fwm891

Good session last night, sheltered from the wind I continued my current fasination with IFN's in Ursa Major. This image captured last night (5th - 6th April 2021) comprises 40x 300s subs and processed in PI using luminance masks. Scope: RASA 8, Mount iOptron CEM60, Camera ASI533, Filter Baader UV/IR cut Software: capture SG Pro, image PI. Hope you like

Hi Goran - I'm under Bortle 4 skies. I keep forgetting to flip images from the RASA. Your IFN image containing M81-M82, have you dropped in another image of 81/82 onto your IFN image to retain the details?

Like that Adrian. Good luck with the RC

Mmmm, In P.I. I tend to stack each of the panes first,, use STF and Histogram Transform. Then SCNR to remove the green. DBE comes next to even out the backgrounds (pull the DBE process to the desktop and apply to each pane for consistancy). I then save as 16 bit tiffs and open them in PS CS3 to assemble the mosaic. Alternately if using APP just throw all your subs in the lights box, make sure you have mosaic mode selected and go and make coffee/watch a film while it sorts the whole image out for you...

Hi Goran, The ASI 533 only has an anti reflective coating on the chip cover glass and I've found that the UV/IR cut filter really reduces star bloat. Plus having removed the Celestron supplied protective filter it needs those 2mm of glass as part of it's optical train. Francis

I have two intervalometers. They're both different so the best thing is to experiment. Your initial delay is for everything to settle down and stop vibrating. Next will be your exposure then the delay between exposures, then the count down through the exposures. One of my intervalometers wants me to set a time of 'x' seconds between each exposure - I normally set this as 8 seconds that gives the camera time to download/save the image. The other intervalometer wants me to set an exposure time (say 60 seconds) but when I set the delay between exposures it wants me to enter the delay value (say 8 secoonds as above) plus the exposure! so I have to set a delay of 68 seconds to get an 8 second delay after the exposure. Try different settings in daylight so you can see/hear what's happening. My guess is that your 2 seconds is not long enough for the camera to have finished saving one exposure befoore starting the next.

Interval too short

Hi Ed, I have a RASA 8 and yes the wires/cables do need some attention in use. Generally it's best to curve the cables to avoid diffraction spikes which is easy enough to do. I've not done any mono work with the RASA but your limitation is with the back focal distance with the RASA 8 either 25 or 29mm depending on where you measure from. There are filter draws that can be fitted allowing you to change filters manually which is quite simple. I use an ASI 533 Pro cooled OSC with my rasa and have now switch filters to a Baader UV/IR for broadband use and an IDAS NBZ for multi-narrowband captures. I won't now go back to mono imaging I'm having a far more productive time with my OSC. While many will say OSC cameras can't produce the quality of a mono system (and I probably agree to some extent) what the cooled OSC and the RASA combination allows me to do is capture images far more quickly - which suits me given the poor weather the west of the UK has to live with. A lens shield is a good idea with the RASA as the corrector plate sits right at the front. https://www.astrobin.com/users/fwm891/ Hope that helps

The integration time on this image has now reached 6hrs 10mins, and probably the final sub count. This one has been processed entirely in PI using a luminace mask to help control both the background and foreground areas. Total subs: 37 all 600secs durations Scope: RASA 8 Mount iOptron CEM60 Standard Camera: SAi 533 Pro, Cooled OSC Filters: Baader UV/IR Cut (luminance filter) and an IDAS NBZ (multiband for OSC) Guiding TS 80mm guider with ASi120mm camera and PHD2 (Rev4?) Capture and scope control: SG Pro Processing: PI

Captured 18 x 600s subs using my RASA 8 and an ASi533 Cooled OSC camera tonight (02 04 2021) with a Baader UV/IR cut filter. Processing has been done in PI with a tweak in PS. I need to check the orientation. Processing pushed a little too far - hope to get more data and reduce the noise somewhat. Hope you like

Great stuff Carole - can't believe what you get from your B 8 skies (with or without a moon).

If your looking to mount a 4-5 inch refractor I'd look at a CEM60. Granted they're out of production but they're a really stable mount and they do come up on the SH market. Yes I have one and a 4.5 inch refractor but hopefully not biased.

Great imaging Goran

Try fitting the guidescope forward and underneath the OTA. That's how I got over balancing my 6 inch RC

Lucky B, if only my neighbour was so thoughtful. Lots of hints dropped...👍

Grand worth the wait (knocks the spots off mine) 👍

From memory (I've now sold my SA) the USB socket is for firmware upgrades not a guiding interface. The SA I think has an ST 4 socket which connects to the guide camera to provide single axis guiding. I don't remember ever connecting my SA to a PC/laptop in use. See link below for PHD The only other external connection is a direct link to a DSLR camera via a jack socket... Link to my ST4 guide tests:

Hi @AstroM1 Apologies for the late reply. If your imaging with the D5100 then to get clean stars right across the frame you will need a field flattener (I use the adjustable version and set as the manual (11.4mm) on it's engraved scale.) I have not cleaned the lens but I do use a dew heater strap so no moisture builds up on the front element. When not in use I keep the cap on to minimise dust spiders etc... I do keep the focuser rack clean with an old tooth brush to stop a build up of dirt/dust etc and a little furniture wax on the rack to reduce friction. Plus a damp cloth occassionally on the outside to remove airbourn muck.

Managed to get a few subs (7) on the Cone nebula area last night as a further test on my IDAS NBZ NB filter and OSC camera (ASi533 Pro cooled). Images processed in PI.

Great image. I have one basic with RC collimation: Leave one adjuster locked and do all the remaining adjustments with the other two - that way you keep mirror spacing reasonably constant as small changes in separtion of the optics makes a big difference in the final focal length and the position of back focal plane.

Are the filters the same optical diameter or are your older OIII & SII filters in heavier mounts? Some older filter mounts/holders have a smaller internal diameter than newer filter mounts - that may cause vignetting at the corners. Just a thought