Saturn 24 April

EricB (Eric) · #1 25-04-2013, 07:03 PM

Hi there!

I had a small window of decent seeing last night before the clouds rolled in.

I had a quiick go at Saturn and the Moon. Here is Saturn.

and some of the specs:

Frames captured=1000
Camera=ASI120MM Camera (ZWO Design)
ROI=352x288
FPS=71
Shutter=14.28ms
Brightness=10
Gain=43
Gamma=51
Histogramm=43%

Cheers,

Eric

Larryp (Laurie) · #2 25-04-2013, 08:51 PM

Nice image, Eric. Very sharp

allan gould · #3 26-04-2013, 10:14 AM

Nice catch Eric. I guess you love the camera. Are you using a Barlow?
Allan

EricB (Eric) · #4 26-04-2013, 12:45 PM

Thanks Laurie and Allan.

Allan, yes, I love the camera. I am using a x2.5 Powemate.

Cheers,

Eric

U.K.Cowboy (Stuart) · #5 26-04-2013, 09:08 PM

Nice Saturn Eric. I'm correct in thinking the 2.5x powermate is parfocal therefore an extension tube wont work?

EricB (Eric) · #6 26-04-2013, 10:26 PM

Thanks Stuart. As to your question, I am not quite sure as I have never tried to add an extension tube. Others will know, not doubt.

Cheers,

Eric

Quark (Trevor) · #7 26-04-2013, 10:35 PM

Nice crisp image there Eric, a bit more magnification would be good, might be worth having ago at using the 1.5 or 3x drizzle in AS.

Cheers
Trevor

Troy · #8 27-04-2013, 08:35 AM

Sharp little Saturn there, good image Eric

EricB (Eric) · #9 28-04-2013, 09:32 AM

Thanks Troy and Trevor.

Trevor, I agree, but the seeing conditions haven't yet allowed me to use the x5 powermate. I have tried a quick 1.5 drizzle in AS, as you have suggested, but I lose detail in the belts (see picture).

Cheers,

Eric

Shiraz (Ray) · #10 28-04-2013, 10:08 AM

very nice Eric - good detail and processing.

hope you don't mind me answering Stuart: the Powermate is telecentric, so magnification does not change appreciably with an extension tube. the optimum for the ASI120 in good seeing is f19 final focal ratio.

EricB (Eric) · #11 28-04-2013, 10:36 AM

Thanks Ray. i was hoping someone would answer Stuart's question.

A quick (and probably silly question). Focal ratio is easily calculated, but what about when a camera is rigged? How is the camera taken into account in the focal ratio calculation?

Cheers,

Eric

Shiraz (Ray) · #12 28-04-2013, 10:42 AM

turns out to be very straightforward for any system Eric.
http://www.iceinspace.com.au/forum/s...d.php?t=105057

regards Ray

EricB (Eric) · #13 28-04-2013, 01:57 PM

Thanks Ray. Very interesting stuff.

In fact I meant focal length by the way, not focal ratio. For example, in my case here, with the AI120 I am imaging at a focal length of 1200 x 2.5 (powermate) = 3000. Is that correct?

Cheers,

Eric

Shiraz (Ray) · #14 28-04-2013, 02:01 PM

yep.

However, the optimum FL will vary with aperture for a given camera, so it's best to use FNo.

EricB (Eric) · #15 28-04-2013, 05:55 PM

Got it. Thanks Ray.

Eric

U.K.Cowboy (Stuart) · #16 28-04-2013, 08:26 PM

Quote:

Originally Posted by EricB

Thanks Ray. i was hoping someone would answer Stuart's question.

A quick (and probably silly). Focal ratio is easily calculated, but what about when a camera is rigged? How is the camera taken into account in the focal ratio calculation?

Cheers,

Eric

The 2.5x powermate actually reduces slightly in magnification with an extension :
http://www.televue.com/engine/TV3b_p...id=53&Tab=_app

EricB (Eric) · #17 29-04-2013, 09:00 PM

Thanks Stuart.

eric