Peter Drew

I have often asked an audience how many stars can be seen with the naked eye on a clear dark night. The truth is none. They are so far away that only the light from them can be seen. An analogy is being able to see the light from a torch several miles away but you can't see the torch. So what you see is just where the stars are. Or are they? They will have changed position since the light started off. 🙂

During the period when a SCT is reaching thermal equilibrium warm air rises from the tube system supporting the sliding mirror facility. This can manifest itself by distorting a star image similar to that of your image. It shouldn't persist eventually once equilibrium is attained. 🙂

Could be a temperature plume though this would depend on the camera orientation. 🙂

I made a "Luntonado" by fitting a Lunt 35mm front etalon to a 40mm PST. The results were amazing but unfortunately the Lunt 35mm etalon became decontacted for some unknown reason. ☹️

That is my understanding. 🙂

A Newtonian parabola is no guarantee of improved performance over a sphere at F8 in a relatively entry level telescope. Parabolic accuracy can range between 1/2 and 1/20 wave depending on how much you are prepared to spend. A "cheap" parabola may also include a turned edge, zones or surface roughness, a good sphere which is potentially easier to produce would likely outperform a so-so parabola. 🙂

Another good one is GONG solar

You are correct. 🙂

I've said this before but the main reason these mounts break or end up with bent adjusting screws is because the mount pivots are set too tight at the factory. I would urge all owners to back off the adjusting screws and check whether the mount axis can be rocked by hand without undue pressure. If it can't then the side plates need removing and the pivot axis nuts slackened off a bit. 🙂

Thanks Asc. Bedford was my home town before I moved up North. A bit far away to be much help unless all else fails. 🙂

Hello Asc. Welcome to SGL. Where are you based? I might be able to help. 🙂

For small refractors, specially ones for solar , I use an AZ3, Why?, mainly because it has good manual slow motions. It is also relatively light, sturdy and steady if set up properly and can be modified to overcome imbalance issues for high altitude viewing. Also inexpensive! 🙂

This sounds a little odd, do you have an image of the set-up? 🙂

There is usually some sort of pad between the clutch lever and the RA shaft to protect the shaft being marred . Your symptoms suggest that although the lever is released, the pad remains jammed.

Good luck, hope it all works out. 🙂

I have fixed "sheds" that house 30", 20" and 17" Dobsonians plus one for a 50x 300mm binoscope and one under construction for a 150mm binoscope. They are deployed only during suitable weather conditions. Two run off housings ran off in gales! 🙂

Yes. Domes are never too big, only ever too small. I have had a self build 9metre aluminium dome for 24 years and we're still short of room! 🙂

I've had several items of Russian manufacture and found them to be far better than their price suggests. The binoculars are rugged, well collimated at point of purchase and give sharp images both day or night. If anything they give a slightly dimmer or warm image compared to more expensive makes, possibly due to the heavy looking coatings. The 10x50 "Tento" models were so cheap when introduced I use to buy them and then cut them up to make excellent finders. I salvaged the prisms for other purposes and when I supplied some to a laboratory they tested them as being 1/10 wave accuracy. 🙂

Same view naked eye as shown by PaulM in his latest image but in monochrome. Arcs from the East are interlocking overhead with those from the East. Photos don't do justice to the enormous scale. Hints of pink now. 🙂

Very obvious from here in W Yorks. Faint rays of silver grey with the naked eye. Quite extensive and visible overhead with averted vision, no other colour noted. 🙂

"Remember me" ? 🙂

If there is no glass in the component that I suggested removing then the small hole is what defines the field stop of a system of lenses nearer the prime objective. There would then be another tube screwed to the threaded portion that also contains a set of lenses, this is what creates the image erection, the furthest end of this last tube will include a female thread to accept a RAS fit eyepiece. It appears that this tube and an eyepiece may be missing. 🙂

Unscrew the final piece that has the external thread on it and see if there is any glass in it. 🙂

Be prepared to pull the drawtube out a long way! Why wait until tonight, much easier to try it out in daylight. 🙂