PDA

View Full Version : little white specks



mpd525
01-28-2008, 22:08
i got my camera a few days ago, and sometimes when i take pics, i get these little white specks all over the pic. they aren't real noticeable, but still they are there. I notice that it sometimes does it when i use the strobe. The camera is mostly auto, but you can adjust the WB,and ISO on one setting. So any ideas to figure out how to keep it from doing that would be helpful.

and can someone kind of explain to me how the ISO works. the camera has settings for 50, 100, 200, 300, 400 800, and 1600.

I'm new to all this lingo, and even newer and knowing how it works.

I tried posting a pic with the little specks, but it kept locking my computer up, so i finally gave up.

DevilDiver
01-28-2008, 22:25
Most likley you are talking about backscatter. This is caused from the cameras built-in flash hitting particles in the water between the subject and the camera.
This can be corrected with adding an external strobe or strobes and blocking or turning off the cameras built-in flash.

Puffer Fish
01-29-2008, 04:39
I would agree with DevilDiver on the spots, but need to see an image.

The most likely issue with the down load is that you are trying to down load a really large image file... you should resize to say 800 x 600 (a copy, not the original) and then try.

ISO - is the same thing as "film speed". The higher the number, the less light is needed to take a picture.

But higher also means a noisier picture.

If you could, you would shoot everything in the lowest number possible - usually 100 or less. But, if you don't have enought light (from the sun and/or strobe), you either don't take the picture or raise the ISO value.

Like shutter speed, the number is in powers of 2 - so:

1/30 second at F 3.5 using ISO 100, if you change to ISO 200, it would now be 1/60 second at F 3.5.

Going above 200, and you will start seeing a major drop in image quality.

Here are the steps for ISO, lens openning and shutter speed, with each one roughly equal to each other:

ISO F Stop shutter Speed

100 8 1/1000
200 5.6 1/500
400 4.5 1/250
800 3.5 1/125
1000 2.8 1/60

Less than 1/60, and most people will blur the image due to motion. More than 200 ISO and you get fairly grainy images, and as the F stop gets smaller, less and less is in focus...

Hope that makes sense.

dbh
01-29-2008, 09:24
since he got the camera a few days ago.....and lives in OK......they may not be underwater photos. In that case, it is most likely dust on the sensor.

Are they U/W photos?

Dave

Puffer Fish
01-29-2008, 11:28
since he got the camera a few days ago.....and lives in OK......they may not be underwater photos. In that case, it is most likely dust on the sensor.

Are they U/W photos?

Dave
You may be correct, have no way to know. Don't know the camera being used (which might rule out dust or rule it in).

Dust on the lens also looks like back scatter, and is common to only see when using a strobe... again, don't know.

Sadly, being new, he does not know how to do all the stuff one would need to assist him... but getting thru the download process is a major step in the right direction.

jeepbrew
01-29-2008, 11:28
If they are UW pics, I would say it is backscatter from the camera's internal flash... we need more info to know for sure.

mpd525
01-29-2008, 19:14
no they were in the house of the dogs, i'll try to post it again here in a little while. they almost look like lost pixels or something. They are really tiny, my wife didn't even notice them,but it was buggin me.

bversteegh
01-29-2008, 19:58
Was it kind of dark in the doghouse, and you took some pictures with no flash?

I'll bet you have auto-iso on your camera - and as Puffer explained above, lots of compact cameras get noisy at high iso. For most digicams, I wouldn't use ISO above 400 max; and try to shoot ISO 100 whenever possible.

Puffer Fish
01-29-2008, 19:58
no they were in the house of the dogs, i'll try to post it again here in a little while. they almost look like lost pixels or something. They are really tiny, my wife didn't even notice them,but it was buggin me.
Then we really, really need to see the image.

mpd525
01-31-2008, 15:39
try again

mpd525
01-31-2008, 15:41
and again

mpd525
01-31-2008, 15:43
that was after i tried correcting it, i think it was due to high iso settings, i think it's called noise. So when would you use high iso, and why? And with my camera should i just always leave it in the auto settings.

I put it on ISO1600, because i thought it would catch the falling snow, but it had all the "noise" in it. Some of the other pics i took i used in iso 100 and they didn't have that problem.

mpd525
01-31-2008, 15:46
here are some others, i also noticed the only way to get rid of it was to blur the images with the oly software. But then they don't look as good.

Puffer Fish
01-31-2008, 16:41
here are some others, i also noticed the only way to get rid of it was to blur the images with the oly software. But then they don't look as good.
Thanks, that helps a lot.

Yes, that is noise...and you are correct about using a high ISO value. When should you use a high (400 and above) ISO? Only when you have no other choice, as the image quality goes bad fast. Can you correct for it? You can smooth the image out, but the detail is lost forever.

I don't use "auto" unless I have no other choice. That does not mean I don't use the automatic light measurement, but I fix the ISO to 100 and only go higher if that does not work.

Remember -

1. Low ISO = low noise.

2. Slow shutter speed can mean blurred images.

3. Using a really low F stop may mean a very limited range is in focus.

Down to around 1/60 second, I usually give on shutter speed (but there are exceptions). then I give up F stops, and if that all fails, ISO...

If I need to freeze motion, the F stops go first. But ISO is always last.

RoyN
02-05-2008, 01:52
cool! I'll have to try it out!

Rileybri
07-10-2008, 00:17
You are sooooooo off base on this one. I am sorry but I guess this is the kind of answer you get when you ask a scuba specific board a question like that with out posting the photo. ITS SNOW!!!!!!

In all seriousness that is some good info below! Another helpful hint if not using a strobe is to hold the camera upside down when using the on board flash. It greatly reduces back scatter (at least for me). Another is to cut a piece of opaque white/clear milk jug about half the size of your camera. punch a whole in in one corner and thread it through the camera lanyard. When shooting hold it up over and up to the flash. it make a decent and cheep flash defuser!



here are some others, i also noticed the only way to get rid of it was to blur the images with the oly software. But then they don't look as good.
Thanks, that helps a lot.

Yes, that is noise...and you are correct about using a high ISO value. When should you use a high (400 and above) ISO? Only when you have no other choice, as the image quality goes bad fast. Can you correct for it? You can smooth the image out, but the detail is lost forever.

I don't use "auto" unless I have no other choice. That does not mean I don't use the automatic light measurement, but I fix the ISO to 100 and only go higher if that does not work.

Remember -

1. Low ISO = low noise.

2. Slow shutter speed can mean blurred images.

3. Using a really low F stop may mean a very limited range is in focus.

Down to around 1/60 second, I usually give on shutter speed (but there are exceptions). then I give up F stops, and if that all fails, ISO...

If I need to freeze motion, the F stops go first. But ISO is always last.

Geoff_T
07-10-2008, 04:40
actually this looks like a combination of High ISO and snow. While some cameras can handle higher ISO settings (Nikon D2x/D3) better than others it is better as others have said to avoid high numbers. If you have enough light use a higher shutter speed for fast motion or a slightly crisper image. If you have less light turn the shutter speed down no lower than 1/60 sec for hand held or put it on a tripod and you can do some fun long exposure shooting at night type stuff.

One other thing to be aware of is that dirt on the lens can sometimes cause image issues as well. Think shooting sports on a dusty day. But in your case I think it is a simple case of not enough light.

CompuDude
07-10-2008, 15:55
High ISO is definitely the culprit. Use as low an ISO as possible. Especially since these are outdoors shots with lots of light... cranking up the ISO is the exact opposite of what you want. High ISO is only good for low light situations where you have no other choices.

Using a faster shutter speed would help those shots, too, as they're over-exposed. Snow can be a PITA to photograph.