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jetstream

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Posts posted by jetstream

  1. Hmmm... no response to a scope testing at the top of the heap. It must be an internet thing or something that feeds momentum in certain preferred directions.

    From my thinking this 127D might be a big hit for people, maybe one of their best sellers.If it works out down the road I'll buy one and compare to my Tak 120. With regards to sample to sample optical test result variations a buddy in the business told me an optic is worked until it meets a minimum spec or worked to the highest spec possible and then stopping when the numbers start to go backwards a tiny bit.

    It is therefore normal for this variation.

    IMHO any refractor that tests over .90 Strehl in all colours and is nicely smooth will provide fantastic views. In reality any refractor that goes over .80 Strehl, is reasonably smooth and with good colour correction will give good views. I feel my SW120ED falls in between these 2 boundaries and the views are now very good.

    From the reports I believe the TSA120 tests typically in the mid 90's Strehl, is very smooth and has a balanced colour correction. It is amazing that the SVX127D has some tests in the same league and maybe better in some.

    I love comparing test results for refractors and have done so for years- amazing that some well known, preferred scope brands give great views can have a spec or two "off" a bit by todays sky high standards.

    Gerry

     

    • Like 3
  2. 57 minutes ago, BrendanC said:

    I guess I'll just keep collimating with the secondary centre aligned to produce the offset pattern as before.

    Its not something that you choose really.... offset away from the focuser is fixed from mounting and using a sight tube provides the offset down the tube. I highly recommend a sight tube cheshire combo or much better yet, the Catseye separate sight tube and cheshire.

    For me, I use the sight tube, then a Glatter laser to line up the sec on the primary and then the Catseye cheshire for primary collimation. Doing so allows extremely high mag lunar/planetary viewing.I dont autocollimate anymore- 700x+ on the moon is good enough for me with my 15" f4.8 dob.

    A collimation cap does not provide adequate collimation IMHO. I also have a cheap but excellent Celestron sight tube /cheshire combination tool that works great.

    I wish Mr Khadder was around here still to run through things for you.

    Gerry

    • Like 1
  3. On 15/05/2023 at 16:00, Spile said:

    If the secondary is centred then you will see the dark bulge “pointing” towards the primary. That was how my Chinese reflector was set up and how I align it. It’s model E in Vic Menard’s secondary alignment method. About halfway down the page and final diagram by Jason Khadder. https://vicmenard.com/addendum-to-perspectives/

     

    Glad you posted the link, they are both great helpful guys 👍 Ive seen some try to argue about collimation with them... one better be well versed in collimation so as not to look silly at the end of the conversation lol.

    • Like 2
  4. Over on the other forum another SVX127D tested very well, the first one excellent the second one unbelievably good! Not sure why I'm starting this thread really- I'm puzzled by the lack of attention and reaction to these tests actually- I know I'm pretty excited though! To see any doublet of any brand test this well is a testament to the makers ability, triplet level correction in a doublet lens- and at near 130mm aperture... not that easy.

    If anyone has one of these and gets it under great seeing, please post the results. I feel the SVX127D would at least equal my TSA120 and keep up to my sometimes extreme temp swings at certain times of the year.  The fit and finish of the new SVX line is said to be fantastic.

    I know this- I want one of these telescopes....

    Any banter on anything related to the DPAC testing, SV scopes or others welcome.

    Gerry

    • Like 4
  5. On 15/05/2023 at 07:37, BrendanC said:

    Thanks for this (and I was sure I was following this topic otherwise I'd have replied sooner!)

    So, of the diagram I included, which should I be looking at? Option 1, 2, or something else? 

    All you have to do is use a sight tube and a cheshire- everything is then set up automatically. If you really want to collimate for a closed light path buy the Catseye autocollimator.... I have one of those too lol

    • Like 1
  6. On 10/05/2023 at 05:02, Littleguy80 said:

    I believe the DGM NPB was designed to include a Ha pass as well as OIII and HB. I think it’s the only visual filter that does it.

    It’s pretty popular as UHC type filter. 

    I believe the new Astronomik UHC does as well whereas the Astronomik made Televue UHC does not. I have the NPB and new TV filters- the TV filters are the best I own.

    • Like 1
  7. 22 hours ago, DirkSteele said:

    I bought the 3-6mm back in 2012 to fit a specific brief. I was travelling abroad to dark sites with a scope and limited weight and space allowance and the zoom allowed me to cover multiple focal lengths in a single small EP. It fit the brief perfectly and I was so impressed it I bought the 2-4mm Zoom to pair with my two small Taks. Now I use the zoom almost as much at home as I do when I travel.

    Wrote a review of the zoom back in 2020 which echos a lot of what has already been written in this thread.

     

    http://alpha-lyrae.co.uk/2020/05/16/tele-vue-nagler-zoom-eyepiece-review/

    👍

    I'm in the NZ camp too- wont ever be without one, even owning other zooms.

    • Like 3
  8. 10 minutes ago, Highburymark said:

    The CN poster said he was getting spectacular results with a Quark through this technique.

    Years ago I did this with a Baader single variable polariser with excellent results and posted on solarchat. The views with a Quark are superb with one.

     

    11 minutes ago, Highburymark said:

    though I’ve found I have fewer satisfying sessions with the TSA-120 than my old 100 DC because of sensitivity to seeing.

    I find the same thing Mark- strange how 20mm of aperture can cause seeing issues but for solar it sure can IMHO. My 90mm SV Raptor is my most used solar scope.

    • Like 1
  9. @BrendanC there are 2 offsets - away from the focuser and down the tube. No big deal visually- but the non offset away from the focuser can cause DSC to be less accurate. Full offset-in both directions- allow us to use a bit smaller secondary - my 24" is fully offset- and has very low central obstruction.

    For an imager, full offset will allow for the smallest central obstruction with the needed high fully illuminated field.

    • Like 1
  10. 5 hours ago, dweller25 said:

    How well does oil spacing work in your chilly climate Jerry ?

    I called Astrophysics about a refractor a while back- unobtanium...but the lady had a very knowledgeable employee call me back about the oil spacing deal .He called me back right away- what a great maker Astrosphysics is. It turns out its not the cold temp itself that causes problems- it the rate of cooling that can cause issues. Taking an oil spaced scope outside from 20c in the house to -30c is a no no. However, taking the scope out in a case or "scopecoat" (wife made me one out of an old quilt) is fine, slowing the cooling rate. Once cooled properly there is no issue storing it "outside" (seacan in my case).

    Knowing this I would not hesitate to buy an oil spaced triplet for use in my temps. No issues going from -10c to -30c over the course of a day etc.

    • Like 3
  11. 20 minutes ago, Louis D said:

    BVs on Mars at opposition were transformative for me.  Mars went from being an overexposed orange-red blob to having a wealth of detail.  I suppose I could have tried a moon filter on it for monovision, but none was necessary for BV usage.  I was seeing detail in my Dob rivaling photographs.  In particular, one night, Mars looked very similar to the upper left image below:

    spacer.png

    I was able to easily discern the light/dark/light row of fine detail near the center of the image (Xanthe Terra region, I believe).  The best I've done in monoviewing has been to discern Syrtis Major in the lower right image, but only as a featureless dark marking.  That, and the polar caps are fairly easy, but featureless.

    I love seeing the light cloud on Mars , amazing we can see it. My 10" years ago gave me a similar view to your description. IIRC I was using a 3-6 Nagler zoom.

  12. 14 hours ago, John said:

    The TV Bandmate 2 Nebustar 2 inch is £299 now. It is really excellent though, by all accounts.

    This TV UHC does actually best a very good old Lumicon, but if I was in UK there is no question I would buy the Astronomik UHC based on price. I  have a superb TV Nebustar 2 UHC which beats an excellent Lumicon UHC. My old Lumicons are really top tier filters but these new ones take it up a notch in side by side comparisons using my 15" with a filter slide.

    These new TV filters hold a special spot, sitting in the 24"...objects like the Veil look photographic using them.

    • Like 1
  13. veil.jpg.42d2e0aa7163655102670d38ee7c7795.jpg

    4 hours ago, jetstream said:

    @Ratlet Do yourself a favour and buy a top OIII from either Astronomik or (New)Televue. The difference between a very good OIII and a mediocre one is staggering from dark skies like you have. Pickerings Wisp just wont be seen in your 10" dob/top OIII it will show very nice detail.

    Top OIII are just wide enough to catch both OIII lines completely and have very high transmission. Transmission matters contrary to some beliefs about our ability to detect it. IMHO

    Gerry

    Just to add, the 10" dob will show at least as good as this mine does better here. I have an old, excellent Lumicon OIII that shows this but the new TV OIII is a bit better. This is a borrowed illustration. Exit pupil matters to maximize views and I find that for some unknown reason 100 deg EPs excel on objects like this. The "Majesty Factor" perhaps? (Nagles idea).

    veil.jpg

    • Like 2
  14. @Ratlet Do yourself a favour and buy a top OIII from either Astronomik or (New)Televue. The difference between a very good OIII and a mediocre one is staggering from dark skies like you have. Pickerings Wisp just wont be seen in your 10" dob/top OIII it will show very nice detail.

    Top OIII are just wide enough to catch both OIII lines completely and have very high transmission. Transmission matters contrary to some beliefs about our ability to detect it. IMHO

    Gerry

    • Like 3
  15. Thanks all!

    I can say this my old school Sky Commander never failed once- the only thing that impacts it is an unsteady base, like ice under my dob. This will throw it off but thats it.

    I'm seriously thinking of the Nexus- can you make your own list of "favourites" ? This is what I do with the SC and find it great to obs from.

  16. 1 hour ago, Coco said:

    Sorry to answer not specifically about DSC but my take on it against Nexus II.

    I nearly bought the DSC but having seen both in action I chose the Nexus II which runs Sky Safari just as well as the DSC, that said, if you think you will need setting circles as a fallback then go for it.

    I'm running the Nexus II & S6 encoders with 10,000 ticks through a Samsung 10inch  tablet which mounts onto my dob 'hook and eye' style, both are powered by an Anker PowerCore+ 26800  dual USB port, after 5 hours in winter it's not 1/3 drained. I Flew to the USA - movies and podcasts without issues, with plenty left over. 

     

    What I like about Skysafari Pro is the ability to change the pointer to a Telrad or your chosen eyepiece finder position indicator.

    No bad experiences of a sort, but it does sometimes get out of sync after a couple of hours, I just re-start sky safari and in 5 minutes you're all good to go.

    HTH

     

    Ok, I know nothing about this stuff and use an old Sky Commander- no longer available. Nexus II is DSC right? What does Sky Safari do?

    Thanks

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