Cop this for a photo

I wish I could take stuff like this, absolutely fantastic shot I reckon

http://www.buytelescopes.com/gallery...o.asp?pid=4892

[ballaratdragons (Ken)]

That is brilliant.

I tried to put a comment in about IceInSpace.com having Astrophotos too, but I have to give my address and join or I can't place a comment. What a rip off!

Damn nice photo though.

[RAJAH235]

T'scope must be mounted on a truck! 8500mm fl?=27 feet long????
Brilliant pic. tho. All that detail, looks like a flyover.

[iceman (Mike)]

ah yeh, Wes Higgins is one of the masters. Him and Bird are the masters of lunar photography, they really are doing excellent work and their processing is so nice.

They both post their stuff on CN so you can compare their work. Wes usually gets a bit more focal length due to having an 18" telescope, compared to Birds 10"!

[[1ponders] (Paul)]

Not necessarily a truck Rajah. with a 4X powermate even a modest 10" dob's FL becomes 7.2 meters (assuming its normal FL is about 1.8m. EFL (Effective Focal Length) = M (Magnifiying Unit. Not your usual magnification (Tel FL/EPFL) ) X OTA FL.

ie EFL = M X FL (ota)

Regarding focal length, trying to come to terms with your equation. My tak fl is1000, it is a F7.9 I think from memory, and I have 2 powermates, a 2" 4x and 1.25 5x . In the equation what is Tel FL? I understood using a 5x powermate would bring the FL to about 5metres and using the Toucam which is equivalent to a 6mm ep (I have been told) gives a magnification of over 800x..Based on this assumption one would need absolutely perfect seeing to see anything, I would reckon. All very confusing stuff at times methinks..

[iceman (Mike)]

I think the focal length he's referring to is simply the focal length of his mirror, times by the 4 or 5x powermate he's using.

My 10" dob is 1250mm focal length (f/5). Anthony has a 10" mirror but got it designed at f/6, so he must have a longer focal length. I've only got a 2x barlow so my images are all at focal length 2500mm. Maybe a little more when I slide the barlow and toucam out a bit.

[[1ponders] (Paul)]

Mikes onto it

If you are not using a barlow or Powermate then M = 1
Standard formula as follows:

f/ration = FL/Ap = 1000/130 = 7.9 (this is the same as the next formula with the M taken as = 1 so is not included)

Or with Powermate

f/ration = EFL/AP

Effective Focal Length (EFL) = FL X M(Barlow or Powermate) = 1000 X 4 (PM) = 4000/130 = 30.7 (It might be simpler to think of the M as a "multiplier" rather than a "magnifier)

magnification without PM or Bar.

magnification (m) = FL/EPFL (Eyepiece Focal Length) = 1000/6mm= 167x

or with PM or Bar

Total magnification = EFL/EPFL = 4000/6 = 667x With an f/ration of f/30.7

Or using a 5x barlow

= 5000/6 = 833x With an f/ration of f/39

It gets more complicated when you add optical elements together. eg. A 2x barlow added to a 4x powermate isn't 6x but 8X