24 June 2020 at 8:26 am #574653
Where can I obtain mirror locks?
Essex UK24 June 2020 at 8:49 am #582678
My C14 (in 2014) came with these bolts to secure the mirror. They were screwed through the back of the tube to secure the mirror fixed in place and needed to be removed or at least loosened so the telescope could be operated. There were strict instructions that they should not be used to lock the mirror during observations. Celestron said it was okay to remove them completely. (Unless the telescope was to be shifted – which was what they were designed for, they were not to be used.) So I removed them completely and stored them appropriately labelled. I covered the holes with adhesive rubber pads. I don’t know whether this has helped… Maybe they can be safely used by a responsible adult… Where to get them? Perhaps from Celestron or a dealer. You can see the ‘mirror lock screws’ in the attached image.
I seem to have very little image shift anyway, but my work is not critical.24 June 2020 at 8:52 am #58267924 June 2020 at 9:49 am #582680Daryl DobbsParticipant
Rother Valley Optics or 365 Astronomy might be worth contacting, I needed similar fixings but can’t remember which one had them? Both companies were very helpful.25 June 2020 at 10:06 am #582683
Peter and Daryl,
Thanks for your replies.
Jack29 June 2020 at 4:25 pm #582702David ArdittiParticipant
The bolts that are supplied with the telescope are about 2″ long, smooth-shanked and threaded with a ¼” Whitworth thread in the top ½”.
They work by the thread engaging with the mirror cell while the unthreaded section passes through the hole in the back of the scope and the knob clamps tight. Owing the varying mirror position at different focus points, I am not sure if they would succeed in in locking the mirror at any point in its focus range, or not.
Assuming they do, and assuming you are using one optical configuration with camera at a fixed distance out in a Crayford or similar focuser, I don’t see why you should not lock the mirror in position with these screws after you have established the approximate focus point for the mirror, with the Crayford in the middle of its range, to give a bit of temperature compensation around that point. However, I have not tried this. I tend to do my critical work around the same part of the sky, the meridian, so the collimation does not change much.29 June 2020 at 8:16 pm #582704
These bolts were not supplied with my previously owned C14.
I just have the 2 transport locking bolts 1″ long.
Rother Valley optics cannot obtain these accessories. I will try 365 Astronomy.
Jack30 June 2020 at 3:48 pm #582707Mr Andrew Jonathan WilsonKeymaster
I hope you don’t mind but I thought I’d ask what problem it is you are trying to solve.
I remember you were having issues with wavelength shift in your spectrograph. If this is the problem then I don’t think mirror flop in the telescope is likely to be the cause.
Of course if you are having trouble with shifting position of the star when you cross the meridian then that would be fixed by solving mirror flop.
Andy30 June 2020 at 4:14 pm #582708
I don’t mind at all.
I thought Schmit C’s suffered from this, there was an issue with focussing, after winding the focussing knob backwards and forwards a few times (which has to be done regularly), spectra are much sharper, perhaps it was that.
Jack30 June 2020 at 4:26 pm #582709Roy HughesParticipant
I was curious. So I googled around and found this site giving a DIY version of what you are trying to do.
Certainly looks do-able, advisable?, who knows.
Hope this helps.
Roy30 June 2020 at 9:37 pm #582710Michael O’ConnellParticipant
I use a pair of eye bolts and they work very well.2 July 2020 at 2:22 pm #582713
Ingenious ! how long and what thread are the eyebolts ?
Jack2 July 2020 at 2:23 pm #582714
Thanks for the link, very informative.
Jack2 July 2020 at 2:27 pm #582715
What do you use the secure the eye bolts, can see something but not in detail ?
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