Dual rig DSO imagers, the Moon can be your friend

[JamesF]

11 minutes ago, wimvb said:

Btw, does @Tomatobro have the original focuser on his MN190, or an upgrade?

On mine I have a motorised Moonlite, because that was what was fitted when I bought it.  Sadly rather like Göran, mine has been sitting on a shelf for some time, waiting for other work in the observatory to be completed.

James

[wimvb]

3 minutes ago, gorann said:

If it is not on the same mount, it does not count as a dual rig, does it?

It gets twice the amount of data in one night, AND has the advantage of imaging two objects at the same time, or doing simultaneous mosaicing. Whatever you call it, it makes more sense than spending time and money to fix this

[gorann]

2 minutes ago, wimvb said:

It gets twice the amount of data in one night, AND has the advantage of imaging two objects at the same time, or doing simultaneous mosaicing. Whatever you call it, it makes more sense than spending time and money to fix this

One of the plans for my dual RASA 8 rig that I will put together for the next season is to enable just that, have them look at like that guy in the picture producing a two panel mosaic in one night!

[wimvb]

But you gents are thinking too small

the current rig is at 2 times 24 telephoto lenses. What do you call that? (Other than asking for trouble)

[wimvb]

9 minutes ago, JamesF said:

On mine I have a motorised Moonlite, because that was what was fitted when I bought it.  Sadly rather like Göran, mine has been sitting on a shelf for some time, waiting for other work in the observatory to be completed.

James

Unfortunately that seems the sad story of the MN190. I get the impression that people replace them sooner or later.

[JamesF]

3 minutes ago, wimvb said:

Unfortunately that seems the sad story of the MN190. I get the impression that people replace them sooner or later.

I have no intention of getting rid of mine, but since I got the observatory partially up and running, clear nights have been sufficiently rare that I've wanted to be actually doing stuff rather than making kit work.  The time will come though...

James

[JamesF]

10 minutes ago, wimvb said:

But you gents are thinking too small

the current rig is at 2 times 24 telephoto lenses. What do you call that? (Other than asking for trouble)

Well, there's no denying it's ambitious   It's always good to think big, I reckon.

James

[wimvb]

17 minutes ago, gorann said:

Quite a few mounts would handle a dual MN190 rig but the question is if the primary mirrors stay steady in place - dual reflectors could be a challenge if the mirror move on the scope that does not have the OAG on it.

Differential flexure. If you are careful enough and adjust the mirror clamps the same, then as long as the mirrors move the same, differential flexure may be manageable. But just another reason to have two mounts.

[gorann]

2 minutes ago, JamesF said:

I have no intention of getting rid of mine, but since I got the observatory partially up and running, clear nights have been sufficiently rare that I've wanted to be actually doing stuff rather than making kit work.  The time will come though...

James

My thought too, one day the time will come for the MN190 - I just could not resist buying mine since I found it in a local ad in mint condition for near to nothing - apparently they are hard to sell since people do not undertand what it is.

[wimvb]

3 minutes ago, JamesF said:

Well, there's no denying it's ambitious   It's always good to think big, I reckon.

James

It’s a university project; always enough students handy to tinker with it.

[gorann]

6 minutes ago, wimvb said:

Differential flexure. If you are careful enough and adjust the mirror clamps the same, then as long as the mirrors move the same, differential flexure may be manageable. But just another reason to have two mounts.

Yes, I have heard of the problem and hope that it is minor for RASAs at FL 400mm. The flexure problmen should be the same for refractors, but with reflectors mirrors may move but I though that would be small slips that happen once or twice in a night, and then there will probably still be enough to stack.

Edited May 25, 2021 by gorann

[wimvb]

I think it will depend on how the mirrors are held in their cell. Either accurate adjustments of clamps, or silicone blobs to ”glue” the mirrors. Either way, as long as the mirrors move in tandem, it should be ok.

[Tomatobro]

2 hours ago, wimvb said:

Btw, does @Tomatobro have the original focuser on his MN190, or an upgrade?

Still the original focuser but with a Nema17 stepper motor running through a 6mm 0.2 pitch timing belt. The motor hub is 20 tooth and the driven hub is 100 tooth. This 5 to one reduction runs on the 10 to one spindle (50:1 overall ratio). I have rebuilt and adjusted the focuser and it just about holds the weight of the camera and filter wheel. A upgraded focuser is on the list. The controller is a HitecAstro one (Black case version).

I will post a picture of the setup tomorrow

[Tomatobro]

[tomato]

12 hours ago, wimvb said:

But you gents are thinking too small

the current rig is at 2 times 24 telephoto lenses. What do you call that? (Other than asking for trouble)

It is starting to look like the compound eye of some giant robotic insect. That Paramount will be earning it's keep.

[wimvb]

25 minutes ago, tomato said:

It is starting to look like the compound eye of some giant robotic insect.

A dragonfly actually. It’s called the dragonfly telephoto array, and is configured this way to study extremely faint structures.

https://www.dragonflytelescope.org/

[JamesF]

OMG! as the kewl kids say...

[wimvb]

One could do a budget version of this with samyang lenses and ASI1600 or ASI294MC.

[JamesF]

3 minutes ago, wimvb said:

One could do a budget version of this with samyang lenses and ASI1600 or ASI294MC.

For some definitions of "budget" :)

James

[wimvb]

1 minute ago, JamesF said:

For some definitions of "budget"

James

It’s all relative [to the original, which uses high end Canon telephoto lenses].