John

I wonder if it is going to be simpler and lest costly to add some locking screws to the current arrangement ?

Well done on finding a good deal on the 8mm. I use 28mm Baader Fine Tuning Rings as 2 inch barrel extensions on my Ethos 13, 8 and 6. Mostly because I can then use 2 inch filters with them.

Yep - I've got the OVL brochures somewhere that show them changing over time. I think the crayford focuser that this thread started out on is the latest focuser type used on this scope. Astrobaby reviewed here 2008 model and that had the crayford fitted, rather to her surprise: http://www.astro-baby.com/reviews/TAL 100RS/TAL 100RS Review.htm The TAL Apolar 125 that I reviewed back in 2011 used a revised version of the crayford focuser as well:

Just a further note on upgrading this. The metal dish piece that forms the end plate of the scope acts as a stiffener for the alloy tube that Orion Optics use. If you replace this piece with another mirror cell, you will also need an end ring to fit the tube otherwise it will simply not be rigid enough. You can see such an end ring in use in this Orion Optics scope fitted with a much more up to date mirror cell: I thought long and hard about upgrading the mirror cell when I had the 10 inch version of this scope and concluded in the end that it was more trouble than it was worth.

Not sure. I like all the ones I've owned / currently own. The 10mm is the only one that I have not owned or used - perhaps that's the best one ! If Don Pensack sees this thread his opinion would be valuable I think.

It's vandalism. If caught doing it you would get charged with putting public property out of action. Do I have to keep repeating myself in this thread ? No suggestions of vandalism or anything else of a similar sort please, or the thread gets locked.

This piece by Phil Harrington is quite useful as well: https://astronomy.com/-/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

I think the Lumicon is a MUCH better choice than the ES. I currently have an ES UHC and it's mediocre to say the least

Sounds like your scope is one of the old Europa models. I had the 10 inch version with the same rather basic collimation / cell arrangements. Seemed to work OK though. My 12 inch dob is slightly more recent and does have locking bolts but I don't tend to use them unless transporting the scope in a car. Perhaps you could add locking bolts to the arrangement that you currently have ?. They are just bolts that press against the bottom of the cell that holds the mirror. Inside the back cover of your scope will look like this:

The seeing was poor here during the short period of clear sky that I had. Iota Cass is usually wonderful with my ED120 but had mushy star definition last night. Saturn and Jupiter were far from their best as well. @Sunshine congrats on Zeta Herc with the 115mm. A tough one ! When the seeing is better I'm enjoying challenging my refractors on Lambda Cygni - another toughie !

That's a great result Stu I have the Lumicon O-III in the 2 inch size and it's my best and most used deep sky filter.

Hi Paul, This article below explains the difference between these types of filters. A UHC filter, if it is properly executed, should fit into the category of narrow band filters explained in the article. The Light Pollution Reduction Filter fits into the category of broad band / LPR filters as explained in the article. I hope that helps a bit : https://www.prairieastronomyclub.org/useful-filters-for-viewing-deep-sky-objects/

I have toyed with the idea of the 10mm Ethos. It is reputed to be one of the best in that range. My frequency of feeling the need for something between the 13mm and 8mm is low though so it's difficult to justify a £600 investment on top of the 10mm Pentax XW I'm obviously not quite 100% addicted !

It looks like some fluid between the lens elements ?

An F/6 is more of an all rounder in my view. Slightly kinder to wide field eyepieces as well.

Welcome to the forum At least you can post on here on how you find the scope and if there is anything that you wish query you will be able to get some feedback on it. Also lots of suggestions on how to test the optics.

My "100"'s are 21mm - 13mm - 8mm - 6mm. These 4 focal lengths are my "staple" set with my 12 inch F/5.3 dob. I have a 1.25" set which I use with my refractors and that has more focal lengths in it so I guess you can make do with less eyepieces if you use 100's. My refractor set includes a 10mm Pentax XW but I only very rarely use it with the dob. I do use the 5mm and 3.5mm XW's with the dob when I want really high magnifications. I do find closer spacing of the short focal lengths useful to get some more choices at higher powers. I did have a 17mm Ethos for a while but found myself often skipping that focal length and going straight to 13mm. I currently have a 17mm ES 92 degrees in that slot because its very good but a lot less expensive than an Ethos 17 so I don't feel so guilty if it does not get much use. I really ought to amalgamate these two eyepiece sets into a single one to serve all my scopes but I suppose I am still to some extent an eyepiece addict. Not the best person to talk you out of expanding your collection, really

Yes - that was a very early model. Don't see many of those for sale now.

I always think your observatory looks like a rather posh if small dining room in which someone has installed a very large telescope Mike !

I have one under another branding and it does not have a T-thread under the rubber eye cup I'm afraid. The eye cup is actually quite difficult to remove and when you do what you are left with is a metal ring that twists up and down (usually with the eye cup on it) but no T-thread. I do think all the versions that you link to are the same eyepiece though. The Lunt does have a different colour segment but otherwise is the same design. I don't think the AFoV figures are always given that accurately. Same for other zooms ie: the Baader 8-24 which has been measured differently from what the specs say. By comparing it with other eyepieces that I have, I would estimate the AFoV to be around 38 degrees at 21.5mm and 55 degrees at 7.2mm. Here are a couple more versions of it: http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_330 https://www.teleskop-express.de/shop/product_info.php/language/en/info/p4651_TS-Optics-Premium-Zoomokular-7-2-mm-bis-21-5-mm---1-25-.html I'm very pleased with mine despite all the above confusion and use it often with a Baader 2.25x barlow to get a high power 9.55mm - 3.2mm zoom I have to admit though that my version cost well under the prices currently being asked even by FLO.

Sorry for the delayed reply. I have not used the ES 2" focal extender but I have used the 1.25" inch version and found it's performance very good. I'd hesitate to say that it is 100% as good as a Powermate but it must be 90% of the way there. I would expect the 2" version to be similar.

I can't really justify it, unfortunately . I have the Delos 14mm, the Ethos 13mm, the Pentax XW 10mm and the Ethos 8mm. And a zoom which covers 7.2mm - 21.5mm for good measure. They are the ONLY reasons that I've not bought a Tele Vue 11mm Apollo of course https://www.widescreen-centre.co.uk/tele-vue-apollo-11-special-edition-eyepiece.html

Eye cup position is usually the key to avoiding these sorts of issues. I don't wear glasses when I'm observing and find that the uppermost eye cup position is almost always the one that works best.

As long as it has been looked after. If a triplet gets a knock then it can be a specialist job to get the elements re-centered, aligned and collimated.

I owned all the Nagler T6's at one time, except the 11mm ! In fact I don't think I've owned an 11mm eyepiece for around 20 years for some reason I expect the ES 11mm 82 is a pretty decent eyepiece and close to Nagler performance.