10" Focuser/350d Update

[Scorpius]

Having now completed exhaustive tests and enquiries. There apparently is not a real way of matching a Canon EOS 350D to a 10" dob with a standard GSO type focuser, which has a minimum racked in height of just under 3".

I carried out the following test the other night and removed the adapter plate from the focuser and fed the barrel thru the hole remounted the mounting plate and secured it with two screws and a piece of cord as the holes were now out of alignment. Fig 1. I found that the 350D focused nicely around 7-8mm racked out and took a photo of Saturn using a 2" T Ring adapter I had made by a local engineer (Half the price of a bought one!) Fig2

The photo of Saturn came out blurred as it was a timed photo of 6 seconds and with the string and chewing gum tad difficult to focus. However it is identifiable fig 3 However I can go thru the focal point with ease.

So the answer. As far as I can see there is only one, a Moonlite CR2 with a compression drawtube option. I have checked out JMI EV focusers and they have a racked in height of 2.2" which is a tad too close. The prices are roughly similar.

It is cheaper to buy direct even with import/gst - Sorry local traders but prices are too high. Typical example Celestron NexImage CCD package with reduction tube $AU150 landed. Local price $AU300 -- anyway off my soapbox.

Provisionally I am going to have the mounting plate from the old R&P Milled to open the hole by a further 2mm diameter. The GSO barrel will then fit inside the enlarged hole. By drilling and tapping the sides of the plate with four set screws one can align and hold the barrel as far in as necessary. The hole diameter will still be inside the 3 original mounting screws for the R&P barrel if one wanted to be so mad as to use it again.:rofl:

[iceman]

Interesting Dave, thanks for the update.

[Scorpius]

Here is the mod done by my engineer mate Opened the 0riginal R&P focuser hole plate by 1.82mm so the crayford would slide in and held by grub screws. Focusing tests tell me its pretty well spot on. Go away clouds .....Pleeeeese.

[Scorpius]

Clouds cleared around late evening and plugged the 350D in Spot ON. :D Focuses beautifully about 10mm out and having to add a 50mm extension for the EP now, that also focuses great about mid rack out. So I can save my money and just grab another GSO to put on the 8".

The GSO mounting base can also be machined out to allow the focuser barrel OD to pass thru it and then be held by the existing grub screws. So have saved myself heaps of bux not having to buy an extra low profile focuser from Moonlite.

Incidently did you know that Jaycar sells some very neat little motors with gearboxes on the end. Be ideal for focuser motors with a small voltage reducer. They are 12 volts but will run as low as 3V.