Undercuts - Love or Loathe?

[JamesF]

Here's a pic of one I made:

There's a very slight taper from about halfway down the barrel to the first shoulder, which brings the diameter back out to the full inch and a quarter again.  It should be clear from the picture I hope.  It means the extension can't "rock" in the holder, but neither is there anything for a compression ring to snag on.

I guess that yes, it is an undercut of a sort, but of a different profile to the usual one.

James

[bambuko]

Is it like this one?

[JamesF]

Certainly looks pretty similar.

James

[jetstream]

I have no strong feelings either way, but if the undercut saves one of my TV's from a tragedy I like that. Long frac owners with long heavy eyepieces will know what I mean.

[alan potts]

I don't really like or dislike them to be honest. I do though find TeleVue undercuts are not so good in none TV diagonals, they work perfectly and slip cleanly in and out of the sleeve of their own diagonals but are horrible on the WO diagonal I have which I use on a top scope. They also do not work well with reducers found in other scopes I have, clearly they do something different in the making.

I have had eyepieces almost fall out of diagonals but that was the visual back spinning round on the Mak 180mm which has since found the bin, some of the eyepieces I have do weigh a bit and are not free with Frosties.

Alan

[bambuko]

The real culprit in this affair is the so called "compression ring".

It is nothing of the sort - it doesn't compress, it only applies pressure locally, where the screw is.

The rest of the brass strip doesn't do anything...

You might as well replace this abomination with brass or plastic tipped screw (or even plastic screw if you brave enough ) and you will never have any problems with snugging

That would solve the problem for majority of you whose only concern is snugging.

It would never do anything for me (or the users of parralizer) but that's another story...  

[YKSE]

As indicated in this post, GeezerGazer is draging Al Nagler to the thread for a comment. Those who have strong opinions about undercut have their chance to make their voice heard there.

[Roy Challen]

The real culprit in this affair is the so called "compression ring".

It is nothing of the sort - it doesn't compress, it only applies pressure locally, where the screw is.

The rest of the brass strip doesn't do anything...

. 

Exactly right! Perhaps I should have called this thread Compression Ring Woes or something similar

[Mak the Night]

Compression rings can be awkward at times. I find that undercuts or compression rings work fine if you take your time with them. As I predominantly have to use my left (non-dominant) hand to insert and remove eyepieces I have to be patient anyway.