Focal Length Query

[Crossway]

This has surely been asked before....but is there an optical system which halves  a telescope's focal length.  The reverse of a Barlow in fact.

[nightfisher]

Yes, you can buy focal reducers, but it depends on what scope you plan to use it with, if you used an 0.5 reducer with an f5 scope it would produce poor views, but with an f10 it would be better, if that makes sense

[ronin]

Reducer.

Used mainly in the imaging areas as then the f number is brought down and the brightness of the image increases, size is decreased.

In a refractor there can be Reducers or flattener reducers.

[jambouk]

Crossway, what are you trying to achieve?

James

[damnut]

Focal reducers are common for sct's (and relatively cheap), because they usually have such a large focal length....The questions remain as above...And why??.

[Crossway]

Nothing at all !  Just idle curiousity really  but thanks to all for explanation.  Feel terrible if I have wasted your time.!

Pete

[jambouk]

Not a waste of time at all, it's just that some people ask a specific question but in fact there is an easier solution to the problem they are trying to solve, but they don't know that. So academic questions are good and interesting, I ask lots, but often knowing what lies behind the question makes the responses more thorough.

Keep asking the questions!

James

[glowjet]

Asking questions is certainly not a waste of time, as it adds to your knowledge and that of others who come to read what has been said. There was a general notice in my tool factory years ago, "If in doubt ask", the same applies in the SGL forum to-day, enjoy