Taking photos under actinic lighting

[GeoHawk]

Nice pics Brent. I have tried to take photos under my blue leds and they don't come out half that good

 

[Brent Ward]

I may sound dumb, but what is "underexposed by a stop" mean? Did you black out the background with editing? Thanks

If your exposure is 1/60th @ f8, you shoot it at f11 or 1/125th exposing the image a stop under the correct exposure.

 

[GeoHawk]

If your exposure is 1/60th @ f8, you shoot it at f11 or 1/125th exposing the image a stop under the correct exposure.

LOL, Maybe I just need to take a photography class :)
I understand the 1/60th and 1/125th but f8 and f11 lost me

 

[Brent Ward]

The "f" numbers are your aperture. Smaller the number, the bigger the aperture. Also, larger the number, the more depth of field you will have.

 

[gparr]

I may sound dumb, but what is "underexposed by a stop" mean? Did you black out the background with editing? Thanks

Underexposed by a stop means that I shoot with a shutter speed that is one stop faster than the one that the camera's meter suggested is the correct exposure. For example, if the meter in your camera suggests a shutter speed of 1/60 sec., moving the shutter speed to 1/125 sec. (twice the speed) will underexpose the shot by one stop, i.e., make it "darker." Moving the shutter speed to 1/30 sec. (half of the speed), will over expose the shot by one stop, i.e., make it "lighter."

Aperture determines depth of field, i.e., how much of the image is in focus from front to back. As the f/stop, or aperture, gets higher (moving from f/8 to f/22, for example), the lens opening gets smaller and the amount of the subject, from front to back, that is in focus increases. If you take a series of photos of the same subject (a fence, for example) at different aperture settings you'll see how the amount of the subject that is in focus changes with the aperture setting.

For these basic photography questions, it would serve you well to read a book or use one of the hundreds of websites devoted to teaching the principles of photography. Also, at some point, the only way to learn is to take your camera and go shoot a bunch of photos of anything, make some notes, and start to learn what happens when you change settings. Note that it's much easier to learn these things if you're taking pictures of a building, tree, or a fence than it is to learn the basics while trying to do close-up photography of corals.

Gary

 

[fsu1dolfan]

Underexposed by a stop means that I shoot with a shutter speed that is one stop faster than the one that the camera's meter suggested is the correct exposure. For example, if the meter in your camera suggests a shutter speed of 1/60 sec., moving the shutter speed to 1/125 sec. (twice the speed) will underexpose the shot by one stop, i.e., make it "darker." Moving the shutter speed to 1/30 sec. (half of the speed), will over expose the shot by one stop, i.e., make it "lighter."

Aperture determines depth of field, i.e., how much of the image is in focus from front to back. As the f/stop, or aperture, gets higher (moving from f/8 to f/22, for example), the lens opening gets smaller and the amount of the subject, from front to back, that is in focus increases. If you take a series of photos of the same subject (a fence, for example) at different aperture settings you'll see how the amount of the subject that is in focus changes with the aperture setting.

For these basic photography questions, it would serve you well to read a book or use one of the hundreds of websites devoted to teaching the principles of photography. Also, at some point, the only way to learn is to take your camera and go shoot a bunch of photos of anything, make some notes, and start to learn what happens when you change settings. Note that it's much easier to learn these things if you're taking pictures of a building, tree, or a fence than it is to learn the basics while trying to do close-up photography of corals.

Gary

Thanks for the quick layman's explainations...You really should think about getting a sticky thread and update once a week with tips/definitions/anything that will help us out.

 

[gparr]

You're more than welcome. I assume you read/studied the numerous stickies that are already at the top of this forum?
Gary

 

[REEFCRAFT]

:crossedlips:

 

[CJO]

Gary, in the presentation you gave at our local club, (IIRC) you said that you generally shoot with an ISO of 400. Have you experimented at higher ISOs with the newer cameras and their ability to shoot at higher ISOs without getting grainy?

Thanks,
CJ

 

[Brent Ward]

Gary, in the presentation you gave at our local club, (IIRC) you said that you generally shoot with an ISO of 400. Have you experimented at higher ISOs with the newer cameras and their ability to shoot at higher ISOs without getting grainy?

Thanks,
CJ

I'm not Gary so I hope you don't mind if i answer your question.

My zoa shots are done at iso 3200 and at web res are just fine. For magazine covers I don't usually go over iso 400, but will go up to around iso 1000 if the situation warrants it.

...and a sample of my other photography for a client.

 

[gparr]

My main camera is a 7D and it will deliver good images at higher ISO settings. However, at settings higher than ISO 400, I still start to see grain/noise. Bringing Brent's comment into this post: I don't shoot images for one specific use, i.e., online only, print only. I shoot images such that they can be used for any application. To accomplish this I need to keep my ISO setting as low as possible. 400 seems to work best. Many times, I'll use 200 if I feel I can get away with it. I've also not seen an ongoing need to shoot at higher ISO settings. Since I'm always shooting corals with a tripod, the higher setting rarely helps. If I'm using flash, there's also no benefit. If you're trying to shoot corals handheld, you almost have no choice but to use higher ISO settings. Any of my other work (flowers, architecture, etc.) is almost always done at ISO 200.
Gary

 

[Brent Ward]

Gary, have you read much about the native iso of your camera's sensor?

A lot of them will give a cleaner file at iso 160 instead of 100. Small differences that will make a difference when printing big.

I use a high iso to shoot under blue LEDs with a tripod. I also shoot them for fun, so I know I'm not going to blow them up like I would for a client.