badhex

Interesting theory, I had not considered thread depth but that makes sense as a potential cause. One theory I had was that the other filters, (including the one I'm using as an adaptor) all have a shorter thread length than the Astronomik. This means that there are fewer threads mating at any time, and the filter is fully screwed in after fewer turns, so doesn have chance to bind. Although, this only really applies if the issue relates to the Aero ED / Panoptic having a 0.6mm pitch.

Looks great as a little grab and go! Really interested to hear how it performs under the night sky. What's the built in mounting plate like? Sturdy?

It's very odd John and I am also perplexed that others don't seem to have any issues, although perhaps it's just that specific eyepiece and that specific filter 🤔

I did read about that research somewhere on my travels today.t TBH I had assumed that the Aero ED had poor QC or weird threading, but thing that is a bit of a shame is that the extremely expensive Televue behaves exactly the same as the Aero ED. The filter was also expensive, so I'd at least expect the two expensive items to play nicely if they both have good QC and follow the standards.

I look forward to hearing about this!

Had the EPs and filters out today to do a bit of testing, and also did a bit of research online. The issue seems to be that the Astronomik filter is M48x0.75 per Astronomik's website, but it might be that the Aero ED is actually M48x0.6 - and also, it turns out, possibly the Televue Panoptic - although this is unconfirmed. As per SGLers comments earlier in this thread, it does seem that most manufacturers are broadly using 0.75mm pitch standard, but not always, and manufacturing tolerances etc. mean some accessories just don't quite fit with other accessories. I tested a number of my 1.25"-2" adaptors and diagonals which were all fine, but both the Aero ED and Panoptic start to bind after a turn or so, and leave a gap between the filter and the barrel: The filter, on closer inspection does have a small manufacturing issue/blemish where the very last part of the thread is a little malformed, however I do not believe this is the problem as the filter has no problem with the adaptors and diagonals, and it starts to bind well before that part of the thread is in contact with the eyepiece barrels. Looking at the barrel interior itself, I crudely measured the thread as best I could and it definitely seems more like 0.6 than 0.75: I also tested other filters I have and what I did find was that the cheapo skylight filter (none-astro, picked up as part of an ebay bundle) not only fits all of the eyepieces/adaptors perfectly, but will stack and accept the Oiii perfectly as well. With that I mind, I fashioned a lens spanner and removed the filter glass from the skylight filter, and can use it as a 'universal adaptor' of sorts. It will add a few mm onto the optical train but I don't envisage it being a problem.

Slightly off topic, but has anyone here owned both a BGO and BCO in the same FL at the same time and been able to do a direct comparison? @John I know you reviewed the BCOs for FLO some years ago.

I did not know that. Seems daft not to to be following a standard for something so widely used as filters! Hmm, weird. Thanks for checking - surely mine must be the right pitch as well then and maybe it's paint on the thread or something else. Looks like I will have to get everything out tomorrow and do some testing! Will report back.

It's a great scope. Really glad that my original plan to get the TS 70ED didn't work out!

Ah - mine is the 35mm which I understand is technically a 'new' eyepiece and not a clone of the original TMBs. Could it be that the thread is different on the 35mm? Not sure if they use the same bodies or not but seems odd that they wouldn't. I guess it could also be that thread blackening paint is causing the issue but there's definite resistance after a partial turn which feels like a threading mismatch, and I've not been willing to risk tightening it further! I actually have a cheap skyglow which I could perhaps use as a sacrificial lamb. I guess I'd better have a look at it in the daylight which I haven't yet done.

Hello all, Why on earth have the 2" Aero ED / TMB clones got a filter thread that is not the same pitch as standard 2" filters? 🤯 More importantly, is anyone aware of an adaptor that may exist so I can use my expensive Oiii filter in it without fouling up the threads on the filter? I have no clue what pitch the Aero ED is using though.

Lovely little set there Stu!

My word... It's full of eyepieces!

Oh and I was using it with a 35mm Aero ED which didn't help. The threads on that EP are not standard filter threads, I've been meaning to post asking about that.

On your advice @Stu I picked up an Oiii (Astronomik) and did see a portion of the veil (NGC6992) for the very first time! Sadly I didn't really manage to pick up much more of it though. I did struggle getting used to using the filter a bit at first, and I suspect the gibbous moon was drowning out the finer details. I think as well I need to get myself a list of targets - stressful work situations prior to going away meant I didn't plan the sessions ahead of time which was definitely a mistake.

Hello small scope fans! Just wanted to give a very quick update on the ZS73 and travel kit I've been using for a while. So far it has been away on 3 trips to dark (darker, at least) skies and a few sessions at home, and honestly it's been an absolute pleasure. There have been a few refinements to be made with the travel kit itself, but from an optical perspective it really has performed well. I've observed whole stars fields, planets (even Uranus) and nebulae with excellent results. Although not intended for travel kit, I just tested out my new Morpheus 4.5mm and it works really well as a high/highest power EP for this scope. Couldn't be happier!

Funnily enough I was also in the Dodecanese for two weeks in September, although only briefly on Rodos. During my time there with a small scope I realised that I had forgotten that my small travel tripod does not have a spirit level, so I've picked these up and will buy a 3/8" nut to make a bolt-on level. I was also away from home on another trip early Sept and I returned to find that Deutsche Post had thoughtfully decided to ram this parcel containing a book into my postbox 😱🤬 Thankfully the excellent book in question survived miraculously unharmed: Thanks @Ags for creating books that even Deutsche Post can't destroy!

After what seems like an age (I've been on holiday + weather here also poor) I've finally had chance to try out my 4.5mm with the ZS73. I do have a BST in 5mm FL for lightweight travel use, but for use at home where weight is not an issue, I wanted a high-quality, short FL EP for giving me the best possible high-power/planetary views with the ZS73, and I'm happy to say that the Morpheus has nailed it! I found that the most comfortable configuration was with both extension ring on and eyecup folded up, same as the 17.5mm. Actually, I suspect the perfect combo would be with an extension ring that was about half of the optical length, say 4mm, but I can nestle my eye closer into the cup and get the same effect. I had been concerned about the small 0.76mm exit pupil being a problem and causing blackouts, which I'd experienced in a brief daytime viewing session, but happy to say I had no problems under the night skies once I'd played around with the extension ring etc. I started out with Saturn, which was at a reasonable elevation but unfortunately was suffering a little from shimmer, I think due to a nearby chimney or rooftop. In fleeting moments, the view was very crisp, with a surprising level of detail visible and nice clean shadows cast on the surface by the rings. Jupiter was higher up and further east, so it seemed to avoid whatever was causing the swimming effect. At magnitude -2.7 Jupiter was insanely bright even in my light-polluted Bortle 7 skies and I noticed just a little colour haloing on the edges of the disc. This seemed to calm down after a while, so either my eyes adjusted or the scope/EPs were still not sufficiently cooled. That said, Jupiter looked magnificent - crisp, colourful and somehow huge in the eyepiece even at only 96x I also tried using an ND4 filter to tone down the brightness. It did certainly make it a bit easier to pick out detail in the banding, but I'm never sure if I like the dimmer image! Jupiter was the target I used to compare the BST with the Morpheus. I'm surprised at how well the BST stands up, especially given the price tag, but in the end the views through the Morpheus were still better. I wouldn't say that it was a hands-down, streets ahead difference, but the combination of eyelens size, build quality, FOV and crispness/contrast of the image means the Morpheus edges out the BST - in all categories except price! Definitely worth the extra money though if you want to fine tune that last 10-20% of the experience. As Uranus is up and about I thought I'd go for a more challenging target for this combo or scope/EP. What suprises me is that even at 96x and being not super familiar with Uranus and surrounding sky, I was readily able to distinguish the small, pale green/beige from other stars! Of course no detail can be distinguished beyond that with this small scope but it was gratifying nonetheless. Finally, I spent some time with totally different type of target - M57. I have struggled to pick up M57 from my skies before and written about it on SGL - but tonight was no problem at all. Of course it requires averted vision, but it was strikingly obvious as soon as it entered the FOV, much more so than with the BST on other occasions. I actually thought, at first, that I had somehow defocused and was looking at a star, until I realised that I was looking at the ring! All in all a good first night out with the new Morpheus in my collection!

Funnily enough was talking to another member on here who had a 2" 20mm version which had a similar problem. I wonder if these EPs are susceptible for whatever reason? Formulation of the coatings or something. There was no obvious fungal growth on mine but whatever caused it is on the outside of the field lens and the coating has degraded.

I'm yet to write up a report (only got back yesterday), but here is a shot of my ZS73 on recent adventures under bortle 2/3 skies, taken with a Samsung Note 20 Ultra.

Yes, I understand this is very common practice - it's shameful that on top of that is an extra dose of gender discrimination. Plus his whole bit about the "captain not being the same as the crew" or whatever is 🤬

Sorry for the derail Ags! Already looking forward to the next book.

As well as the mechanical considerations, there is also the fact that quite commonly (at least in the UK when I was growing up) 'normal' scissors are ergonomically shaped to fit a righty, but not a lefty. Putting your thumb through that hole is like torture. Observe: Hence the left handed scissors, which are in all aspects (ergonomically and mechanically) mirrored.

This is what worries me Baz! Indeed. The 9mm is presumably about halfway between the two and I suspect would look great sat there instead of the HD60 😂

After 30+ years of struggling with right-handed scissors, it only in the last 5 years occurred to me that we could have TWO pairs of kitchen scissors - lefty for me, righty for my partner. Occasionally, if my pair are momentarily out of sight or drying on the washing up rack and I attempt to use the rightys it basically triggers sudden onset PTSD 😂