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Got some photos last night - well pleased!


Kaptain Klevtsov
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Well pleased with these - I usually only get one Pic every two days or so that I can keep.

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This is the Horsehead Nebula, almost got it, I can see it when I have it in a window next to a real image.

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This is Saturn below the Beehive cluster

For those who don't do DSLR imaging, the exciting thing is that you don't get to see what you got until you empty the camera into the computer and then mess about in Photoshop. This means lots of standing around in the cold wondering if the tracking went off, the focus went off, or the aim is wrong. Saturn is easier because you can actually see to aim and focus.

Kit was Nikon D50 DSLR with Sigma 400mm APO f/5.6 lens wide open on a home made mount.

If anybody enjoys these even half as much as me I'll be thrilled. Got to get me one of those telescope things soon! I can even see stuff in the Bresser 10x50 Binos that amaze me. I spent a lot of time when I was spotty making telescopes for astronomy out of old junk camera and microscope lenses and the penny has only just dropped that its not magnification of the image that you need, its more light as in bigger aperture, f stop, call it what you will.

Hope you like

Jonathan

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The horsey one was 4 30 second exposures at iso 1600, the Saturn one was 5 seconds, also at iso1600.

WRT amp glow, I was playing at dark frames at 1600, a 30 second exposure looked completely black. In Photoshop I had to go into levels and move the white slider to 26 before anything showed at all. Even at 16 there were only a few speckles.

Amp glow is the bane of DSLR long exposure imaging, it is caused by the amplifier for the analogue to digital converters heating the CCD unevenly. This shows up as noise in the image where false photons are captured because of the heat. Real CCDs for astrophotography are cooled to prevent this from happening (the coolness is expensive so the more cool, the better image, the more cost).

To reduce amp glow on webcams modified for astro use I've read that the amplifier is moved away from the CCD chip for this reason.

HTH

Capt. Chaos

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... Sigma 400mm APO f/5.6 lens wide open

Congratulations Jonathon and thanks for sharing :lol:

(If a lens is stopped down, even by one stop, the optical quality improves - noticeably. The optimum aperture is about 2-3 stops down from the minimum aperture; on most lenses that puts you at about f8; not ideal for astro imaging because of the need for longer exposures but worth knowing nonetheless)

Steve

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