Would this dual rig combo work?

[tomato]

This project is a real prospect now so I would appreciate opinions on if it stands a chance of success, particularly with regard to combining the subs from each scope and camera configuration for a single image. 

Scope and camera no. 1:

Esprit 150 and G2-8300 taking luminance

Scope and camera no. 2:

Altair 102 mm Apo and Atik 314 OSC taking RGB.

All mounted piggy back on a Mesu 200, guiding with a separate 60mm scope and camera.

Targets will be principally galaxies.

Assuming all the mechanical and imaging issues are sorted (how’s that for a sweeping assumption?) and even though the FOVs and arcsec/pixel resolutions are different,  I think APP could put the subs together, I have successfully combined subs taken with both cameras on the Altair using this software.

I do like the idea of significantly increasing the imaging time on a single target, the scopes are going on the same mount anyway so worth a try?

Any views on a better camera choice than the Atik?

[vlaiv]

Why Atik 314? Any particular reason (like having one, or being able to purchase cheap second hand)?

If not, and if still in budget, why not something like Atik 460EXc OSC?

According to this, it is a bit better match:

http://astronomy.tools/calculators/field_of_view/?fov[]=267||8||1|1|0&fov[]=267||2||1|1|0&fov[]=161||102||1|1|0&messier=8

Large pixel of 314 will produce rather poor color resolution, 460 will be a bit better at this (remember these are OSC cameras, so debayering needs to be taken into account) due to a bit smaller pixels (but not too small).

[Tomatobro]

The other camera that Tomato will have access to is the Atik Horizon Cmos 4644 x 3506 4.54 um. the G2 is 3358 x 2536 5.4 um.

I guess this would be better than the 314L but what do others think?

[ollypenrice]

This may have some relevance:

I have tried using TEC140 luminance on Tak FSQ106 RGB. It is horrible. One might have expected Tak RGB to look like roughly TEC RGB binned 2x2 but it simply doesn't. I can only guess at why this is but it may be to do with the fact that stars are point sources so the TEC finds many more of them with its larger aperture. (The image scales un-binned are 1.8"PP and 3.5"PP.) The TEC certainly does find more stars - many more - than the smaller Taks and the stars are much smaller. I do blend TEC data into Tak widefields but just to enhance key areas, and I tend to blend TEC LRGB, not TEC luminance, when doing so. I never blend TEC data at full opacity, either.

I'm not suggesting that using lower resolution OSC would be impossible but my experience above suggests that the mismatch in aperture should not be too great. Working only from pixel scale may not predict the true outcome.

Olly

[tomato]

Thanks Olly, interesting observations. This set up is what we will have to hand first off, so it might be worth experimenting, there is nothing to lose in trying.

With Tomatobro’s Atik Horizon on the Altair the pixel resolutions would be almost the same on each rig, but I hadn’t counted on the impact of the different light gathering capacities. And one is a CCD and the other is a CMOS, plenty to get stuck into.

First off, we do have the challenge of getting the dual rig to work.

 

[ollypenrice]

Best of luck and keep us posted.

Olly

[tomato]

Thanks Vlaiv and Olly, 

I’ll start a thread on the engineering aspects once all of the main components come together.

[swag72]

It's certainly worth trying...... nothing ventured, nothing gained. For me hindsight is a wonderful thing and I'm not altogether sure I'd have tackled the dual rig in the same way as I ultimately did. But it's too far down the road now so it has to continue.

[ollypenrice]

3 minutes ago, swag72 said:

It's certainly worth trying...... nothing ventured, nothing gained. For me hindsight is a wonderful thing and I'm not altogether sure I'd have tackled the dual rig in the same way as I ultimately did. But it's too far down the road now so it has to continue.

What would you do differently, S?

Olly

[swag72]

3 minutes ago, ollypenrice said:

What would you do differently, S?

Olly

I would have bought 2xHEQ5's and mounted each scope and it's associated paraphernalia separately. 

[ian_bird]

3 hours ago, swag72 said:

3 hours ago, ollypenrice said:

What would you do differently, S?

Olly

I would have bought 2xHEQ5's and mounted each scope and it's associated paraphernalia separately. 

Gulp! Oh well. I'm already down the route of a single mount with two scopes.

And to be honest my wife would probably reach for the knife drawer if I suggested two mounts! 

Cheers

Ian

[ollypenrice]

12 hours ago, swag72 said:

I would have bought 2xHEQ5's and mounted each scope and it's associated paraphernalia separately. 

Wow, that's a surprise. Elsewhere you've mentioned hassles with PC and motor focuser but none of this strikes me as being down to the presence of two scopes on one mount. Wouldn't you have had these problems on separate mounts? Is there some aspect of the dual mounting which has brought new issues?

While some people are surprised to find our dual rig so 'manual' I wonder if this isn't part of its success. Inevitably you have two motor focusers, for instance, and they are not particularly reliable. Anecdotally I know of lots of failed units. And I've also sent back enough of those USB hub devices (of two makes) on behalf of their robotic owners to know that I'd rather put up with the extra cables. I also think that two computers make life easier than using one.

It's odd that we have had such different experiences of dual rigs but there you go. This is a funny game. 

Olly

[tomato]

That is a really interesting comment Sara. Totally separate rigs I guess keep the unknowns to a minimum, you just follow the tried and tested routine but do everything twice. On the other hand, a single guided mount, if it’s up to the job, must remove a number of variables out of the equation but certainly not less expensive. 

I don’t think one PC ‘to rule them all’ would work for me, that would surely be fraught with problems and be a source of major frustration?

[swag72]

1 hour ago, ollypenrice said:

Wow, that's a surprise. Elsewhere you've mentioned hassles with PC and motor focuser but none of this strikes me as being down to the presence of two scopes on one mount. Wouldn't you have had these problems on separate mounts? Is there some aspect of the dual mounting which has brought new issues?

While some people are surprised to find our dual rig so 'manual' I wonder if this isn't part of its success. Inevitably you have two motor focusers, for instance, and they are not particularly reliable. Anecdotally I know of lots of failed units. And I've also sent back enough of those USB hub devices (of two makes) on behalf of their robotic owners to know that I'd rather put up with the extra cables. I also think that two computers make life easier than using one.

It's odd that we have had such different experiences of dual rigs but there you go. This is a funny game. 

Olly

Sure almost all of the hassles that I've had (apart from flexure) would have been the same on two separate rigs, but all of the issues would have felt less 'huge' on two separate rigs. Also, I would have got imaging from the start whereas if you remember I fought with the clamshells initially for months as well and had to buy rings all round....... I could have still used the OAG on one of the camera's....... 2 computers is easier for sure.... Yes, with hindsight I would have gone for 2 HEQ5's

[ollypenrice]

6 hours ago, swag72 said:

Sure almost all of the hassles that I've had (apart from flexure) would have been the same on two separate rigs, but all of the issues would have felt less 'huge' on two separate rigs. Also, I would have got imaging from the start whereas if you remember I fought with the clamshells initially for months as well and had to buy rings all round....... I could have still used the OAG on one of the camera's....... 2 computers is easier for sure.... Yes, with hindsight I would have gone for 2 HEQ5's

Yes, the clamshells problem was bad luck, for sure. (For anyone reading this, the clamshell style mount is OK for imaging if the guidescope is mounted on the main scope like a finder guider, or if you're using an OAG. But it doesn't hold the tube stiffly enough for a dual rig and the guider cannot 'see' any flexure the clamshells introduce. You do need good tube rings.)

If we try the dual TEC140 idea we might not have the easy ride which we had with the Taks, especially at 0.9"PP. Hmmm, is this a good idea???

Olly

[kirkster501]

On 28/02/2018 at 13:20, ollypenrice said:

 

I have tried using TEC140 luminance on Tak FSQ106 RGB. It is horrible. One might have expected Tak RGB to look like roughly TEC RGB binned 2x2 but it simply doesn't. I can only guess at why this is but it may be to do with the fact that stars are point sources so the TEC finds many more of them with its larger aperture.

I tried that too (with FSQ85 in my case) and I agree, Olly,  it does not work at all. I thought Pixinsight (other image scale tools are available too) would rescale so I could mix and match.  Not so.  The stars look mad.

[kirkster501]

This is my dual rig side-by-side.  Took me a while to get this all sorted and cabled but is is now working great and meridian flips perfectly.  I just need to neaten the cables up a bit with 30 and 50cm USB cables).  I just run one Ethernet cable to the PC mounted atop the FSQ and one power cable to the 12V PowerPole distribution atrip.  The PC has 10 x USB2 ports.

Next step is a guide scope (my ED80 that I use for solar) and I can then run both scopes and camera's simultaneously.

 

[tomato]

Nice rig Kirkster, good to see a Mesu handling this level of hardware given we are going with an Esprit 150 and an Altair 102.

[sloz1664]

That's one hell of a setup Steve. Getting all the wiring correct must have been a nightmare. BTW how did you align the scopes.

Steve

[RayD]

Impressive Steve. You must be well pleased.

Cabling is always a chore.  You may already know, but if you want custom length leads for your Lakesides, Peter will make you one up to your exact requirements for a very reasonable cost.  he's done a couple for me and pops them in the post next day 

 

[kirkster501]

On 03/03/2018 at 18:03, sloz1664 said:

That's one hell of a setup Steve. Getting all the wiring correct must have been a nightmare. BTW how did you align the scopes.

Steve

Incredibly they are aligned to within about 20 arc minutes without me doing anything Steve.  I have repeated this by removing the scopes and replacing them and again, I am pretty much aligned again.  That said these scopes offer such different FoV's that I am not really doing dual imaging just yet for the same image.  I just run both as seperate scopes.

[kirkster501]

On 03/03/2018 at 18:23, RayD said:

Impressive Steve. You must be well pleased.

Cabling is always a chore.  You may already know, but if you want custom length leads for your Lakesides, Peter will make you one up to your exact requirements for a very reasonable cost.  he's done a couple for me and pops them in the post next day 

 

Thanks for letttign me know Ray.  I now use a 20cm USB for the FSQ Ray as I never manually focus with that scope - it is a pure AP scope and always under software control.

However, I use the TEC for visual as well lunar AP. So I need to be able to move the TEC control box off of the scope so I can control the focuser with the control box manually in my hands.  So that has a 1.5m USB lead.

[ollypenrice]

57 minutes ago, kirkster501 said:

Incredibly they are aligned to within about 20 arc minutes without me doing anything Steve.  I have repeated this by removing the scopes and replacing them and again, I am pretty much aligned again.  That said these scopes offer such different FoV's that I am not really doing dual imaging just yet for the same image.  I just run both as seperate scopes.

Wow, that's good going! Our pair of Taks were miles out.

Olly