EOS RP sensor noise ? red pixel-level spots in astro photos

[migEOSRP]

I noticed that there are some red spots in the images of time exposures I've taken of star fields. Zooming into the images, these are about a pixel in size and as seen in attached zoomed image are red. Picture taken with a Rokinon 135mm f/2 lens with a modest tracker and imo are quite good and sharp (I wonder if the Canon RF 70-200mm L zoom lens would be this sharp at 135mm). I decided to check a "blank" image with no camera lens attached but with the camera cap on with similar exposure settings as the astro shot (ISO-800  20sec) in fully manual mode. That "in the dark" photo shows quite a few similar pixel-size spots under those photo settings. Is this to be expected? They look like random "hot" sensor pixels. Doubtful they would be noticeable in regular camera photos but they are evident in star photographs .. most noticeably the red ones!

The web-page page below has 3 images with the original astro photo (25Mp  L jpg) and the zoomed in view showing red "hot" spots (same as photo attached), and the "blank" shot. Clicking either full image shows the full image size in the web page and can be scrolled to see the spots.

Canon EOS RP Sensor Noise

So the question is will the sensor on the EOS RP (or any other modern FF sensor) have these types of spots on images? 

[Peter · Accepted solution]

At long shutter speed you will have faster dark current build-up in some pixels. 

Solution for astro photos is to use a dark frame. Your camera has that feature too and that is called Long Exposure Noise Reduction.

[Peter]

To deal with hot pixels at normal shutter speeds you can just run "Clean now". It is documented in the manual at page 383.

Long Exposure Noise Reduction is found at page 159.

[migEOSRP]

thank you. Exactly what I was looking for.

[kvbarkley]

All "Clean Now" does is shake dust off the sensor. It has nothing to do with hot pixels.

[Peter]

 

[kvbarkley]

That makes absolutely no sense, unless cleaning does something to reverse latchup.

[Peter]

R50 and M200 also have a hot pixel removal feature, but not via Clean now.

[johnrmoyer]

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@kvbarkley wrote:

That makes absolutely no sense, unless cleaning does something to reverse latchup.

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I am guessing, but it might make sense when using a sensor that has dual pixel auto-focus, half of a bad pixel might be mapped out and the good half used for both. Another possibility is to use the average or median of surrounding pixels for the value of the bad pixel.

It is in the manual as Peter mentioned.

In my experience, clean sensor now seems to help as a sensor ages.

[migEOSRP]

thanks for all the replies. For context, my ES RP is very new and Im very careful with not letting the camera body open except for very brief moments. So I think my results represent a typical result for a new camera sensor.

I setup a fairly dark basement area with a flat bluish sheet as target and did these 3 shots with full manual settings and 20sec ISO 1000 with Rokinon 135mm f2 lens on tripod

(1) no noise reduction (2) with LENR enabled  (3) then put cap on lens and ran "Clean Now" .. which runs for about 10sec. After this, took the third shot without LENR to see if Clean Now effects the pixel hot-spots in a subsequent shot.

Results: lots of hot pixels in shot (1) and no hot pixels in (2) with LENR as expected. The final shot after Clean Now (with LENR off) basically shows all the same hot pixel spots as in (1) so for the types of spots I see (around 50) Clean Now has no effect.