BST v's TMB's

[Bigdaddyjeff]

Hello all and just before i start my review i offer sincere apologies for lack of technical specifications and terminology for the visuals my meagre eyeballs have witnessed!!

So the anticipated trial EP’s arrived Friday morning so as soon as i got home i was planning on getting out. Scope outside cooling down around 18.45 giving me chance to do my household/daddy duties and back outside for 19.30.

Out of the box and all the EP’s look like very good pieces of kit so at this point I’m chomping at the bit to get them into the viewfinder!

Jupiter is out so in goes my 40mm to enable me to centre the finderscope for when the 5mm’s are in. Centred nicely and raring to go the 40 mm is resigned back to the box and the new EP’s are jumping out their boxes.......

First off is the TMB Pl2,focused onto Jupiter and straight away the bands are clearly visible, not as crisp and clean as I thought it would be but I put that down to maybe seeing conditions or collimation issues. Field of view is very good with Jupiter drifting across the EP and starting to lose focus maybe 15-20% to the edge of the view. 3 moons very clearly visible with one of them being very close to Jupiter itself indeed. Next into the focuser goes the TMB design, obviously similar to the Pl2 in looks and design but would the view through be similar too.....well not quite. First thing was that I had to re-focus which gave me the impression there’s a slight difference in focal length and secondly I found that when moving my eye around the view I would often lose what i was looking at so therefore readjustment of my eye was needed which i found very off putting. So to the last EP which was the much raved about BST, into the focuser with a little re-focus the out popped Jupiter once more. Now whether it was just my imagination or the pre read hype about this EP but it did seem that little more clearer, not much, but even to a very new and untrained stargazing eye just a little and as Jupiter floated across the fov it was almost to the edge of the eyepiece and the bands and moons were still nicely and easily visible.

Sorry for going on and on...once I start rambling there’s no stopping me!

After trying out the EP’s on some stars such as Alderbaran and Bellatrix I noticed a fair amount of comma (I do believe that’s the correct terminology for a comet like trail view around the star???) so I’m not sure whether this is down to collimation or the EP in my scope??

This morning I gave myself another half hour outside with the EP’s and had a view of Saturn and the moon. Saturn was amazing (as always) but particularly stood out in the BST for me, just a little crisper again and the bonus of staying in focus for that little longer. The moon actually made me whisper a slight, OMG to myself as the detail upon the surface gave me the impression I was literally about 30ft from the moons surface......unbelievable!!

So all in all I think I may of decided the BST’s are the EP’s I would like to have in my collection or at least build it up before I can afford the likes of a televue!! I will be sending the TMB’s back and looking forward to purchasing a few BST’s (well within my budget) in the forthcoming months.

Thank you for reading my review, I hope it may help in some way if even only to amuse you at my complete lack of knowledge and ineptness att being surgically clinical in me assessment of astro kit!!

Wishing you all clear skies

Gaz

[ronin]

About the same as I found, the BST's are just that little crisper, not a lot in it. The one disadvantage of the BST's is the jump from 5mm to 8mm, and nothing below 5mm.

The TMB's go down to 3.2mm if I recall, and have increments of 1mm up to somewhere around 7mm. So a greater range for magnification.

If they did BST's in 4, 5 and 6mm (and the rest) I would just use nothing but the BST's on everything.

I suppose only having 5mm and 8mm means you are not swapping eyepieces trying to get that little bit extra.

[russ.will]

Thanks for the review Gaz. Hurry up and send the rejects back, because I want to try them next.

Russell

[Bigdaddyjeff]

@Ronin....yeah the TMB's go down to 2.5mm so maybe it's food for thought but the 5mm will keep me going for a while now.

@Russ...rejects are on their way

[Moonshane]

totally agree with you Jeff based on what I recall of the BST's performance in particular.

re " secondly I found that when moving my eye around the view I would often lose what i was looking at so therefore readjustment of my eye was needed which i found very off putting." This is due to the exit pupil being quite small and you could improve this with adjusting the eye cup up or down. the BSTs were certainly more intuitive to use for me.

also, coma is a feature of parabolic mirrors and is revealed when you use decent quality eyepieces. nothing much you can do other than use a relatively expensive coma corrector. it does not really bother me at f5 though.

[Bigdaddyjeff]

Thanks moonshane,looks like i'll be looking for a decent coma corrector now then