Jupiter 5 Nov 2012

[MarkS]

My first Jupiter of the season - an equipment test, really.

DBK 21 camera on Celestron C11 and 2x barlow at 15 frames/sec.  
This is 800 frames stacked in Registax and deconvolved with a Gaussian of 5 pixel radius (which indicates that the seeing was not that good, though not terrible).  Taken around 10:30pm.



If you want to see what it should really look like - see Chris Go's version of last night 4 Nov:
http://jupiter.cstoneind.com/

And he caught Io!

Mark

[MarkS]

In all, I recorded 3 hours of video.

The seeing improved a bit later to allow me to produce this:



This was 1000 frames in Registax and deconvolved with a 3.5 radius gaussian.  I need to play around a bit more to remove the ringing artifacts near the edge.  I think I need to restack this in Avistack.  But as an equipment test, I'm pretty happy.

Mark

[julian]

Very good Mark, all you need now is Io. 

[The Thing]

Looking good Mark, the Jupiter season is well underway now!

Does the DMK let you know what exposure length you are using? From recent ecotone when seeing is not so good shorter exposures work wonders even though gain has to be set higher and the image may look too dim.

[Ivor]

Good effort, I can only admire your commitment at 01:30 last night to be processing as well as capturing. I received the warth of my wife last night as I left the rig out and got up twice to check it.

[MarkS]

Does the DMK let you know what exposure length you are using? From recent ecotone when seeing is not so good shorter exposures work wonders even though gain has to be set higher and the image may look too dim.

Ecotone?

No, neither the SPC900 or the DBK (nor the Canon 600D for that matter) seem to give the actual exposure time.  It's clearly faster than the frame rate but by how much, I don't know.  I have a suspicion that at a given frame rate, the DBK is taking shorter exposures than the SPC900 - I just need to think of a way of testing this - maybe point it at a spinning disc and measure the blur length.

Mark

[mickw]

Rather than spinning disk, couldn't you use a spreadsheet to sequentially flash coloured bars ?
Sorry, I know how much you hate maths 

Nice Jupiter by the way

[MarkS]

Rather than spinning disk, couldn't you use a spreadsheet to sequentially flash coloured bars ?

No - we are talking about pretty short exposures here - probably similar to the refresh rate of a screen.

[mickw]

Oops - forgot about refresh rate 

[MarkS]

I received the warth of my wife last night as I left the rig out and got up twice to check it.

At least you were at home, out in the garden.  Other husbands might be down the pub or getting up to all kinds of other things!

[Carole]

I received the warth of my wife last night as I left the rig out and got up twice to check it.

When I am imaging I stay on the settee to sleep so I don't disturb my husband by keep getting up.  He's happy that I do that rather than disturb him, I think he'd go mad if I kept getting up from our double bed.  Also I have to set my mobile to wake me up at intervals, otherwise I might sleep right through and that wouldn't go down well at all !!

Carole

[The Thing]

Ecotone?

Ecotone is a smelling inspection of the Android Swype variety!

[The Thing]

In Sharpcap the exposure time (and everything else) is given in raw units as understood by the camera. The Phillips camera control dialogue translates this into the right value, however this varies with frame rate! See section 4. Shutter speed tests on this page.

WcCtrl is a better bet if you want to set the shutter speed of the SPC900 to a known value, it can be run at the same time as SharpCap and used instead of SharpCaps controls. In WcCtrl Options you can opt to see raw units or not...

[MarkS]

As a point of interest, the meteoblue and skippy sky seeing forecasts were pretty accurate - indicating good seeing (which is why I ventured outside).  The 7timer seeing forecast was rubbish - it indicated really bad seeing conditions.

[Carole]

Very nice Jupiter Mark, seeing a lot more detail.

Carole

[MarkS]

The trick was to put a white paper disk with a thick black line drawn on it on the end of a slow running drill.

Anyway, the upshot was that using VirtualDub with the SPC900 and setting the shutter speed to its slowest setting then at 15fps the exposure time is actually 1/15sec - verified by recording the spinning disc.

For the DBK21AU04 with ICCapture it is important to manually set the exposure time and not let it go to auto.  Doing this it is possible to set an exposure of 1/15sec at 15fps and 1/30sec at 30fps - again verified by recording the spinning disc.

Unfortunately, when I took this Jupiter image, I had the exposure set to auto (I know this because I deliverately saved the configuration to use next time), so I've no idea what exposure speed it actually selected.  

Mark

[MarkS]

Here's another from slightly later that night:



1000 frames stacked in AutoStakkert.  It's my first attempt with AutoStakkert (I can't yet bring myself to use that awful exclamation mark in the name) - it certainly seems to be easier (and faster!) to get a good result in AutoStakkert.  I'll probably use it in preference to Registax and Avistack from now on.  It's a bit quirky to use though - best to use the Jerry Lodriguss tutorial:
http://www.astrokraai.nl/software/manual/as2_planet.html

I imported the TIF into Registax for the post stack processing (RGB alignment and wavelets).

Mark