Evostar 90 Refractor Ep Upgrade from standard

[Lodestar]

I am looking to upgrade my standard Ep's and am thinking Xcel or bst's.

 The question is how much mag. is practical under our typical seeing conditions?

Thinking 3 ep's soon so 25mm 20mm and 8mm are my initial thoughts.

8mm=112 mag. @ 900mm Fl.

Ps. I have a 2x barlow that came with the Evostar.

Regards Steve

[nightfisher]

Yes go with the BST ep`s, they are a good choice

[ronin]

I would have picked 8mm, 12mm and 25mm. :rolleyes:

That would mean BST's as there is no 8mm in the X-Cels.

In X-Cels that would likely mean (if my selection) the 7mm, 12mm and 25mm.

With either the 12mm would give in effect a 6mm with the barlow.

[Lodestar]

Thanks ronin

I see your point. Cant wait to see some decent ep's in either of my scopes. The 25mm in the Travelscope will be nice too.

[YKSE]

BST are nice upgrade from stock EPs, if you intend to get these, please keep a close eye on the used market here:

http://www.astrobuysell.com/uk/propview.php?

All the BSTs do show up quite often, buying used will save you some quid if you feel like to upgrade late on.

Another solutions is to buy EPs you don't need to upgrade, unless you hunger for huge Field of View EPs like 82 or 100 degree with equally good optical performance. A 24mm MaxVision with 68 degree FOV is noticeable better than BST 25mm, works perfect as finder EP in 1.25" focuser, an 18mm Baader Classic Ortho is optically as good as best EPs(only 50 degree FOV though), 2mm exit pupil should be you most used EPs for many objects. with a baader QT 2.25x barlow, which can be screw on EP directly for 1.3x,  you get 8mm and 13.8mm equivalent EPs, the total costs will be virtually the same as buying three new BSTs (or two BSTs with barlow).

http://www.firstlightoptics.com/baader-planetarium/baader-classic-ortho-bco-eyepiece.html

http://www.365astronomy.com/explore-scientific-maxvision-68°-eyepiece-24mm-125-p-3902.html

Search in this section, you find many site members comments on Maxvision 24mm, about BCO 18mm, you can read John's review here
http://www.firstlightoptics.com/blog/baader-classic-ortho-plossl-review.html

[Chris]

8, 12, & 25mm BST's would be a good upgrade from the standard EP's and a great upgrade would be to get some ES Maxvision's for not much more money. I bought my 16mm and 24mm Maxvisions at the same time and I think it was around 120 quid shipped for the pair so only 20 quid more than a pair of BST's. The BST's are great for the money but the MV's are fantastic!

Chris 

[Lodestar]

Thanks YKSE for such a detailed post. Lots of stuff to research there. Saw 3 BST's on AB&S last weekend and they did not last the day. 

I will look at the others too as 68 degree FOV in the 400mm scope would look great. I gather comparing 2 ep's of the same FL the wider FOV one give a wider view at the same mag? 

The more I re-read your post the more it makes sense to choose tailored ep's for each ep fl. many thanks for your considered reply.

Regards Steve

[Lodestar]

Thanks Starfox

The thing abot the Mv's is they would be an easy matching choice. YKSE's proposal looks interesting as stated above, may take more time but has optical merit.

Steve

[Lodestar]

Ordered the Baader ortho 18mm and the QT 2.25 barlow for now. Still pondering the Maxvision or the Xcell in 25mm.

Regards Steve