Gina

If clear tonight as seems a possibility for a couple of hours, I shall be imaging with the 28mm lens in OIII. Meanwhile, I'm going to have a theoretical look at a fork mount for ASI1600MM-Cool + ZWO FW mini + SLR 35mm film camera lenses of 28mm to 200mm focal length. I estimate the total weight as around 1Kg and fork depth around 100mm or so. The mounting would consist of a 3D printed clamp system like a double sided version of the fitting I'm using with the dovetail mounting. I'll draw some diagrams in SketchUp later. The imaging rig mounting would have axles coming out of the sides with a drive wheel on one side of say 100mm diameter - this will form the DEC axis drive. For the RA drive the shaft of the fork is turned and the fork framework would have another large wheel for the RA drive.

Quite so - no Arduinos involved Connect Pi GPIO to Pololu A4988 stepper driver and connect that to stepper motor "simples". And yes a 5v 28BYJ-48 wants 12v to drive it in bipolar mode. Handy because I have several 5v stepper motors I'm not using.

Been out this morning and lunchtime but now back and have added the focuser quadrant gear which clamps onto the focus sleeve on the lens so now ready for remote focussing is the sky is clear tonight. Had some deliveries while I was out including another 64GB micro SD card and used medium format SLR camera lens - 45mm FL and f2.8 - quite some piece of glass I shall need to sort out the mounting as this has a bayonet mount.

The RPi makes a mini obsy with dome and DIY fork mount a definite option. I could run a 12v feed from my main observatory for the power or maybe just a car battery in the base of the mini obsy. I would need to work out the maximum current required. An RPi could also provide the mini mount drive control. I would use NEMA stepper motors as the gearbox on the 28BYJ-48 motor has a peculiar ratio - it is only approximately 64:1 and I would want precise steps. I guess a mount is not as precise as a clock but avoiding a peculiar ratio gearbox is still best I reckon. With a widefield rig that is well polar aligned (I have the PoleMaster for that) the mount should only need RA tracking at 15 degrees per hour so sidereal tracking should be quite easy. A DEC drive would be needed for slewing of course. I would also use a NEMA stepper motor for the dome azimuth drive. Not sure about the shutter but I guess another NEMA would make things simple. I can see my large 3D printer having some work to do

Sorry to read that Dave Yes, it was a good imaging night Roof started cutting into the frame at about 2am but with subs captured both before and after the meridian flip I reckon I should have over 100 viable frames for processing out of a total of 130 up to 2am. We had a very heavy dew but I had no dewing problems with the rig - probably due to the heat given off by the camera and mount. No dew shield or even lens hood on the lens. The orientation of the observatory and the roll off roof is not ideal for the current widefield imaging and a better option will be the planned 2nd observatory - a miniature one, maybe with a dome. One thing that determined the full sized observatory orientation was the neighbour's billion candlepower flood light in addition to the lie of the land and the gradient - I live on the side of a hill. I have two options for the mini observatory - an NEQ6 mount ready to go or a DIY mini fork mount. Both have pros and cons. The big problem with the NEQ6 is it's size. In particularly the large volume required to accommodate the GEM system - this is total overkill for a widefield rig with the mini filter wheel and camera lenses. Of course, the EQ8 mount looks even more ridiculous with this "pimple" of a rig sat on it I know I've got enough projects on the books ATM but several of these are being shelved following the amazing results form the ASI1600MM-Cool camera. They might even be ditched altogether though I might go for a triple imaging rig again later on. The benefits of the compact and lightweight single ZWO camera and mini FW make for a much more viable mini fork mount in a small dome. Also, the thought of building my own mount is more appealing than a much more bulky and heavy triple rig.

I've examined a small portion of the image in the brightest part - the centre of the NAN and the white level is just touching saturation so this is the maximum exposure at this gain setting (500 = 50db). If the sky continues clear I should have 3+ hours of imaging time. 100 x 2m = 200m. OTOH I think Cygnus will have set below the observatory roof by then. Oh well, have to see what I've got tomorrow morning. So far so good

The sky is looking even better now so will continue with Ha imaging having just completed a meridian flip and re-centred. I'll add the focus quadrant to the lens tomorrow ready for the night in case the forecast of clear skies materialises. Here is another flipped only image - no histogram stretch.

The sky clarity seems to have improved. Here is another sub, same parameters as before but this time histogram stretched a little. I shall need to take some flats for this lens and also darks at this temperature and exposure. I shall be interested in seeing what I get in OIII and SII but I need the remote focuser connected up before I can change filters. These lenses are not apochromatic in the red end of the spectrum. SII focus is usually not very different from Ha but the OIII is something like 20 odd focus steps different.

Whilst this image is far from perfect, it does show the relative positions of the DSOs in Cygnus. Near centre are the NAN and Pelican, and the Cygnus Wall. Just above centre left is the Cygnus Loop and top right IC1396. The Crescent Nebula is also in there - very small - about 7 o'clock from the Cygnus Wall towards the bottom right of centre.

28mm f3.5 lens set up but no fine focussing yet - this is just with manual focus. 120s Ha sub at -29°C and gain of 500. Flipped image but no other processing - saved in PNG format full frame. This is the raw, untouched image. There are signs of image curvature around the edges.

Looks like we just might get some clear sky tonight So... what to do with it. I think it will be several days yet before I get a viable Linux system working for astro use, though I seem to be making progress. Trying to do proper imaging with my present Win7 laptop and apps is just not worth the hassle! So I think I'll just do more playing about - much easier on the old nerves Maybe I'll try the extra widefield 28mm lens and cover a pretty huge area of sky above

Used as a finder with ASI185MC camera the FOV would be 7.3mm x 4.6mm divided into 28mm giving tanθ of about 0.25 and 0.16 and θ of about 15° x 10°. With a 460EX and 12.49mm x 9.99mm sensor - tanθ of 0.45 x 0.36 and FOV of 25° x 20°. The latter would be a useful FOV for an electronic finder. OTOH with KStars/Ekos/INDI having plate solving an electronic finder may not be needed.

Now have the hardware to construct another power distribution and focus box though with reasonable progress with the Linux based system and Raspberry Pi I might leave it for now and see how I get on with that. I've also bought another ex film SLR camera lens - Asahi Pentax SMC Takumar 28mm f3.5 which I can use either for even wider FOV or as an electronic finder scope with astro camera. As the 55mm f1.8 lens seems to give problems at full aperture, an f3.5 lens might be better. The 28mm FL will cover twice the FOV of the 55mm, of course, so that something like 40° by 30° - should be interesting

No I didn't, but thanks for the suggestion A cold boot with several seconds off time seemed to help a bit but things were still not working so I closed the roof, packed up and went to bed.

I thought about SGPro but it's Windows again and I'm afraid I'm just fed up with Windows!! This new ZWO camera is showing great promise as is the rest of the hardware I'm using for widefield DSO imaging. Now if only I can get the software working I foresee some very presentable images emerging CdC frequently disconnects from EQMOD, APT sometimes just stops at the BUSY point in a capture session and even SharpCap plays up at times - currently failing to stop imaging at the end of the exposure set up. I'm hoping I can get Linux software working better but I'm having problems with the Raspbian OS on the RPi. I may try using a laptop running Linux Mint and using that with INDI.

Tried rebooting and APT still won't run And now SharpCap is playing up!! Maybe it's bedtime....

Got to find something other than APT!!!!!!!

Trying to do OIII now but try as I might, I can't get APT to work - just stops at Busy at the end of the first sub

Clear sky ATM and imaging NAN&P. Here's a 60s Ha sub at -28C and gain of 500.

Looks like I shall need some extra bits to build a new power distribution and focus box so I'll be using the current one for now. Here are some photos. On table, on EQ8 homed, on EQ8 and pointing at far trees.

The circuit for the lens version could be a bit different and include a ULN2003AN stepper motor driver chip on the circuit board with stepper motor socket rather than having an external motor driver module. That would be tidier. And it would only want 3 fuses as the filter wheel is USB powered.

This is the circuit diagram of the power distribution and focus box. This shows the filter wheel power which is not needed for the lens rig. For the Esprit scope rig the second power plug can be used for the USB hub which runs off 12v (nominal). I'm not currently using dew heaters with the lenses or the Esprit scope but it might be needed for extreme dewing conditions.

I think I shall use the bad weather to do a bit of a tidy up of the rig. The power distribution and focussing control box could do with re-making and given a proper bracket rather than attached with rubber bands. But rather than stripping the current circuit down I think I'll make a new one just in case the clouds go away before I've finished. The wiring could do with tidying up too - with fixing in place.

The weather seems to have caught up with the forecast Now clouded right over and starting to rain! I was about to take the imaging rig and laptop out to the observatory to set up but I'm not taking gear out in the rain! I'll take a photo of the rig with new filter wheel on the table shortly then instead of on the mount. Unlike the Atik EFW2, the ZWO filter wheel needs no 12v power - it works entirely off USB and at least it has a full size type B USB socket rather than the dreaded mini USB. Just the one power cable from the distribution box to the camera plus USB cables from camera built-in USB hub to focuser and FW. The only other USB connection required is for the EQ8 and that's run directly from the laptop. USB from laptop to camera completes the wiring. (Apart that is, from power from umbilical to distribution box and power from pier to mount.) Last night's session at least gave me some information - the viability of unguided imaging. Guiding was not necessary for up to two minutes exposures, maybe three but not quite four - that was showing star trailing. I have the OAG built into the SX wheel if needed but I will need to get access to another USB for the guide camera and that will mean a USB hub. Fortunately I have a selection including a highly recommended professional metal cased powered USB hub that I bought a while back for my multiple imaging rigs.

Downloaded the ZWO EFW mini ASCOM driver ZWO EFW ASCOM Setup V1.0.0.7(Add support for editing filter name and focus offset ) and installed on my imaging laptop. Needed reboot to work. Then ran SharpCap and from Settings in the File menu selected the Hardware tab and filter wheel from the list. EFW mini recognised and selecting a filter ran the filter wheel to the right position Then tried in APT and same result - all working fine. Edited the filter names to Ha, OIII and SII - so that's that set up and tested Both SharpCap and APT allow for changing the focus according to which filter is selected so it's looking like it's getting near time I made my remote focuser ASCOM compliant Then, having determined the focus settings for each filter I could put them into the system and run a complete NB imaging run under APT as process controller.