I have just half-completed a very scary summer project!  The Hyperstar III lens assembly is a fantastic technological achievement which turns an ultra-slow f#10 Schmidt-Cassegrain into an ultra-fast f#2 Schmidt-Camera.  There is a slight problem though with all that glass in the Hyperstar – thick lenses – and the edges of the lenses are frosted, not blackened.  This means that if you wish to image a bright constellation star, you will unfortunately get some lens flaring.  For non-bright constellation stars I rarely get any problem.

So – just as I did with the Hyperstar I, I took the whole lens assembly apart (scary) and then painted the edges of the lenses matt black (VERY scary!) they are now all sitting on my desk in the sunshine for the paint to thoroughly dry off.  I use Revell colour Black Matt 9 – this is the paint used on Airfix kits.  It is probably not the best paint to use – there is a proprietary paint you can get from the States that is made especially to paint the edges of lenses.

I will keep you informed of how things progress (or not) when I rebuild the Hyperstar III and take my first image with the modified lenses.  Keep everything crossed for me 🙂


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3 Responses to “An extremely scary upgrade”
  1. Javier Villarreal says:

    Hello Greg,

    I would really like to know how it went with this mod.
    I’ve been trying to image the WitchHead and i get this very annoying scattered rays from Rigel which wash my subs.
    Thank you so much for letting me know.
    Maybe Dean at Starizona will be interested in upgrading their HS to blackened edges. Who knows.

    Thank you very much
    Javier.

  2. Greg Parker says:

    Hi Javier,
    Unlike the original Hyperstar where this approach completely eliminated flare, I reduced the flare a lot but did not eliminate it entirely. I am sure that if I had used the right stuff – there is a paint you can get in the States, basically it is Carbon black in suspension – you would again completely eliminate the flare from bright stars. I didn’t persevere with this approach as I am currently using the C11 at f#10. I think Dean will blacken the lens edges for you, but I’m not sure if he has the correct paint in stock.
    Greg

  3. Greg Parker says:

    By the way – if you dither your subs you can greatly reduce (if not eradicate) lens flares from bright stars.
    Greg

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