Spots on RAW files

slat · May 21, 2018

I shoot both RAW and JPEG. I was trying to capture some shots of lightning the other night and when I viewed my shots the ones in RAW have red white and blue crosses (dots) on them. The JPEG does too but they are less noticeable. Next two nights the shots seemed just fine. Seems to happen when the shot is darker. Happens at various ISO and F stops. Any way to fix this or am I just going to have to live with this on again off again problem. It just recently started.

tirediron · May 21, 2018

Some examples would help greatly.

Overread · May 22, 2018

Agreed, there are several things that can cause strange spots in photos so it helps to see examples of what you are seeing to help work out what specific issues they could be.

smoke665 · May 22, 2018

When was the last time you checked/cleaned dust off the sensor?

Overread · May 22, 2018

Dust spots are unlikely to appear as red/white crosses.

Dust spots on the sensor appear more like a blurry dark smudge on the photo. They are most visible at small apertures (big f numbers) and on a clear scene (low to no detail). So taking a photo of a clear sky or a sheet of paper at f16 will often show them up whilst at f2.8 they can be invisible.

smoke665 · May 22, 2018

Overread said:
Dust spots are unlikely to appear as red/white crosses.

Agreed, but the OP's description also referred to them as "(dots)", so without an example it's anyone's guess at this point. Checking the sensor for dust is a quick and easy maintenance item that needs to be performed on a regular basis anyhow.

slat · May 22, 2018

IMG_1215 by Steven Emmons, on Flickr

IMG_1218 by Steven Emmons, on Flickr

tirediron · May 22, 2018

Looks like you've got some bad pixels.

slat · May 22, 2018

They are harder to see in JPEG and I'm not sure how to upload a RAW file?

Tinderbox (UK) · May 23, 2018

Some camera`s have "pixel mapping" removes faulty/dead pixels from the image, there will be a option in the settings or you change the date to a month or two ahead to activate it, what camera do you have?

Overread · May 23, 2018

You basically can't upload a RAW file to any image share website, you need a file share system because a RAW isn't an image but a data file. That said from the crosses they appear to be dead pixels. That you can see more on the RAW and less in the JPEG means that the auto editing in the camera is either removing or masking them.

As Tinderbox says you want to look at the pixel mapping feature in your camera manual (most are online if you've lost it) which should be able to run you through how to take a photo and have the camera scan and auto edit out the bad pixels. I'm not sure but dust-delete "might" also remove them or be bundled with the pixel mapping (I've never done a pixel mapping to really know).

As a point the only thing I know that can cause dead pixels is a laser beam going into the lens, especially whilst shooting video. Something that people shooting at clubs/concerts have experienced with those spinning laser shows. I'm sure there are other things which can cause dead pixels but I've never had the issue to look into it in any great depth. You've quite a few though so it might be prudent to look into common causes as you could be doing something regularly that might be contributing to the problem.
As they are only 1 pixel in size once they are mapped out they shouldn't be an issue.

smoke665 · May 23, 2018

slat said:
shots the ones in RAW have red white and blue crosses (dots) on them. The JPEG does too but they are less noticeable. Next two nights the shots seemed just fine. Seems to happen when the shot is darker.

Your description "small crosses", doesn't fit the description of a dead pixel
Dead vs Stuck vs Hot Pixels - Photography Life

Read the "what do they look like" in the article on hot pixels
Hot Pixels