Am I looking at a faulty sensor?

[Andy56]

Hi,

I've had a Canon 600d for a few years and moved over to an ASI2600mc for a few years.

I've been experimenting with a more portable rig and started to experiment with a SAM and my astro modded Canon 600D for wider angle.

The last session gave me images with a line across it as you can see in the attached Persius image.

This image was 90x 10secs stacked with DSS, 50mm Pentax at F5.6 and ISO800. There is walking noise because I hadn't turned on the dithering because I forgot and it was the first night out with it etc...

Overall I'm impressed with the SAM

The second image is an uncropped 16x60secs at 135mm with a lot of dithering so the line can disappear. Plenty of light pollution, bortle 5 and it shows the lens defects.

So the question is, based on your experience is this a failed sensor with one line failing to readout?

Cheers

Andy

[alacant]

2 hours ago, Andy56 said:

is this a failed sensor

Hi
We had similar row with a 700d. Someone then dropped it, after which the line disappeared. Whilst we don't recommend the gravity method, a sharp nudge in a warm room may help.

Otherwise, just work around it in software. Rather than resort to dark frames -which will introduce further artefacts- simply run the sequence via Siril's banding algorithm before registration. Or even easier, on the end result: 
Cheers and HTH

Edited January 31 by alacant

[Andy56]

Hi alacant,

A software solution is quite preferable over the gravity solution.

I'm going to give Siril a try although I've never used it before. I used dark fame on this data because the lack of dithering showed many hot pixels after stacking. I'll try with and without.

It'll save buying another camera.

 

Cheers

Andy

 

 

[Andy56]

As a Pixinsight user I found the "CanonBandingReduction" script.

So I'm not the only one!

I also found that it only occurs in low light situations ie darks and lights. It doesn't show in flats or bias frames even if I give them an extreme stretch.

I tried a series of darks from ISO400 10, 60 and 120secs also ISO800 10, 60 and 120secs. Giving them an equal stretch the line is visible in all but ISO800 120secs.

So it seems that there is some clipping at the bottom. I don't fully understand it, maybe some one can explain.

This gives me a lower limit on the exposures I can use. If the weather was any good I'd have tried it outside but darks were the only testing I could do.

Cheers

Andy

[edarter]

What software are you using to stack? I had horrible horizontal banding on my EOS 600D that I spent ages trying to get rid of. Changed USB cables, tried battery power an mains for the camera and capture laptop, different ISO's and all sorts of changes to calibration and DSS settings. Nothing shook it off until I switched from DSS to APP for stacking. Never had an issue since.

[Andy56]

Sorry about the delay, the notifications aren't happening.

I'm using DSS and Sequator for fast results.

I don't have APP but I have PixInsight so I gave WBPP a try, good results (see below) but it took 1hr 10mins as opposed to a few mins in DSS or Sequator.

I generally use PixInsight when doing deep space objects but then the whole kit, including the camera, is much better.

I was trying to be economic with time as I'm planning a trip to the Southern Hemisphere but it doesn't pay. You have to pay somewhere equipment or time!

Cheers

Andy

Orion last night:

Star Adventurer Mini 0.5arcmin dither + home built dec ditherer, all running from a USB battery pack.

Canon 600D, ISO800, 75x19secs lights,  10darks,  20flats

Pentax 135mm at f8

72%moon bortle5 (or worse)

Quick processing Stack, Background Neutralisation, Manual Stretch, Noise XT, Blur  XT

Given the moon was 71% and 30deg from Alnitak I'm quite happy with this. The background needs some work though, but considering I overlook the town and the light pollution probably what is to be expected.