Focus Light for Night Dives

Hi,

after having read the backscatter article about focus lights James mentioned in the

previous posting, I would like to share my thoughs about it:

Some of the focus lights in the article are "heavy light cannons"! I use the

Hartenberger Mini as my main dive torch - not as a focus light.

During daytime I use the built-in focus light of my Ikelite SS200 with a halogen bulb,

which normally is strong enough - sometimes even too strong! If you have a look at

the first picture in the backscatter article, you can see that the pygmy turns away its

head; I think this comes if the focus light is too strong. Or, ever tried to take a

photo of a basket star with a bright focus light?

During nightdives I used to use the SS200 with a lower intensitiy bulb - and for

many dives this was the only light I used, no additional torch. (I "frosted" the

surface of the bulb with a diamond bur to get a soft light pattern.)

But even with this setup some nocturnal creatures turned away/retreated when I

shone the light on them.

So now I use a bulb which I painted with a red-orange transparent colour. The

critters obviously are not bothered by this light, and my camera (Nikonos RS with a

very slooow autofocus) has way enough contrast to focus!

If there is much plankton around, I turn on my Hartenberger torch and place it on

the ground one arm lenghts away - the plankton then dances around the torch and

not around my camera/strobe, so there is less backscatter in the picture.

I still have to try if the intensity of the red light is good for daytime too.

Regards,

Jock

Jock,

thanks for these big tips!

Can you provide detail information on painting the red-orange on the bulb? What type of paint did you use? I would love to use this techique.

I was on a mandarin fish dive in Lembeh and my dive guide who knew what he was doing had a red or orange filter on his dive lite with him and helped me get some pics. The guides from KBR, didn't. Go figure.

thanks.

Hi Will,

so you learned about the red focus light at Lembeh resort - same with me! Bruce, who used to run the dive center (I think he has left) showed me the trick!

I purchased the paint in a shop that sells electronic parts of all kinds. It is especially made for painting bulbs! They had a dark red and a yellow, so I mixed. Normally, it is not suitable for Halogen bulbs, but I think this refers to 20 or more Watt bulbs. Never had any problems with my Ikelite bulb (which is appr. 5W).

Cheers,

Jock

Go to your local art supply store & look for red-orange tracing paper (or similar). Cut out a circle of it to fit inside the light head. Its alot cleaner than paint, can be removed & acts the same as a more expensive color filter.

Alternatively, if you have a friend who owns an Inon strobe and doesn't use the waterproof red stickers that come with it, you could just paste one of those on the central portion of your strobe

Saves the hassle and risk associated with opening the strobe and reassembling it.

Sounds like the new hot ticket might be the DS-125, the high intensity bulb, red filter, and the new NIMH battery pack that about doubles the usage. Theatrical gel filters are pretty cheap by the sheet, and a sheet will make a bunch of dots.

"Sounds like the new hot ticket might be the DS-125, the high intensity bulb, red filter, "

 

8 to 9 years ago painting bulbs red was all the rage. Rumour was it worked better with the critters and since the SS200 was the hot strobe at the moment removing and painting the modeling bulb was relatively easy for many of us. Unfortunately most of us came to realize it really didn't work as a result of the color. The color of the bulb doesn't really matter. I think what happened was some people put so much paint or color on the bulb that they inadverdently benefited from lowering the apparent output/intensity applied on the subject and came to the mistaken conclussion it was the color at work.

 

Lower intensity lighting really works well. Either LED or halogen FIX Light turned way down seems to be the best way to go for the skittish critters.

 

I use a LED these days, but when I used my Fix Light the subjects were a lot more comfortable when I had the power turned way down. I'm pretty convinced it is all about the heat the subject feels.

Mandarins...most fish for that matter don't care what colour your light is...they care how much light you throw out. I was on a mandarin dive last year and had an 8W UK 400R. The fish were everywhere! I've successfully shot all manner of tropical reef critters with a broad beam light...then again, come dive BC waters and the fish don't care how much light you put on them!

Stu

I haven't tried it on fish yet, but I have seen the effect of a red light on enough other animals to give it a try.

Even if some critters are sensitive to red light - most deep sea fish can't see it but I guess higher up the column many can - it is still a good plan as it doesn't cause human eyes to stop down. This is why we use it as emergency lighting and low level lighting for night time use. Obviously if you're diving with a light canon as a dive torch, the effect is somewhat nullified, but useful to know about anyway.

Martyn

I think that the important thing is not the colour but the intensity of light. And the lower the intensity the better. However, there is a massive difference between the AF performance of difference cameras ( and if you are a manual focus bod - the viewfinder optics and eye sight of photographers) and this defines how low an intensity light you can use.

Lots of variables to consider in addition to the critters.

Alex