niallk

Hi, I've been eyeing up a "Linear" Binoviewer for reaching focus primarily in my lovely lil' Lunt LS50DS, but also potentially for use in my Obsession 15" Classic. I do have a Baader Maxbright BV 1st gen), which was a revelation for plantets / moon in my SW 250px - before i donated that scope to someone. Unfortunately the Maxbright won't come to focus in the Lunt... hence I've been intrigued by the promises of a Linear Binoviewer... plus the Maxbrights + GPC just dont play well with the 15" dob either. Unboxing - comes in a rugged & oversized plastic case: pluckable foam for storing pairs of EPs - very good! The BVs feel heavy, solid and give the impression of being well made: no issues. I have the Moonlight dual speed focusser upgrade on my LS50DS. There's an undercut on the BV which means it waggles in the compression ring fitting in the Moonlight 😖 Not to worry: if i pull it out and clamp on the smooth sides i can still reach focus - phew! 😅 I popped in 2 TV 15mm plossls & roughly adjusted the inter pupil distance. I normally observe with my right eye, so focussed with the Moonlight for my left eye, then used the diopter adjustment on the BV for my right - back to a helical focusser after purchasing the Moonlight! 🤣 Voila! No issues merging, but adjusted the IPD a little more. My first impression was great i see a merged image, but it's a little soft. I iterated on focussing with left eye, then right, the both together via the Moonlight. It takes a little patience, but i got to a point where I'd say the views were almost as sharp as mono - and was removing and comparing with a single mono 15mm. So far I think the views are not quite as sharp - much more complex optical path, but certainly it is very nice to view through both eyes! It's heavy... and caused a little focusser slip with the sun at its highest: had to tighten the lock screw a little for extra friction. I'd say I'm not immediately a convert as i was when i tried my Maxbrights in my 250px on Jupiter. However, i will give them a few more sessions... i really want them to become my default choice, but i love that fine crisp detail achievable mono with a tv plossl and the fine adjustment with the Moonlight. We'll see... will report back! Will also test on the moon in my 15" when i get a chance 😎

Wow!!

Very cool!

No more 12.5" being made, unfortunately!

I've an FT on my 15" dob, and it just works - solidly takes my Paracorr + Ethos EPs, and on occasion a PMx2. Tight tolerances, smooth operation, no discernable 'waggle' or sag. Ive a Moonlight on my Lunt LS50, and it too is great. Tbh, i had a stock focusser on my SW 250px, and i bought the €60 Lacerta dual speed upgrade, and then it became a pleasure to use! Obviously the FT on the 15" is a big step up in quality, but the dual speed upgrade really transformed the stock SW focusser.

Nice one! By chance I caught it visually with my LS50DS on Apr 20th - saw beautiful detail evolve as mass was ejected.

Things could get a bit awkward if my wife ever googled the price of Ethos EPs 😳😂 Or the Lunt double stack etalon... 😳😳😱 I literally haven't bought astro gear for a few years now, and what I have are lifetime investments...

In addition to the other comments, cooling is key too along withcollimation, and I'm also in the habit of checking the jetstream forecast if thinking out viewing planets - seeing needs to be good. The planets need to have reasonable altitude from your location. Seeing due to thermals of concrete & rooftops you can strive to avoid by where you set up. For the higher atmosphere, this link is useful - if you have seen it (or an equivalent): https://www.netweather.tv/charts-and-data/jetstream I don't even bother if the jet stream is overhead...

My 10" was a solid tube Skywatcher 250px, and there focuser travel wan't an issue! Not so for my 15" truss dob... I'm very tempted to get the Astrocrumb filter slide which attaches to the threads on a Feathertouch - ie on the inner 'secondary mirror' side. It encroaches a little into the light path. I only had a cheapo filter wheel from TS, but it was the business in practice: it really became a joy to flick between no filter, UHC, O-III, and I had a neutral density filter in there too for the moon. I'd like to get that sort of convenience back for the 15".

Absolutely, yeah i phrased that poorly - meant lots of targets on which to use it, and it can give a dramatic enhancement; but it's all nicely covered in that famous link! I use the Astronomik O-III, and also their UHC. Next filter I plan to get is a Hb... and an Astrocrumb filter slide at some point. I had a filter wheel for my 10" dob and it was very handy for flicking in - especially when using moderate to high mag and you don't wish to lose your target

Congrats on the scope! My 1st time viewing Ha was at an outreach event through a double stacked 60mm Lunt, and a TV Binovue 😎. The views were exquisite! I'd love to binoview, but can't attain focus in my LS50DS. Enjoy - great activity on the sun these days after a long quiet period

I love my Obsession 15" Classic, but the trusty Skywatcher 250px will always be special as my 1st scope which showed me so much, and I learned a tonne with I wouldn't want my lil' Lunt LS50DS to feel left out ... I love you too!

O-III for sure on DSOs: makes elusive detail visible on a wide range of objects: https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

Nice one & thanks for the link! There was a beautiful clear sky here, so I took a 5 min break from work and on a whim, threw the scope out... wow! Beautiful sight with the most delicate of tendrils connecting the bright ejected mass back to the limb. You could see it evolve in real time. A joy to see 😉😎

It's not visible on Gong, but defo worth a look!

Big prom lifting off... 😎

My mirror is on a sling with a 9 point floating cell. I think what's important is that the mirror doesn't shift in use - after collimation (and i collimate every time i set up). I point my scope at the horizon, lightly push the mirror off the floating cell and let gravity take care of the mirror sitting centred in the sling, gently let it back on to the floating cell, then proceed to point at say 45° and collimate. I do this after the scope has been out for cooldown, and I'm about to start observing. In use, I move my scope smoothly and gently, and aim to set up on reasonably level ground. My scope has 'felt' pads on the 9 contact points, so there's non-zero friction, which helps to suppress slip shift. The actual mirror clips are like a cm from the mirror, not a fraction of a mm 🙂, and only serve to stop the mirror from falling out if the scope was on its side for transport or something... so yep, the mirror should be loose!

Can I ask a probably silly question please (& apologies for veering a bit off topic): when it's said that a smaller aperture suffers less than larger aperture in moderate to poor seeing, do people mean comparing the views at similar magnification? I presume the answer is yes... I tend to check the jetstream forecast before committing to cooling my 15" dob if I want to look at planets. Usually i can then use >= 200x on Jupiter, but I've often been intrigued by all the advocates for a 4" frac!

Haven't used a Delos so limited capacity for giving advice! I do have some Ethos EPs, and the 7 & 13mm T6 Naglers. The N13T6 is a gem of an EP - remarkable performance in such a compact form factor. My first TV purchase, and probably the last one I'd part with. I'd hope you too won't regret picking one up!! 😉

Interesting! I'm travelling with work in the US at the moment and won't be back in time, unfortunately. Enjoy Magnus!

Ffs.... 🙄 There's gonna be a cascading smash up. Edit: Wot @DaveS just said 😂

Mine too - 15" from OMI has an 'x' etched marking the centre, and checks out as the geometric centre, but the 'O' donut sticker was a few mm off. I respotted with a catseye using their handy template... particularly easy with the etched mark too. To the OP, you can just peel the existing one off: you don't need to be overly precious about the centre of the mirror. If you have a ring punch reinforcer, or punch a clean circular hole in a sticker the outer edge doesn't matter for basic laser alignment, only the inner circle placement, if using barlowed method.

I chose to get push-to on my 15": to try to see more on the nights I can get out. I traded the weight of a magnifying optical finder for an AN unit by the EP. It works very well indeed! However, on my 10", it was find myself - and yes it sometimes very frustrating, but when I got a new target there was a sense of exhilaration and achievement that is lacking with push-to. There was also more of a sense of accomplishment in learning my way around the sky over the seasons. When I started it took me 5 nights to find Andromeda 🤣🤣 But wow... when I did!! 😉

To the OP: I upgraded to the Moonlight option - highly recommended! The stock helical focusser is usable, but the fine dual speed control of the Lunt is just what you want to pull out those crisp fine line details 😎

I got this one I think it's the same as the Lunt (but cheaper): https://www.teleskop-express.de/shop/product_info.php/info/p4651_TS-Optics-Premium-Zoom-Eyepiece--7-2-mm-to-21-5-mm---1-25-.html It's pretty handy - performance drops at the 7mm end of the adjustable range, but ~9 -15mm is the range I use the most.