What is this crap? - DPChallenge Forums

Nikon AF Nikkor 50mm f/1.8D

02/06/2006 12:47:32 PM · #1

I wish I could show everyone a full size image, because its alot harder to see at this resolution.

There are some white specks in the dark areas of this image. I just got a new camera and in some of the darker areas of my images I am seeing these white specks. I was thinking sensor dust, but they are not always in every image or in the same place. Any thoughts?

wavelength

Nikon D300

02/06/2006 12:50:22 PM · #2

If it's not uniform, meaning it changes image to image, that would point to your image processor to me....

maybe some crops would work better, take a few picture of a dark grey uniform surface and see if the pattern really changes that much.

bledford

Canon EOS-300D Rebel

Canon EF-S 18-55mm f/3.5-5.6

02/06/2006 12:51:50 PM · #3

Can you post a 100% crop of the area? It's hard to make a judgment from that image. It actually looks like pollen from the flower, but if you say it's on other images as well...?

cpanaioti

Canon EOS-40D

Canon EF 70-300mm f/4.5-5.6 DO IS USM

02/06/2006 12:53:55 PM · #4

I concur. Could be pollen. Do a 100% crop of the section with the white specs and upload that.

kirbic

Canon EOS R5

Canon RF 24-70 f2.8 L IS

02/06/2006 01:07:35 PM · #5

I agree that a 100% crop would be helpful to make certain, but they don't look like they were present in the image, they look more like capture artifacts. They look like hot pixels, but to have tha many showing up at ISO 400, 1/200s would be very unusual. Here are a few questions:
- Did you shoot this in JPEG mode, or RAW?
- Did you correct exposure much during post-processing?
- Did you notice what the histogram looked like on-camera? Was the peak toward the left?

Canon EF 17-40mm f/4L USM

02/06/2006 01:17:17 PM · #6

Originally posted by kirbic:

Thanks for all the input so far and yes I need to post the full frame.. un-processed image... I am at work, but will post a link to the full image unprocessed when I get home.

-I shot this in JPEG
-I don't remember my post steps... I can update this when I get home
-You lost me on this one... histogram is on my list of things to read... I know what it is, but can't tell you what it was at the time.

Thanks for the help so far... I will get more information up

LoudDog

Canon EOS-350D Rebel XT

02/06/2006 01:28:04 PM · #7

Take a photo with the lens cap on (intentionally). If it's hot pixels they will show up as white spots and be pretty easy to see at 100%.

02/06/2006 07:01:30 PM · #8

Here is a 100% crop

Here is another example..

Gordon

RIM BlackBerry Curve

Canon EF 85mm f/1.8 USM

02/06/2006 07:06:56 PM · #9

In the first case, it looks like it is on the flower, in the second case I have to confess to not seeing what you are talking about.

Edit: unless you mean the slight patterning in the solid green and blue areas, which is sensor noise. Depending on the ISO you are shooting at you'll see this - what ISO are these shot at ?

Given how soft the edges are, I'm guessing you are shooting these handheld at a highish ISO which would explain the really soft pictures and sensor noise.

Message edited by author 2006-02-06 19:10:52.

02/06/2006 07:11:50 PM · #10

Originally posted by Gordon:

400 handheld

the first picture with the purple flower... that is the 100% crop of the first post image... you don't see the little spots?

Message edited by author 2006-02-06 19:12:47.

Gordon

RIM BlackBerry Curve

Canon EF 85mm f/1.8 USM

02/06/2006 07:18:07 PM · #11

Originally posted by res0m50r:

400 handheld

the first picture with the purple flower... that is the 100% crop of the first post image... you don't see the little spots?

Yup, it looks like dust on the plant - those spots are slightly blurry like everything else in the image. If it was on the sensor, it wouldn't be affected by handholding at too slow a shutter speed.

I don't see anything like that on the second crop though - other than the effects of motion blur.

Message edited by author 2006-02-06 19:19:12.

kirbic

Canon EOS R5

Canon RF 24-70 f2.8 L IS

02/06/2006 07:22:50 PM · #12

Ahh, heh, the frst case is actually stuff ON the flower. It LOOKS like noise at the reduced resolution because contrast and brightness have been increased and sharpening has apparently been applied.
the patterning in the green in the ower shot is noise, and that level of noise is normal at 400 ISO with no noise reduction. The shot may have been a bit underexposed, and that will contribute to noise as well, if you later raise the brightness.
Do read up on use of the histogram, and also read this after you've familiarized yourself with histogram basics. It will make a difference.