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Tandem Tak, first light.


Guest ollypenrice
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Guest ollypenrice

After an abortive start with an unsatisfactory EQ8 and ADM Maxguider HD we started again using a Mesu 200 and Cassady T GAD tilt pan adjuster. The mount was here already but we (Tom O'Donoghue and I) bought it from Yves. This will be our default rig for guests and when it's free I'll send the data to Tom in Ireland and we'll do joint projects, mostly mosaics. The rig looks like this;


 


Twin%20Tak%20Mesu-Th.jpg


 


...and before midnight on Saturday night, when a big black blob of cloud parked right on our target and nowhere else, we had collected 2 x 3.5 hours on the Cone, our guests' choice of object. After a few minutes with the calculator I found this was really 7 hours  :D  and I was able to say to the cloud, 'Sorry pal, we still have an image....'  The wind, throwing out some nasty sharp gusts, failed to derange the Mesu which really is a competent mount and has still to drop a sub to mount-related guiding issues since it arrived here over two years ago.


 


Here's what we got, in HaLRGB:


 


cone%20twintak%20web-M.jpg


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Guest ollypenrice

Sheila, Steve, we need to set up a triple Tak rig now at SGL :lol: Who's mount can handle it? :D:o

 

Awesome result Olly and I too am seriously green with envy :)

 

The payload for the smallest 10 Micron is marginal. I did think about it because the mounts are so good. Trouble is, the FSQs are heavy and and the tilt-pan device for aligning them is about 6 Kg. I think we are already approaching 35kg.

 

Adding a third one does have to be at least a possibility though. The Mesu should be fine up to about 60kg depending on length of tubes. We need sponsors! Heh heh.

 

Olly

Edited by ollypenrice
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Sheila, Steve, we need to set up a triple Tak rig now at SGL :lol: Who's mount can handle it? :D:o

 

Awesome result Olly and I too am seriously green with envy :)

 

i posted a similar envy when i first saw this.  Well an 85, 106 and 130 might be slightly unbalanced :lol:

would have to be the 8 i suspect although mine would make an attempt at it :lol:

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Guest Kheldar

i posted a similar envy when i first saw this.  Well an 85, 106 and 130 might be slightly unbalanced :lol:

would have to be the 8 i suspect although mine would make an attempt at it :lol:

 

I was thinking more Baby-Tak, Baby-Q and Q just to be on the safe side :lol:

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Guest ollypenrice

I've tried a few mounts. I'll keep the Mesu!


 


Why have different scopes on the mount? The idea with this rig is to work on the same picture but twice as fast. It might also be possible to orientate the scopes to produce two panel mosaics in a single shoot. The Cassady tilt pan would allow us to orientate the two OTAs so as to produce two nicely overlapping panels at the same time. This would be an effective chip size of nearly 7Ox26mm. Scary!!  However, there might be complications arising from guiding. Maybe if your guide star were in the middle of the 'effective chip' region it would be OK but I suspect that the slightest polar misalignment would begin to show as rotation at the edges of the 'instant mosaic.' I'd be happy to stand corrected.


 


Finding that the dual rig could do clean 30 minute subs was a relief because an ealier attempt (at a big-scope dual rig) ran into some peculiar guiding oddities. The mount guided well but one scope always trailed. Others have found this with dual long FL reflectors too.


 


But there is an advantage to twin parallel scopes in terms of S/N ratio. After stacking and calibration there is still residual noise which defeated calibration. (Don't we know it.) But the residual noise is different in both cameras so when their images are combined there is a cancelling effect. This, at least, is my thinking and experience of combining data from two cameras suggests that it is better tahn the result of doubling the subs from the same camera.  (Discuss!)


 


The dream scenario for us would be to swap the older Atk 11000 for the proposed full frame 29 meg they are said to be developing. This would catch the luminance at much higher resolution and the big pixels of the 11 meg would gulp down the colour at 3.5 arcsecs per pixel.


 


Olly


Edited by ollypenrice
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Guest ollypenrice

Olly

 

perhaps it is cos we dont have 2 x 85's or 2 x 106's or 2 x 130's :o  would be nice though :o

 

:D

 

You poor dears! :D 

But what you could do is work on planned projects together. Someone does a widefield with a short FL. Others, with longer FLs, pick certain regions of the widefield to catch in greater detail. You then compose the lot in Registar. We do a fair bit of that down here. It works really well. Even a small amount of long FL data (perhaps just in Lum even) will still boost a widefield in the most exciting of ways.

 

Olly

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