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New Contributor
Posts: 2
Registered: ‎07-18-2020

Artifacts when photographing at night

[ Edited ]

I went out to photograph C/2020 NEOWISE F3. Some pictures came out well, but nearly all had artifacts, dozens of them. You can tell the stars from the artifacts because long exposure caused blurr. 

 

As an experiment, I took a long (30 second) exposure in a completely dark room and they showed up in that one too. 

The red is the reflection of the SD Write LED in the mirror.

 

Camera: 70D, exposure: 30 seconds, ISO 400

 

IMG_3594.JPG

 

Some show up as white "X"s, some show as red pixels and some show up as blue pixels.

 

You have to download the image to see it. They don't show up on this post.

 

Any help/comment would be appreciated.

 

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Esteemed Contributor
Posts: 4,314
Registered: ‎02-17-2016

Re: Artifacts when photographing at night

Hot pixels, that is why your camera has a dark frame removal setting. After a long exposure, the camera will take another exposure of the same time with the shutter closed, and subtract any pixels that show up.

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New Contributor
Posts: 2
Registered: ‎07-18-2020

Re: Artifacts when photographing at night


@kvbarkley wrote:

Hot pixels, that is why your camera has a dark frame removal setting. After a long exposure, the camera will take another exposure of the same time with the shutter closed, and subtract any pixels that show up.


Thanks, that seemed to work on the aforementioned experiment. Let's see how it turns out tonight.

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