Darks yes, but this??

[pmrid]

Can this be right? Here is a 10 minute dark. It looks like Surfers Paradise on New Years Eve. Is this normal?
Peter

[iceman]

That's pretty nasty.

Camera and settings?

[sheeny]

That's odd!

Apart from the blue and red "galaxies" there's some interesting patterns around the white hot pixels... a clue perhaps? (no idea what to yet!)

Do you get the same affect happening on your lights?

Al.

[leon]

Wow that is extremely odd, have never seen that before, and really cant give an opinion on that one.

Leon

[Tandum]

I've had similar images from my DSI camera when the usb cable had a poor connection.

[pmrid]

Camera is a 300D with DSUSB taken in Nebulosity at ASA1600 for 10 mins. No idea about those odd cruciate artifacts. It can't relate to dust on the mirror or CCD because it's a dark. Nor can it be related to the IR mod - same reason. It was using a Canon power supply. I used the same caables (USB DSUSB) to run similar tests on my 1000Ds but they were normal so this is related to the camera itself. It's a horror but is it fixable?
Peter

[Gama]

Try placing aluminium foil over the dust cap to seal the light correctly. Then try another dark.
Most dust caps are not IR proof. So light can pass thru with phsicodelic patterns.

Theo.

[pmrid]

Tried that - or something similar. I put the camara inside a sealed dark box while the exposure was under way. So it isn't stray light. As I write this I wonder whether the rear LCD screen is illiminated during a long exposure?

The unresolved issue is the power supply. I'll have another run at it using battery only and see what occurs.

Peter.

[sheeny]

Keep us posted.

I wanna know how to take a Hubble Deep Field shot with the lens cap on!:P

Al.

[avandonk]

Peter is it a jpg straight out of the camera or a processed RAW?

Your sensor will heat up by about 15C with long exposures. Try doing a continuous sequence of dark exposures say 10x6 minutes from a cold start. You will see the darks get progressively brighter (hot pixels etc) with each sequential exposure until equilibrium is reached for the sensor temperature.

Bert

[[1ponders]]

Is that a crop or full frame? If crop what program to do the crop and was it then upsize

[Jazza]

Stupid question maybe... but check if you have ICNR on.

[[1ponders]]

Damn wrote heaps of good stuff and then lost it. :P Well i thought it was good stuff.:lol:

Did you shoot in RAW or JPEG. If JPEG what size (L, M, S)

How did you download the image to the computer and what program did you open it with? Did you save changes when you closed it?

When you uploaded this sample was it a crop or full frame reduced? If a crop did you upsize it at all and if so what program did you use?

I know it's not possible but to me it looks like an out of focus dark frame. :P

[[1ponders]]

btw 1600 on the old 300D is pretty damn noisy at the best of times.

[batema]

I was shooting on New Years Eve on the Sunshine Coast and it was about 25c all evening.

Mark

[pmrid]

Bert. It's a capture from Nebulosity. I captured it as a 10 minute dark and the image captured was then saved as a JPEG.
To answer other questions:
1. the 300D doesn't have ICNR (sadly);
2. the image is full-frame - exactly as captured by Nebulosity;
3. it was saved as a L JPEG

I've just run off a series of 30 sec darks but without a DSUSB - just saved to camera and downloaded to comuter later and the image is pretty much as it should be. No Hubble Galaxy images or odd artifacts that I can see. I'll atach one of them. I also did a 3 minute sub (dark) and it isn't significantly different.
I'm beginning to wonder whether the artifacts wern't produced by the DSUSB. Anyone had any similar?

Peter

[pmrid]

Getting close to the culprit. In the previous post I uploaded an image stored in-camera rather than in-computer. Here is a dark take without a DSUSB via Nebulosity. It was a 400 ASA 30 sec Preview in Nebulosity that I saved as a JPEG. It is full image, not cropped. It displays the same artifacts as the ghastly ones I posted yeterday. So the DSUSB is not the culprit. It has something to do with the way the camara and Nebulosity are communicating, it would seem.
Peter

[[1ponders]]

Try doing the same thing using RAW Peter and see how it goes. Just as an experiment.

[pmrid]

Yep. Did that. The Nebulosity version (just on a USB connection with no DSUSB) at 400ASA is almost identif=cal to the ones I put up yeterday. The RAW taken through the native EOS utility shows a few bright blue spots bu none of the florid colours and artifacts of the other.
Peter

[Tandum]

When my DSI camera was doing this to me I got a sewing needle and carefully scratch cleaned the usb pins in the socket and tried to lift them a little to improve the connection. I don't know if that fixed my problem or not, but it hasn't happened again.

I'd hate to have to try that on one of those miniature usb sockets on a cannon camera. I guess I'd be using a can of contact cleaner there instead.

[bmitchell82]

I have to say that i have the same problem with Nebulosity 2.0, the Canon 40d should have reasonable darks, but sometimes its all over the show. though im running though a dodgy kinda usb hub. :D so there might lay the inherent problem.

Lose the hub get dedicated USB leads and be done with it...

[pmrid]

Here's a thought. I don't know the answer and it is entirely speculative but if I have ICNR on, and Nebulosity patiently waits for the internal dark frame to complete, what is it that it receives by way of image? Is it the exposure minus the dark or is it the exposure only? I can't put this down to dodgy cables or hubs because I've tried endless perms and coms with these things with no change. I took some frames last night and Nebulosity displayed them progressively and the background noiuse was terrible. But then it occurred to me that what it was showing was a FITS image unprocessed and maybe that's normal. The rubbish gets dumped in the stacking process? Perhaps??
Peter

[avandonk]

A Canon camera when in ICNR mode will subtract the 'dark' from the 'light' in camera at the raw pixel level. The resulting RAW and jpg is sent to where your little heart desires. I do not know what the problem is but a decent computer and USB 2 really helps.

Bert

[Glenhuon]

I have a similar setup, 300D and DSUSB and never had this sort of problem with it. I use DSLR Focus though and save the RAW's direct to PC. If you set it up that way it saves a RAW and a Jpeg for every exposure and gives you a chance to do a quick check of how it came out. As mentioned before I did have a similar problem with the DSI 1, it turned out to be a dodgy USB cable.

Nothing wrong with the 300D Avandonk, mine has given me some real nice pics even with my original old Dell and USB 1.1. May not have the bells and whistles of later models, but suits my purpose (and pocket).

Bill

[IvanTheTerrible]

If you think it might be a suss USB cable then you could try reading direct from the memory card.


Ian