Gina

Single 30s Ha sub of IC1396. Histogram stretched and resized.

Capturing 30s Ha subs of IC1396

Nearly finished the Cygnus Loop IC1396 next I think.

Here's the first SII sub histogram stretched in Ps, resized and saved as PNG as usual.

Now have the first OIII sub to show. Changed from FITS to TIFF and then histogram stretched in Ps, resized and saved in PNG format.

I won't have any OIII subs to analyse until I've finished transferring all the Ha subs from obsy laptop to desktop PC and that will be over an hour. I'm capturing umpteen gigabytes of data with this new camera! Data collection is running at nearly 64MB a minute. That's over 3GB an hour Yes, it is that much. Each frame is 32MB and I'm capturing 2 frames a minute (nearly). Each frame takes a few seconds to transfer from camera to HD. Probably running at about 60MB a minute then or 3600MB/hr! I shall be capturing 100 OIII subs to get 50 stacked and that is 3200MB = 3.2GB. Just over half way ATM - should be finished by 11pm then I shall change filter to SII and grab a hundred of those. After that I shall go to a different DSO if it's still clear. I could be up all night - I haven't got this process automated yet as I need to be on hand to move GBs of data about. Plus focus needs changing between filter wheels and that's manual currently. I'm hoping I can get things more automatic once I get the RPi/Linux system worked out.

Have captured another 50 Ha 30s subs of the Cygnus Loop and now changed to OIII filter and taking 100 subs. The preview looks alright Refocussed for the new filter. Count for Ha was -3 and now for OIII is 31. The remote focuser is working fine - using SharpCap for focussing with zoom at 200% so that I can see individual pixels and I can get the focus to about 1-2 pixels. The focussing resolution is adequate after all - I had thought it needed to be a bit finer but it's just alright. The focus was changing slightly due to the seeing and this was around 2 counts.

Amazing what you can do with rubbish I have such a lot to be thankful to Blue Peter for I was going to 3D print one but then I had a thought...

The dew shield is a nice push fit on the lens

I used to live in Farlington

Here are a couple of photos of the dew shield. BTW in resizing these images I noticed that the DSLR has fewer pixels than the ASI1600MM-Cool sensor!

OK... Waggled USB connector and got connected. Laptop lost its pointer though so another reboot Now have pointer back and connections to both FW and focuser and both working. Phew! Just hope they stay working until dark!

H-beta is a sort of pink colour and one quarter the strength of H-alpha and yes, it's produced by the same gas as H-alpha so adds nothing. I think that's right As for other wavelengths, there are thousands of stars in the Milky Way so any DSO in this region will be swamped by the stars. An Ha filter will block most of the light from stars making them much weaker in the image and allowing you to increase exposure until the emissions from the hot gasses show up. Yes, the moon and earth borne light pollution also add to the background unwanted light.

Been trying again. Got FW showing in DM with a ? "No Driver Installed" so I reinstalled the driver and Artemis Capture now recognises the FW. A little later... Tried changing filters and it works Hooray - one problem solved - next is the focuser. I often get problems with the USB connection on this. It's an Arduino Nano with a mini USB connector and these are notoriously troublesome! I'll go out and waggle it...

I've made a Blue Peter style dew shield using an empty plastic bottle (contained peanut butter) with the ends cut off and sticky backed plastic in the form of flocking paper from FLO, to line it with and prevent reflections. I'm hoping that will be enough. I've checked that there isn't any vignetting of the view across to the next hill. If I still get dew problems I'll have to add a heater. The filter wheel problem is USB connection woes. I've tried rebooting the laptop to no avail - neither the FW nor my focussing system are showing in the Device Manager The focuser was working last night, the FW wasn't, now it's neither!!! The camera is working and the mount is working though from another laptop port. FW and focuser run off the USB hub in the camera. Strange thing is that the laptop beeps when these are connected but they don't show in DM.

I think I need to look into the DSS settings further - it's a complicated beastie with lots of settings, many of which I don't understand - must read some more tutorials on it! I haven't done any other imaging but Ha so far with this camera though I did set the FW to the Luminance filter to try and find a DSO I was hunting (without success). Yes, the NB filters reduce the general light enormously - which is their function - only letting through light of a certain wavelength and a little bit either side. The amount of the unwanted light either side of the wanted wavelength depends on the bandwidth. The narrower the less unwanted light comes through. Unfortunately, the production costs rocket as the bandwidth decreases eg. a 3nm Astrodon Ha filter costs 4 or 5 times the price of a 7nm Baader one. Both firms make excellent quality filters but narrow costs more. To answer your specific point, a red filter will let about the same amount of Hydrogen alpha light through as a narrow band one but the red filter also lets a lot of red light of other wavelengths through. So hydrogen gas emissions tend to get lost is other light wavelengths. RGB filters come in for galaxies mainly which have a wide spectrum of light. Nebulae consist of clouds of gasses, mainly hydrogen but also oxygen and sulphur (I don't like the newer American spelling of sulfur! Nor does my English spell checker). These gases emit light of several discrete wavelengths and have been labelled hydrogen alpha and beta - oxygen I, II and III etc. Don't know if there are other wavelengths for H and O. The usual wavelengths used for narrowband imaging are Ha, OIII and SII though there are other wavelength emissions they are weaker and less used.

This may be alright when I get faster broadband in a few months but 5m to upload and over 2m to download the full size image is not good. But it does seem to work and the full size image may be good for others to view. I didn't have this "problem" with the Atik 460EX because the frame size is much smaller. These large sensors with huge megapixel numbers are in a whole different ball-park! Wonderful! The new ZWO CMOS cameras are fantastic! - to the point where I'm wondering if I will ever use the 460EXs again. But I am preparing myself for a fall - can this really be? Can these CMOS cameras really beat CCD hands down?? I think it's blown my mind!

I'm going to try something - what happens if I try uploading the full size image of 4656×3520 pixels... Please wait - uploading will take a long time with such a poor internet connection... 1m 2m 3m 4m 5m ... Ah here it is

35 of 71 subs stacked in DSS (it's still choosing about half the total), rotated 180° to put it the usual way up and histogram stretched in Photoshop. Reduced in size and saved in PNG format for upload here. No other processing as yet.

A couple of hours of clear sky last night and I managed about 70 x 30s Ha subs on the NAN & Pelican. I was going to change to OIII but Artemis Capture couldn't find the filter wheel, just when I wanted it. It was working... So that's something to sort out. As I had already captured a fair number of Ha subs on the Cygnus Loop I decided to find another DSO to grab in Ha. Having looked up the positions of several and found them in CdC I decided on IC1396 in Cepheus, a large nebula which includes the Elephant Trunk, as all the others were too low down. After slewing to it with CdC, all I could see was a misty disc with a bright star on the edge. Yes, this was it but... I checked the lens and it was misted up. Very heavy dew Cleaned that and still misty - thin high cloud had rolled in Gave it half an hour but no joy so I packed up for the night. Tonight looks more promising from the forecast but I think dew could still be a problem so I shall be sorting out a dew shield and maybe dew heater for the lens. I also hope to find out what's the matter with the filter wheel. Yes, it was connected to power and USB just as before. Meanwhile I have a nice crop of Ha subs to process. I'll be back soon with the results...

Thanks Dave Several members have said the improvement with the 3nm filter is considerable and well worth the extra cost so I'm hopeful and much looking forward to trying it

Thank you very much Stu Yes it's really great to be imaging again after so long. Have to say I'm very impressed by the new ZWO ASI1600MM-Cool CMOS camera. Also by the quality of the Asahi Super Takumar 135mm f2.5 lens even at full aperture. The large image sensor with 16Mpx is much bigger than I've used before, other than DSLR. It gives me much more scope to cover a wider view of the DSO I'm imaging and crop it without losing too much resolution. And it's equivalent to mosaics on the larger ones. Have to say, I'm really enjoying this combination This is only the start and the first night for a couple of years that I've had a really decent clear night sky. I plan to go on to add OIII and SII to the images and process to Hubble Pallet. There are also a huge number of DSOs to go for. I have ordered the Astrodon 3nm Ha filter in 1.25" size from Ian King Imaging. Though the 5nm seems to be doing quite well ATM the 3nm will be a benefit when the moon's out and probably also for fainter DSOs. I might need to increase the exposure for these but so far 30s subs seem to be doing pretty well and don't need guiding.

Here is what I captured of the North American and Pelican Nebulae, again 30s Ha exposures. Run through DSS which chose 4 of 8 subs then in Photoshop, cropped and histogram stretched only followed by resize to 1200 px wide and saved in PNG format.

Ran subs through DSS and after several goes at fiddling with the settings eventually got it to stack 26 lights out of 53 without darks because the darks I had were different exposure. These lights are 30s with Ha 5mn Astrodon filter - 135mm lens f2.5 at full aperture and ASI1600MM-Cool camera at -23°C. Processed in Photoshop:- Rotated and cropped to include just the Cygnus Loop. Histogram stretched (actually I think I've squashed the whites), Enhanced DSO & Reduced Stars then Space Noise Reduction. Resized to fit upload frame max size of 1200 px (about 50%) and saved in PNG format.

Thank you I'm using it at full aperture - it doesn't seem to be showing any aberrations - these are superb lenses