Butchering an eyepiece to achieve focus

[Gmx76]

So I brought a cheap finder off ebay which works well with my 25mm Skywatcher eyepiece.  But I wanted a diagonal so bought a cheap one from ebay.  Now I can't achieve focus as the minimum focal length is too long,  I.e not enough in-focus. 

So I was thinking if I could unscrew the top part of the eyepiece and attach it direct to the metal barrel that slots inside the finder.

Would this work?

Does it actually unscrew? It doesn't seem to want to.

I don't want to damage the eyepiece if I can help it.  

Thanks

Greg

[John]

I think adding the diagonal is the issue here. You really need to shorten the finder tube to allow for the light path that the diagonal uses up. If you can get that right then the eyepiece should be able to reach focus without the need for modifications.

 

[Gmx76]

It might be hacksaw time then!

[Gmx76]

Thanks!

[JamesF]

Hacksawing the tube might cause problems if the original eyepiece holder screws into a thread on the inside of the tube though.  I know some finders are designed that way.

I wonder if you would get enough "inwards" movement if you could unscrew the eyepiece holder from the diagonal, unscrew the barrel from the eyepiece and put the top of the eyepiece straight onto the diagonal?

James

[Gmx76]

sounds a bit less destructive! can you remove the top of these eyepieces? i am talking about the bit surrounded by rubber, from the main barrel?

[JamesF]

1 hour ago, Gmx76 said:

sounds a bit less destructive! can you remove the top of these eyepieces? i am talking about the bit surrounded by rubber, from the main barrel?

Sometimes it is possible to remove the barrel that goes into the eyepiece holder from the rest of the eyepiece.  It depends on  the eyepiece though.  I must have a 25mm Skywatcher eyepiece around somewhere to check, but I can't remember where at the moment.  Sometimes they have additional lenses inside the barrel, but from memory I don't think that one does.  It's just an idea to look at, anyhow.

James