Gina

Light now off so new image. Exposure 10s, gain 150, gamma 50, temp 9C. This image shows the problem with the differential focussing. To the east the focus is good, in fact better than I've achieved before but to the SW it's way out. NW seems reasonable though it's a bit difficult to tell. To bring the rig indoors, tweak a screw setting the put it back out and see if it's any better and repeat until good focus would be very tedious and time consuming. This is not helped by interaction between the adjuster screws.

Rain has stopped and I've put rig on the guttering. Next door have their gazillion power floodlight on but here is the image anyway.

Much better Adjusting the offset was easy. Moving lens in tube by hand was the coarse focus and adjusting all three adjuster screws together provided fine focus. Individual screws will provide differential focus if required probably by trial and error on the outdoors. Can't put it outside ATM as it's raining.

Going to try a simpler approach - large holes in the three legs of the lens adjuster then washers under the heads of the adjustment bolts.

This is not proving easy The adjustment for offset doesn't work very well. I reckon it's going to need another re-think!!

This will fit over the camera. Grub screws either side (top & bottom of sensor) will allow adjustment for offset. The other three holes will be tapped for the lens angle and height adjustment screws.

Slowly getting there The domeless approach really does seem to be paying off. Seeing the stars even with the moon in the FOV was never really possible with the dome and however good, the dome always seemed to produce some distortion. I've decided that trying to keep the present casing is causing more trouble than it's worth. A new casing is only likely to cost around a fiver plus some time and effort to design but the time and effort to make things fit the present one is just as bad. I'm not even happy with the way the stepper motor is supported and covered. Consequently, I'm firstly concentrating on getting the lens adjustments sorted out and this may include some thermal insulation for the camera. Printed plastic with the air cells contained in it makes a very good insulator and can combine that with the mechanical aspects.

Soon be ready to assemble the lens adjuster parts with lens and camera and try it out. Having got the focus so good it seems a shame to take the thing apart but it would only need a touch on the side of the lens and it would be out again.

Some bright red TPU, a springy filament, will provide the spring for the lens adjuster and also thermal insulation and sealing of the camera top to help with cooling and also stop condensation on the camera window.

Lens adjuster wasn't high enough so redesigned it.

Parts for the lens adjuster designed and now printing.

This turned out to be a GIMP problem as the file opens correctly in PixInsight. While there I cropped the image to just the relevant portion and increased the gamma a bit. Some problem saving in PNG so I saved in JPG format. Exposure 30s, gain 240, gamma 1 (but increased in PI) and camera temperature was close to freezing. When I brought the rig in this morning the camera had a couple of mm of ice on it. (Rig was uncased.) Could probably do with some thermal insulation round it. Focus seems good - if I could retain this I would be satisfied Nice image of Orion about to set though Betelgeuse and Rigel are overexposed and lost colour.

Here's an image captured just before dawn this morning. This is the FITS file cropped in GIMP. It was the wrong way up so I had to flip vertically, also there's no sign of colour which is puzzling.

Another image. Screenshot from 2017-11-12 23-16-41. Exposure 20s, gain 240, gamma 1, Camera temperature 2 .2°C. Some cloud coming in. Orion has risen but seems to be in a bit of thin cloud.

I think the adjusters might just fit into the current casing.

Here's a diagram showing a possible method of providing manual lens adjustment. This is a simplified diagram that doesn't show the offset.

Regarding focus etc. I shall need to redesign the camera to lens holder to allow for three vertical adjuster screws whether manual or remote controlled. May need springs. It's looking rather like it may need a new casing

Screenshot from 2017-11-12 18-54-00. Exposure 20s, gain 240, gamma 1, Camera temperature 3.2°C.

Exposure 10s, gain 388, gamma 1.

Brought rig in and adjusted focus. Put it back out without casing. Exposure 10s, gain 240, gamma 20.

I guess that to provide full control over the focus and angle it would need three adjusters as there are three dimensions to adjust. These could be vertical motion at three points at 120 degrees around the lens.

Looks like a nice clear sky - rather out of focus! Still sunlight to the SW but the Milky Way is visible. Pity the stars are out of focus!

Back to the working system (my experiments are with a separate RPi and card). It looks like I am going to have to arrange remote control of the focussing and lens angle. The image attached was after manually focussing and then putting the casing on. It's not bad to the SE but well out to the NW. I think maybe putting the casing on disturbed it and if that's the problem I might be able to improve the manual adjustments and make them stronger.

First attempt with Ubuntu Mate wouldn't boot so trying again with a new image write to card.

Currently investigating shorter exposures for the daytime. Discussion on the indiserver forum. Seems this should be possible. I'm now conducting experiments with a new microSD card and new RPi using Ubuntu Mate instead of Raspbian as the OS.