Gina

I think within a degree or two of horizontal. I think the far hill to the east may be a bit higher than here. Just done a triangulation from indoors. Line of sight from bottom of east window to top of trees on far hill is 6" in 170" above horizontal. Tan A = 0.035 giving A = 2 degrees. There are no towns in that direction for many miles.

I also have an 18mm lens though a zoom so probably not as high quality but at least is supposed to be f3.5 at that zoom. I'm planning to try it eventually.

It's not looking good

Cloudy tonight as forecast. Tomorrow I'll set up the 28mm lens on the camera unless it's raining all day.

Yes indeed I moved over into Monoceros to include the Rosette Nebula - couldn't see anything interesting the other side. The only disadvantage of the 28mm lens if the smaller aperture of f3.5 but it did alright in Cygnus

Here are the fields of view of the Orion region with 28mm and 55mm lenses.

Couldn't find the 28mm lens so I set up the 105mm lens rig ready for imaging, took it out to the observatory, attached it to the mount and connected the various cables. While out there I found the 28mm lens on the warm room bench Anyway, I have the 105mm f2.8 lens all setup and roughly focused ready for imaging whenever we get some clear night sky. Not that I'm expecting it to be clear tonight but it's been a nice sunny day and relatively mild so I've been doing outside jobs, including running my CAT6 outdoor cable to the observatory properly. Bored a hole through the east facing window frame in the living room and likewise in the wooden wall of the observatory. Cable supported in the middle on a fence stake hammered into the ground so that it's out of goat reach.

Thinking about what I would like to image next time we get some clear night sky, and from seeing a widefield image of Orion, encourages me to get my 28mm lens out again and give Orion the FOV I used for Cygnus a little while back. It seems this winter imaging is going to be mainly experimenting with the ASI1600MM-Cool and various camera lenses rather than concentrating on a few objects in depth - currently there just isn't enough clear sky time to do all I would like.

Black ABS 1.75mm filament has arrived so I can print the encoder wheel.

With both Clear Outside and the BBC Weather Forecast showing cloud for tonight I am not prepared for imaging but a look outside shows a lovely clear sky!! Oh for a good weather forecast!!! Clear Outside even forecasts rain in an hour or two.

Except that it's not right - I'll do another. Meanwhile here's the hub which should be to scale.

Here's an updated cross-section of the wind vane hub.

Maybe the only benefit is to reduce the amount of data generated. I haven't tried binning with this camera but I have with the ASI178MM and that didn't seem to increase the sensitivity. But it was useful for zooming in and focussing as I could image faster over my WiFi link with the Raspberry Pi 3.

This diagram shows the placing of the optical sensors. Two at right angles read the outer ring and the other two the middle and inner ring. Separating them makes for a small overall design as it doesn't need 2x the side width of the sensor between rings.

In fact it doesn't need the full disc for support and some filament could be saved. If it's worth it for a couple of pence worth

The encoder. Showing my workings and the final model.

The base part.

Working this out shows the diameter of the hub unit will be just a bit more than the original. I'll post screenshots of models shortly.

These ITR9606 slotted sensors from Amazon are much cheaper and delivery is quicker (Monday). Slightly bigger but I don't think that's of much consequence. 5mm slot rather than 3mm. Minimum ON current 0.5mA which is still quite adequate. Datasheet

I can take this a stage further so that the optical sensors can be standard slot type. TCST1103 datasheet These are extremely efficient and give a minimum collector current of 2mA in the ON state. The gap of 3mm means plenty of room for the encoder and some tolerance. The height of the hub unit is much reduced. (Oh dear, this screenshot has suffered badly from pixel creep! But I think the general idea can still be seen.)

I have another idea for the encoder. Turn it from a disc to a cylinder - just as easy to 3D print but has the advantage that both PTs and LEDs can be fixed to the base part and the encoder can be withdrawn without needing to be in any particular position.

Must get back to some data processing now that I have some more experience/knowledge of PixInsight. What with the new software and the new camera and imaging setup, this is a great learning experience

And now printing the LED support plate. Just a five minute job

Printing the Gray encoder disc. Run out of black ABS in 1.75mm so printing in dark blue. I have ordered more black but the delivery looks like being about a week.

Model of the wind vane hub (yellow part above). The top takes the encoder disc, the projection to the left takes the damping magnet and hole on the right, the aluminium tube with the vane.