telescopics

[LaNeK779]

hi all,

it has been discussed and applied in practice that a combination of pcx and pcv lenses of i.e. 75 and -25 FL creates a telescope with a 3:1 ratio

can the same result be achived with a 45 and -15 combination? or am i missing something here?

[danielbriggs]

can the same result be achived with a 45 and -15 combination?

Yes.
Ratio of FL's.
Smaller FLs = More sensitive alignment.

[shrad]

drlava's cylindrical lenses are already a real pain to align with several diodes combined, so I cannot imagine with a smaller focal length...

there are several types of telescopic setups though, and some are easier while other are smaller, so you can always choose a variant

[LaNeK779]

thanks for the answers guys!

this setup will go in front of some knife edged LOCs (at some time in the future, sooner than later i hope). so all i have to decide now is gallilean or kepplerian telescope, not much difference though with the lenses'prices on surplus shed, i might just as well build both and try them

alignment is just the process of moving one lens back and forth until the desired result is achieved. what can go wrong?
(i am just writing this, so i can come back later and swallow my own words )

[Doc]

It will cost you about £60 for both lenses from Edmund

[andy_con]

http://www.laser-man.co.uk/2006/content/view/107/74/

[LaNeK779]

http://www.laser-man.co.uk/2006/content/view/107/74/

i already know this by heart andy, thanks for the info on your site and your posts here


it is just that the edmung optics are 60quid as doc says, or i could get something similar from surplus shed for 8 dollars both (and 400-700nm ar coated aswell)

and i wanted a shorter length telescope (physical length), so maybe i will try this 45 / -15 combination. i hope to have a red module up and running in a couple of months, so if anything interesting comes along in terms of telescopix, i will let everyone know

[andy_con]

just remember you get what you pay for! the lens from edmund optics are extremely good quality and losses are pretty much 0.

you may come across issues at distance when altering distances between lens. but test and let us all know how you get on

[shrad]

alignment isn't only sliding back and forth, but also pan and tilt, but it is way less painful with circular lenses