Red filter?

[dbuster]

Just bought my first, relatively inexpensive, digital camera with underwater housing and plan to use it on an upcoming Caribbean trip. I know that, below about 20 feet, I'll need a filter to compensate for the lack of red light in the spectrum below that depth. I think I need a red filter, but I'm not absolutely certain. And is there a particular NUMBER of red filter I need?

And, just for a point of information, if I'm at, say, 50 feet and am shooting up towards the surface (maybe I'm shooting another diver who's a couple dozen feet above me or some such), do I need to keep the filter on the camera? I'm guessing yes, because I'm still shooting through 50 feet of water, but I'm uncertain.

Thanks much.

[freedivernd]

Hey dbuster,
I'm not familiar with using filters other than on my old 35mm camera.. but with the digital camera if you have good editing software like photoshop or similar, it's so easy to adjust your photos in the computer.. you can layer on as much red as you need.. adjust the light, contrast, etc., etc..  And I know in photoshop, something that works very good in a pinch is the image/adjust/auto levels (shft-ctrl-L), super quick and about gets it right 90% of the time.
Like I say, I'm not familiar with a filter, but I would think that if you try and pick the right filter.. you're still going be adjusting the photos with software.

What did you get?
Fred

[jleech]

There are some specialty filters out there specifically formulated for taking pictures underwater.  The exact color is guarded, as these companies make money by selling the filters at a premium fee.  Most are some shade of magenta I believe.

UR/PRO is one of the companies that sells specialty filters.  To be fair, the filters really aren't much more expensive than any other quality filter for a camera.  They have versions for tropical blue-green water, and green/algae water (Fresh & salt) 

I've had a filter that Ikelite provided with my first UW housing for my digital still camera.  It was some shade of magenta, and was made to go over the lens port of the housing.  I actually never used it in water it was designed for - tropical blue-green water.  I tested it a couple of times, and found that it blocked too much light for the shots I primarily was taking, which were mostly local.

I found a couple of good and simple steps in photoshop that did the majority of cleanup.

I would like to play with a filter in tropical, since most pictures there are done using ambient light, and there is usually abundant light, even down at 80-100 ft.

One of the drawbacks to filters, is that you should compensate for white balance using the filter.  This is reasonably easy to do at the camera for some setups, for others you may need to take a picture of something with white or grey in the field of view, then use that setting to balance the rest of your shots in a photo processing tool like photoshop.

Most people just let the camera do the best it can, with or without a filter, and then color correct in something like photoshop.

  For most 30-50 ft dives in tropical locations, you are probably in the heart of what the filter was designed for, so shouldn't have to make any real corrections

Underwater photography can be a lot of fun, but it can also can get very confusing and complex if you let it.

My recommendation would be to not worry too much about a filter, and just take a lot of pictures!  The best part about digital is you can take as many pictures as you want, and it doesn't cost any more than just taking 1.

For tropical diving, you probably can't go too far wrong with one of the commercial filters.  If you do decide to get a filter, try some with and without the filter so you get a feel for what the filter is doing for you.

Either way I'll be jealous, because you'll be diving somewhere warm, and I'll still be in MN.

Jeff

P.S.  I hope I didn't confuse you too much!

[Qix]

Please note, my opinion is based on diving with a video camera (although I take several stills). I'm in the camp of using a filter if you have one. My housing has an internal flip-in UR/Pro tropical "Red" filter. I always flip it in when I pass about 10' and keep it in the entire time I'm in the 15-80' range (in clear tropical water). Once you get too deep (combined with water color and viz) it will just give you dark images. I remember the mistake of using the filter when I shouldn't have on a 120' dive in the Sea of Cortez.

A few places where the red filter will get you. One is when you are in about 20' (or less) of clear ocean water and taking pictures up (as you mentioned). The shallower you are the more pink/red you will record. Another place is if someone shines a dive light on something and you have your red filter on. You will not like that picture, it will be saturated with red/pink.

Other than that, I find the color restoration much easier to manipulate and it needs less addition of color (however you may need to slightly brighten to compensate).

In case you didn't know. When I first heard of a red filter I thought it added red AFAIK, no passive filter can add light that isn't already there. It can just attenuate certain wavelengths. In this case the filter looks red/pink because it filtering out most of the other colors except in the red/pink range. That's why the image gets darker, the blues and greens have been toned down to be more balanced with what little red was available.

I've watched a few real good photographers. When they shoot high end digital SLR's, they will still use a red filter (when no flash is available such as wide angle scenery, etc). However, they shoot in raw mode (no compression, no loss of any data) and then white balance back on their PC.

When it comes to video and still cameras w/o raw mode (ie every frame is compressed), if you can manually whitebalance on the fly the results look really good. You just need to remember to whitebalance as often as the conditions change.

And if you decide not to go with a Red Filter you just need to do post adjustments of adding red and toning down green/blue as Fred mentioned.

Also, if you get a red filter, make sure it is easy to put on, take off and not easy to loose. On the dive boat you will have it off for daylight shots. In shallow water you'll have it off. As you start your dive you'll be putting it on. As you end your dive (shallow water, safety stops and bobbing on the surface) you'll want it off again.

[dbuster]

Thanks much for the help. The camera I purchased is an Intova IC600, a small Chinese-made thing. It's essentially a land camera in a plastic housing that I suspect may be worth more than the camera itself. <grin> No underwater setting, just the usual portrait, landscape, macro, etc.

I've been trying out the camera, sans housing, and it really does take pretty decent pictures (6 megapixel, 3x zoom, nice and clear, no evidence of camera shake, etc.). Of course, I'm on dry land and not a few dozen feet underwater yet, trying to keep my neutral bouyancy and persuade a fish to smile and get close enough for a mug shot.

I've found a strobe designed to work with the camera, and, of course, red filters abound. The problem with the filter approach is that as you filter the light, you lose some of it, too, and the camera has to compensate. I think I may just try the camera as it is when I dive this winter in Mexico, and wait to buy the strobe til I see if I'm really going to need it.

I'm a newbie to diving -- 5 dives -- tho not to photography, and I think I may just keep things as simple as I can on this trip -- me, the camera and the housing with all its buttons. I'll rely for now, as a couple of you suggested, on Photoshop to bail me out on any overly blue or green pix.

Can't wait to get down to Tulum and into the water. Four more months to wait tho. <sigh>

Thanks again.