John

Great report Doug ! I love zoom eyepieces for double splitting I have my 130mm refractor out cooling just now so I will visit Bootes if it stays clear.

Despite all the useful information, formulae etc, etc, I've found that there is no substitute for trying things for yourself to see what works best for you under your skies. Thank goodness for the used astro equipment market !

This is Tele Vue's take on some of these issues. Myth #2 is relevant: http://www.televue.com/engine/TV3b_page.asp?id=86

I compared the Baader 32mm Classic Plossl with the Vixen NPL 30mm. I slightly preferred the Vixen. I did not use them for solar observing though.

Have a look at Don Pensack's post above.

The diameter of the field stop inside the eyepiece coupled with the focal length of the eyepiece define the AFoV. It can be as wide as the internal diameter of the eyepiece barrel but is frequently less because the optical quality of the lenses and overall optical system of the eyepiece would not support acceptable definition over their whole diameter.

Exit pupil is calculated by dividing focal length of the eyepiece by the focal ratio of the scope. Apparrent field of view (AFoV) is not part of the calculation. Where AFoV does come into play is to determine the amount of sky (true field) that will be visible. With a very wide AFoV eyepiece, it is possible to have: - reasonably high magnification - see a good size chunk of sky - maintain an exit pupil that is really effective The above are some of the key reasons that ultra and hyper wide angle eyepieces are popular and effective with fast focal ratio scopes.

Many UHC and O-III filters have a very similar band pass width so deliver very similar performance. The higher performing ones (which also cost more) have a slightly narrower band pass width with sharper cut offs outside of the permitted band widths. These attributes lead to them delivering more contrast enhancement with receptive nebulae. Some of the lower cost O-III's are actually closer to a UHC in terms of band pass and performance and equally some UHC's are almost broadband in what they permit. Astronomik have recently started to manufacture the new range of Tele Vue Bandmate 2 filters which are developing a reputation as about the best currently available. At a cost of course !

Agreed - best not to discuss taxation / import policies on here

It will not affect performance but will affect re-sale value and you paid for a scope that should not have that defect and that's what you should get. So you have done the right thing and I hope your supplier reacts positively.

I agree - the Skywatcher Deluxe 2x barlow would be a sensible choice. It is pretty decent quality for it's cost as well. This one is the same I think: https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html

I use a 7.2 - 21.5 zoom eyepiece with the mobile phone held over the top of it in a very cheap clamp affair (which is pretty rubbish to be honest but it just about does the job). I "zoom" the image on the mobile a bit so it's difficult to say exactly what magnification is actually being used. Its about the simplest form of astrophotography so I can cope with that !

While you wait for replies, you might want to have a look through the posts in this thread that I started a few years back. It may well cover some of the topics that you are interested in:

I got these with my old mobile and ED120 refractor a few nights back. Thats about as far as my imaging goes !

Have you tried a Pentax XW ?

What scope and eyepieces will you be using the barlow with, or is it for imaging ?

Very good - thanks for the "heads up" Jeremy

Another excellent UHC filter is the Omega DGM NBP but I don't think FLO stocks those.

They usually use hacked e.bay accounts with excellent feedback scores. So that element is probably genuine but has no association with the fraudsters who are now using the account of course.

IMHO great "Horsehead" eyepieces are either the 20mm or 25mm Tele Vue plossls. The light transmission on those is really high from measurements I've seen. Higher than most other comparable eyepieces. I also reckon the 18mm Baader Classic ortho is good for this task. "every little helps"

That is a Skywatcher EQ5 fitted with a dual axis drive system. There is a GOTO system that can be fitted to it: https://www.firstlightoptics.com/sky-watcher-mount-accessories/synscan-pro-goto-version-3-upgrade-kit-for-eq5.html

No, it does not work like that. Generally deep sky objects are observed at low to medium magnifications. Some deep sky objects are very large in the sky so very low magnifications are used. Some are very tiny so higher powers work on those. How "deep" you can see depends really on the darkness of your skies and the aperture of your scope.

The Astronomik is more effective. I have both. The ES works though, it's just that the Astronomik has a more effective band pass with sharper cut offs and therefore the contrast of nebulae is slightly more enhanced and the stars more tightly defined. I can't put a figure on the difference or what that is worth though The ES UHC will give you a fair idea of the potential of these filters. They only have an impact on nebulae though, as you probably know.

My ED120 with the Moonlite focusser, 2 inch diagonal and 9x50 RACI finder is 6.5kg.

Do both the 6mm SLV's you have show this or is it just the newer one ?