E&T News Issue 4

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  • #612321
    David Arditti
    Participant

    I have just published a new edition of the Equipment & Techniques Section Newsletter. The PDF may be dowloaded from here:
    https://britastro.org/document_folder/baa-document-store/sections/equipment-techniques-section/et-news

    I hope you enjoy it, and if you think you might be able to write anything for a future issue, do let me know and I can provide some guidance.

    David

    #612333
    Daryl Dobbs
    Participant

    Excellent review on the EVscope, I’ve read very mixed opinions on this item, but Alan’s review is very informative and interesting from someone who uses it and clearly enjoys it and mentions the pros and cons without any commercial bias. It puts the reviews I’ve read online and also in some magazines, very much in the shade, perhaps it can be a standalone article on the website as I’m sure many people will find it very useful before they take the plunge and buy one.

    Wal Best’s water tower observatory is unusual, climbing up and down at night looks fun! are there crash mats at the bottom I wonder? I had an observatory next to a pond, and yes I did end up in it one night much to the fish’s disapproval. I have heard of an observatory which didn’t rotate on wheels but golf balls acting like crude ball bearings, apparently it did work!

    I too am a fan of the ASAIR but I have the V1 in the plastic case, a friend of mine has the V2+ with the external antenna but the WiFi range causes him problems as the range isn’t great, the V1 is slightly better in my opinion Wi-Fi range wise but one thing I wish they will do is not force people into software updates, some of their previous ones has caused no end of problems and rolling back to a previous version is an exercise in frustration.

    I read with interest the comparison between the achromat and ED glass, something which I have wondered in the past if it is worth upgrading or just a manufacturers marketing gimmick to charge more for little improvement. Something else to put on my wish list.

    • This reply was modified 2 months, 4 weeks ago by Daryl Dobbs.
    #612336
    David Arditti
    Participant

    Thanks for your comments Daryl. I’d say if you spend much time looking at the Moon and planets, or double stars, an ED refractor is a very worthwhile upgrade from a standard doublet. The resolution and colour perception are both substantially enhanced by the almost total lack of chromatic fringing. The other advantage is an ED can be made shorter for its aperture and still give good images. The standard 100ED refractor is f/9, but its performance is better probably than a normal 100mm doublet at f/13.

    • This reply was modified 2 months, 3 weeks ago by David Arditti.
    #612337
    Peter Anderson
    Participant

    Thanks Darryl and David,
    Wal Best’s Observatory at Bardon, Brisbane: I supply some background. Wal Best was a retired gentleman who built his observatory in the early to mid 1970’s. His property was quite vegetated and his wife wasn’t too keen on cutting a number of trees down, so he elected to use an old water tank on his property that in past times had been used to supply gravity fed water to the house. He had recently retired so it was a suitable work intensive project. So he trimmed off the tank at around 4″ in height from the base and filled it with concrete upon which he lovingly built a single skin circular brick wall and crafted a very fine aluminium dome with marine plywood frame. The quality of the work was outstanding. The dome was about 10ft diameter and a 12.5″ Dall Kirkham Cassegrain was installed within. He used this for perhaps two decades.

    When Patrick Moore arrived for the 1988 ‘Brisbane Expo’, he was keen to climb up, but was prevented by a wartime injury. (He was in the RAF and said he had fallen out of a bomber onto the tarmac during the war and the knee injury continued to be troublesome.) I know all this because I took the photo. The other person is Susan Niven, a local club stalwart.

    150mm F8 Achromat compared with ED glass version: This is a typical example of me being too stingy. (‘Tight-arsed’ as my wife puts it.) I saw the Celestron 150mm F8 optic tube half price for $600 AUD and I always wanted a big refractor so I bought it and mounted it in a cheap superseded heavy duty DX mount. Less than 18 months later the Skywatcher 150mm F8 ED was reduced from $3,000 to $2,000 as a special and so I swapped over selling the Celestron for a loss. In the meantime I had done quite a bit of testing and it was easy to conduct the same tests again for a direct comparison with the same mount, and same camera etc.
    I support David’s statement about the performance comparison, but I do feel that the standard achromat does have its points. Call me perverse, and maybe it was the spurious colour it introduced, but I felt that the standard achromat produced a bit more contrast on (say) the planets. From the lunar images – base of page 25 in the E&T News you will see that the spurious colour effects become troublesome towards the outer areas of the field. I have a series of these comparison lunar images if anyone is interested.

    #612339
    Daryl Dobbs
    Participant

    Very interesting edition of the E&T, I enjoyed it very much and well done to all who produced it.

    Very interesting background information regarding Wal Best, his observatory I find fascinating, I’d need a lift to access and like Patrick I’ve got an old RAF injury but not falling out of an aircraft but due to a roll of carpet falling on my back in the 70’s!

    Yes, I would very much like to see the comparison images.

    David: I do spend a lot of time looking at the moon and planets as DSO’s are difficult due to the amount of light pollution/security lights around here, so thanks for your comments, I’ll certainly add an ED refractor to my wish list.

    #612341
    Dr James Dawson
    Participant

    Yes an excellent edition. Well done David and team. It is great to see the work we are doing on our observatory in Nottingham mentioned. It is still very much work in progress but we are getting there. I will write up a report for the Section in due course about the final version and the issues we faced. The current intermittent issue relates to the surface of the capstan; too “dry” and the rope doesn’t slip well, but too “shiny” and there is insufficient friction. It’s all good fun.

    #612342
    David Arditti
    Participant

    I look forward to an in-depth account of the work at the observatory James. It sounds like the capstan needs high friction in the hoizontal direction but low in the vertical, so maybe it should be grooved.

    #612371
    Mark Fairfax
    Participant

    As a fellow avid eVscope user I particularly enjoyed the balanced & comprehensive “Using the Unistellar eQuinox” article by Alan Thomas.
    I heartily concur on the ease of use and portability for the eVscope & eQuinox and look forward to seeing where this new generation of ‘smart telescopes’ takes Astronomy.

    Well done to Alan!

    Mark Fairfax

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