UNDERWATER LASER POINTER: As a surface snorkeler, I like to hold my camera below me at arms length to get about two and a half feet closer to the subject and to get a somewhat better perspective. I am thinking of attaching a small laser pointer aligned along the axis of the camera lens for aiming purposes. I would be using this in the daytime.

Since the red beam is likely to show up as a bright red streak passing through the water I plan to mount the pointer so that I can use the index finger of my left hand to block the beam as I push the shutter release with my right index-finger. Sort-of one-two and release.

At night I plan to use a small underwater flashlight instead [or in addition to]the laser pointer. That will serve the dual purposes of aiming and of providing light so that the camera can focus. Digital still cameras [without the built in low-light focus beam] seem to have a major problem focusing in low light conditions.

Does a small 4-AA battery light provide enough light at night for the camera to auto focus? My point and shoot Olympus D-560 has no manual options. I’m assuming that the intensity of the camera’s built in flash will easily mask the non-uniformity in the illumination of the flashlight beam.

Anyone have any thoughts [or experience] with any of this? Bill

Bill the laser idea, sounds like a great idea for snorkeling. I have a terrible time seeing the LCD in bright light and most snorkel shots are from the hip.

At night the light from the flashlight will make a bright spot in your pictures eg.example. I have been told that aluminum foil in the flashlight reflector will spread out the beam. I usually just turn off the flashlight when I take the shot. My camera does have a focus light.

Your picture was worth a thousand words.



Thanks for posting it. I have attempted to repost it [smaller size] above as my first uploading of a photo to BT. Hope you don’t mind.

Do you recall if the flashlight you used was a small AA powered one or a larger dive light?
Unfortunately, I ordered an “Underwater Kinetics” small high intensity 2 watt L.E.D. light from diversdiscount.com [mfg part 14512]. I ordered it at about the same time that I sent my original post. If I had known what I learned from your photo, I would not have ordered the high intensity version. Patience obviously isn’t one of my strong suits.

I see several solutions to the bright spot from the beam that is so evident in your example picture. .

1. Mount the light in place of the laser pointer -- Light at night and Pointer by day. For use at night I would then simply cover the beam with my left index finger the same as for the red pointer beam in the daytime. That’s probably the simplest solution. It has the advantage that I still have full beam strength for spotting and focusing in deeper water [I’m a snorkeler so by deeper I mean 15 to 20 feet ] or when there is less than optimum visibility .

2. Glue a small neutral density filter to the front of the flashlight to reduce the beam’s brightness.

3. Sandblast the flashlight’s reflector thus diffusing it‘s output.

Your photo was great. I am planning a dry run trip to the Florida Keys in a month or so to try out my camera, housing, and spotting/ focusing arrangement and that photo headed off what would otherwise have been a failed attempt at night underwater photos. Thanks again. . Bill

Bill that LED light will be as bright but hopefully more diffuse. The above was taken with a 6 C battery light. Solution one is the best, I would not do anything to reduce the light output. On #3, you really do not know at this point if you have a problem and I would be reluctant to make a permanant change for a problem that might not happen.

I thing I did not mention is I tape my light to my camera. That way the light is pointed at the same thing as the camera. This also frees up a hand to fend off the sharks (very important on night dives). I do this while gearing up and use either duct tape or electrical tape. Then I rip it off when I get out of the water. Simple and effective.

It will be interesting to see if the red laser light beam interacts with the camera focusing... Should be testable on land.

the strobe if pointed properly should engulf the flashlight and one should not get a spot...

though somehow i have seen the spot on some of my wide angel shots???

it did occur to me that good shots at night happen because you are FORCED to shoot properly - the modeling light to help focus and point the strobe at the target...

anyway...

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quote:

At night the light from the flashlight will make a bright spot in your pictures..........

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Wow, some great responses and inputs:

First it was Cecil’s photograph illustrating the problem. Click on “example” in his post #4593 above if you haven‘t seen it. .

Then Robert Fishman’s post #221 which gave me -- and others I’m sure -- an education in lighting basics.

Robert:
1. Your point that faster shutter speeds can reduce/eliminate the bright spot is something that I would not have thought of on my own. The discussion of Steady-State Ambient Light versus Short Duration Flash in photographing near-field objects I found very interesting. If you have manual controls on your camera higher shutter speeds would be a simple way to go Unfortunately my underwater camera [Olympus D-560] has no manual control over shutter speed so that is not an option for me.

2. Night Shots:
A. Your suggestion to a. use “spot focusing” and b. to hold the shutter button half-way down to focus are both options with the D-560. I almost always do the shutter button half-way down focus but not the “spot Focus,“ I will start using spot focus in my underwater and close-up shots. That should help the camera to arrive at focus more quickly and it also should increase the odds of an in-focus critter. I’ll just have to remember to switch back to ESP when I start shooting again above water.
B. I also liked your recommendation of using a red filter in the beam of the illuminator flashlight to reduce stress on the critter. Do you have any suggestions as to what to use or where to get the red filter to put in the focus light? Would a little disk of red cellophane be ok? .. or would it get too hot?

3. Testing the system on land makes sense and is where I am heading once I get all of my goodies together. The LED Light has been ordered. I received the camera and underwater housing earlier this week and I plan to order a laser pointer within the next few days. I also plan above water tripod mounted tests and then maybe some in water tests -- either over the side of my kayak or a calm day at the ocean -- Cocoa Beach area of Florida .

Glen’s comment of possible interaction of the red laser beam with the ambient light [Daytime] will be interesting as well. It may be that in that condition [Daylight] ESP will be better then the spot focusing. Well, when I get all the pieces together, I will run some tests and post the results. Thanks you all for your inputs. WDG.

I'm fairly sure my post about the red laser and focusing didn't express what I was thinking so here goes again.

Underwater the laser beam appears as an interrupted line from the light to the target because it is reflecting from particles in the water (i.e., backscatter), and even from small turbulence areas. (It doesn't do that here in the room I am in, in air which has no particles. I have seen it consistently with the measuring lights used on an ROV, and using a laser pointer myself when diving.)

I was wondering if the camera focusing function would hunt continuously along that line looking for a point to focus on, or perhaps, pick one of the light points at random. May not happen but...

I suspect using spot focusing on a spot not including the laser spot would work. It will be interesting to see what happens. Hopefully not as spotty as that sentence!

Glen: You pose an interesting scenario. Yes, I have seen the bright streak in photographs and videos of both pulse and cw lasers operating at night and of course at laser light shows where they intentionally introduce particles into the air. In the water, I would expect the beam to be even more visible.

If the beam does present a focusing problem, I believe that the setup I plan to use would still function albeit it may need a slight change in procedure. The key is that I can block the laser beam with my left index finger while focusing or taking the picture. Hence worst case wise I would foresee the following:

1. Aim the camera using the laser pointer [left index finger lifted] .
2. Cover the laser beam with the left index finger while pressing the shutter release [right index finger ] ½ way down to establish and to LOCK the focus.
3. Holding the locked position check aim by lifting the left index finger. Correct aim if necessary and re-block the laser beam .
4. Depress the shutter release fully to take picture.
-If the above goes as planned the rest is icing on the cake
5. Lift left index finger to see if still aimed at critter
6. View the picture on the LCD screen and repeat steps 1-4 above if necessary.

I’m not a young fellow anymore [67] but the above only involves two fingers and a small amount of coordination and dexterity. With some practice it should not be too difficult.

A key of course is coming up with a fixture to hold the aiming laser and the camera such that the left index finger normally rests on the front lip of the laser light [allowing it to easily drop in front blocking the beam] and that the right index is on/over the shutter release button.

I think I can do that using standard ½” or ¾” PVC pipe and a short aluminum bracket. I own a 40 year old drill press, hole saws from ½” up to 1 ¼ inches, a hack saw, saber saw, etc. so I think I can design build and modify something that will work and not cost more than a few dollars. It may be a bit of a cluge [sp] but I’m mainly interested that it not be bulky, that it is rigid and sturdy, and of course inexpensive.

At any rate, I’m having fun and having to think and those are both important. Oh, I did order the laser pointer tonight on E-bay. $21.99 including shipping from an outfit by the name of Genaldi. Good to 50 meters -- takes 2 AA batteries.

Thanks for your inputs. WDG

William,

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quote:

........Do you have any suggestions as to what to use or where to get the red filter to put in the focus light? Would a little disk of red cellophane be ok? .. or would it get too hot?

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Re laser and focusing: using the KISS principle, try keeping the laser spot outside the focus spot. Don't want to dampen the creative spirit though!! I also used to do development engineering.

Re the red filter: I have used red 'cellophane' type filters in diving lights from MityLites to a 4 C-cell light with no heat problems. Don't forget that the lens will have rather good water cooling during a dive.

For least critter interaction with the red dive light, glue a small circle of alum foil in the center of the filter to block direct rays from the filament (for other than those new-fangled LEDs). If you look at a red-filtered light, you will see the filament as yellow-white. That bit of light will be seen by critters and fish. With the foil spot I have put the 4 C-cell light right up to a lobster that will run from a white MityLite at 15 feet.

Robert: The "DIY RED FILTER" is a great link! Thanks. I think Jennifer [see link] will have her results posted before I have mine.

Glen: I appreciate your input relative to the red cellophane. I have some left over from a Christmas project a few years back so I think that I will start there.

The small circle of foil is a good idea but as you pointed out it wont work with my light [currently on order] as it is one of those " new-fangled LEDs" [Underwater Kinetics MINI Q40 e.LE.D. PLUS].

Actually, the quotation marks were an attempt to not say actual cellophane! :–)

I really used photo filter material from a sample stack that is buried here somewhere but I was too lazy to go and dig out a brand name at that time last night. Cellophane on hand might be worth a try and would be inexpensive.

Bob's suggestion certainly will work.