Off aixs flares were an issue for the CDK17 as well. It required several solutions in my case. A redesigned secondary shroud that covered the last 3-4m of mirror, baffles that went in the primary tube and also the corrector. And the last one was around the primary mirror itself where it meets the tube.
Hey Marcus! I've just caught up with all this and it is all looking very impressive! Although it is an annoying issue the problem with reflections of the edge of the flattener should be relatively easy to fix.
I'm looking forward to seeing some high-res shots from you real soon
Off aixs flares were an issue for the CDK17 as well. It required several solutions in my case. A redesigned secondary shroud that covered the last 3-4m of mirror, baffles that went in the primary tube and also the corrector. And the last one was around the primary mirror itself where it meets the tube.
Greg.
Quote:
Originally Posted by David Fitz-Henr
Hey Marcus! I've just caught up with all this and it is all looking very impressive! Although it is an annoying issue the problem with reflections of the edge of the flattener should be relatively easy to fix.
I'm looking forward to seeing some high-res shots from you real soon
Thanks guys. Yes, stray light usually just requires some additional baffling and that's what OS are intending to provide me. In the meantime I bought some flocking board (heavy & light) and self adhesive tape.
Using the heavy board I fashioned a crude secondary shroud enlargement in the form of a truncated cone (think of one of those protective dog collars). I enlarged the obstruction from 44% to just over 48%.
Using the tape I flocked all the trusses
I flocked the full length primary baffle using the light board
I extended the primary baffle by 10mm
I made 2 ring baffles out of heavy black art paper and placed one at the back end of the primary baffle and one just in front of the flattener. It's a bit of guess work without ray trace and schematic diagrams so I just eyeballed it
I flocked strategically inside the imaging train in two places - there were a couple of obvious shiny spots.
Flats show some vignetting but it's not bad - 18% at the extreme corners of the STL (see CCDInspector result below). No doubt the official OS fix will be better that this!
I just need the weather to go away now to test, but I'm crossing my fingers that I've done enough to start imaging!!
Last edited by marc4darkskies; 27-01-2014 at 12:15 PM.
I flocked my trusses as well but I did not notice any difference from this. What I did notice made a difference was the angled secondary shroud Planewave made and the primary mirror baffle. Baffles around the corrector made a small difference but not that noticeable to me (perhaps more than I realise as once something does not flare when it would have before you really need the same field before and after to see the difference).
I see Astronomics promote the fact they blacken the edges of their secondary mirror and the corrector lenses. Something to consider. I haven't done that myself but wonder if its worth it.
I flocked my trusses as well but I did not notice any difference from this. What I did notice made a difference was the angled secondary shroud Planewave made and the primary mirror baffle. Baffles around the corrector made a small difference but not that noticeable to me (perhaps more than I realise as once something does not flare when it would have before you really need the same field before and after to see the difference).
I see Astronomics promote the fact they blacken the edges of their secondary mirror and the corrector lenses. Something to consider. I haven't done that myself but wonder if its worth it.
Greg.
Hard to say what has the biggest effect but flocking the trusses will help. I also had fairly shiny plastic netting around one truss hiding a ribbon cable to the secondary that was probably a significant contributor. In any case, there is almost no part on the inside of a scope that doesn't contribute to stray light so the best thing you can do is to get totally flocked!
My flocking and baffling effort worked a treat! Beautifully contrasty flat field (after applying the flat of course).
I did have other issues crop up though - unrelated to the scope. Guiding artifacts suggesting my PME probably needs a spring plunger adjustment to accomodate the heavier load (around 45kg). My Obs lappy is suffering BSODs that I think are caused by overheating (Toshiba Qosmios have a reputation for doing that). If the theory is correct I think I have a work around for it.
The good news is that OS have designed quite a clever fix for my problem so I can do away with my secondary dog collar and primary baffle extension. ETA uncertain but not far away I think! Their fix means my secondary obstruction will return to 44% (before I added the dog collar)
Marcus does the secondary mirror have blackened edges? Also the corrector?
I saw an ad for Astronomic telescope and they were promoting blackened edges of the secondary and the corrector lenses.
The Planewave isn't.
Greg.
I don't know. I haven't asked nor has that been advertised. In any case, the result after flocking & baffling tells me nothing more is needed. I'll let you know after I've imaged the Horsehead with Alnitak out of frame!
This gives you an idea where I'm at right now. THIS IS ONLY A TEST IMAGE of the the field I'm using for the commissioning process, replete with guiding errors and less than perfect collimation. It's a mere 40 mins of exposure (8 x 5 minute subs) - far less than it would need for a "real" imaging run!!
During this test I discovered I have a guiding problem by virtue of the fact that the payload on the Paramount ME is now larger than before (45kg or nearly 100lb). I believe the spring plunger adjustment on the RA and DEC axes needs some tensioning. The mount's accelaration also needs to be reduced. The stars in this image are actually elongated towards the bottom of the frame in the raw subs and just visible here. The elongation has been disguised by the stacking and stretching I've done - but it's there!! Collimation is also not as good as it can be.
FOV is 38 x 25 arc minutes @ 0.59 arcsec/pixel imaged between 31 and 41 degrees altitude with average seeing. Some cropping to eliminate stacking artifacts. Processing was rough-as-guts minimal with stretching and some noise reduction only. No deconvolution was done.
I'm salivating at the thought of getting a proper imaging run under my belt after I get the issues sorted!!!
Last edited by marc4darkskies; 01-02-2014 at 08:43 AM.
Looking good Marcus. Elongated stars at the bottom of an image but not at the top would indicate a tilt problem rather than a tracking problem which would be global.
You may need to shim your adapter to pack it up on one side. A bit of trial and error.
Which night was that? We had good seeing 2 nights and bad seeing on another. Thurs night was the bad seeing night and Wed and Fri were good.
Looking good Marcus. Elongated stars at the bottom of an image but not at the top would indicate a tilt problem rather than a tracking problem which would be global.
You may need to shim your adapter to pack it up on one side. A bit of trial and error.
Which night was that? We had good seeing 2 nights and bad seeing on another. Thurs night was the bad seeing night and Wed and Fri were good.
Greg.
In the raw files the elongation is about equal but there may be some tilt as well. There were other obvious symptoms of acceleration and spring plunger issues - elongation in the direction of travel when calibrating. One step at a time though!!
I did this on Sunday and Monday nights (above average seeing) - but I only had short tinkering sessions because they were work nights. I was also also dealing with BSODs (maybe resolved) and trying to get the rotator to work in synchrony with CCDAP and TheSkyX (unresolved)
In the raw files the elongation is about equal but there may be some tilt as well. There were other obvious symptoms of acceleration and spring plunger issues - elongation in the direction of travel when calibrating. One step at a time though!!
I did this on Sunday and Monday nights (above average seeing) - but I only had short tinkering sessions because they were work nights. I was also also dealing with BSODs (maybe resolved) and trying to get the rotator to work in synchrony with CCDAP and TheSkyX (unresolved)
Oh Gawd, getting devices to work with Sky X - ouch. I can't get it to connect properly to my SX camera. I am sure they will get there eventually.
I sometimes see elongation when callibrating. Not always though. So that is a symptom is something needing adjustment?
Oh Gawd, getting devices to work with Sky X - ouch. I can't get it to connect properly to my SX camera. I am sure they will get there eventually.
I sometimes see elongation when callibrating. Not always though. So that is a symptom is something needing adjustment?
Greg.
It's not TheSkyX - it's more CCDAP->TheSkyX. I think I'm just doing domething dumb. I've NEVER had trouble getting anything to work with TheSkyX.
Well, if the payload on your PME is large, the inertia of the scope may cause the worm to ride up on the gears when it stops & starts - a kind of slop I guess. The spring plunger adjustment instructions say when the payload gets to 100lb then the spring plunger screws should be 2 turns out (pushing the worm against the gear harder), not 2.5, and slew speed should be reduced to 75%.
This gives you an idea where I'm at right now. THIS IS ONLY A TEST IMAGE of the the field I'm using for the commissioning process, replete with guiding errors and less than perfect collimation. It's a mere 40 mins of exposure (8 x 5 minute subs) - far less than it would need for a "real" imaging run!!
During this test I discovered I have a guiding problem by virtue of the fact that the payload on the Paramount ME is now larger than before (45kg or nearly 100lb). I believe the spring plunger adjustment on the RA and DEC axes needs some tensioning. The mount's accelaration also needs to be reduced. The stars in this image are actually elongated towards the bottom of the frame in the raw subs and just visible here. The elongation has been disguised by the stacking and stretching I've done - but it's there!! Collimation is also not as good as it can be.
FOV is 38 x 25 arc minutes @ 0.59 arcsec/pixel imaged between 31 and 41 degrees altitude with average seeing. Some cropping to eliminate stacking artifacts. Processing was rough-as-guts minimal with stretching and some noise reduction only. No deconvolution was done.
I'm salivating at the thought of getting a proper imaging run under my belt after I get the issues sorted!!!
Looking good Marcus viewed at 70% in my browser you wouldn't know there was a problem so when it is sorted you look to be on a winner ...regarding the PME issues (I hear about a lot of these ) get yourself an old Tak NJP mount...loaded up to the hilt and no PEC or ProTrack... it just keeps on keeping on... ...in the 9 years I have had it not one mount adjustment has been made (touch wood)...can't do a meridian flip or remote stuff though ...still, wouldn't mind me a PME
....I was also also dealing with BSODs (maybe resolved) and trying to get the rotator to work in synchrony with CCDAP and TheSkyX (unresolved)
Got the same drama myself. The rotator will not connect in SkyX when commanded by CCDAP. It will work though if you connect rotator in CCDAP alone. Something to consider.
Looking good Marcus viewed at 70% in my browser you wouldn't know there was a problem
Now why didn't I think of that!! You should see underneath our rugs at home - there's so much dirt under there I keep tripping on them!
Quote:
Originally Posted by strongmanmike
...regarding the PME issues (I hear about a lot of these )
My PME is a gem (pun intended). So it's not so much an issue or problem but an adjustment. They do say to adjust spring plungers depending on the payload.
Quote:
Originally Posted by strongmanmike
...old Tak NJP mount...loaded up to the hilt and no PEC or ProTrack... it just keeps on keeping on... ...in the 9 years I have had it not one mount adjustment has been made (touch wood)...
Try putting 46kg on it?
Quote:
Originally Posted by multiweb
No pressure. All forgiven then...
Seriously I can't see anything wrong with that field. When's first light you tease.
The annoying thing is ... I attempted to fine tune collimation yesterday and completely ballsed it up! I've still got my collimation L-plates on!!! Tell you what ... this large aperture commissioning stuff is not for the faint of heart!
EDIT: My stray light issue set me back a couple of weeks, otherwise I'd have been imaging by now.
Quote:
Originally Posted by Paul Haese
Got the same drama myself. The rotator will not connect in SkyX when commanded by CCDAP. It will work though if you connect rotator in CCDAP alone. Something to consider.
Everything connects fine and works in TheSkyX and CCDAP, but CCDAP doesn't move it to the right angle when I start a session. Some kind of offset I think. I'm just controlling it from TheSkyX "manually" at the moment. I can also link it to the FOV indicator in TSX and it works fine. I'll figure it out when I fix my collimation blunder.
Guiding artifacts suggesting my PME probably needs a spring plunger adjustment to accomodate the heavier load (around 45kg).
I wonder what they put in those scopes to make them so heavy? Is the construction lightweight, or does it just not matter on the big mount?
Btw, is that with or without counterweights...? If you have another 45kgs of metal sitting at the other end of the shaft then the inertia must be quite a bit when making fast guiding corrections. What guiding frequency to you plan to use?
Just for comparison, although mine is a bit smaller at 12.5" it's weighing in at 16kgs which rides very smoothly on the Losmandy G-11 I figure a 14" version would push it to maybe 18kgs.
Although it is an annoying issue the problem with reflections of the edge of the flattener should be relatively easy to fix.
...regarding the PME issues (I hear about a lot of these 
) get yourself an 
...loaded up to the hilt and no PEC or ProTrack... it just 
...still, wouldn't mind me a PME 
I've still got my collimation L-plates on!!! Tell you what ... this large aperture commissioning stuff is not for the faint of heart! 
I wonder what they put in those scopes to make them so heavy? Is the construction lightweight, or does it just not matter on the big mount?
