Gina

This is better - flipped in GIMP.

Just realised what's wrong with these images - they're reversed - east is to the right!!  Very strange!

The sky is now pretty much covered in clouds   And waiting for the moon to set but it looks like I would have to wait until nearly 1am

Gamma reduced to 20.

Exposure increased to 10s.

Auto White Balance turned on.

Well, that's better   This is with 5s exposure, gain on Auto and showing 240, gamma on 50 and brightness on 1.  No camera cooling and no dew heater.  Image capture with SharpCap and this is just a screenshot of the Preview.

I opened the window and did my best to focus on the moon.  Then put the camera on the pipe and hung it on the guttering.  The FOV seems alright though can't be sure until it's in it proper position on the observatory.  Here's a screenshot from SharpCap.  Out of focus unfortunately.  I've cropped the image in the X axis only.  Bright lights cause reflections in the lens, it seems.  This is without a dome.  Think I'll bring it in and try focussing on the moon again.  The sky has almost cleared now.

I could do with a finer method of adjusting the focus than just by moving the lens in its support tube.  The screw adapter wouldn't engage with the offset, hardly surprising.  I'll do some more thinking

New print is fine though the lens is a little tight in the tube but the offset isn't enough.  I reckon it needs twice as much so I'll change the design and print again.  I've increased the offset by another 0.7mm giving 1.2mm altogether.  If this is too much I can turn the support on the camera to reduce the Y offset and add a bit of X offset, which doesn't matter as there's plenty of room in the X direction.  In fact there is already some X offset which I could reduce by turning the support tube in the right direction.

The print is a nice tight fit on the camera but too tight on the lens so increasing the lens tube by 0.2mm diameter which should be about right.

Now printing my third attempt at a lens support that fits   First was a little too small, second a lot too loose so now on the third which is just 0.2mm bigger in both the camera and lens fittings than the first.  Fingers crossed.

Photo of the camera and zoomed in to aperture showing sensor and alignment grid.

Added a marker to show north (or south, depending on which way the sensor is out).

Here is a design for the lens support with the inside offset by 0.5mm from the rest.  This is the basic shape and I'll add holes I can tap for grub screws once I've checked this for sizes.  You need a keen eye (or a ruler) to see the offset as it's pretty small.  Side view, top view, bottom view and cross-section.

Here is the ASI178MM image from above cropped to represent the coverage of the ASI185MC when the image is shifted appropriately to fit it on the sensor.  This shows that the coverage should be quite adequate - I don't need to see the ground below the trees

I shall be interested in seeing how well the ASI85MC and Fujinon fish-eye lens combination work at night.  I plan to use it only for dusk to dawn imaging and make up a much cheaper combination for daytime - maybe RPi camera and CCTV fish-eye lens 12mm board camera mount - possibly for web streaming. 

This is the full frame of the ASI178MM which shows how the image circle is offset on the sensor.  All these cameras seem to have the sensor offset a bit from centre.  With the ASI178MM and the sensor covering more than the image circle it doesn't matter - just crop off the unwanted margin.  But for the smaller ASI185 it does matter.  I therefore propose to design a 3D printed adapter to carry the lens and be attached to the camera.  Being plastic this will also thermally isolate the lens from the camera body so that the lens can be heated and the camera cooled.  Hopefully small variations in temperature with resulting varying expansion will not result in the image going out of focus.

With the lens in its normal position I get this view.  So I think I need a lens support that permits adjustment in the Y direction as well as Z for focus and which holds the lens with its optical axis at right-angles to the sensor.

If I can persuade the lens and camera to line up optimally the sensor will very nearly cover the FOV as can be seen in this screenshot.  I have the ASI185MC attached to the Fujinon fish-eye lens and focused by unscrewing a bit.  OK so this is focused on the room and not further away on stars or moon or even distant trees.  I may try that tomorrow.  I would be quite satisfied with this coverage.  This image was obtained using SharpCap on my Win7 laptop.  I have yet to check it out with INDI and RPi.  I just used the quickest way to check the FOV as I haven't got the RPi wired up ATM.

I think I may try the ASI185MC camera and see what it looks like.  The resolution is much less both because the camera pixel size is bigger and in going from mono to colour - but OTOH when I was focussing on the moon the lens only seemed to be able to do around 6 pixels of the ASI178MM when I zoomed right in so I might not be loosing anything.  If I ever get around to planetary imaging, the ASI178MM would be better than the ASI185MC.

This is an image taken back in June 2015 when I was using the Fujinon zoom lens with ASI185MC.  The Fujinon fish-eye lens is vastly superior in light transmission.

Looking through my old files and images from earlier versions of my ASC I have to say I much prefer the colour images.  I think the Fujinon fish-eye lens would work well enough with the colour version of the ASI178 but I really can't keep buying cameras and certainly not ATM with a big bill on the horizon for repair of my Rayburn (essential equipment).  I have an ASI185MC camera not doing anything at present but the sensor on that doesn't quite get all the sky image in.  It's close (but no cigar!)  The 178 sensor is 5mm high and the 185 is 4.6mm.

Here are the comparisons :-

                        ASI178                                      ASI185
Resolution      6.4 Mega Pixels 3096*2080    2.3 Mega Pixels 1944*1224
Pixel Size        2.4µm                                       3.75µm
Sensor Size    7.4mm*5mm                            7.3mm*4.6mm

Of course it actually goes this way up

A couple of photos of the casing fitted to the ASC insides and aluminium tube that forms the mast.

I'll now crawl back into my shell   Or get on with something else...