Yet Another Triple Imaging Rig

[Gina]

For the future - I am only thinking about this project ATM

I have an Esprit 80ED Pro and two Evostar ED80 Pro with FR/FF scopes.  Not quite a match but might serve until I can afford three Esprits   Used with these will be three Atik 460EX mono CCD cameras (when I get them all).  I currently have one 460EX and another ready for collection second hand.  If another second hand one doesn't appear in a week or two I shall be buying new from FLO.

I don't think I shall put all three of these scopes on the EQ8 mount with the MN190 but assemble them as a separate imaging rig complete with their own guide system.  Not sure what the latter will be ATM but an OAG on one of the scopes seems favourite rather than adding the ST80.

I know I could sell the Evostars and put the money towards an Esprit but the Evostars are so cheap even new that the return from both would not buy a single Esprit.

With all this new kit in mind I'm just hoping that we will get a much better main astro season than last year!

[Horwig]

Is there no stopping you?

You might be interested in this then, http://www.progressiveastroimaging.com/viewtopic.php?f=13&t=9412

Huw

[Gina]

Is there no stopping you?

You might be interested in this then, http://www.progressiveastroimaging.com/viewtopic.php?f=13&t=9412

Huw

I hope there's no stopping me   That rig in the link is certainly interesting   His mount looks rather strange though   Scopes and cameras are pretty close to what I'm thinking of.  But my mount is an EQ8.

One of my Evostars has a Baader Planetarium dual speed focuser on it and that is a dream but the other has just the original SW focuser.  With just the 460EX cameras and no filter wheel (just a fairly small adapter with built-in filter) the load on the focuser shouldn't be too bad but if I find the SW focuser unsatisfactory I'll do something about it.  Maybe make my own R&P focuser.  Have lathe and 3D printer - "we have the technology"   Ha Ha ...

[Gina]

I have the heavyweight ali plate that I was going to use for the two Evostars and the MN190 that I could use for this, though it's a bit OTT

That plate would take 4 80mm scopes side-by-side so I could use the ST80 as guide scope but I think an OAG or finder-guider might be more suitable.  OTOH there is plenty of spare weight capacity with the EQ8

I guess just screwing all the scopes onto that plate with a Losmandy style dovetail plate underneath would be a quick and easy construction method.

[Chris]

Count me signed up to this thread ! :-)

[DIYASTRO]

Hi Gina,

Go for your ali plate! Its amazing when you have all that mass acting in unison how much flex is created.

You will have seen from my rigs just how many support rods and ties there are between plates, its not for jolly, they need to be there. When I first tried a multi-rig, I was amazed at just how much things move around when you are basically magnifying every error in the construction.

I also find the config of the 'link' a bit odd... with all that technology involved in its fabrication I would have thought that some far better config could have been adopted.

With regards to the focus problems.... this is why I made my own using worm gears and various slow linear movement mechanisms. You know yourself just how small a margin you have with camera lens for focus issues.

Even with duel speed crayfords I use a lower ratio gearing system to drive them, but prefer to build my own units then I know what the tolerance of movement really is.

One day I may get to build the one I described to you in earlier post.... 3 x 12" reflectors with 6" refractor finder scope all doing what you call 'multiple imaging'!

Boyd

[Gina]

Thank you Boyd   Yes, I shall be using the 500mm x 250mm x 10mm ali plate.  And I think I might as well use the ST80 for guiding - more rigid than finder-guider and less messing about than OAG.  Only needs a couple of holes drilled in the plate and assembling - "simples"

Remote focussing is simple - just brackets onto the ali plate to hold stepper motors with timing belts and pulleys to the slo-mo focus knobs.  The Baader SteelTrack even has a timing pulley part on the 11:1 drive - it would be nice if all manufacturers did this, though I've found timing belts directly on the knobs work perfectly well enough.  BTW the stepper motors I use have a 64:1 reduction gearbox built in.  I have another batch on order from China   I'm now using the 12v version.

As for camera lenses, I have found stepper motors and timing belts driving the focus sleeves (with an inverted belt attached to form a timing pulley) perfectly satisfactory.  The inverted timing belt is tensioned with a piece of foam rubber or plastic under the belt where the drive belt doesn't contact it. ie. on the side nearest the stepper motor.  Details are given in my widefield triple imaging rig.

[leelee970]

With all that lovely kit I do hope the cloud Gods are kind to you Gina. 

If not then that big cloud may effect those living close to you. LOL

Lee

[Gina]

Thank you Lee

[Gina]

Seeing as the ali plate was designed (and drilled/tapped) for mounting the MN190 in the middle with the two Evostars either side and that the Esprit is currently mounted on top of the MN190, one option would be to use the same arrangement.  That would save swapping imaging systems when swapping between MN190 and triple ED80s.  The EQ8 mount will take the load   The Lodestar X2 on OAG on MN190 could be used for guiding either imaging system.  It's already being used for guiding the Esprit.

[Gina]

I may be getting a C11 for planetary imaging but I don't think I could add that to the above combo   I will be reinstalling the equipment hoist so swapping assemblies is possible

[Gina]

Just designed and now printing brackets to take the stepper motors for the scope remote focussing.

[Gina]

I said in my first post in this thread that this was a project for the future...  Well, the future is here   I'm working on this project right now   It could even get finished before the widefield triple imaging rig which I'm also working on - side-by-side as it were

[ollypenrice]

Good stuff.

Regarding the choice of scopes, I presume some of them will be mainly collecting narrowband. The difference b

[sloz1664]

Hi Gina,

There is no resting on your laurels with you is there Gina 

i don't envy you with setting up your triple rig. I have had a lot of problems setting up my twin rig with alignment, balance and flexure.

Still not perfect, but I will conquer it.

As always, I wish you well in your myriad of projects  

Steve 

[Gina]

Hi Gina,

There is no resting on your laurels with you is there Gina 

i don't envy you with setting up your triple rig. I have had a lot of problems setting up my twin rig with alignment, balance and flexure.

Still not perfect, but I will conquer it.

As always, I wish you well in your myriad of projects

Steve 

Thank you Steve

I like to keep busy but currently I want to keep my mind on pleasant things and avoid certain other thoughts

I'm using a 10mm thick aluminium plate to connect the scopes so hopefully flexure will be contained within acceptable limits.  I know from results already obtained that the flexure between the MN190 and Esprit 80ED is insignificant as I'm using the MN190 for guiding when imaging with the Esprit.  I may have to elongate the fixing holes for the Evostars and/or use shims to get all three images in alignment.  The Esprit with slightly lower FL will cover a greater FOV so it will probably be just a matter of aligning the Evostars. 

Eventually, when I've collected sufficient funds, I'm hoping to swap the Evostars for Esprits so that the FOV matches.  Currently the focal lengths are 400mm for the Esprit and 510 for the Evostars.  Effectively the Esprit will be working at 510mm FL though still at f5 versus f6.3 for the Evostars.  The better quality of the Esprit image will easily make up for this I believe.

The above will apply once I've acquired another 480EX camera.  I still have one or two 314L+ cameras so may put one of those on the Esprit for initial testing.  That will reverse the FOV situation with the Esprit and 314L+ having the smaller FOV.  Of course, there is the possibility that I shall have sold both 314L+ cameras before the clouds allow testing   Or even found a second hand 460EX to buy

[Grotemobile]

I may be getting a C11 for planetary imaging but I don't think I could add that to the above combo   I will be reinstalling the equipment hoist so swapping assemblies is possible

Hi Gina,i sold my C11 & bought this

http://www.firstlightoptics.com/cpc-deluxe-hd/celestron-cpc-deluxe-800-hd.html

This scope might be 3" smaller, but the

optics, are way in front of the C11.

Never got a picture, with the C11

like this. Just my thoughts.

Steve

[Gina]

Hi Gina,i sold my C11 & bought this

http://www.firstlightoptics.com/cpc-deluxe-hd/celestron-cpc-deluxe-800-hd.html

This scope might be 3" smaller, but the

optics, are way in front of the C11.

Never got a picture, with the C11

like this. Just my thoughts.

Steve

Ah yes, that's a more advanced and higher specced scope.  More expensive of course, but that does include the mount.

[Stu]

Good stuff.

Regarding the choice of scopes, I presume some of them will be mainly collecting narrowband. The difference b

What happened to Olly? Did someone turn him off mid sentence? ;-)

Sent from my iPhone using Tapatalk

[Gina]

I wondered that too   I can answer the first part that did get through though   Yes, practically all my imaging is NB.  Only galaxies and planetary are different.  I generally use the MN190 with EFW2 for galaxies and the C11 with OSC/webcam will be for planetary though there is the faintest of possibilities of a Hyperstar in the future to reduce it to f2 and 560mm FL for DSOs

[Gina]

This photo (from a while back) shows how the two Evostars fit either side of the MN190 - represented by its two scope rings.  The Esprit goes on the ali bar on top.

[ollypenrice]

What happened to Olly? Did someone turn him off mid sentence? ;-)

Sent from my iPhone using Tapatalk

Heheh, the net went down! Drives you potty sometimes out here in the sticks.* Still, no LP.

I was just going to say that with a small chip and a narrowband filter there is precious little difference between a high end apo and an ED80. Really only the speed.

Olly

*But Monique says I was always potty...

[Gina]

Ah yes

[Gina]

Until I get the full setup of 3 Esprit 80EDs and 3 460EXs I shall have to make do with a compromise.  I'm hoping this will still be better than just the Esprit and 460EX with filter wheel.  The resulting resolution will be half that which I'm currently enjoying with the Esprit and 460EX combo but I will be able to capture many more photons in the time. 

I have 1 Esprit 80ED Pro and 2 Evostar 80ED Pro with 0.85 reducers.  The cameras are 2 460EX and 1 314L+.  The only way of combining these to give a similar FOV is with the 314L+ on the Esprit and the two 460EXs on the two Evostars.

Esprit with 314L+ gives a FOV of 1.3 x 1.0 degrees  and a resolution of 3.3 seconds per pixel

Evostar x0.85 with 460EX gives FOV of 1.4 x 1.1 degrees and resolution of 1.6 secs per pixel

Thus the FOV is very similar but the resolution is a factor of over 2:1.  If I were to bin the 460EXs 2x2 the resolution would be 3.7"/p quite similar to the 314L+ on the Esprit and 3 or 4 times the sensitivity. 

Now to the filter arrangement...  I have Ha 5nm, OIII 3nm and SII 5nm which give pretty much a match when used on the same focal ratio and camera.  However, in general Ha is stronger than the other two wavelengths and one option would be to use a 460/Evostar combo unbinned for Ha and use it as a luminance channel on the OIII and SII to give higher resolution while the other channels run at over 3 secs per pixel

Another option is to bin both 460s and use those channels for OIII and SII - I think this will give higher sensitivity due to the 460 being a better camera.  The Ha would then be captured by the 314 on the Esprit.  With similar resolutions this would make for easier processing.

I would appreciate comments on these ideas - thank you   In particular, have I got all this correct?

[Gina]

Been working on this while I've been off-line - I'll post a progress report tomorrow.