4 replies to this topic

[andrewstuartallen]

Hello everyone.

 

For my Orion Tri-Mag barlow, in the process of removing the lens (a cemented doublet, I think) from its cell for edge-blackening purposes, I may have flipped* the lens, so now I don't know which way it should be oriented in its cell. 

 

One side is flat or nearly so, and the other is distinctly concave. I *think* the concave side points toward the eyepiece, but I'm not sure.

 

Does anyone know the answer?

 

Thanks in advance.

 

Andy

 

*The flip happened just after I had removed the retaining ring but while the lens was still in the cell. The lens was lightly stuck in the cell, and when I applied a small amount of pressure with a microfiber cloth, the lens appeared to quickly flip over within the cell, but it happened so fast, I'm not sure that it flipped all the way over.

[KBHornblower]

I would mount it flat side forward, as that is how my old TeleVue Barlow is set up.  It is strongly plano-concave.

[andrewstuartallen]

Thank you!

[Starman1]

Hello everyone.

 

For my Orion Tri-Mag barlow, in the process of removing the lens (a cemented doublet, I think) from its cell for edge-blackening purposes, I may have flipped* the lens, so now I don't know which way it should be oriented in its cell. 

 

One side is flat or nearly so, and the other is distinctly concave. I *think* the concave side points toward the eyepiece, but I'm not sure.

 

Does anyone know the answer?

 

Thanks in advance.

 

Andy

 

*The flip happened just after I had removed the retaining ring but while the lens was still in the cell. The lens was lightly stuck in the cell, and when I applied a small amount of pressure with a microfiber cloth, the lens appeared to quickly flip over within the cell, but it happened so fast, I'm not sure that it flipped all the way over.

Yes, concave side toward the eyepiece.

[andrewstuartallen]

Thank you for confirming!