Last night I spent 2 hours collecting Ha photons from Eta Carina. Mount was guiding well using my new converted finderscope/guiding scope but there was a problem with the image download leaving artefacts in every sub and dark frame (see 100% crop). I think the culprit was using an external USB Hard drive for storing the downloads with my EeePC 701 - also the first (and last) time I've used an ext HD in the imaging process.
Last edited by telemarker; 03-03-2010 at 01:31 PM.
That looks like a readout problem. Basically the image download stream is interrupted. Save on local then transfer to your remote drive later. Real shame coz the image is gorgeous.
Thanks for the commiserations guys. It was one of those Grrrr moments when I saw what had happenned to the subs. But I'm satisfied with the way the new guidescope works and the way the mount is tracking, so all is not lost. This was a fill in while waiting for the primary target to rise but cloud put paid to imaging that (luckily really ). Time yet for another crack at it once all these clouds nick off.
Hi Keith,
congrats with your guiding, looks as though it's working well.
As Peter pointed out, your focus is off though. Your small stars in the cropped version haven't resolved to solid points of light.
I use to wait till my optics were well cool and spend at least a further half an hour checking focus in a binned mode to get my FWHM's to the lowest possible number then eye ball a full test image, magnifying to see if things were good.
All these little things will become second nature.
It's all fun!
Thanks Peter, Rich. I see what you mean. I guess that is one of the problems with using a 7" EeePc screen for setup and capture. I might have to look at an electric focuser (already have a FCUSB I use with my SCT/Meade Zero shift focuser) for the refractor. Any suggestions that don't cost an arm or a leg that I can use with FocusMax?
Any suggestions that don't cost an arm or a leg that I can use with FocusMax?
Here's a cheap way to go and similar to what I did... not exactly though. You'll have to make some sort of a bracket to attach to your scope and couple to focusers shaft. With the below motor, looks as though you might need to remove the connector and retro fit to the FCUSB controller.
You will have to load the ascom driver that goes with the shoestring usb focus unit (FCUSB) then you'll be able to use Focus Max.. works a treat..
THe read out issue could be to do with the USB download speed too... I had similar problems when using that camera on high speed download mode...
Using a tiny screen shouldn't affect your focus accuracy if you use the information on the screen - use FWHM or HFD values to focus rather than how the stars look on the screen..
THe read out issue could be to do with the USB download speed too... I had similar problems when using that camera on high speed download mode...
Using a tiny screen shouldn't affect your focus accuracy if you use the information on the screen - use FWHM or HFD values to focus rather than how the stars look on the screen..
Thanks Alex, I did better this time around:
1 - no external hard disk
2 - put more effort into improving the focus
3 - checked the download speed
4 - threw money at the problem (bought a motorised focuser, yet to arrive)
Heres the new and improved image. 2 hours Ha with 10 min subs, curves levels, greyscale, 30% darken blend with wavelet sharpen.
Hells bells another Eta...... new and improved
). Time yet for another crack at it once all these clouds nick off.
