John

I'm hoping for some clear skies tonight to give the Rowan AZ100 a run out with my 130mm triplet refractor on board. Since setting the scope and mount up blue skies have been replaced with a cloud layer but perhaps that will give way to something better in due course.

While I wait for darkness, here are some more photos of the mount. This mount head has been upgraded by Rowan to have what they term as damping knobs fitted to the altitude and azimuth axes. The purpose of these is to allow some adjustment to the mesh of the worm gears to obtain the smoothest motion when a heavy and potentially slightly imbalaced load is on board. The original mount head that I was sent has had the same modifications made and is now with @Stu for him to test in parallel with my own trials.

The head pictured here does not have encoders fitted (hence the plates covering the openings in the body of the mount) because I will be testing the mount as a manual one. @Stu will be giving the Nexus Digital Setting Circles unit and the encoders a thorough work out during his tests.

I must say that Dave at Rowan Astronomy has been really responsive to feedback that I've provided on the mount so far - thanks Dave

Just to remind readers that the units that @Stu and I have are pre-production versions so there may still be small variations to the final product

I thought for a moment that the guys in the distance with the yellow hi-vis vests and hats on were working on your observatory !

The scope is OK but it's way undermounted in my opinion - the mount is about the equivalent of a Skywatcher EQ3-2 and the aluminum tripod is hopeless with such a scope on board. You would need to invest in a replacement mount and tripod which is going to add £200 or more to what you pay. overall.

Now if you could get the scope tube alone for well under £100 and make a DIY dobsonian mount for it, you might have a lot of observing potential for very little outlay

This is a 9 year old thread.

Bristol Astronomical Society are holding a Telescope Surgery in the evening of Friday 22nd November.

Those who are thinking of getting a scope or binoculars or those that have them but don't feel that they are getting much out of them are welcome to come along, with or without their equipment. There is no charge.

A range of astronomy equipment will be present and Bristol AS members will be pleased to talk about their instruments. There will also be a short presentation introducing practical amateur astronomy and the range of equipment currently available.

If anyone is interested please message me on this forum in the first instance so that I can give the Society some idea of numbers of potential attendees and equipment that might be bought along.

The event will start at 7:00 pm and will take place at the Bristol Photographic Society, details at the top of this webpage:

http://www.bristolastrosoc.org.uk/www/pages/resources/faq.php

Robin Hood and the merry men !

2 minutes ago, j4y7223 said:

😐🔫

Fair point

To get back to your original question, at the focal ratio that the 130 / 900 is operating at, I think a spherical figure will work fine.

I've used one of these scopes (unmodified) and it performed pretty well for it's aperture on a wide range of targets.

I wonder if the FT dual speed addition has any side affect on the stability of the focuser ?

I don't get sideways play with my R&P focusers - the tension on the grub screws on the top of the focuser pushes the drawtube onto the guiding strips / shims which seems to keep the drawtube from moving from side to side.

I'm going to be mobile on the day of the event. I did manage to catch a few minutes of the last one from my graden but that was down to luck and a little gap in the otherwise solid cloud layer that day.

I'll probably use my Vixen ED102SS and the Lunt Herschel Wedge - on the AZ-4 mount it's a pretty mobile setup.

15 minutes ago, joe aguiar said:

....just saying

Feel free to say - the more opinions, the better

Sikhote Alin specimens can vary quite a lot in appearance. If they have not been cleaned since being picked from the ground they can look like Kn4ftys piece as can uncleaned or "as found" Canyon Diablo, Nantan and other irons.

The cleaned up specimens fall into two further types, the ragged, twisted pieces known as "shrapnel" such as Lukeskywalkers specimens and the sculpted individual pieces that show reglmaglypts, flow lines and roll over lips (AKA flight markings).

Needless to say, the nicely shaped individuals that show these flight markings are the most sought after and most expensive !

I used to have a 200g piece that looked like the one below but sold it years ago to fund more astro gear. I sometimes wish I'd kept it

I've owned an AVX and an HEQ5 and I think the C9.25 would be more comfortable on the HEQ5. The AVX would carry it but it would be somewhat closer to it's limits. I didn't have any issues with my AVX but I have read about plenty of frustrating stuff from other owners. The HEQ5 is a well proven mount. Not perfect but it's quirks are well known and there is plenty of info out there on how to deal with them.

3 hours ago, mikeDnight said:

I tried adjusting my DC focuser shortly after I bought the scope, as it was quite stiff. Using the three grub screws to adjust the tension I ended up making a bit of a mess of things, ending with very noticeable image shift. I phoned Nick Hudson at True Tech, who told me to remove the pinion, loosen off the three grub screws so the draw tube slides freely. Then he said to tighten each grub screw equally, counting the turns on each, until the draw tube friction moves smoothly. Then reassemble the pinion, gently tightening the two screws. It took me a couple of attempts, but the focuser image shift and the initial stiffness that prompted my intervention disappeared. I also attached the Tak micro focuser. It seems image shift is the result of the three grub screws being unevenly tightened!

Thats very similar to Vixen's advice for their R&P focuser (lower one for refractors):

http://miltonhill.us/Tele/Vixen_Focuser.html

It does work !

28 minutes ago, daaveyboy said:

Hi many thanks for your reply, regarding the mount I have a 10 Micron that will handles it OK.

As this is a new set up I have not had any good skies to set it up, hopefully this will change soon.

I agree - the weather has been very poor for observing or imaging lately. Hopefully it will get better and with the clocks changing soon, we can enjoy the Autumn / Winter skies

You mention that you are considering an 11” HD edge F/10 OTA. Have you considered what mount you will use it on ?

One of my society friends has one of these on the Celestron fork mount. A very capable scope but having helped him set it up and take it down they are large and heavy scopes - definitely not "grab and go" !

Sorry to hear about these problems.

The trouble is, once you have had some negative experiences with a piece of kit, it can be difficult to build up confidence and enthusiasm in it again.

I'm sure FLO will do all they can to help though.

How is coma impacting your view of the Moon Piero ?

I replaced the finder bracket on a couple of Meade refractors that I used to own. I did need to remove the focuser in both cases to be able to get to the nuts on the small screws that hold the bracket in place.

I found that the SCT type vixen / skywatcher compatible finder bracket bolted on using the existing holes in the tube so no drilling was required. This is what the bracket looked like that I found fitted (it is the bottom one in this picture):

The Pup star follows the primary star as it drifts across the field of view with the mount undriven.

The separation is around 10 arc seconds so thats not the challenge - it's spotting the much fainter star amidst the glare from the primary that is the trick.

I did it 1st with my 12 inch dob a few years back and I've since got the split with my 130mm refractor and my Tak 100 but not as yet with the ED120 !

The seeing conditions are a key part of spotting the Pup - they can make or break the attempt.

The focusser on my DL was a little stiff when I got it so I adjusted the grub screws slightly which has made it spot on. No side to side movement on mine though

Have you tried adusting the screws on the bottom of the focuser that tension the pinion ?. They are under the plate that covers the pinion mechanism:

Is it the finder bracket that is attached to the scope that you want to replace or the one that holds the finder scope ?

The Topic refractor looks very similar to my 1960's Tasco 60mm. The focuser wheels and lens cell / dew shield design are exactly the same.

These were sold under a variety of brand names back then. I think they might have been made by Towa - check to see if there is a "circle-T" logo on the label.

15 hours ago, JamesF said:

Yes, I see it with my ST102 as well.  For some reason it seemed even worse on the ST120.James

It would be. False colour increases with aperture if the focal ratio stays the same.

With a little TLC that will be a super scope !

Vixen made stuff for Celestron back in the 1980's and 90's.

The mount is a Vixen Polaris but I'm sure you know that.

The focusing arrangement on the scope was unusual using a side to side movement with the whole secondary assembly moving back and forth along the optical axis as I recall.

46 minutes ago, Mick H said:

It can also get expensive if you don't know if your buying the wrong bit/thing, EP 🤑.

Thats why forums like SGL can bs so useful - just keep asking the questions, there is a heck of a lot of experience on here