Another Cold Finger Experiment.

[glend (Glen)]

That looks like a Jules Verne creation you have there Brent! Why not if it fits and can support the weight and can be balanced.

Re the "glass removal" are you talking about the sensor cover glass or the front LP1 filter. After my mono experiment I appreciate the role of the sensor cover glass in the prevention of fogging. The sensor face is going to be cold and IMHO it helps to have the sensor coverglass (or the Astromonic MC Clear replacement) there to create a double glaze chamber to prevent fogging (especially if you can seal it and fill it with Argon or dry air).

I run a Baader 2" UV/IR Cut on the front of the T-Adaptor and this creates another chamber inside the T Adaptor to further insulate the sensor. Last night when I was packing up I noticed that the outside face of my UV/IR Cut fitler had fogged slightly due to the cold that had been transmitted through the T Adaptor from the Cold Finger - but that is unusual as it was a really warm damp night - never happened before.

[ZeroID (Brent)]

I am meaning the front LP1 filter. I would always have the IR cut filter on the nosepiece possibly along with the 2 x Barlow lens.
Trouble is once you've broken it out there is no going back.

Balance with my 'Jules Verne' creation is good. both the 450D and the 1200D are quite lightweight. I can just slide the dovetail back a wee bit to compensate. 'Jules Verne' is a bit of a tight fit in the Ob though and I have to park it horizontal.

If I hadn't already named the scope as the Russell\Nankivell 8F8 Astrograph I would name it 'Jules Verne', nice one !

[rcheshire (Rowland)]

It's not nuclear powered... is it?

[ZeroID (Brent)]

Originally Posted by rcheshire

It's not nuclear powered... is it?

Nah, runs on stardust ....

[ZeroID (Brent)]

Update on this. Having got all the mount rebuilt and running well I decided to add some IR info to my earlier Horse & Flame.
For some reason I had left the IR cut filter on the front of the nosepiece. I started cooling the 450D down at 5 volts on fan and TEC and with 15 mins it was heading below zero ! Ambient was about 20*. I think the added insulation of the front filter gave a sealed system and reduced thermal losses.
Now I need to build a controller for it as I got to icing up very quickly despite silica gel pacs.

On an added note I've now also got CDC, ASCOM and EQMOD all talking to the mount so PC control. I'd prefer Stellarium for it's visuals and ease of use but I can't for the life of me get it to run. This OpenGL requirement is a sod to try and fix.

And I've setup up PHD2 to use the camera rather than GPUSB connection. Not sure if that is working yet but it all seems to connect.

Now the place is full of clouds, must have come down with the ASCOM\EQMOD downloads. Didn't know you could download clouds ..

[ZeroID (Brent)]

Just ordered 3 x 12-24 volt 8 Amp dimmer\motor controllers from DX. I can get one over here for $43.00. I got 3 for $14.00 from DX.
Use one to manage the TEC on the 450D, the other two for future projects and experiments.
About to remove the last filter from the 450D as well.

[ZeroID (Brent)]

450D is now full spectrum.
And it fired up first time when I got it back together, amazing how much abuse it has taken and still keeps going.
Weather is good but I'm too knackered to test tonight. Been a hectic weekend. Hopefully the weather will be kind for a night or two later. We've been having an 'Indian' summer over here, still very warm.

[ZeroID (Brent)]

Weather not helping much at present so I opened the 450D up and cleaned the sensor. I'd also ordered 3 x 12-24v 8 Amp motor controllers from DX which turned up Friday. Jaycar had them at $43, DX had them at $4.41... .
Wired one of them into the TEC supply and ran a test.
At about 50% the temp moved down quite rapidly from 20*C to about 12*. I then wound the dimmer back to almost minimum and it settled at about 9.4* so as a starter I can manage the dew and ice problem by a bit of manual tweaking. It will do for now. Between that and some small silica packs I can run some more trials.