Quick attempt at Pleiades

[Peter Reader]

Hi all,

Took 5x40s exposures of Pleiades as I was packing my equipment up for the night and managed to get this:

The first process is natural and nicer to look at I think -I love the colour of the young blue stars:

The second process was to see if I'd got any nebulosity -which I think I did

Comments welcome

[Psychobilly]

Are you taking Darks Peter..?

They will help a lot...

More subs will really drop the noise and give you more nebulosity...

Peter...

[Digz]

Definitely take darks. If your D80 is anything like my D200 (and it looks like it is) they will definitely help with the ampglow and noise.

Having said that a great attempt, just bag more subs.

[Peter Reader]

Yeah I will definitely try this again properly. This was literally an off the cuff point and shoot attempt out of curiosity.

Darks are the same exposure and ISO as the pictures taken after the imaging session at the same temperature with the lens cap on yes?

Thanks for the replies!

[Luke]

For me you can definitely see some really encouraging nebulosity in the second shot, from my admittedly limited experience, another vote for more exposures if you can, to drop the noise down and at the same time bring out more detail in the nebulosity. Hope you get a chance to do some more imaging on this jewel in the sky.

Have you seen this lovely animation showing what more subs can do to bring noise down? (click on the link right near the bottom, "This image"):

pic and description page

Apologies if you already know about more subs for less noise.

[Psychobilly]

Darks are the same exposure and ISO as the pictures taken after the imaging session at the same temperature with the lens cap on yes?

QUOTE]

yep thats it...

I would also do an experiment to see how many subs it takes the ampglow to stabilise...

When I was using a D200 it would take up to 10-16 mins before the ampglow stop changing.. that was with 2 min exposures.. and I found that if i left 1min between them then the glow would stay pretty constant meaning the darks would be fairly well matched...

If your taking shorter exposure maybe the best way is to leave the in camera long exposure noise reduction on.. this will halve the number of lights you get but you wont need to take darks and each frame will have had a well matched dark automatically subtracted..

For longer exposures I would shoot darks every couple of lights with the In camera long exposure noise reduction off

Peter...

[Peter Reader]

OK I understand. However what do you class as long and short exposures? I personally think that my 40s exposures are pretty damn long but when I compare them to 10 minutes that some people with guiders can do they're minuscule.

Luke: I can't believe how much better the image gets with a stack of 30. Thanks for the insight!

[Rossco72]

It can be a right pain at times, but flats, bias and dark frames really do make a difference when you calibrate and stack in processing.

Good start though, keep up the good work!

[Psychobilly]

Hi Peter...

it's all down to your experiences with your own camera...

It's nearly always better to get more lights as thet contain the "signal" as well as the noise ...

The more lights you get and combine the lower the noise will be...

But if the ampglow isn't stable between frames (and my D200 definitely wasn't for the first 10-25 mins or more depending on the ambient temp) then your probably better of letting the camera take "auto darks" by using the in camera long exposure noise reduction for the first 20-30 mins at least...

Peter...

[Peter Reader]

Damn. Just read this. Scope is outside imaging as I type but not set to noise reduction mode... Will post my result of what I get when processing is done. Should be the Horsehead and Flame... But I centred the shot on Alnitak so may only get the flame now that I look at stellarium...

Thanks for the encouragement and knowledge!