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First M51 with cooled 1100D

Gina

By Gina
in Imaging - Deep Sky

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Gina

Gina

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Just 17 lights and 3 darks of 300s at ISO 800 and EXIF T of -7C.

I don't think this is as good as my last attempt at M51 maybe due to fewer subs, poorer conditions or possibly condensation - I did let the sensor temperature get lower than I had intended. And when I packed up there was dew everywhere plus lots of frost on the exposed part of the cold finger.

The background seems rather light and I'm wondering if it's light pollution showing now that I've reduced the noise.

A couple of JPEG images :-

  1. The result of stacking in DSS with the usual adjustments, converted to JPEG and scaled for here.
  2. The above image with stretching and saturation increased plus cropped to a third in x and y and then scaled in GIMP.

M51_2012-04-19_23-50-47_ISO800_300s_-7C_1.jpg

M51_2012-04-19_23-50-47_ISO800_300s_-7C_1a.jpg

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badgers

badgers

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Hi Gina,

Lovely image and with only 3 darks I guess the cooling is really helping on noise levels.

The background will drop away if you tweak the levels a tad more. I think you've gone slightly conservative on the RGB levels.

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ncjunk

ncjunk

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i´d check for dew problems and misting up somewhere in the imaging path if the background lighter than expected. I´ve had similar results to this where the window in front of the ccd was misting. with mine you could see it spread across the pictures over the course of the series of exposures.

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Gina

Gina

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Looks like condensation somewhere between the sensor snd the optics. The giveaway is the halo around the brighter stars.
I thought it might be. Next time I'll reduce the cooling.
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Spikey

Spikey

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I thought it might be. Next time I'll reduce the cooling.

It's all time consuming trial and error Gina. When we have precious little clear nights it always seems a shame to waste an evening tweaking kit but it will pay huge dividends in the long run.

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Quatermass

Quatermass

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Only 3 darks for this one you say.. if that is so then more darks for sure but that water cooling device is amazing when summer comes along that is really going to help things. Conditions are dire at the moment so much rain and wind about here in suffolk its wet and windy for the rest of the week as well.

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Gina

Gina

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Only 3 darks for this one you say.. if that is so then more darks for sure but that water cooling device is amazing when summer comes along that is really going to help things. Conditions are dire at the moment so much rain and wind about here in suffolk its wet and windy for the rest of the week as well.
I think we might just get a clear night tonight :) Yes, more darks for sure and I'll run the sensor at a higher temperature - that was rather too cold last night I think. I'll check carefully for condensation. The atmosphere has been very clear today after the rain so hopefully should be good tonight. Yes, I'm very pleased with the water cooling system - really effective and light weight on the camera :rolleyes:
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Chris

Chris

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Wow Gina your doing the cold finger thing now:) I can only imagine what your kit will be like in a few of years if you keep on going at this rate:D Once you've solved the dew issues I recken you'll be well on your way!

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Gina

Gina

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Running at -3C tonight and it seems alright. Here's a JPEG scaled for here. Just a single sub of 5 mins at ISO 800. No processing of any sort other than scaling the full frame to 1024 wide.

post-25795-133877765833_thumb.jpg

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Gina

Gina

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My coma corrector dews up very easily with the cold from my cooled DSLR and I'm only getting EXIF temps of -2C to +2C. I always run a dew heater tape wrapped around the focuser and don't have problems any more.

Cheers,

Ian

Do you cool your whole camera or just the sensor? I definitely seem to have had condensation last night at -7C but it seem fine tonight at -3C. I was going to set the temperature on freezing but it seems OK at -3 so sobeit. I'm running the TEC on just 4v (-33% of full voltage).
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Gina

Gina

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Wow Gina your doing the cold finger thing now:) I can only imagine what your kit will be like in a few of years if you keep on going at this rate:D Once you've solved the dew issues I recken you'll be well on your way!
Thank you :) So far so good this evening on the dew front :rolleyes: I think tonight's subs are best yet :eek:
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Chris

Chris

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I agree, that single 5 minute sub looks nice as an image in its own right! :)

Oh know Gina, if you can't get guiding up and running you could switch to 120 sec subs unguided and stack them in a seperate tab in DSS with their own flats and darks maybe?

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