Re: First attempt at starfields - Orion & Lovejoy

[MarkH]

OK that's not listed on my chart but yes the orange star is what I see and others as bright are listed so I make you right.

[Kenny]

You've started something now...

This was the following evening from Cudham. 28th Dec @ 23:13. Canon EOS 450D. 15 seconds at f/4.5, 18mm, ISO-1600. The green blob has moved.

[MarkH]

Oh yes so it has, you can see it quite clearly just above the trees. Surprising how carried away one can get. That other object on reflection anything that bright would have been catalogued long ago.

[MarkH]

How did the sky in cudham compare to otford ?

[Kenny]

How did the sky in cudham compare to otford ?

They are fairly comparable.

The problem with Cudham is trees all round the recreation ground so not the lowest horizon you could have. There's a really bright light in the pub carpark (facing away) to the north. And the recreation ground carpark has a motion-sensitive light that goes on when cars go by. It does feel like a safe site though. The light in the night sky is fairly even in every direction, possibly evenly coated by light pollution from London.

Otford recreation ground has much better horizons (I used this site for my ISS transit of the Moon) but it requires more of a trek from the carpark into the recreation ground to get away from the streetlights and carpark lights (particularly the lights outside the toilet). It doesn't feel safe there alone and I've seen boy racers mucking about with their cars in the carpark once. As you've seen from my photos, the light pollution n/nw from London is more obvious when facing that direction. It does have the advantage that there are very few streetlights and I've sometimes seen those switched off late at night.

p.s. both have excellent access to nice pubs.
p.p.s. I believe Flamsteed use Cudham.

[MarkS]

This was the following evening from Cudham. 28th Dec @ 23:13. Canon EOS 450D. 15 seconds at f/4.5, 18mm, ISO-1600. The green blob has moved.

It's definitely much clearer in that image.  It's the same night I imaged the comet next to M79.  Though M79 is probably too faint for your image.

Well done!  I really hope we get some clear sky for the January Deep Sky Camp.

Mark

[MarkS]

Here is your 28th Dec image, binned and brightened with the comet circled.



Mark

[MarkH]

Kenny pm me if you plan to go to otford as I live only a few minutes walk away and may be able to join you.

[Kenny]

I've split the topic. I've also managed to stack half a dozen of these images from the same evening using DSS. Will post here later.

[Kenny]

Ok. Reprocessed. 6 lights, 2 x darks / flats / bias in DSS. I wasn't sure whether DSS would be able to cope with foreground landscape - it's done not a bad job but you can see blurring of the trees.

I've annotated the JPG version to show the deep sky artefacts I think are visible.



Master file (unanottated) is here. Apart from the star distortion at the edges, particularly the top left, I'm quite pleased with this.

[Carole]

Great progress.

Carole

[Mike]

Well done Kenny.

[RobertM]

Great start Kenny.  There's lots of mileage in stacking short subs but noise is your enemy as you're finding out.

[Kenny]

Great start Kenny.  There's lots of mileage in stacking short subs but noise is your enemy as you're finding out.

Yeah. iSO-1600 is my enemy. It's a learning process. But my ISO-800 6xsub stack didn't show as much detail.

[MarkS]

Yeah. iSO-1600 is my enemy. It's a learning process. But my ISO-800 6xsub stack didn't show as much detail.

On the contrary, ISO 1600 is your friend.  At ISO 1600 the read noise on your 450D camera is less than it is at ISO 800.  This means that for shortish exposures a 6x sub stack at ISO 1600 will pull out more faint objects than a 6x sub stack at ISO 800 with the same exposure time.  If you are taking short exposures and want to extract as faint detail as possible, always ramp up the ISO to 1600 or 3200 unless you are trying to prevent saturation in the brighter parts of the image.