I am curious about film speed - on land we use a faster speed in dimmer light. I notice that a lot of photographers/divers use 100 or 200. Wondering what others thoughts are on this
Thanks
Thanks
Flim Speed
- Thread starter nauifins73
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The biggest difference is, we take our light with us underwater. The powerful strobes provide the light we need, making film speeds 200 and over unneccessary. With slide film, the usual speed is 50.
I'm sure there's a more technical way to describe it but I'll leave that to those who can describe technicalities!
I'm sure there's a more technical way to describe it but I'll leave that to those who can describe technicalities!
vicky
Guest
Most of the light "we need" comes from the strobe. However, the strobe only iluminates a cone (usually 60-100 degrees) and effective only at distances less then ~2meters.
Then there is ambient light.
During daylight, the camera is set to get a correct exposure of the background. The strobe adds the touch of grace to the subject. So you get a nice photo and the subject is colorful and outstanding. The water gets a nice blue color.
At night or low visibility, you can forget of any correct exposure of the background and the strobe is the only source of light. It only iluminates correctly the subject. Whatever is closer gets overexposed, and the background gets underexposed. Water will be very dark blue or black.
So, what does it matter which film speed?
If you're using a 50 ASA film and your lens biggest aperture is f/4 or f/3.5 (and let's suppose that you can't shoot faster than 1/30 without blurring the picture), you can already guess that most of the time you will not have a good shutter/aperture combination to properly expose the background. It will be underexposed. The subject will get its light from the strobe and that's all you'll see in your photos. Daytime pics will look as if were taken in a night dive.
And then you may suddenly see a whale shark swimming at 10 meters from you. Oh no! The strobe is not effective at this distance! Let's turn it off. But Alas, with your 50 ASA & f/3.5 the camera tells you to shoot at 1/2 second. You can forget from the whale shark picture. Ain't it pity?!
So each film has its cons and pros. If you're going to take ambient light pictures (without strobe), you better get a faster film. Nothing's wrong with 400 ASA and there are some excellent 800 ASA films too in the market. If you take a 50 ASA film with you, you also have to be ready to pay the consequences if a whale shark or a group of mantas pass nearby. Moreover, slide film is less forgiving than negative film for incorrect exposures.
Some other things to consider when choosing film are:
water visibilty, cloudy/sunny day, depth of dive, type of lens, etc.
Have fun and dive a lot!
Then there is ambient light.
During daylight, the camera is set to get a correct exposure of the background. The strobe adds the touch of grace to the subject. So you get a nice photo and the subject is colorful and outstanding. The water gets a nice blue color.
At night or low visibility, you can forget of any correct exposure of the background and the strobe is the only source of light. It only iluminates correctly the subject. Whatever is closer gets overexposed, and the background gets underexposed. Water will be very dark blue or black.
So, what does it matter which film speed?
If you're using a 50 ASA film and your lens biggest aperture is f/4 or f/3.5 (and let's suppose that you can't shoot faster than 1/30 without blurring the picture), you can already guess that most of the time you will not have a good shutter/aperture combination to properly expose the background. It will be underexposed. The subject will get its light from the strobe and that's all you'll see in your photos. Daytime pics will look as if were taken in a night dive.
And then you may suddenly see a whale shark swimming at 10 meters from you. Oh no! The strobe is not effective at this distance! Let's turn it off. But Alas, with your 50 ASA & f/3.5 the camera tells you to shoot at 1/2 second. You can forget from the whale shark picture. Ain't it pity?!
So each film has its cons and pros. If you're going to take ambient light pictures (without strobe), you better get a faster film. Nothing's wrong with 400 ASA and there are some excellent 800 ASA films too in the market. If you take a 50 ASA film with you, you also have to be ready to pay the consequences if a whale shark or a group of mantas pass nearby. Moreover, slide film is less forgiving than negative film for incorrect exposures.
Some other things to consider when choosing film are:
water visibilty, cloudy/sunny day, depth of dive, type of lens, etc.
Have fun and dive a lot!
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