Gina's Observatory - The Build

[Gina]

Nice shot Gina and nice to see you settling in to the new obsy.

PS is your webcam broke?

Thank you

Yes, webcam is off ATM - I've fixed it and will be putting it back up shortly.

[Gina]

Hi Gina

I don't think buying a bahtinov mask was false economy, having also bought one. It would take alot of time and effort to make one that was an equal to one of these.

Yes, that was what I thought. Thank you for confirming it

[malc-c]

I purchased one of Keith's masks for my 200P - best £18 I have ever spent - the quality of the material used and precision of the cutting gives nice sharp defraction lines that make getting the scope focused a doddle

http://www.morris-engraving.co.uk/starsharp.htm

[Gina]

Recent Progress.

Not very much progress yesterday and even less today. Some of the odds and ends I'd ordered came yesterday including the sliding door handles. I cut the framework of the dividing door to take the handles. Two 22mm holes, one at the top and one at the bottom were drilled with a hole saw then the wood in between chiselled out to clear the back of the handles. Then one handle was screwed onto the warm room side of the door.

The other main improvement was to the focussing control box circuit. I replaced the pre-set variable resistor with a pot with shaft and knob and added capacitors to ensure stability. The pot varies the output voltage from 1.2 to 6.6 volts but I may change this after testing.

The following images show the door handle and modified circuit for the focus control. I've also included a circuit diagram of the modified circuit showing two versions - the ideal using two SPDT push button switches and my alternative using a DPDT biassed centre-off toggle switch, as mentioned above.

[Gina]

Focus control box (not connected yet).

[Gina]

Connected the focus control box up yesterday afternoon and checked it out - seems fine, the bottom end is just about slow enough. The atmosphere was quite clear so I thought I'd try a different target from the garage. There are a pair of communication towers on the hill to the south of Honiton near the Sidmouth road. These are just over 8 miles from here as the crow flies (somewhat further than that garage ).

Here are a couple of images taken with the MS LifeCam, one directly at prime focus and the other with the Tal 2x Barlow. These images show just the top bit of one of the masts peeping out above the trees. Following these I have included a screenshot from Google Street View showing the two masts from the A375 Honiton to Sidmouth road. The images are about the top eighth of the left hand tower.

[Astrokev]

Hi Gina

Those towers look a great target for testing and comparing your cameras and optics. Lots of fine detail. Your images look quite grainy. I presume this is general camera noise ?

[Gina]

Managed to do a bit this morning before the rain came back. Took off the latch and lock unit that I'd put on before and which stopped working and replaced it with a mortice latch - I'll sort out a lock later. Managed a quick photo of the outside handle - I may take photos of the rest of it later, though I think everyone's seen ordinary household mortice latches

Photos of focus control exterior, now connected up and outside door handle.

[Gina]

Hi Gina

Those towers look a great target for testing and comparing your cameras and optics. Lots of fine detail. Your images look quite grainy. I presume this is general camera noise ?

Yes, the light was going and I had to turn the exposure up. I'll do some more when the weather permits. I ordered an extension tube from FLO just before the holidays and hoping that'll come Wednesday. Then I won't have to use the diagonal to get focus and hopefully, less wobbly. I'll try the 2" ED Barlow too - I think it's a bit better than the 1.25" Tal, although the Tal seems very good.

I can only use the tower when the atmosphere is really clear with the visibility exceeding 8 miles. Even when I took those images the image was wobbling about quite a lot and focussing was difficult.

[Gina]

Just had a hail/sleet shower but the sun's come out now. Just been out to the obsy and checked visibility with bins but it's too poor for using the scope. Also made a discovery... Due to the trees I'm getting a different view from the obsy from that from the house and I've picked on a different comms tower from one of those two. So it's back to Google maps (or OS paper map) to find the tower I'm actually seeing with the scope. The twin towers are hidden from the scope by trees.

[Gina]

To give an idea of the scale of the tower and magnification, here are a few DSLR photos. Firstly, the standard view of about 60 degrees - 35mm FL @ DSLR frame size (equiv to 50mm for 35mm film) then with 300mm fl. Finally, a view from outside the house containing both the tower imaged (on the left) and the two towers near the A375 (on the right). The first photo was taken from the scope room with the roof half open to shade the camera from the sun (the downpipe from the roll off roof guttering can be seen at the left).

[Gina]

Today's Progress.

A mixture of sunny spells and heavy showers of rain, sleet and hail today - quite cold. But I did manage to cut some D section moulding to form the framework to hold the acrylic sheets for the dividing door window, and screw them on. Replacing the temporary strips of wood on the scope room side.

Took DSLR photos of the dividing door showing the new strips.

[Gina]

Atrocious weather this morning - torrential rain and gales and when I looked out of the back porch I saw that the ditch next door was blocked and a stream of water was running down our grass and under my observatory, then out and along the bottom boundary where it then flowed down to the adjacent field. We phoned our neighbours but they were in a worse position with flood water running right through their house! So I donned wellies and waterproofs and took a spade to the blockage and eventually managed to clear it. Fortunately the water did not rise high enough to reach the floorboards of the obsy. The joists were well treated with wood preserver so I'm hoping there will not have been any damage and it will all dry out once the water level goes down.

Here are a couple of photos from the porch doorway (keeping camera dry).

[Astrokev]

The way the weather's going, your upturned radiator will soon be a bridge across the moat

[malc-c]

The way the weather's going, your upturned radiator will soon be a bridge across the moat

Kev,

Then all Gina needs to do is to attach two ropes to it and use it as a draw bridge

[Gina]

That's about right It was a bridge this morning! I'm thinking of naming my obsy "The Ark"

[htj]

Ouch.

As this isn't your first run in with water (I think I saw something elsewhere in the thread), have you considered digging some more permanent ditches to prevent this from happening again. Having the base submerged in water 2-5/year isn't going to be great thing, even if the woodwork is well-treated. With night frost some erosion (from water expanding) might also gnaw on the obsy.

I'm rather impressed with the build as well. And well-documented too :-).

[Freff]

Yes I think some serious grainage is called for Gina. More digging..

[Gina]

Yes, I've thought that too. I'm going to dig a small trench across from this end of the building into the field next door filled with rubble. I also have planned a rubble filled trench round the building with the extended vapour barrier stopping water from going underneath, as was suggested when I had the help with the shiplap. There's a small bank along the south boundary which I'm thinking of digging out. All this wants some better weather though - I don't fancy doing in the rain!

[MikeWilson]

Hi Gina,

I've only just come across this thread and have thoroughly enjoyed reading it - what a wonderful site and observatory you have. I hope that it gives you much enjoyment over the coming years - I really wish I could justify one myself

All the best,

Mike

[Gina]

Thank you Mike Just want some decent weather now!! This isn't the best location for good weather

[Gina]

Today's Progress.

Although still quite windy, it's been dry today with some sunshine. Been doing a bit more to the inside of the warm room.

1. Measured and cut two plywood panels for the north wall.

2. Screwed panels to framework.

3. Cut and screwed on D moulding to cover middle join in plywood.

4. Measured up for bench.

5. Measured and cut two panels for south wall.

The 2" 80mm long extension tube and Bahtinov mask arrived today so I put the extension on the scope and the 2x ED Barlow and DSLR camera. The Barlow went fully into the extension tube and focus was obtained with the draw tube halfway out - so that's perfect The setup is very much more rigid than using the diagonal. Took a few images of the moon before dark. I have a feeling the image plane of the viewfinder is not perfectly co-planar with the CCD as reflected in the mirror - when I have seemingly perfect focus in the viewfinder it seems a bit off in the image. I've been trying to check this out.

Looking good for tonight ATM so I'll try a few things

Here is one of the best images :-

[Bizibilder]

Gina - does your camera have live view (or any way of getting the "view" on a computer screen)? It makes life far easier than using the viewfinder.

[Gina]

Gina - does your camera have live view (or any way of getting the "view" on a computer screen)? It makes life far easier than using the viewfinder.

No it doesn't unfortunately, that's why I'm getting a Canon EOS 1100D body. Current DSLR is a Sony A200 which is a great camera but has no live computer connection nor any way of seeing the image on the sensor without taking a photo and then looking at what was saved on the CF card. There isn't any way of magnifying the image to help focussing.

[Anweniel]

From my few plays with the 1000D live view appears to still not be a complete solution so reviewing pics seems a necessity anyway, or maybe its just me judging it badly on the smallish LCD screen?

Still to make my bahtinov mask, got paper templates made but may just buy one if I stall much longer!

Obsy looking great though I see you are still having trouble getting that coating off the window, sorry to hear about the drainage issue I guess some more hard work is needed :/