Peter Drew

Another good one is GONG solar 

47 minutes ago, vlaiv said:

If I'm not mistaken, Lunt 40 has front mounted etalon while PST has etalon in that unit at the back together with blocking filter and diagonal - the thing that gets transplanted to larger scope.

With front mounted etalon - you don't really care how fast the optics behind it is - because etalon is working in collimated beam that arrives at aperture. With rear mounted etalon - its working in converging beam and it's optimized for some angle of convergence (it actually has diverging lens that makes beam collimated again and then another converging lens behind the etalon - again, if I'm not mistaken).

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.

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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!    🙂 

1 hour ago, maw lod qan said:

9 metre. Wow, my standard mind quickly visualized 27'!

How tall did that turn out?

Any chance of an image?

I think I could happily set that up for living!

30 minutes ago, Stephenstargazer said:

Following with interest as considering simìlar possiblity after house move 🫰. Do the 'pro domers'  have a minimum size to recommend ?

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.     🙂

I think this may well be a terrestrial version   There is no provision for a finder and the male threading on the rearmost end will not accept an eyepiece but possibly a camera.  its also possible that the last component is actually an eyepiece. I have a few of around that vintage and they have a very small exit aperture that defines the exit pupil to improve terrestrial contrast.  Finally there could be yet another tube to screw on to the end thread, terrestrial erecting systems of the period had a number of translation lenses that gave a lot of back focus.  Have you tried a look through it?      🙂 

As mentioned by others, the pressure pads under the locking screws would be my first port of call as they are likely to be stuck.  The bearings on the old EQ5 are plain metal and the grease may have hardened over time.  If stripped and cleaned, re-grease with something like Superlube, not lithium grease which is too thin.     🙂  

Yes, you can use a 50mm aperture refractor or larger.  The larger refractor will probably be a better telescope but it will still operate only as a 50mm.      🙂 

Are you sure that it is the blocking filter that needs replacing?  It's usually the ITF filter, the one that is fitted before the blocking filter that fails and needs replacing.      🙂

Could cable management have anything to do with the problem?        🙂

Referring back to the original photo there is probably another clutch between the motor and the worm shaft, this is to protect the motor should something restrict the rotation of the wormwheel.  It is the bushing next to the motor output.  There are two rows of grub screws forming the connection, one set possibly fixed to the motor shaft and the other connecting the worm shaft with some facility for slippage in the event of a problem.  If this is the case it is another area for unwanted drive variation.      🙂