New to DSLR photography, faced with hot pixels

[Hypernova]

Hi all,

I've been on this forum ages as a mainly observer with some planetary webcam photography. I have taken a long break from astronomy for various reasons and I've been trying to haul myself back in to the game. Since we've all but been confined to our homes I'd thought I'd try out DSLR photography since I've never owned one. I ended up buying a Canon 600d and standard 18-55mm lens this week from CEX for a a reasonable price. So far I've been pleased with it and have been getting to grips with the various settings and manual zoom and focus options, it's certainly a huge leap from a smartphone and compact digital cameras.

 

Tonight though I tried out long exposure for the first time using some settings similar to what I used  on my old IXUS 95; around 10-15 seconds exposure, ISO 100-400 and F3.5. The initial shots seem hopeful but the images are pockmarked with hot pixels. The blue, red and white pixels all seem to be in the same place and are present even with shots with the lens cap on. They can be removed with the camera's noise reduction setting but that requires another exposure of equal length to be taken right after the first.

 

Are these hot/stuck pixels typical of what I should be experiencing or is this abnormal and indicative of a defective sensor/camera?

 

Cheers 😁

[wxsatuser]

The pixels are most likely normal, there are usually quite a few.
If your taking short static shots just use the in camera noise reduction and let it take the second shot.

[wxsatuser]

BTW you can get rid of the pixels by using manual sensor clean.

This should remap the pixels and hopefully remove them.

Go to P mode and find sensor clean, yellow menu, click and find manual sensor clean.
After it's done it's thing turn off camera, next time you turn on it should have cleared the pixels.

Edited April 12, 2020 by wxsatuser

[Hypernova]

Thanks for your reply. I have tried using the manual sensor cleaning mode but it didn't make a difference to the result, the hot pixels are still present just as bad as before.

I have successfully used Photoshop (which I've never, ever used before now) to subtract the pixels using the dark frame from my last post. It produces some artefacts in the shape of small back holes where the hot pixels were, I presume with some more knowhow these could be remedied.  It's not ideal and I would've hoped to be able to shoot up to 30s without a mass of hot pixels invading my image 😕

[MarkAR]

Hot pixels are normal on every sensor. the only way to remove them is to take dark frames. 

Dark frames are subtracted from the image via stacking. The camera can do it with noise reduction but as you say it's another exposure and time lost.

Getting into astrophotography is a steep learning curve, even if you only want to take simple wide field images.

If you do not have a mount that can track the night sky you will be limited to around 30 secs exposures depending on the lens (look up the rule of 500).

To get the best out of any image, take multiple shots all the same exposure, take dark frames and also flat frames, stack these images in a good astro stacking app then edit the result.

[Hypernova]

I see, I'm glad at least that my camera isn't duff and I need to go trough the faff of sourcing a replacement.

I'll keep what you've both said in mind for the future, thanks 😀

[wxsatuser]

6 hours ago, Hypernova said:

Thanks for your reply. I have tried using the manual sensor cleaning mode but it didn't make a difference to the result, the hot pixels are still present just as bad as before.

I have successfully used Photoshop (which I've never, ever used before now) to subtract the pixels using the dark frame from my last post. It produces some artefacts in the shape of small back holes where the hot pixels were, I presume with some more knowhow these could be remedied.  It's not ideal and I would've hoped to be able to shoot up to 30s without a mass of hot pixels invading my image 😕

 

The pixels will not remove if you are shooting jpeg, use RAW only.

A good RAW converter should remove the pixels, ACR in Photoshop should do it.

Make sure the camera has reached ambient and do the clean.

Edited April 14, 2020 by wxsatuser