Which ISO setting do you use for UW?

[HowardE]

Hey, just noticed you are from Breckeinridge!

Could you recommend good place to dive in CO?

MG

Nope... I have never dived in Colorado. We live in Florida too No point in diving in cold dark lakes...

You should ask Ron Frank, and/or post in the "Rocky Mountain Oysters" forum

[/hijack]

 

[Warmwater Wank]

The 26mm era? I missed that one (must have happened during a safety stop?). Film has more or less sensitivity to light in part due to grain structure and size and in part due to the thickness of the emulsion. A "slower" film has less apparent grain along with a thinner emuslion, which should give better resolution and acutance (additional factors that effect image quality but usually aren't discussed). All this translates to "Gee, that's sure sharp" or "Hey, this is real grainy".

As has been noted, digital cameras have varying quality results at various ISO's (the international system that replaced ASA several decades ago). While the means for achieving light sensitivity are different in digital cameras, we tend to view the results in a similiar way. Some digital cameras do ok at higher ISO's but many do not. Whether shooting film or digital, the effect of raising the ISO allows for raising either the aperture number (increasing depth of field) OR raising the shutter speed (or both!).

This part of the equation has been missing in this discussion--the shutter speed aspect. May not mean much when shooting in close with a flash but it explains why those quick grab shots of turtles or divers, at a distance beyond the flash range, can look blurry. Either the subject or the photographer was not holding still and a fast enough (higher) shutter speed was not used.

A shot that's blurry but "noise free" (probably a better term than grainy for digital pics) doesn't look much better than a grainy/noisy shot that stops the action or has adequate depth of field but is hard to see. Play with your camera settings more and try to keep track to see what works best for your camera and shooting situations. Smaller images used online can get away with a lot. Bigger printed enlargements need all the quality they can get. Oh yeah, and forget diving in Colorado. The water isn't any warmer than in Oregon. It's why I chose to be a Warmwater Wank.

 

[SuPrBuGmAn]

I did some test shots where I set the camera up (topside) and focused on a color image (a calendar on my wall) and shot in 100, 200, 400, and 800.

I could definitely notice a difference between all 4.

At 100 - there was no noise at all in the image.
200- noticible noise in some of the colors, but not all
400- noticible noise all around (but not too severe)
800 - noise.

So - really experimentation is probably your best friend in this situation.

Viewing distance and viewing size also come into play. A resized image or a smaller print, even medium sized prints will not show as much grain as at 100%. There is also more than one way to achieve grain, underexposing a shot and pushing it in post processing will also create noise, usually worse than a higher ISO shot exposed correctly. Something to keep in mind when you can't get a decent exposure with workable shutterspeeds and apertures... and shooting upwards is not an option

Then again, sometimes grain makes for a more dramatic photo in the first place

 

[Jamdiver]

Viewing distance and viewing size also come into play. A resized image or a smaller print, even medium sized prints will not show as much grain as at 100%. There is also more than one way to achieve grain, underexposing a shot and pushing it in post processing will also create noise, usually worse than a higher ISO shot exposed correctly. Something to keep in mind when you can't get a decent exposure with workable shutterspeeds and apertures... and shooting upwards is not an option

Then again, sometimes grain makes for a more dramatic photo in the first place

Hehehe oh yeah, I know all about that 'noise' from post-processing........ :14:
Great post Bugman .

 

[HowardE]

So - after shooting today in ISO 200... I've decided that I'm going back to 100 and probably keeping it there.

 

[BurBunny]

It may have helped your friends out if they seen Howard Hall's hammerhead shots with a strobe and shooting in an upward direction. Shooting upwards will give you more than enough light to properly expose an image at the lowest ISO, even without a strobe. Shooting upwards is another rule of U/W photography, keep that ISO setting low for the finest image possible.

Since the friends I was referring to are multiple international award winners, I'm certain they're aware that in general you want to get low and shoot upwards. But since they actually dive and photograph regularly, they also know that sometimes isn't enough depending on conditions. Sometimes you have to boost the ISO as well, and many times use of a strobe isn't the effect they're looking for.

True artists are willing to explore many ways of achieving the desired effect. That means experimenting. And sometimes breaking the rules. They're the ones who expand the art.

I know which people to rely upon when looking for advice on shooting techniques... and who just quote others without demonstrating their own acquired knowledge.

 

[Diver Dennis]

It may have helped your friends out if they seen Howard Hall's hammerhead shots with a strobe and shooting in an upward direction. Shooting upwards will give you more than enough light to properly expose an image at the lowest ISO, even without a strobe. Shooting upwards is another rule of U/W photography, keep that ISO setting low for the finest image possible.

Then one can argue that the higher ISO can give you better DOF or one f stop (smaller aperture openings) for every one increase in ISO setting...big deal! For what is the gain in DOF when the light from the strobe cannot travel far enough to properly expose the "back" in-focus part of the subject without burning up the "front" part of the subject?

http://www.howardhall.com/

Depending on depth and topside conditions using ambient light by shooting up will not give you enough light to properly expose and image. Even if there is a lot of light coming from the surface, your subject will be dark against the surface without a strobe. Why do you think that the Hammerheads in that link were shot with a strobe?

 

[SuPrBuGmAn]

The obvious answer is to use the setting you need to get the picture. If you have the light to shoot at ISO100 all day long, by all means do it, less you want to make a grainy B&W(I love those). If you need more light and can't make it up with shutterspeed, useable aperture, strobes, ect - make it up with a faster ISO. D'uh?.

Its foolish to think you have to keep the ISO at the lowest possible ISO no matter conditions. Just about any current dSLR will make medium sized prints without much noticable noise at ISO400 if it was exposed correctly. Even if you gotta push it further, a grainy shot is better than none at all.

 

[HowardE]

This wasn't a question to be answered... Just to see what other people do.

"Which ISO setting do you use for UW?"

Not - "which ISO setting SHOULD I USE"

I'm still going to make my own decision for myself by experimentation / trial and error. I don't follow "rules" - i do what works for me. I just wanted to see what other photographers on ScubaBoard use for their own personal experiences.

 

[SuPrBuGmAn]

Well I guess the answer to your question would be, whatever ISO I have to shoot at dependant on conditions. Maybe as low as possible, maybe much faster.