8 replies to this topic

[John Higbee]

I'm having a problem with the finder to my C14 Orange Tube.  I disassembled it to clean the optics (took off the objective cell and the eyepiece)...upon reassembly, I can't get it to a sharp focus at infinity. 

 

The finder is close to sharp focus for objects at close range (30 to 50 feet) but remains blurry for objects farther away, through the full range of the finder's helical focuser.

 

I've never had a problem with this before.  Any help or suggestions would be gratefully appreciated!

 

thanks, John 

[deSitter]

Did you install the objective backward? Should have the more convex side toward the sky.

 

-drl

[John Higbee]

no - I didn't remove it from its cell...

[J A VOLK]

Can you unscrew the lens cell a bit to achieve focus?

[jragsdale]

Can you unscrew the lens cell a bit to achieve focus?

Yep, some finders have a large threaded range for the front cell and a locking ring behind it. Unthread to focus at infinity, then loosen locking ring until it's tight against the cell.

[davidmcgo]

The old style orange tube finders did not focus at the objective. If you didn’t actually pull any lenses from their cells, there is a chance the knurled eyepiece lock ring is on backwards and restricting the eyepiece going in as far as it needs to reach focus.

 

Dave

[John Higbee]

This finder is the older model - with focusing at the eyepiece knurled knob.  Have tried the suggestions above...no improvement.

 

One other symptom - the finder has a simple single cross consisting of 2 small wires.  When I look through the finder  now, it shows two crosses..one "cross" slightly offset from the other.  I get that regardless of the eye I'm using.

 

John

Edited by John Higbee, 24 November 2024 - 04:49 PM.

[ccwemyss]

That sounds like a lens in the eyepiece is tilted. 

 

Chip W.

[John Higbee]

...and that's what it was!  Thanks, Chip!

 

John