John

I've recently learned that a colleague at the Bristol A S has an APM/LZOS 152mm F/7.9 triplet. I just need to persuade him to let me have a look though it now, when the clouds allow ! Although the last thing I want to get is "LZOS aperture fever" looking at the current prices 🙄

Very nice ! Where did that clear patch of sky come from ????? Nothing doing here tonight - drizzle and solid cloud 😒

In your situation I would try and raise the additional funds for a Tak FC100. I don't think the Tak FC76, lovely scope though I'm sure it is, would deliver much more than your WO73 does, apart from the 3mm of additional aperture.

I believe the same source was rather sceptical a while back about reports (on SGL I recall) of seeing Sirius B with modest instruments.

For interest, this document is the specification that APM gave LZOS for the objectives. It is in the public domain (APM post it on their website) so it's not breaking any confidentiality: APMApo-Linsen-Spezifikationen.pdf My understanding is that LZOS supply the individual objective testing data to APM to demonstrate that they meet the specification. APM choose to include them with scopes and objectives when they are sold. In the past I've seen independent tests of LZOS objectives which have matched or (more usually) slightly bettered the ones supplied by LZOS.

After my eye has adjusted, I usually get a faint halo of resolved stars around the brighter globular clusters and the unresolved portions have a sparkling texture when using my 100mm - 120mm refractors. With a 150mm - 200mm scope they start to look a bit more like their images and with 250mm-300mm they can be quite stunning. It does depend on the globular though - some are more condensed than others. After many years observing I find these days that I can usually see most of what larger apertures show with a smaller aperture but I have to work that much harder to tease it out. Sometimes it's right on the edge of visibility. I have sometimes thought that using a large aperture scope vs a smaller one is a bit like the difference between 1.1 litre car and 2.5 litre (we had these for a while). The small engined car could certainly push along at 70 mph on the motorway but the larger one did it with a lot more ease and the engine was barely turning over (or at least gave that impression). I'll probably regret that analogy - car comparisons usually backfire when used on astro forums 🙄

The views of globular clusters seem to improve with aperture more than most astro targets IMHO.

As well as the focuser check mentioned above, once you have done that you can check for objective tilt using a cheshire collimator:

I really enjoyed reading your review Matthew. Thank you so much for compiling it and posting the link 👍 Yours is undoubtedly the most comprehensive review of this instrument that I have read to date. Yours and my 130mm F/9.2 objectives come from different ends of the manufacturing life of the optic. Mine is from 2006 and yours 2017 from the optical test certificates. Mine is a mid-range .965 strehl whereas yours is in the top tier for the objectives. LZOS measure in green light. As you so rightly say though, these figures are only a small part of the story. In the field (where it matters !) my scope delivers the best pure optical performance that I have experienced from any telescope I've owned / used. It would be interesting to know how many of these there are in the UK. I know of one other SGL member who has one (apart from yourself). There are probably a few more out there I guess but they are not a commonly encountered instrument. Thanks again for the excellent and comprehensive review. I will probably print off a copy to hold with the other documentation I have on these scopes 🙂

That could give a 160mm apo refractor a run for it's money at about 25% of the cost 🙂

One issue that has affected me (non-bladder related !) is that having been in the hobby for quite a long time, when the conditions are doubtful it can be quite hard to get motivated. It helps if there is some new gear or modification to try out or a special event in the sky to try and see though 🙂 That is also why doing some outreach is important to me perhaps more so now than it was in the past. Being with folks seeing things for the first time is almost as good as seeing them yourself for the first time 🙂 I have occasionally thought about selling up most of my portable stuff, buying a big dob and a small mobile home with a trailer for the dob and travelling around just showing people the sky. I suppose it's following in the John Dobson tradition in an odd way 🤔 Not sure my other half would approve of me turning into a type of wandering astronomy minstrel though 🙄

I've had two outreach sessions over the past couple of weeks that did turn out reasonably clear. Last Saturday was particularly good. I'm using the good vibes that I got from those sessions to sustain me to the next clear night. The exclamations from folks seeing Saturn and Jupiter for the first time through a scope do help to re-charge the enthusiasm 👍

Great report Rob 👍 Reminds us of the wonders that are up there if only the cloud cover would shift ! I had the pleasure of observing through a couple of 20 inch dobs at SGL star parties a few years back and the views of targets such as M51 and M13 are still etched in my memory 😁

Apart from the wider field of view, there is probably not a lot of difference in the performance. Especially in an F/11 mak-cassegrain which are not too hard on eyepieces. I doubt that the Baader zoom will show you anything that the SVbony will not.

It has been a poor year hasn't it ? 😔 I look around my scopes and other equipment from time to time and wonder if I might as well let it all go except for one setup and a few half decent eyepieces. The trouble is, with everyone else seemingly having an equally frustrating time, who would want it 🤔 I have not quite reached the "sewing machine acquisition" threshold yet though. If I do, my mum is a keen quilter and has a number of the things. Maybe I'll offer her a "hobby swap" 😁 My other half keeps telling me that I must find a hobby that I can do when the weather is cloudy. I'm still working on that ....... One of my favourite quotes is from Snoopy of the "Peanuts". He told Charlie Brown once that the secret of life is to own a convertable car and a lake. That way, when it's raining, you can think "well, at least my lake is filling up" 🙂 You just need the lake now @Stu 👍

I have one of these, as well as the more expensive Baader 8mm-24mm zoom: Hyperflex 7.2mm-21.5mm Eyepiece | First Light Optics The Hyperflex 7.2mm-21.5mm has a narrower field of view than the Baader but is a surprisingly (for it's price) sharp eyepiece. I've not used one of the SVbony mid-range zooms so I don't know how it compares with those 🤔

I can understand why Tele Vue stopped at 21mm for their 100's.

Excellent report and sketches 🙂 So much to explore in and around the Veil Nebula. Here is a nice guide to stuff to look for by Bob King on the Sky & Telescope website: Explore the Veil Nebula - Sky & Telescope - Sky & Telescope (skyandtelescope.org)

Plossls have eye relief that is around 70% of their focal length. The eye relief stated can be misleading if the eye lens top surface is heavily concave or the eye lens is inset below the eyepiece top or below an inflexible eye cup. Actual useable eye relief can be somewhat less due to these factors. Edit: apologies - I am repeating what I have already posted earlier in this thread 🙄

I've replied to your other thread on this:

There are some calculators on this web page which might help. They are designed for those making their own eyepieces: Astronomy Boy: Eyepiece Focal Length Calculators

Those DPAC tests that they discuss on CN tell some interesting stories about correction in differing wavelengths of light.

It's only a matter of time before the forum gets renamed "Satellite Gazers Lounge" 🙄

Yep. I think it's 10mm for the EQ3-2, EQ5, Skytee II and HEQ5 and steps up to 12mm for the EQ6. Edit: actually it is the lower thread that the OP is interested in (that holds the eyepiece tray) and I think that might be 12mm 🤔

We saw something similar from here in the west country on Saturday evening at about that time. I was at an outreach event with Bristol AS. A chain of lights appeared to rise up from the western horizon in a straight line and then winked out one by one as they went into the earths shadow.