jetstream

I stand corrected- I just went and looked. But hey I'm new to the razor sharp Tak club

Takahashi Super Apochromat

Are you sure the Tak owners are just having a bit of fun?! I also wonder why it bothers some people who read about the Taks- why read it if it bothers?

😁 I'll trade you a bit of cash for it but I'll probably be buried with my Taks (and fishing rod)

@JeremyS In all seriousness, I dont want to miss great seeing opportunities because of the acclimation issue or local seeing issues- Ive addressed the latter ie thermal slide, base etc. I plan on the Tak 100 next to the 120 side by side and if things work out I slide over to the 15" which is always in the wings.

Whew!!! Ive been looking for an excuse to buy one and the wife is finally on board with my latest reason😁 Coming in sad, bummed out because my scope wont keep up to the drop , only giving 225X lunar views 😔 Ive been rehearsing for a while

Well, maybe you can help me out with this. My temps can fall substantially for a long time right when the moon/planets are great to view ie just after dusk. Eventhough the TSA120 is "acclimated" during these times it can lag the temp drop a bit. I'm talking say from +5c down to -15c or 0C to -20c etc. Normally, later on in the evening the temp stabilizes. Will the doublet Tak 100 keep up substantially better than the triplet during these temp drops? Please say yes

In my eager dream to test the new 2.5mm XO, I set the TSA120 up for lunar and initiated the final cooling process. Not wanting to waste this observing time I set out to see a couple of favourites, M51 and M42. Avg (-) transparency had the NELM around 5.9, not the best, but OK. M51 was low during the cooldown time but it was in between the trees and so observable. I'm not sure how many have played round with smallish scopes on this object but the views can be very good. In these scopes its best (to me) to play around with the mags and try a bunch of different eyepieces. The 24ES 68 found M51 manually and presented a nice very distinct set of galaxies, however experience told me there was much more in there. In goes the excellent 18BCO and some intermittent "mottling" appeared in the outermost of M51, knowing what this meant the 16T5 Nagler came out. If you ever observe M51 as round with no spirals, but with intermittent streaks in the outer portion of it, you are actually seeing the spirals. These streaks can be seen as faint small mottling or in my case last night as distinct, faintish intermittent streaks. Magnification brings these out and usually around a 2mm exit pupil in small scopes works well. A very fine view! M42! What can I say! The Tak bought out a highly green core with massive wings espc on the one side and M43 showed a nice but small comma shape. The extensive glow of the Running Man was in your face and the whole thing was dazzling! The 18mm BCO and in particular the 16T5 presented an almost delicate, highly contrasted view that reflectors do not. Pinpoint tiny stars, jet black background, yes the frac was doing its job very well. Wait until it sees the best skies... I wont mention the diag differences and some other things, Ive been yapping too long lol which is not uncommon if you know me Gerry

@davidc135I dont see it there but they are selling like hotcakes rumour has it.

I'm not on EBay but can you give me a link please? My sis in law can get it for me

@SuburbanMak your scope might also show up differences in sharpness between eyepieces once you get playing around - its the excellent optics in the scope that will show this. As Jeremy says -no rush to get a bunch more stuff though, you have an excellent prism diag and nice EP's.

@SuburbanMak Excellent report. For you to notice the difference in sharpness immediately, the difference is significant IMHO. I have zero doubt that when you get a high spec 2" diag the views will equal the Tak prism. Baader BBHS comes to mind. Congratulations again for owning this fine telescope. Gerry

@davidc135 I'm thinking of the Edmund Optics #11-858 optical window. https://www.edmundoptics.ca/p/150mm-dia-10mm-thick-uncoated-lambda4-n-bk7-window/41182/

I would love for you to test it! However we are 6000km apart as Im in the middle of Canada. Great info again, I'll attach the specs in a bit on the flat I'm thinking from Edmund in the US.

You leave my Zeiss orthos alone!!!

Thanks, Brian said he found it in an old stock display case or something. If you ever here of a 5mm out there let me know will you?

@markse68 Thank you. I'll be using it as much as the other eyepieces I have eventhough it is kind of rare. My stuff doesnt just sit on the shelf. The thing behind it is a DPAC eyepiece, to set a Ronchi screen in and an LED to backlight it. Once I have a suitable flat I'll test my fracs for the fun of it. @Sunshine made these DPAC EP's happen. I look forward to comparing the 2.4 HR and the 2.5 XO, hopefully Monday.

@davidc135 thank you very much for this needed information. Ok, this is where I get different opinions. Some say that because the area used is small in the scheme of things that the surface of the flat is not critical. Others say no it needs to be very flat and actually very smooth. For what I'm doing a 1/4 pv 40-60 scratch dig was suggested as "OK"- thoughts? My natural first thought was 1/10 PV and smoother... What effect will a flat less than 1/10 PV 20-40 have on the fringe results? Thanks for the help David

XO has landed and I love the look and build of it, I now need the 5mm.

I'll also test the scopes through different diagonals to see the effects, if any. Ideally I'd like testing through the eyepiece/diagonal/scope as well, but I'm not sure if this is possible.

I'll be testing here once I get the needed equipment. A big thank you to member @Sunshine who has provided me with the DPAC EP's where the LED and Ronchi screen will fit. The files were from Moshen on CN who put the 3D printer files available to anyone. Maybe members here would be interested in printing the EP's to try.

Years ago I purchased the TSA120 because of its reputation for well figured optics that tests well across the spectrum and because of how highly regarded they are among very experienced refractor owners. I plan to test the highly vaunted, and recommended here SW120ED in double pass autocollimation -DPAC- to see where it stands . I dont believe it necessary to nit pick the fringes seen and one look should tell the tale. Hopefully the TSA120 tests well and can be used to correlate visual observations to the test results seen in the other refractors. This image is from another site

I'm slowly assembling some things to start along the path of DPAC testing. It should prove interesting, and from what I understand it is very accurate. Just ordered some transparency film to try printing off the Ronchi screen on my laser printer and hopefully this goes well. If it does I'll order an optical flat, 1/4PV 40-60 D/S or better yet find a cheaper flatter laser flat off E Bay or somewhere. This testing seems popular on another site- anyone here try DPAC testing refractors? I'm almost scared to see what this shows up... Gerry

Could you change the focuser down the road if need be Neil? I dont like big, long hvy eyepieces in a frac- the 42mm LVW is pretty light for what it is however. The lightweight 16T5 is great in my fracs for M42 etc as a higher power option on them. Oddly , I hardly ever use the 20mm APM in my fracs.

This is the key!! A scope should be picked based on the preferred eye illumination at the mag the the seeing usually supports, IMHO.ie dimming the planet at a mag that the seeing supports. I do this all the time, with various scopes. A binoviewer beam splitter does this at lower mags because the splitter "halves" the volume of light to each eye/ per conventional exit pupil. AKA "the false exit pupil theory". This fact, IMHO, is why many find binoviewers provide a better view, combined with the idea of binocular summation.