John

OK Dave1 but when you see the way that the scope tube is made you will understand why I felt that the mishape was created during manufacture rather than during transit. My comments on dealer attitudes are based on 1st hand discussions as well. I've taken up enough of your thread so I'll bow out with my fingers crossed for you but I will be very pleased if your TAL Apolar 125 turns out to be a very satisfying telescope to own and use. Maybe I have been unlucky with review scopes - I had two Skywatcher ED150's sent to me for review and both were damaged in transit. Clearly North Somerset is not a safe place to send a telescope !

True Dave, but I honestly believe that many left the factory in a poor state as well. One of the TAL Apolar 125's that I received had a welded tube that had the profile of an egg rather than being even roughly round (not squashed in transit - badly formed and welded that way) The 2nd welded seam between the level and tapered sections was rusting and covered up by a black elastic band. The objective cell had scratches all over it as well. The central triplet element had come loose and had smashed which was probably a transit issue but the rest of the scope was not pretty at all. The 2nd scope that I received was in better shape but still had plenty of rough edges including some mis-collimation and even though the focuser had a 2 inch format drawtube, when a 2 inch diagonal was fitted, no 2 inch eyepieces would come to focus due to lack of inwards focuser travel. At the time I was testing the TAL Apolar 125 I had an Intes 150mm maksutov-newtonian and there was simply no comparison between these Russian products - the Intes was superior every way, fit, finish, design and performance and yet the list price in the UK at that time was roughly the same. I understand that dealers in the UK became very wary of handling TAL orders because they knew that the chances of customer issues with them would be high unless they spent a significant amount time checking and prepping scopes prior to dispatch. Most were content to move away from supplying them to customers. Good luck with yours though, @Dave1

The one that I tested (the 2nd one, that was delivered with the optics actually intact) did have colour correction that was as good as a chinese ED doublet, maybe even a touch better. Not quite up to LZOS standards though, IMHO although I have only owned one LZOS refractor. Colour correction is one aspect of performance though and it was in the overall star test quality, particularly the form of the intra and extra focal diffraction rings and the at focus airy disk where I found some issues as I described in my report. This might have been addressed through collimation of the optics but it was not my scope (a loan organized by First Light Optics) and the manual at that time proposed a return to the manufacturer for such adjustments, so I decided not to tamper. An owner with some experience of refractor optical testing and adjustment, who likes to tinker and is not over-concerned with fit and finish quality, could well have a lot of enjoyment from a TAL Apolar 125 I'm sure. If I had invested £1,000+ in the scope I would have been pretty disappointed I have to say. My best TAL was a 1999 TAL 100RT which was great for £250 delivered direct from TAL in Siberia. I've owned one since that which was OK and another which was rather poor so I view TAL as scopes that can be great if purchased for a low cost and with suitable expectations. All that said, I really hope your TAL Apolar 125 proves to be an enjoyable experience for you and I look forward to hearing about your experiences with it

I wonder how many folks have actually seen, handled and used TAL Apolar 125's "in the flesh"

One of the challenges is getting at the lens groups that are contained within the scope tube to adjust them. The outermost is a 125mm clear aperture singlet retained in a cell with a conventional retaining ring. Easy to get at. The cell for that one appeared to have some lateral lens adjustment through grub screws set in the walls of the cell but I don't recall a tilt adjustment. The next group along the tube is a triplet which may well be a cemented group. It's containing cell seemed to be secured within the tube with 3 grub screws around the diameter of the tube. The heads of these were recessed and their cavities filled with white rubber seals. Not sure what provision for tilt adjustment there is with that group. Presumably the 3 grub screws are used to centre it. The final lens group is a doublet which I think is housed in the top end of the focuser housing unit which is extended for that purpose. No idea on the adjustment provision for that - maybe through tilting the focuser housing ? While star testing is obviously useful for checking the overall collimation of the optical train and a laser for checking the optical alignment of the focuser (and presumably the doublet group housed within it) the traditional cheshire eyepiece test for objective tilt did not seem to work, presumably because of the 2 lens groups that lie between the cheshire eyepiece and the rear of the large singlet element. I hear what Mr Spock says regarding the build of TAL's generally but I have to say that the 2 examples of the TAL APOLAR 125 that I have handled were rather shoddily put together I'm afraid. Both were supplied new and direct from TAL in Novosibirsk, Siberia.

I use to have the Nagler 3.5 and 2.5mm. Didn't use the 2.5mm much. I have the 3.5mm Pentax XW now and that get some use even with my 12 inch F/5.3 dob. Very often used with my refractors.

Good attitude 👍

My choices are the Ethos SX 4.7mm and the Pentax XW 5mm for my 12 inch f/5.3 dob. I'm lucky enough to have both. I understand that a number of brands 110 degree 5mm / 4.7mms carry the same optics as the APMs. Pick the version with the ergonomics and price that suits you best. If you go for a Pentax XW you will loose nothing in optical quality to an Ethos IMHO, just in AFoV.

Good luck if you have a go at collimating the 6 elements in 3 groups ! Lets hope your example does not need such adjustments.

I think green light measurement is a little harsher than red, at least where visual observing is the intended use. The real proof is in the star test though and how challenging "on the edge for the aperture" targets are handled, IMHO.

I wonder how consistent the figuring and polishing accuracy achieved by surface tension is across the whole diameter of the lens at the levels that we astronomers want ? I'm not trying to be skeptical, it's just that astronomy is so demanding !

Meade used to make just that - a variable amplification barlow lens: The Baader VIP modular barlow is also used that way through different extension combinations.

Most zygo testing seems to be done at that wavelength - 632.8nm. The Orion Optics test reports are done at that wavelength. I believe that it is quite complex and there is some additional cost to do a zygo test using another wavelength because the laser used has to be changed. I think the advantage of testing in green light is that it is closer to how our eyes see. I did see a rough conversion formula to estimate what a PV reading in red light might convert to if done in green light which involved multiplying the figure by 1.2 or 1.3. I don't know if that works or not though.

That is red I think.

Possibly. The original certificates were to demonstrate that the objective met or exceeded the required specifications. Do you know what wavelength of light your latest tests are done in ?. The originals are done in 532 nm which is green I believe.

That does look good. Whenever I've seen independent tests done on LZOS objectives they have been even better than the original test results that were supplied with the lenses by LZOS.

Excellent report and a lovely description Nik My clear(ish) patch last night only lasted long enough to have a look at Jupiter, Nepune, the rising moon and Theta Aurigae before the cloud cover thickened. I'd like to have a crack at 7 Tauri with my 130mm refractor when I get a chance

This review dates back a few years but I think is of the same scope, or at least the 2007 version of it: https://astromart.com/reviews-and-articles/reviews/telescopes/refractors/show/vixen-ed115s-refractor

Nice report and pics ! It was nice while it lasted here Messier and Messier A were showing rather nicely tonight I thought. You caught them in your 1st pic, bottom left.

Too cloudy now for observing. Just to prove that it was better earlier - snapped with my mobile at the eyepiece. Colours inverted for fun

Actually had some clearish sky for a short while here so managed to get the 130mm refractor out and cooled in time to see Jupiter and Neptune. It's mostly cloudy again now although it's thinnish stuff so I've left the scope out for now in case another clear patch comes along.

One of the things that is striking about the ED150 is how much larger than the ED120 it is:

I had the 30mm and 40mm Aero ED's for a while recently. The 40mm is a better corrected eyepiece than the 30mm in scopes faster than around F/8. It was actually pretty well corrected almost across the whole field of view even in my F/5.3 12 inch dobsonian. I understand that the 35mm is also a better corrected eyepiece than the 30mm but I've not used that one.

Interesting this. The packaging of the ED150 both externally and within the scope case was improved to prevent the sort of damage that my examples sustained during transit. This has I believe been successful. The issue with the misaligned objective elements was caused by the lens retaining ring coming loose from it's threads and simply not doing it's job any more. From feedback that I've seen on another forum the US Skywatcher vendor indicated that some small modifications were made to the objective cell design in the form of a more substantial lens retaining ring and a greater depth of thread for the retaining ring to screw into. As far as I am aware though the UK Skywatcher distributor has not confirmed these changes. Since my early encounter with the ED150 I have not read of further such issues from other owners. Reports of the performance of these good examples are very encouraging

I think the same scope under different branding is being discussed in this thread from another forum: https://www.cloudynights.com/topic/784837-adventures-with-a-helios-explorer/