John

I know quite a bit about the AZ100 Alan - I had two of the early ones to beta test and I performed some tweaking to them under the guidance of Rowan Astronomy. I'm in no way knocking the AZ100. I realize why it costs what it does but that does put it out of reach for many. When the AZ100 was first mentioned (by FLO I think) early thoughts were that it might fall into the sort of price range that I was hoping for but it was not to be and I can see why. So the niche is still there - perhaps Rowan can fill it as @johninderby suggests

I did actually use the HB filter last night - by accident ! I was observing the Dumbbell with my 100mm refractor and wanted to see what impact the Astronomik O-III would have. In dim light I selected the Astronomik HB instead, installed it and spent a frustrating 10 minutes wondering why I could not see M27 at all with the filter when it had been quite nice without a filter. And then the penny dropped ..... I did actually manage to see a trace of the Dumbbell eventually with the HB but it was virtually invisible compared with the filterless view. The O-III bought out the halo surrounding the core very nicely - when I managed to find the right filter. Obviously M27 is not a good HB filter target !

I have an Astronomik HB. I use it very rarely. It did help me to (eventually) see the Horsehead Nebula but I have to be honest and say that is the only object that I have actually managed to see with it. I'm pleased that I have the filter if that was it's only achievement after a few years of trying. I know there are some other HB targets out there. I probably need to put more time into those.

Back in August last year I posted this in a thread on heavy duty alt-azimuth mounts: Shortly after that the AZ100 was announced and, after some beta testing, shipped to very happy customers. The AZ100 is a wonderful mount and, having sampled a couple of units, I can see why it is priced as it is. However, even in it's basic form, once you have a DT clamp, a counterweight bar and a weight, it is a £1000+ mount. Having reminded myself of the post I made back in August, I still feel the niche that I mentioned is still there. We need a heavy duty alt -azimuth mount that sits between the Skytee II / Giro Ercole and the high end £1K glories that the AZ100, APM Maxload etc. Something priced around £400-£500 ready to use. My one regret about the AZ100, as soon as I saw the pricing, was that whatever it's qualities (and it has lots), it has missed this niche

Interesting report, thanks for posting it Developing a taste for Tele Vue's ? - expensive !!!

That's what I do - play around and see what works best

This post on another forum by the filter expert David Knisely is worth a read: https://www.cloudynights.com/topic/549184-narrow-and-broad-band-contrast-filters-and-exit-pupil/?p=7417928

I keep my eyepieces at a warmer than outside temperature to stop them misting or dewing. Other than that, I've not found dewing an issue with my 12 inch dob Where we live and I observe from is 300 ft above sea level so maybe that makes a difference ?

Yes - the Dumbbell is great with and without filters.

I was observing the Veil last night with my 100mm refractor. Both the UHC (an older Meade 4000) and O-III (Astronomik) filters showed the east and west segments quite nicely. In the field of view that I had last night, I could only fit one segment in at a time ! Without a filter = no nebulosity to be seen at all ! The O-III nicely bought out the halo surround the "apple core" of the Dumbell nebula as well. You need dark skies though - these filters are not "magic bullets" if there is much light pollution about.

In due course you will want to have both but a UHC is useful on a wider range of targets. The "kick" that the O-III gives to the Veil, Owl and others is highly addictive as well though ! Maybe get the UHC now and start saving for an O-III ?

I think Rob is primarily a visual astronomer.

I've been observing the binary stars in Lyra this evening with my Tak FC100-DL. Rather an impromptu session because the forecast was not for clear skies. Lots to choose from in this small but lovely constellation. A first for me, as far as I recall, is Beta 648 which is close to Gamma Lyrae. I got a definite split of this close uneven brightness pair at 281x and 300x. The 8th magnitude secondary lies at a position angle of 251 degrees from the magnitude 5.3 primary and the separation is currently 1.2 arc seconds according to the Cambridge Double Star Atlas. I confirmed these details after getting the split and the PA seems to match where I could see the dim secondary star, just ahead and a wee bit south of the primary as the pair drifted from east to west across the field of view. The primary appeared to be pale yellow and the secondary star greyish. A nice one to get in 100mm of aperture and I can't recall getting it before

I'm not a chemist either but I believe that isopropyl does react with aluminum. Which is why I wondered if this mirror did not have overcoating, or had poor quality overcoating.

I agree - my point was that some mirrors don't have an overcoating (quartz or otherwise) I was wondering if those would be affected by the isopropanol.

This thread has moved on from eyepieces I see !

As I understand it, mirrors are usually overcoated ie: have a protective coating applied over the reflective coatings. It has been known for certain brands not to apply overcoats to their mirrors. The mirror works fine but the reflective coatings degrade faster than they normally would had the overcoating been applied. It is possible that a mirror that is not overcoated could react differently to a coated one when something like isopropyl is applied. Unfortunately it is not possible to tell an overcoated mirror from a non-overcoated one just by it's appearance.

Great - I'll replace the original link with that one. Thanks for the feedback

Some interesting developments in the pipeline for the AZ100 by the look of this https://www.cloudynights.com/topic/708353-rowan-astronomy-az100-arrived/?p=10275688

I think this might be a working link to the original article: https://www2.wwnorton.com/college/astronomy/astro21/sandt/startright.html

You are right. It seems as if the original piece has been taken down now. Shame because it was a good one but I guess 11 years have gone by. I'll see if I can find something to replace it.

I think you would need a refractor of around 10 inches / 250mm in aperture to equal a 12 inch dobsonian on deep sky objects. The budgets would not be comparable for such instruments The refractor you are think of must be 140mm in aperture ?

The Nagler T520mm was one of my favourite 2 inch eyepieces for quite a time. It was a wrench to let it go but I had to fund the 21mm Ethos somehow

Making the best of the imperfect is what we are about I think

Ask on this forum - somebody on here will have used / owned the item in question and you should get opinions quickly. UK Astro Buy & Sell is much better than buying from e.bay in my experience - it's run by astronomers for astronomers.