does STARTRAVEL-120 have similar light gathering to 6 inch reflector?

[FLO]

Surprised nobody's mentioned Takahashi

Takahashi

[SteelRat]

Don't worry - the SV was second hand and cheap but I wasn't suggesting this ACTUAL scope as an option. I know of MANY people who rate the Skywatcher ST80 very highly - I was just saying that I like MY 80mm.

Anyway, it's not like anyone's brought up Losmandy mounts or anything yet... oops, there I go. Stick one of those Taks on it if you like

[SteelRat]

Apparently PO raids used to be considered the way to go - Land Rover with girder mounted in front was the tool of choice in the day. Drive straight through a wall and still able to drive away... so the story went. Amazing what you can learn from TV. Personally I think that premium bonds involve less risk

[tenbyfifty]

Apparently PO raids used to be considered the way to go - Land Rover with girder mounted in front was the tool of choice in the day. Drive straight through a wall and still able to drive away...

In this big brother day and age you've probably just broken the law - incitement to commit robbery or something like that -

special branch know where you live!

Come to think of it, I think I know someone with a land rover - Takahashi's all round!

Just looking on this US site and some of th SVs are dirt cheap - can you get them for this price over here?

http://www.handsonoptics.com/tel_stellarvue.html#Nighthawk

[SteelRat]

Heh, in this 'Big Bro' day and age I think I probably break silly laws about half a dozen times a day without knowing it.

While I'm atit... there was a guy back in the early eighties that happenned one night upon a bank that was being refurbished. The whole front was hoarded up. He came back the next night with a saw, a six pack, a packet of fags, a fold up stool, a sack and a home made sign which simply read 'Night Safe'. Reports were that he took away about £11500 in that sack which was a fair wack in those days. And the other side of the whole he'd cut were six empty beer tins, a few nub ends and... a fold up stool.

Beggars have probly got his DNA off the tins and nubs by now. Hope he spent it well.

Not that I'm suggesting this as a course of action for anyone but it still gives me a chuckle remembering this story.

As far as those US prices go (and not just astro-gear but just about EVERYTHING - fuel et al) - by the time the goods are put on the shelves (or whatever - I know, fuel doesn't shelve well) over here the prices seem to have almost doubled. Pah.

[tenbyfifty]

As far as those US prices go (and not just astro-gear but just about EVERYTHING - fuel et al) - by the time the goods are put on the shelves (or whatever - I know, fuel doesn't shelve well) over here the prices seem to have almost doubled. Pah.

Yes those pesky customs/excise type chappies are spoiling our fun. If only we could get one of our American cousins to fill up a boat with optical goodies, cross the pond and land on a deserted Cornish beach in the dead of night - shiver me timbers, I'm a comin' over all piratical, Jim lad. Splice the main brace and keel haul the chef!

Apart from that - what are those £ 250 semi apos like on the scopenskies site?

[SteelRat]

Sounds like a good movie...'Scopes Gallore!' ???

[tenbyfifty]

Sounds like a good movie...'Scopes Gallore!' ???

It would definitely look suspicious, all the residents of Mevagissey turning into amateur astronomers overnight.

[SteelRat]

:laughing9:

[FLO]

This thread appears to have entered the 'twilight zone'

[tenbyfifty]

This thread appears to have entered the 'twilight zone'

I thought it was more Monty Python myself.

[FLO]

[jakey]

Actually I was thinking about something very similar to this when I re read a very old book that I have. It is called Practical Amateur Astronomy. It is edited by Patrick Moore and I think it comes from the 1950's. It is very firm in stating that the minimun aperture for an astronomical telescope is three inches for a refractor and six inches for a reflector. I could not figure out where that opinion came from.

How times have changed.

[The Warthog]

Actually I was thinking about something very similar to this when I re read a very old book that I have. It is called Practical Amateur Astronomy. It is edited by Patrick Moore and I think it comes from the 1950's. It is very firm in stating that the minimun aperture for an astronomical telescope is three inches for a refractor and six inches for a reflector. I could not figure out where that opinion came from.

How times have changed.

I remember reading in the sixties that a 6" scope was the largest practical ATM scope.. That opinion was from Sir Patrick, too. It was the largest common size for an amateur scope back then. Our school bought a 60mm scope, and it was considered quite a nifty instrument. Unfortunately, it didn't get much use.

[tenbyfifty]

Do you think the cost of the materials used in apo scopes eg fluorite will ever fall to the level of normal glass making or do you think it will always be kept high so they can sell high end kit? Are there any other types of wonder glass in development? Think I'll start a new thread with this one...

[The Warthog]

Do you think the cost of the materials used in apo scopes eg fluorite will ever fall to the level of normal glass making or do you think it will always be kept high so they can sell high end kit? Are there any other types of wonder glass in development? Think I'll start a new thread with this one...

Oy! Ya did! Go to tbf's other thread to answer this question, or I'll get confused. :insects1:

[Ags]

I know this is raising a dead thread, but I came accross this thread while googling the ST120. I think you've all got it wrong. Although the central obstruction is only 10%, remember that each reflective surface kills another 10% or so of light. In the case of a Mak like mine, 17% of light is lost (according to Celestron) despite having super-duper XLT coatings. On top of that 17% loss, the central obstruction blocks another 10%. According to my calculations, my mak is roughly equivalent to a 90mm refractor in terms of light gathering.

For an eight inch SCT, the light loss from all surfaces really is similar to the loss of a full inch of aperture.

In any case 10% is not insignificant. People spend good money on dielectric diagonals for exactly that transmission difference.