Orion Nebula M42 80x10s 13.3min 9xDark
Flame Nebula 135x10s 22.5min No Dark
Moon 747 Stacked Frames in Registax
Equipment lists:
Celestron C6 SGT/SCT
Nexstar SLT Mount
Hyperstar Lens FL290mm f1.9
Baader Neodymium Filter
SPC900NC LX/Amp off
Stacked with DSS
It was a very clear night but very cold as well. The moon was 90% illuminated as shown above. The hyperstar collimation was brought to the default position; screwed down all the way back. It seems to be rather acceptably collimated with the default. The moon looks good. The starts in the nebulae photos looks okay as well.
There seems to a problem with the dark frame calibration this time. A total of 29 dark frames from a group of 9 and 20 frames were taken but if all of them were used for calibration, vertical streak would appear on the images. So, only 9 dark frames were used for calibration on Orion Nebula while none for Flame Nebula. Some forum suggested that the streaky image is a result of mismatch dark frames, i.e different temperature between the light and dark frames. This is very much possible as light/dark frame are taken at different time, sometimes at 20-30 minutes apart. Some suggested not to use dark frame. Even without calibration using dark frame, there seems not that much noise after all except for one or two visible hot pixels. The frame capture sequence is as follow, Orion, Dark 9, Orion, Dark 20, Flame.
It was a very clear night but very cold as well. The moon was 90% illuminated as shown above. The hyperstar collimation was brought to the default position; screwed down all the way back. It seems to be rather acceptably collimated with the default. The moon looks good. The starts in the nebulae photos looks okay as well.
There seems to a problem with the dark frame calibration this time. A total of 29 dark frames from a group of 9 and 20 frames were taken but if all of them were used for calibration, vertical streak would appear on the images. So, only 9 dark frames were used for calibration on Orion Nebula while none for Flame Nebula. Some forum suggested that the streaky image is a result of mismatch dark frames, i.e different temperature between the light and dark frames. This is very much possible as light/dark frame are taken at different time, sometimes at 20-30 minutes apart. Some suggested not to use dark frame. Even without calibration using dark frame, there seems not that much noise after all except for one or two visible hot pixels. The frame capture sequence is as follow, Orion, Dark 9, Orion, Dark 20, Flame.
Nice photos. All these taken with the SPC900NC LX plus Amp off mod? Are you using the original ICX098BQ CCD? I have a SPC900NC LX. Thinking of doing the Amp off and later CCD swap to ICX098BL or ICX618ALA. Did you do all the mod yourself? Would you mind sharing with me how you did the Amp off mod?
ReplyDeleteHave a nice day & clear skies.
Charles
Replied.
DeleteHello Charles. Yes, all these were taken using the SPC900NC with LX and Amp off mod. I'm not sure what's the model number of the CCD, but it is the original CCD. I guess I don't have the courage to do CCD replacement which look a bit complicated. I did the LX and Amp off mod myself. I replaced the housing, and put together serial-to-usb converter as well as USB hub in the housing. So all connections are through one USB cable. There is even two unused USB ports which I used oen of them to connect my Arduino motor focuser for the telescope. The mod for LX and Amp off can be found at at the link below. The Amp off mod used in the tutorial might be best method, but it is sufficient to my need with relatively short exposure. Hope that help.
ReplyDeletehttp://www.yesyes.info/index.php/how-tos/modding-an-spc880-900-webcam-for-long-exposure/
Hi TengkuFaiz, I am glad to know that that mod is workable. I have found that link earlier but was skeptical about the effectiveness of the amp-off method which doesn't show any need for cutting a lead on the CCD itself unlike the SC2 mod. Have you tested the effectiveness of the amp-off on your camera? I understand that an 11 Volt Zener Diode is placed between the base of Q3 and a transistor. I couldn't find a more specific mention about this diode. What is the part number of the diode you used? Your creative use of the usb hub is inspirational. I have yet to think about motorized focuser. I would be delighted if you would also share with me on that. You have been very helpful. Thank you.
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