Dual and Triple Widefield NB Imaging Rigs with Remote Rotatable Cameras.

[Gina]

I'm calling this Dual and Triple Rigs because I plan to make a triple imaging rig with three ASI 1600MM-Cool cameras and Astrodon 3nm filters with three vintage film SLR lenses of very high quality. However, I only have two cameras at present so I shall start with a dual imaging rig but with provision for easy upgrade later.

As I mentioned in the DSO Imaging forum, I'm planning a mosaic project covering the Milky Way in NB.  This requires that the cameras can be rotated in unison to line up the mosaic panels.  My plan is to rotate the cameras using gears and stepper motor controlled by the electronics (using a special INDI driver).

The first 3 screenshots show a CAD model of the triple imaging rig.  Two of the main assembly and one of the frame or bracket.

There are a few problems with 3D printing this frame so I have split it into two with each half individually bolted to the Losmandy type dovetail bar. 

The next screenshots show a partial assembly on the dovetail bar and one side in the S3D slicer.  

[Chris]

A) you're awesome at CAD, B ) Any thoughts on which and what focal length vintage lenses you'll use for this project? Pentax Supertakumar's ? 

p.s. It don't half look like a NASA rocket thruster with those 3 dew shields!

Edited December 28, 2020 by Lockie

[Gina]

For the Milky Way mosaic I have Asahi SMC Takumar 28mm f3.5 lenses.  From Cygnus to Orion - The Milky Way as an Ultra Widefield Mosaic - WIP

I also have 55mm f1.8 Super Takumar and 105mm f2.8 Takumar and 200mm f4 SMC Takumar lenses.

Edited December 28, 2020 by Gina

[The Admiral]

Interesting project Gina. You have a remarkable well of project ideas 😊.

Does it matter that the gears turn the cameras in different directions? I can't quite figure out the camera alignment.

Ian

Edit. Ha, I've got that wrong haven't I! They all rotate in the same direction.

Edited December 28, 2020 by The Admiral

[The Admiral]

Sorry, my mistake, I should realise that that isn't the sort of thing you'd get wrong 😉.

Ian

[Gina]

The cameras do indeed turn in the right directions.  Don't they???!!!

[vineyard]

2 hours ago, Gina said:

For the Milky Way mosaic I have Asahi SMC Takumar 28mm f3.5 lenses.  From Cygnus to Orion - The Milky Way as an Ultra Widefield Mosaic - WIP

I also have 55mm f1.8 Super Takumar and 105mm f2.8 Takumar and 200mm f4 SMC Takumar lenses.

If that's the K type 28mm f3.5 that's a lovely lens!

[The Admiral]

10 hours ago, Gina said:

The cameras do indeed turn in the right directions.  Don't they???!!!

Yes of course they do Gina! My mistake. Doh! . Sorry for raising a red herring.

Ian

[Gina]

9 hours ago, vineyard said:

If that's the K type 28mm f3.5 that's a lovely lens!

No, they are the M42 thread type.  I have a K mount one I ordered by mistake which I plan to make an adapter for.  It's actually f2.8.

[Gina]

1 hour ago, The Admiral said:

Yes of course they do Gina! My mistake. Doh! . Sorry for raising a red herring.

Ian

No worries.  I need people to check my designs and theories.

[ollypenrice]

I have an article in the pipleline on making megamosaics. The hard part is going to be generating the template which defines the image's geometry. Do you have a plan for how to do this?

In using a rig like this for mosaics, one bonus will be losing the need for precise alignment of the optical systems. There will be no need for the edges of one channel's image to be aligned with the other channels. They can overlap in different places, possibly with advantage.

Most exciting!

Olly

[Gina]

I'm not sure how to do it ATM, Olly.  I have done it a bit in the past but not with PixInsight which I'm using now.  Should be fun 🤣

[teoria_del_big_bang]

Wow Gina, that's one heck of a project for the new year., not one for the faint-hearted 🙂 

Do you intend the final rig to be 3D printed in plastic or do you think it will need to be machined ?

I am guessing there are some hurdles to get over with this project such as keeping the cameras rigid enough yet able to rotate freely., but if anyone can do it my money is on you 🙂 

Can't wait to see your progress with this it really does interest me.

Steve

[Gina]

Here are a couple more screenshots showing the complete assembly with both camera mounting plates, dovetail and most of the parts.  Cables and connectors left out for clarity (well that's what I'm saying 🤣)  Same with the remote focussing which clamps round the lenses.  May add that later as it is relevant.

[andrew s]

Hi @Gina if the cameras can freely rotate in the two plates what stops them slipping back and forth? Maybe it's just not shown.

Regards Andrew 

[Gina]

You are right - forgot to mention that.  The gears stop cameras sliding forward and I shall be adding detachable plates to stop sliding backwards.

[andrew s]

3 minutes ago, Gina said:

You are right - forgot to mention that.  The gears stop cameras sliding forward and I shall be adding detachable plates to stop sliding backwards.

Thanks, I do also worry about the rolling friction v stability any thoughts on this? Teflon pads?

Regards Andrew 

[Gina]

I have had various thoughts but the camera bodies seem to turn quite smoothly on 3D printed PLA so I'm trying that initially.  This is definitely an experimental project so u8pgrades may be required.

[teoria_del_big_bang]

I wonder if temperature changes will affect the rotation, if the PLA gets very cold will that contract more than the body of the cameras. 
Coefficient of expansion PLA 68µm/m-°C,  aluminium about 23 µm/m-°C (I think that's right).
At a diameter of about 80 mm then 10 degrees fall in temperature may mean the hole closes up by about 40 to 50 micron (very rough in head calculation) so no sure how much this will affect your initial clearance you have. Apologies if my very rough calculations are wrong.

Regarding the movement front to back that is limited by the gears then as the lenses are directly on the cameras this movement I guess some movement here would have no affect on the actual image, it just needs some limitation of the movement to stop cameras falling out.

Steve

[Gina]

I wondered about temperature changes myself.  All I can do is "suck it and see" I think

[teoria_del_big_bang]

6 minutes ago, Gina said:

I wondered about temperature changes myself.  All I can do is "suck it and see" I think

Yep, print one and chuck it in the freezer for a while and try again see if i takes a difference. 

Steve

[Gina]

22 hours ago, teoria_del_big_bang said:

Do you intend the final rig to be 3D printed in plastic or do you think it will need to be machined ?

Can't wait to see your progress with this it really does interest me.

Steve

Thanks Steve.  I intend this to be 3D printed.

[Gina]

Printing the front plate.  ).8mm nozzle and 0.5mm layer height.

[teoria_del_big_bang]

Big area to extremes of bed, I have my fingers crossed for no warping. 🤞

With PLA i am sure this will be nice and flat Gina 🙂 

Steve

[Gina]

No warping and has printed well.  I shall be bringing my imaging rig indoors a bit later to see how things fit.  I have also printed one of the camera gears.