Quick double session and a decision

[RobertI]

Having recently improved the collimation on my Tal100RS (mainly by blind fumbling) I thought I’d make use of clear skies to test the scope on some doubles. Having waited for it to cool I popped in the 5mm BST giving 200x and slewed to  a brightish star - the results looked promising, with some nice even diffraction rings which were were slightly broken by the average to good seeing conditions.  Buoyed by this result, I slewed to the Trapezium. A beautiful sight as always, the E component was immediately visible but the F was hiding from me, despite looking for a good 20 minutes.  Next was Rigel with its tiny companion, followed by the more challenging Alnitak with its companion 2.2” away from the glare, the latter being easy to see with a clear gap between the two. Inspired by the success so far, I thought I’d try some doubles with a split less than 2”. I was over ambitious starting with  32 Orionis, the mag 4.2 and 5.7 components are only separated by 1.4” and try as I might I could not separate them at 200x. Unfortunately I am currently unable to go beyond 200x and I feel I might have had more luck at higher mags. Propus A with mag 3 and 6 components separated by 1.6” also eluded me and my final attempt at a 1.9” double was also unsuccessful, mainly because the secondary was mag 11 (which I failed realise at the time). I think a Barlow or shorter FL eyepiece is needed for these. Finished with a couple of easy old favourites just to remember how nice the scope is for doubles, Castor looking as beautiful as always and Algieba an easy yellow binary. 

One thing this session did achieve is a decision on my next scope. I had been weighing up whether to get a 100ED or a 150P Newt. Having spent much of the session twisting, craning, crouching, crawling and fumbling around for the eyepiece, often with my head in the tripod legs, I remembered how easy Newts are to observe with, particularly at the zenith, and this clinched my decision to get a 150P next. Shame because a few hours earlier I was definitely veering towards the 100ED!! 🤷🏼‍♂️

[RobertI]

Addendum: When I put the scope away, the lens had a light dew on it. I assumed this happened when I brought it into the warmer garage, but on reflection it had probably been like that for a while, and might explain the inability to split closer doubles. Funny how you sometimes lose the ability to think straight when you’re ‘out in the field’. 

Edited December 30, 2019 by RobertI

[Chris]

You'll also save quite a bit of money opting for the 150p Nice report Robert! and have you thought about running a dew band from a power bank? I do this with my camera gear sometimes and just strap the power bank to a tripod leg.

[RobertI]

Thanks Chris, yes I have dew band permanently attached the scope but I just didn’t think to attach it to the power tank, as the weather didn’t look too ‘dewey! 😆 Don’t think I was thinking very clearly at 2 am! 😬