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Deadlake

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Posts posted by Deadlake

  1. 11 hours ago, jetstream said:

    Fundamentally, depth of focus depends on the focal ratio of our eye's own lens. This is why the exit pupil is important in this respect for telescopes in the afocal configuration (where it directs essentially parallel light to the eye as from a great distance.) Note the implication; the telescope objective's f/ratio is of no import, while the eye's own f/ratio is. "

    Great so I'm reporting how my own eye works and not the scope... 😃😆

  2. 13 minutes ago, jetstream said:

    In the real world the best test of optics (to me) is the ability of a scope to take high mag on lunar/planetary before breaking down and the best scopes are almost impossible to break down, of course this take super seeing. Also of course this is just my opinion.

    We can test a scope on an optical bench, however how the scope responds to environment is going to be hard to replicate and we’ve not even mentioned seeing conditions.

    I’d suggest that’s the variation being reported…

    • Like 2
    • Thanks 1
  3. 21 minutes ago, F15Rules said:

    Vixen has a reputation for excellent optics. I believe they are still the market leading brand in Japan. The two examples I had were superb visually. I had one of them for a while when I had also the Tak FS128, so was able to do a comparison..whilst the Tak was "better" in terms of light grasp and brighter images, I can't honestly say that the image quality (airy disk presentation, colour free in-focus, contrast, sharpness on axis and edge to edge etc was any better in the Tak. If a Vixen "ED128s" had been available, and of the same optical quality, I would have happily bought one.

    Tak and Vixens scopes cost around the same in Japan, the price difference is on treasure island. 😃

    One question around the focusing in the doublets you have used, does the FS128 keep the subject in focus other a greater range compared to the Vixen doublet? I find my LZOS triplet easier to focus as it’s focus range is greater then doublets I have used. e.g., on Jupiter I would have to adjust the focuser less with the LZOS compared to a doublet.

    • Like 2
  4. 2 hours ago, John said:

    APM put the specs they use for their LZOS objectives in the public domain. I guess they were stringent back in 2005 but maybe not so much today ?

    APMApo-Linsen-Spezifikationen.pdf 468.53 kB · 8 downloads

    My priority has always been to try and get the best optical quality that I can afford. I've never been too fussy about focusers etc or even the quality of fit and finish, as long as the optical quality is there. With the more expensive scopes I would hope to get better quality in these departments as well.

    Although not too fussy about focusers, even I can appreciate that the Feathertouch fitted to my TMB/LZOS 130 is something above and beyond anything else I've used though.

    With a triplet refractor I think the mechanical design and precision of the objective cell is very important as well. Another area where the LZOS triplets seem extremely well executed. I'm sure that Tak and Astro Physics have great quality objective cells as well.

    tmb3-jpg.202505

     

     

     

     

     

    According to Markus lens design not changed since Thomas Black original design. 
    And lens material, well we have measurements for that.

    One thing I would state is that other manufacturers have been increasing there tolerances, e.g Stellarvue is now fabricated in house Strehl 0.99 lens whereas LZOS has not followed suite as would add at least an extra $1000 per lens. It’s not the lens material but figuring the lens.

    We could also include the C-F correction for a scope.

    Also the PV of a lens, if you have a high Strehl and a high PV which do you priorities, you want a smoother lens as well.

     

    • Like 1
  5. On 27/11/2021 at 10:08, Dek Rowan Astro said:

    We'll be using alumium for the tube so there's 1/2 a ton saved already 🙂

    Here some competition then, the vixen half pillar is a lot lighter (1.8 kg) and easier to attach...

    However it's cast I believe, Japanese like to use this approach... 

    post-42200-0-46389900-1637274626.jpg.0cf35640ede1a32f1f16ceabee01c336.jpgpost-42200-0-22816500-1637274666.jpg.8fe040f7d33423fc50f4de746be34584.jpgpost-42200-0-83235100-1637274646.jpg.4c4a95f5d54452dd11348a7befaf3480.jpg

     

    • Like 3
  6. Anyone here any experience mounting a Newt on an AZ100? On CN I've seen a 115 cm Newt mounted on there AZ100 and that looks possible.

    The Newt options I've come up with are: 

    BS 10" (length 95 cm) weight 11.5 kg 
    BS 12" (length 110 cm) weight 18 kg.

    My main concern for the 12" is the weight however the extra aperture would mean not needing a larger aperture for some time.

    I already have a AZ100 so why buy a Dob mount, especially as I have push too....

    Why not buy a Dob, well these are Boren-Simon Newts and run at F2.5 which is great for NV usage and can be used in prime mode so no long stack attached to the focuser.

    Thanks

  7. 2 minutes ago, Alan White said:

    You didnt ask for Slo-Mo in your question of course....but made me chuckle.

    Would the Scopetech hold a heavy 5" scope though?  A question posed, not a comment on that mount.

    If theory it would hold a TSA-120, however in practise no, just a little to heavy. 

    It's really aimed at Japanese market for holding 4" Vixen/Takahashi scopes

    • Like 1
  8. 12 minutes ago, Alan White said:

    Got to be in no particular order:

    AZ5 (but not the SW one)
    AYOii,
    Ayo Vamos,
    Rowan AZ75 when released.

    Slo-mo? 😁

    If only the Scopetech Mount Zero had push-to....

    Looking at a lot of the comments, maybe another thread, whats the best grab n' go setup. 

    1) What's the lightest setup you find usable?
    2) What's the largest aperture you can use as grab n-go? 

    Two trips is grab n' go? 

    • Haha 1
  9. 2 hours ago, Space Hopper said:

    Thanks for the tip ; i'll get in touch with Marcus.

    Its always a difficult thing to get right : so many different sized mounting rails and tube rings and thread sizes that getting one to fit is near on impossible.

    I've no idea where my original tube rings for my 105 came from : possibly the scrap pile.

    They were so big and heavy, and bizarrely they only had 'Whitworth threads'. No metric sized holes at all. Where did they come from ? Certainly not Germany.

    Although having a new pair custom made was expensive, i bet they've removed nearly a kilo of weight off the scope setup.

    I really like the 'More Blue' rings that FLO sell, but unfortunately non of their range would fit my tube.

     

    The 130 I have are star light, Rupert wanted them to match the anodising of the FT focuser. However the weight is more, I’m sure I could get lighter, but finding them is hard… 

     

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