White Balance

[GTR]

Should/will a white balance setting remain stable regardless of the color of the coral if everything else remains constant. In other words if I set white balance and get accurate color of a red coral can I expect to get accurate color reproduction if a blue color is photographed in the same position in the tank so lighting is equal?

I'm constantly fighting white balance. Then if the color is correct of course that picture ends up out of focus. All my cameras are cheap, but until I have confidence I can make a high dollar camera produce I just gotta deal with what I have. :lol:

SteveU

 

[edwing206]

<a href=showthread.php?s=&postid=9894214#post9894214 target=_blank>Originally posted</a> by gregr
Something else to try is using an additive lid (like the bright white lid from a container of kalkwasser for instance) and holding it under water, directly under the lights. The lids are pretty much pure white and won't harm the tank.

That's what gregr said.

 

[GTR]

I have a piece of white acrylic sheet I use but for the most part the color temp of the bulbs seem to over compensate for the blue and make everything look orangey-yellow. I have few preset options for automatic WB but they do the same or push everything to the blue side.
To fool the camera when setting white balance do I need a little added yellow light to fool it?

SteveU

 

[gregr]

The answer to your first question is yes- if the white balance is set accurately then all colors will look accurate. The answer to your second question is yes too, but it's very hard to do because knowing just how much yellow to add is very difficult.
What camera are you using? Do you have program to edit your photos with? I've been told (never seen it in person) that Photoshop Elements can adjust the color temp of jpegs. If it can really do that then you can probably dial the color balance right in with Elements. I'm skeptical though that the program can really adjust the color temp on a file that isn't raw.
That white acrylic sheet should do the trick- if you're still getting too much blue you might want to experiment with putting the acryllic in a different area of the tank. That's kind of like fooling the wb with adding yellow but instead of adding yellow you're varying the amount of halide light hitting it. Maybe you had the sheet too close to the actinics?

 

[GTR]

Well the camera is a Sony CDMavica #MVC-CD500. I've been reading everything I can here and if I thought buying a new camera would solve my problems I'd do it in a heartbeat.

What gets me is I do get some decent shots now and then, not great, but OK for most uses.

This camera does have a manual focus mode but I can't see to focus since it only has the LCD screen to go by. Also the focus is set with a toggle, .1m, .2m, .5m, .8m, 1.0m. With those settings a lot of times it seems when I see the picture on the PC that it needed to be in between those to be in focus. I just estimate the distance and take several shots with different focus settings and none are in good focus. They almost look like the camera moved but I always use a tripod and the self-timer mode.

These are decent but it's about 1 in 50 that come out OK.

Here's one that shows nothing in focus, at least to me.

SteveU

 

[2fishy]

Nice pictures!!! :thumbsup:

Frags!!! Which one is mine?!

 

[250G]

I used a inexpensive camera for all of my TOTM pics - calibrate your custom white balance with an 18% gray card, not the white colour the manual recommends. Grab one from the camera store -trust me it is worth while.

 

[gregr]

Looks to me like the Tort at the top/middle is very sharp in the last picture. The camera has a minimum focus distance of 1.6" which is great but can only be achieved at full wide angle (with the lens zoomed all the way out). Placing the camera too close may be part of the problem, but the inability to tell if the picture is in focus or not is a shortcoming of the camera and I can see how that would be frustrating. Regardless, all those shots look great, especially considering the challenges of that camera. If you ever do upgrade at least you'll know what features are important to you.

 

[GTR]

Thanks Greg...

From that marginally in focus picture the EXIF date reads...

• Exposure Time (1 / Shutter Speed) = 10/200 second = 0.05000 second
• Lens F-Number/F-Stop = 80/10 = F8.00
• Exposure Program = manual control (1)
• ISO Speed Ratings = 100
• Exif Version = 0220
• Original Date/Time = 2007:05:15 08:18:37
• Digitization Date/Time = 2007:05:15 08:18:37
• Components Configuration = 0x01,0x02,0x03,0x00 / YCbCr
• Compressed Bits per Pixel = 4/1 = 4.00
• Exposure Bias (EV) = 0/10 = 0.00
• Max Aperture Value (APEX) = 33/16 = 2.06
• Max Aperture = F2.04
• Metering Mode = spot (3)
• Light Source / White Balance = other (255)
• Flash = Flash did not fire
• Focal Length = 70/10 mm = 7.00 mm

I don't underatand the F stop listing F8.0 and Aperture F2.04?

I'm wanting to get close up shots and not the wide angle that picture has and I can deal with cropping the image. That picture is under exposed so should I change the ISO, slow the shutter speed or use a smaller F stop number? The ISO I would think to be the last choice since it would show more noise?

Thanks... SteveU

 

[gregr]

I think the f2.04 is what the lens is capable of, and f8 is what it was actually set at.

That picture is under exposed so should I change the ISO, slow the shutter speed or use a smaller F stop number? The ISO I would think to be the last choice since it would show more noise?

All or any of the above, and you're right about the iso increasing the noise. Generally speaking, inexpensive cameras get very noisy very quick.
Increasing the shutter speed will let more light in, at the expense of blur from camera or subject movement. Since you're on a tripod the only bad thing will be that the polyps might blur a little. Using a bigger aperture [smaller f-number] will also let more light in-- at the expense of depth of field. The smaller the aperture [bigger the f-number] the greater the depth of field. Remember that the closer you are to the subject the lesser the depth of field, so you have to use small apertures to get decent depth of field on extreme close-ups.

 

[GTR]

Well I might make it to a real camera store Saturday, they close before I can get there during the week. But in the meantime I've tried several DIY "gray cards" and actually a sheet of canary colored paper works good for one tank with 400w 14k light. Holding it directly under the light the camera will not set the white balance and shows an error. I guess it's overly bright so I have to hold out to the side for it to set.

This is using a gray piece of paper...

and this using the canary (yellow)

These are so out of focus but the color on the second one is accurate. These are top down as you can tell and shot through a DIY box. Problem is a can't hold it steady for even a fast shutter speed (I shake REALLY bad) and I've yet to figure out how I can do this hands free using the delay.

SteveU

 

[jmluna]

The best way is shotting at RAW mode whit auto balance. Then in Camera Raw you can ajust the balance at your Kelvin temperature.

Also you can pick the white balance tool in Camera RAW and chose a white pixel at the picture.

Following pictures were taken and procesed on this way:

The colors are absolutly true.

Grettings and sorry about my bad English.