BST StarGuider for F4.7 dob ?

[ninjageezer]

As above was looking to try a few of these out on my sky-watcher 250p flex which i believe is a fast F4.7 ,can anyone recommend which of these would be a good choice.

planetary mainly.

[cajen2]

Well, the 3.2mm would give 375 X mag if you want to go that high. Seeing conditions would have to be very good, but useful for Saturn and Mars, perhaps. A more usable mag would be 240x, which you'd get with the 5mm. FLO says 'suitable for F/5 and longer', though.

If you want to push the boat out, Pentax XWs would give great, wider views.

[ninjageezer]

Ok thanks but i have read in an F4.7 anything wider than about 60 degrees would only give to much softer edges  ,im not prepared to buy anything too expensive until i can try one as im sure you understand,that is unless someone pops along and says i have an F4.7 and this works very well...😉

[Louis D]

13 minutes ago, ninjageezer said:

i have read in an F4.7 anything wider than about 60 degrees would only give to much softer edges

Then invest in a coma corrector.  The most expensive option is the Tele Vue Paracorr T2 and the cheapest is the GSO/Revelation CC.  The ES HR Variable CC falls in between, but requires the most in-focus of the three.

[Mr Spock]

55 minutes ago, ninjageezer said:

Ok thanks but i have read in an F4.7 anything wider than about 60 degrees would only give to much softer edges  ,im not prepared to buy anything too expensive until i can try one as im sure you understand,that is unless someone pops along and says i have an F4.7 and this works very well...😉

Not at planetary magnifications. Coma is generally only visible at low magnification, wide field views. It's a product of the Newtonian optics, not the eyepiece.

If you want something really sharp for planetary observing, then the Vixen SLVs are 'orthoscopic like'. Much better than the BSTs.

[cajen2]

My scope is F/5 and the Pentax 5mil is quite happy in that. But also a good shout from MS on the SLVs.

Edited February 13, 2022 by cajen2