Jupiter 6/12 from Bembridge

[michael.h.f.wilkinson]

Very nice results. Love the animations

[robbie c]

Great animations Jake 

[neil phillips]

Neil,

Thanks for the caution on the mirror cell, that's probably saved me from an expensive disappointment.    I've done some searching on a glow in the dark collimation cap, though there seems to be little info out there, or a commercial source.     Have you made your own one, using a standard colli cap and some luminous tape?  Or do you recall where you acquired yours?    I have a nagging feeling that we've already had this conversation last year, though I haven't been able to dig the original thread up, though you've mentioned this method in a number of previous SGL threads.

The laser will be an advantage for tweaking from the back of a long tube, though I can just reach on my F4.8 - I have no idea how you can manage this with the F6.3    The other advantage with the laser is it will allow me to tilt the ota and asses the degree of flop.   The mirror cell has three nylon centering screws, which I have gently tightened to minimise the play, but I have been cautious to avoid over doing this.     Perhaps I could replace these with some shims/packing, which would work over a larger area.     I need to remove the cell to check and replace the centre marker, so will give it some more thought.   It will also give me the chance to replace the springs and some better primary adjustment knobs.

Sounds like good ideas from Lee there Jake.

I once talked to Emil, about this, and if I remember the convo. He said something like he never felt the need to replace to a 9 point. with he's 10" Meade.

I think larger sizes above 10 it certainly becomes essential. The colli cap I got secondhand Jake off here. but I cant remember from who ? If I find any sources I will let you know.  

The Glow has died, I need to paint it with glow paint. So I have been using the laser which seems to be quite accurate. Considering many say the Barlowed laser is better.

My laser  straight, coincided well with both colli cap. And Cheshire. So to rely on that I would check against other methods to be sure Jake.

BTW I use Wing nuts for the primary too. And also like Lee a fan and vent holes. I even drilled vent holes in the back of the ally cell. So Theres holes both in the back plate. and cell. reasoning was some air could get to the mirror a little more. My mirror now cools and stays cool better than the original design.

Glad I can help. its what forums are for sharing our knowledge, so we can all do the best we can. And as you say even sometimes prevent rash moves.

I collimate with my laser by memorizing how the laser moves with each screw. ( doesn't always work lol ) and moving back and forth. its too long to do it from the primary end alone, back and forth is a pain.

[SnakeyJ]

I got my Hotech this morning in the post, though did not get the chance to play until an hour ago.    I first checked with the OTA pointing south in a horizontal position (which is my normal parked position).   The secondary alignment was about 15mm off the centre of the primary.    A few tweaks with the secondary collimation screws and I was nicely centred, the cross hair pattern really helps with this.   A couple of minor tweaks with the primary collimation bolts and I had centred the laser on the 45deg display.   I slewed the mount round to Betelgeuse, watching for any deviation on the face.    Looked pretty good until it past the home position and then the primary shifted notably, when it arrived at Betelgeuse I had almost the same error as when starting.   I adjusted the secondary again to find the centre of the primary and then repeated the primary adjustment.    Then I slewed to Pollux (which is about the position that I will start observing Jupiter tonight) - the collimation seemed to hold up well.    I replaced the hotec with my FW and camera and Pollux was showing nice concentric circles in IR both sides of focus.

Jupiter is low but visible to my western horizon, but another hour or so should see it clear the trees.   Hopefully the cloud will hold off so that I can have a quick test run tonight.

Not a very scientific test, but there is definitely a significant flop in the mirror/cell, which I will try to remedy this week.     The hotec is a very nice piece of kit and massive improvement on my cheap Nexgen laser collimator.   The SCA seems to fit the OC1 focuser very nicely and is reassuringly solid when locked off.

[Pete Presland]

Nice animatiions, always interesting to see the difference in detail on an animation from frame to frame.

[neil phillips]

I got my Hotech this morning in the post, though did not get the chance to play until an hour ago.    I first checked with the OTA pointing south in a horizontal position (which is my normal parked position).   The secondary alignment was about 15mm off the centre of the primary.    A few tweaks with the secondary collimation screws and I was nicely centred, the cross hair pattern really helps with this.   A couple of minor tweaks with the primary collimation bolts and I had centred the laser on the 45deg display.   I slewed the mount round to Betelgeuse, watching for any deviation on the face.    Looked pretty good until it past the home position and then the primary shifted notably, when it arrived at Betelgeuse I had almost the same error as when starting.   I adjusted the secondary again to find the centre of the primary and then repeated the primary adjustment.    Then I slewed to Pollux (which is about the position that I will start observing Jupiter tonight) - the collimation seemed to hold up well.    I replaced the hotec with my FW and camera and Pollux was showing nice concentric circles in IR both sides of focus.

Jupiter is low but visible to my western horizon, but another hour or so should see it clear the trees.   Hopefully the cloud will hold off so that I can have a quick test run tonight.

Not a very scientific test, but there is definitely a significant flop in the mirror/cell, which I will try to remedy this week.     The hotec is a very nice piece of kit and massive improvement on my cheap Nexgen laser collimator.   The SCA seems to fit the OC1 focuser very nicely and is reassuringly solid when locked off.

Good work Jake,sounds like you got the problem nailed. After a while you get to know where the flop will happen. I even know which screw will correct the flop on the primary. Though the amount to move it still does require a laser to be sure, It is a pain to have to take the camera out to re collimate .But I only have to do it once in the night.

Better to remove the flop agreed Jake. for while I experimented with the nylon screws.but was never confident I hadn't caused astigmatism. So I prefer a slight flop. It proves to me the mirror is properly free. But if you can take it out, and be sure of no pressure.Even better The extra precision in collimation is worth it especially at F4.8