Micro focusers (1 Viewer)

T

thornlv

Well-known member

• Sep 9, 2010

• #1

Can anyone explain how micro transsmissions work, not fully understanding the 1:10 ratio s quoted ie on one of these

http://www.teleskop-express.de/shop...on-for-retrofitment-of-Crayford-focusers.html

cheers

 

P

Paul Corfield

Well-known member

• Sep 9, 2010

• #2

I presume that turning the small wheel 1 whole turn will move the focuser only a tenth of the distance to a whole turn of the big wheel. One whole turn of the small wheel will only move the focuser about 1mm or thereabouts.

Paul.

 

Last edited: Sep 9, 2010

alphan

Well-known member

• Sep 13, 2010

• #3

Yeah I presume that too, ten turns of the small wheel equals to one turn of the big wheel. Wonder if the backlash of the gears are that fine to accommodate the fine focusing.

 

C

chrissuddell

New member

• Oct 2, 2010

• #4

Hi,

The one you have out the link up for is a replacement to one side of a Skywatcer/Syntha focusor, they have gearing inside with a 1/10 ratio, so you will need to turn the little bit ten times to turn the outer one once. One side of the focuser remains normal.

These are really useful for fine focus.

Chris

 

P

Paul Corfield

Well-known member

• Oct 2, 2010

• #5

The quick fix way to do this with the Synta focusers is to change one of the wheels for a bigger sized one. It's crude but it works as the diameter of the wheel controls the speed or how fine that you can focus.

Paul.

 

alphan

Well-known member

• Oct 4, 2010

• #6

Yeah, like Paul said, just install a bigger wheel and you get similar effect. The Micro mechanism only control the turning of the gear. The pinion remain the same. Thus if you have a slack or if the free play is a little bit high, the micro mechanism won't do any good.

 

C

chrissuddell

New member

• Oct 4, 2010

• #7

Hi Alphan,

There is no pinion in a crayford focuser, I think some of the USA Celestron scopes had Rack and Pinion focusers, but this 1:10 mod would not work with them anyway.

Chris

 

alphan

Well-known member

• Oct 5, 2010

• #8

Hi Chris, thanks for enlightening me on that. What I am saying is, the micro only turn the bigger knob and any free play would still be there, with or without micro. Correct me if I am wrong, please.

Edited: Just found an article on Crayford focuser. No free play with this system, Mostly weight self tensioning.

 

Last edited: Oct 5, 2010