I can't control this. The camera is a Nikon Coolpix.

 

These pics below were taken one after the other tonight, from different angles but nothing else different... one is more red than the other (at least it's not brown anymore!):

 

 

[lanman]

I assume your Nikon coolpix is fully automatic. You don't get to adjust the F-stop (aperture) or shutter speed?

 

Here is what happens - and I 'cheat' with my automatic camera, to adjust the 'color' of photos:

 

Your camera, while probably center-weighted for adjusting itself, also looks at the amount of light coming from the background. When the averaged-out (foreground with heavier weighting, background with less weight) subject matter in the picture is BRIGHT, the camera closes down the aperture, so that less light reaches the 'film'. This makes the subject darker. If it didn't do this, some things in the picture that should be 'light' colored, will be WHITE.

 

Take your camera, and aim it at something very light colored in your tank, and push the button halfway down to do the focusing, lock in auto-exposure, etc. While still holding the button down - move the camera to point at something darker - and it will be VERY dark. Same in the opposite direction.

 

In the good old days (and I really have to say I took a lot better photos when it was mostly manual) - if you had a backlighted subject, or a subject standing on a beach, for example - you would walk up to the subject, and adjust your exposure so that the lighting was correct for that subject, when it was the only thing in the picture. Then - with that exposure manually set and locked in - you would walk back to the point you wanted to take the picture from (to include the beach, sailboats, etc.) and take your picture without changing the exposure. The subject would come out properly lighted, and the beach would be 'white'. Usually you would bracket a few f-stops over and under that, to try and find one that would print with both the subject and the background having good exposure.

 

In our tanks, we run into this a lot. The sand on the bottom is very bright colored, the rocks are very dark. If you try to take a picture of a small coral on the sand with automatic exposure, the coral is dark, and the sand is properly exposed. If you take one of a coral in the rocks - the rocks will be properly exposed, and the coral will be too light.

 

The upshot of this is - if you want to take color comparison photos, you have to have nothing but the coral in the picture - and from the same distance and direction, so that your automatic camera will always adjust for the same thing. -OR- find a 'manual' mode on your camera, and set for the same exposure (f-stop, film speed, shutter speed) every time. At least you don't have to worry about the difference between Ektachrome and Kodachrome!!

 

bob

[Jon Lazar]

Bob's right about the metering. But besides automatic metering, the camera has to deal with the funky lighting temperature of our aquariums. Many point and shoot cameras have different settings for "indoors", "fluorescent lighting", etc., which helps the camera's computer figure out what the colors are supposed to look like. If you're in automatic mode, it uses a different algorithm and guesses. However, none of these modes are designed to take pictures under extremely bright 15k-20k lighting. This is one reason why inexpensive cameras have a hard time capturing reef aquarium colors accurately.

 

So when you take two pictures in a row, the camera's computer is trying to figure out what these colors are supposed to look like. Your two pictures are actually vastly different. The first is about 80% orange and red. The second picture is maybe 30% orange and red. The camera doesn't know whether you're taking pictures of the top part of the coral, the space between two shelves of coral, the rock in the corner, or the surface of the water, so it weighs the colors the best it can.

 

Another option is to use a program like photoshop to adjust the color to be true-to-life.

[lanman]

Another option is to use a program like photoshop to adjust the color to be true-to-life.

 

Unfortunately - she wants to use the images to show color changes over time. So adjusting the color isn't a good option.

 

The best bet would be a manual camera, set up on a tripod, with no changes to anything including location between pictures. Of course - over a longer period of time, you would have changes in the lighting itself - from aging of the bulbs, reflections from other objects nearby, etc.

 

bob

[treesprite]

Thank you for those explanations! I can't change aperature & stuff like I can on a film camera. There are lightness settings, I think ISO setting, settings for dimensions, color ("vivid", "standard", "cyan", etc), zoom, distortion control, and something else. I haven't figured it all out, and I'm kind of too lazy to figure it out - I really need someone to teach me how to use the thing!

 

I obviously can't move the coral because it's encrusted, which means, I guess, that I need to stop re-arranging my stuff in the tank if I want the pictures to have closer properties or characteristics (especially as far as things on the sand bed).

 

Is there anyone who knows how to use this aprticular camera who can explain it to me, so I can get my settings correct for tank pics?