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Old 10-06-2009, 08:28 AM
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pmrid (Peter)
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Darks yes, but this??

Can this be right? Here is a 10 minute dark. It looks like Surfers Paradise on New Years Eve. Is this normal?
Peter
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Old 10-06-2009, 08:32 AM
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iceman (Mike)
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That's pretty nasty.

Camera and settings?
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Old 10-06-2009, 08:52 AM
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sheeny (Al)
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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.

Last edited by sheeny; 10-06-2009 at 08:53 AM. Reason: afterthought
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Old 10-06-2009, 11:18 AM
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Wow that is extremely odd, have never seen that before, and really cant give an opinion on that one.

Leon
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Old 10-06-2009, 11:46 AM
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Tandum (Robin)
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I've had similar images from my DSI camera when the usb cable had a poor connection.
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Old 10-06-2009, 03:23 PM
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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
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Old 10-06-2009, 03:34 PM
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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.
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Old 10-06-2009, 03:52 PM
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Quote:
Originally Posted by Gama View Post
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.
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.
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Old 10-06-2009, 04:21 PM
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Keep us posted.

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

Al.
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Old 10-06-2009, 04:34 PM
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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
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Old 10-06-2009, 05:00 PM
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Is that a crop or full frame? If crop what program to do the crop and was it then upsize
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Old 10-06-2009, 05:45 PM
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Stupid question maybe... but check if you have ICNR on.
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Old 10-06-2009, 05:56 PM
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Damn wrote heaps of good stuff and then lost it. Well i thought it was good stuff.

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.
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Old 10-06-2009, 05:57 PM
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btw 1600 on the old 300D is pretty damn noisy at the best of times.
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Old 10-06-2009, 06:03 PM
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I was shooting on New Years Eve on the Sunshine Coast and it was about 25c all evening.

Mark
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Old 10-06-2009, 08:19 PM
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Quote:
Originally Posted by avandonk View Post
Peter is it a jpg straight out of the camera or a processed RAW?
Bert
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
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Old 11-06-2009, 01:53 AM
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Nebulosity Mystery

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
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Old 11-06-2009, 05:50 AM
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Try doing the same thing using RAW Peter and see how it goes. Just as an experiment.
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Old 11-06-2009, 07:27 AM
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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
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Old 11-06-2009, 02:17 PM
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Tandum (Robin)
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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.
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