Grainy Pictures: Need Help

[Travis L. Stevens]

I just don't know what is causing this. It might be the lower megapixels, it might be user error. I'm still honing my skills, so not everything is the greatest. I'm having trouble with my pictures being grainy, even with them viewed zoomed out all the way. I understand that pictures zoomed in on through software will look pixilated, but this is just plain grainy. Here's some information and pictures

Camera: FujiFilm FinePix S5100 (http://www.dpreview.com/reviews/specs/Fujifilm/fuji_finepixs5100z.asp)

Settings
ISO: 200 or 400
Aperture: Various (depends on exposure)
Shutter Speed: Various (depends on exposure)
Picture Size: 4mF (the largest)

Example Pictures
This is probably the best examples that I have.

Original Picture as large as Photobucket will allow.
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/SupermanRhodactis.jpg

Same Picture, but zoomed in on and saved at the original size of the original picture.
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/SupermanRhodactisCloseUp.jpg

Same picture but zoomed in a little more saved to the same size as the original picture.
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/SupermanRhodactisMacro.jpg

On the other hand, I have some untouched pictures that don't even look as good as some of the ones I was able to crop with Photoshop. I just don't get how to get the graininess out so I can get crisp, clear pictures. Any help would be GREATLY appreciated.

[MIREEFER]

maybe try a lower iso

[Travis L. Stevens]

But it makes the picture REALLY dark.

[BlueCorn]

Exposure has 3 variables; ISO, Aperture and shutter speed.

If you lower the ISO (and you need to if you want to get rid of that noise) you need to use either a wider aperture (lower number) or a slower shutter speed.

[Travis L. Stevens]

Hmm... Interesting. I guess I still need to work on my photo-vocabulary. I don't know about other cameras, but mine has a little meter at the bottom that lets me know if it will be slightly over or under exposed, and I can change my Aperture and Shutter Speed to "balance" it. So, should I just lower the ISO and do what I've been doing? Am I on the right track, but not there yet?

[BlueCorn]

You should be using Aperture priority (AE) or manual.

[Blazer88]

Travis,
Are you under-exposing your pictures by chance? In addition to what Doug said, if you start with an under-exposued picture and "brighten" it back up in photoshop, it will exaggerate any noise and make it much worse.

[Travis L. Stevens]

<a href=showthread.php?s=&postid=9824605#post9824605 target=_blank>Originally posted</a> by beerguy
You should be using Aperture priority (AE) or manual.

I've been using Manual. I'll have to try Apeture Priority, but I like to be able to tweak both if I need it. My camera offers a Program mode (uses common Aperture:Shutter Speed ratios), Shutter Priority, Apeture Priority, and full Manual.

[BlueCorn]

If you're using manual then you need to adjust the aperture and shutter speed to properly expose the subject.

[Travis L. Stevens]

<a href=showthread.php?s=&postid=9824626#post9824626 target=_blank>Originally posted</a> by Blazer88
Travis,
Are you under-exposing your pictures by chance? In addition to what Doug said, if you start with an under-exposued picture and "brighten" it back up in photoshop, it will exaggerate any noise and make it much worse.

According to the exposure meter, it was right in the middle on most pictures. I have a couple that are a step lower or a step higher, and they have the same contrast/brightness. I personally didn't touch any of the brightness or saturation in photoshop. All I did was crop the image.

FWIW, here are two shots of the same thing with two different ISO settings. Unfortunately, to get this shot, I had to crop a LOT out, so it's understandable that this shot won't be that crisp. I only took ISO 400 and 200 shots because anything less was too dark.

ISO 400
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/RicordeaFloridaTwoToneMacro.jpg

ISO 200
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/RicordeaFloridaTwoToneMacro2.jpg

Different shot with slightly different A and S settings, but ISO 100
http://i11.photobucket.com/albums/a184/TravisStevens/Aquariums/Saltwater/Livestock/Large%20Pictures/OrangeFloridaMacro.jpg

[Travis L. Stevens]

BTW, these pictures look a LOT grainier when they are full scale 31.556"x23.667"