BT Explorer 5mm in a 1200mm 200P

[stevetynant]

Just ordered one from skies the limit - but now having second thoughts and considering cancelling / changing

a 5mm eyepiece would give me magnification of up to 240x which I read is right on the limit for an f6 scope at this focal length. I thought this would cover my planetory high mag needs - now I'm wondering whether the 6mm would have been a better call.

I know the EPs are only about £40 so its not the end of the world one way or the other but would appreciate anyone's experience with this combination or general comments before I (possibly) get back in touch with Alan later today as they ship Monday

cheers folks

[hemihaggis]

hi steve , i belive your scope is a 200p f5 with a focal lenght of 1000mm ...

a 6mm ep will give 166x mag ...a 5mm will give 200x mag ... i would say the 5 mm is spot on for your scope ...

if your mirror is 200mm that will roughly be your maximum mag ...around 200x with the usual conditions we have in the uk

ps where did you get 240 from ???

you might want to double check the specs on your scope ... i dont think it is f1200mm , the 250mm pds is f1200 f4.7 , the 200 is f1000mm f5 ?? i think !!!

[John]

The Skyliner 200P has a focal length of 1200mm and is an F/6 so Steve's calculations are correct. 200x will be useful more often than 240x but it's still nice to have the option on really good nights.

[twotter]

The Skyliner 200P is the one on a dob mount Hemi. It's definitely 1200mm focal length and F6.

Steve, I rarely get to 240x mag with my 200P dob. I tend to use around 92x with my 13mm EP up to 150x with my 8mm. There are occasions when I can go higher on certain targets and I've topped out at 375x mag on Mars in January 2010 (6.4mm plossl with 2x barlow). I would suggest the 5mm BST won't see much use.

[hemihaggis]

hi john and steve , i agree the skyliner has a focal lenght of 1200mm , but steves signuture says 200p , no mention of dobs or skyliner ?? lol

so come on steve tell us what you have and put us out our misery !!!

[stevetynant]

Thanks guys- I appreciate the thoughts

Think I will ask for the 6mm but if its too late then so be it - at least I have something for those special nights so all not lost

Steve

[John]

hi john and steve , i agree the skyliner has a focal lenght of 1200mm , but steves signuture says 200p , no mention of dobs or skyliner ?? lol

I see Skyliner 200p there

[stevetynant]

sorry if I've confused things - 200p is a few variants I know perhaps I should have posted it in the header and not just in my signature - I've already contacted Alan to change but if it doesn't happen - well hopefully we will get those special nights form time to time and I'm already travelling into mid Wales for the dark skies so who knows

appreciate everyone's contributions- thanks for the time taken folks.

Steve

[twotter]

I see Skyliner 200p there

Same here

[hemihaggis]

lol ..... well i do have a hangover lol