Taking flats with a new Atik 314L+

[Black Knight]

I'm used to taking flats for a DSLR where it's pretty much a piece of cake to work out the correct saturation both because of the histogram on the Live View screen, and because APT displays a histogram of the most recently downloaded sub.

How do I go about ensuring that I have the right saturation level when I take flats using Artemis? What is the most straightforward/easiest process to use?

[Merlin66]

Good question!

There doesn't appear to be a histogram option under Artemis..

I use my ATiK314L under AA5.

[barkis]

A discussion here about the subject, not sure if it will help you though.

I had to paste the link into my browser to get to the page though.

Ron.

http://www.atik-cameras.com/forum/index.php?topic=232.0

[Black Knight]

I've just noticed in Nebulosity on the info line at the bottom of the window, it displays something like "57,867 = 12225.3". Where the first two numbers appear to be co-ordinates in the image, and the number after the equals sign appears to be saturation. Could I use that and aim for a value of around 20-30,000?

[Black Knight]

A discussion here about the subject, not sure if it will help you though.

I had to paste the link into my browser to get to the page though.

Ron.

http://www.atik-cameras.com/forum/index.php?topic=232.0

Thanks Ron, I'll take a look

[Black Knight]

I don't think it helped much beyond loading an image into paintshop pro or photoshop. Never mind, I'll keep looking

Sent from my mobile using Tapatalk, so please excuse the speeling and granma!

[Uranium235]

The way I do it is to first take one test shot at a length you think is right (depending on your filter). For instance, my SII filter took a whopping 8 seconds, but its a far smaller number for LRGB (less than about 0.5 seconds).

Next save it to your flats directory (usually a sub dir of the channel folder youre working on). Next load it into a program that will display the max and min (and preferably, average) levels in number format (Maxim DL does this very well). Youre looking for an average ADU level of about 20,000. The 314L+ being 16bit has a range of 0-65535 levels, so 20k is roughly one third.

Once youve figured out the correct sub length to get that 1/3, delete your test subs then you can proceed to do your run of flats. Keep the sub lengths for future reference - unless you change your setup, in which case you will have to do it again.

Hope that hepls

[rfdesigner]

I use Artimitis.

I just hover my mouse over the screen to get the pixel intensity in the bottom right hand corner. Then I can see roughly what sort of level I'm getting. Good enough for me on a flat or for guessing sky background in lights.

working out the right intensity is a one off job, there's no perfect answer but a value of around half scale seems to be adequate. I did sky flats recently and got a series of wildly varying levels from which I still managed to generate a satisfactory flat. (not perfect , but I only had a 1st order slope left to deal with)

Derek

[Black Knight]

I use Artimitis.

I just hover my mouse over the screen to get the pixel intensity in the bottom right hand corner. Then I can see roughly what sort of level I'm getting. Good enough for me on a flat or for guessing sky background in lights.

Ah, OK I didn't know you could do that! As you might have guessed, I'm a bit if an Artemis noob!

working out the right intensity is a one off job, there's no perfect answer but a value of around half scale seems to be adequate.

Derek

Sorry to be a pain Derek, but what do you mean by "half scale"?

[Black Knight]

The way I do it is to first take one test shot at a length you think is right (depending on your filter). For instance, my SII filter took a whopping 8 seconds, but its a far smaller number for LRGB (less than about 0.5 seconds).

Next save it to your flats directory (usually a sub dir of the channel folder youre working on). Next load it into a program that will display the max and min (and preferably, average) levels in number format (Maxim DL does this very well). Youre looking for an average ADU level of about 20,000. The 314L+ being 16bit has a range of 0-65535 levels, so 20k is roughly one third.

Once youve figured out the correct sub length to get that 1/3, delete your test subs then you can proceed to do your run of flats. Keep the sub lengths for future reference - unless you change your setup, in which case you will have to do it again.

Hope that hepls

Got it! I think ... :hello2:I don't have MaximDL, but maybe I can find a way to see this min/max/average info in Nebulosity or something else.

It's useful to see what your exposure times are. I'm sure mine'll be different, but at least it'll give me some idea what I should be expecting!

[Uranium235]

No problem

Oh, I forgot to add - those sub length times were based on me using a GN flatfield panel. Depending on the intensity of your flatfield source, those times may differ by +/-.

Rob

[swag72]

I use Maxim for my ADU figure, but the principle is the same. Interestingly, I go for an ADU of about 27-28k and they work fine for me.

[Black Knight]

No problem

Oh, I forgot to add - those sub length times were based on me using a GN flatfield panel. Depending on the intensity of your flatfield source, those times may differ by +/-.

Rob

At the moment I use the old laptop screen and T-shirt trick, which (mostly) works fine for my DSLR flats. Hopefully it'll still work with my Atik - at least, when I've got a decent workflow in place!

[Freddie]

In Neb, load your flat, click the view tab and then select pixel stats.

[Black Knight]

In Neb, load your flat, click the view tab and then select pixel stats.

OK, got it . Knew it had to be in there somewhere! Thanks everyone

[Davey-T]

Don't forget to match the binning, I did a new set recently and started with luminance then wasted ages doing RGB forgetting to reset binning to 2x2.

Davey-T

[Helen]

For those of you using Maxim then download the Sky Flats plugin http://winfij.homeip.net/maximdl/skyflats.html You just set it to the target value etc and it then iterates until it gets the level then takes the flats for you. Simple!

Helen

[AndyUK]

Hi Andy - I use an EL panel and pretty much follow Uranium's process. There's a slight difference of opinion re: flats ADU - I personally aim for c. 22K (65535/3), but I know of others who'll possibly go up to 30k... and recently saw a thread where it was mentioned taking 3 sets of flats at slightly different ADU's to then see which worked best.

As a guide, my 314L+ exposures with my Astrodon LRGB filters are as follows:

ED80: L = 0.027s, R = 0.14s, G = 0.08s, B = 0.049s

MN190: L = 0.046, R = 0.2, G = 0.11, B = 0.06s

[Black Knight]

Hi Andy - I use an EL panel and pretty much follow Uranium's process. There's a slight difference of opinion re: flats ADU - I personally aim for c. 22K (65535/3), but I know of others who'll possibly go up to 30k... and recently saw a thread where it was mentioned taking 3 sets of flats at slightly different ADU's to then see which worked best.

As a guide, my 314L+ exposures with my Astrodon LRGB filters are as follows:

ED80: L = 0.027s, R = 0.14s, G = 0.08s, B = 0.049s

MN190: L = 0.046, R = 0.2, G = 0.11, B = 0.06s

That's very useful Andy, thanks for taking the time to post those values, it's much appreciated.