Not all 2" are the same?

[kerrylewis]

It seems to be happening to me more recently: an eyepiece which is supposed to be 2" does not fit easily into a diagonal or even the Baader Quicklok which is also supposed to be 2". I also have difficulties fitting some 2' filters to 2" eyepieces. Anyone else get this? I was wondering if differential expansion/contraction might be the reason. It's very frustrating on a cold night when I have to almost force the eyepiece in and sometimes upsetting the scope alignment in the process.

Any thoughts? WD40 on the eyepiece perhaps?

[swamp thing]

Never had that problem Kerry. Sounds quite aggravating to say the least. Ive had some 1.25" filter problems in the past but never any issues at 2"

Not sure what to suggest TBH. 

[moriniboy]

I have had a couple like this over the years but assumed they are keeping tolerances tight so that the collimation is not affected.

[alan potts]

Not impossible but I have had difficulty fitting  TV eyepieces into into the TS extention I have fitted to the M/N 190mm though never have an issue with the same eyepieces into a TV diagonal. They are not all the same size, are they?

Alan

[RobertI]

Yes I have a problem getting my Baader Hyperions in and out of my 2" diagonal - it's really annoying. I was thinking of applying some very light lubrication around the barrel and wiping off again and seeing if this improves matters. If not I may revert to the 1.25" fitting (the Hyperions have both) which unfortunately slighly defeats the point of a 2" diagonal.

[YKSE]

It seems to be happening to me more recently: an eyepiece which is supposed to be 2" does not fit easily into a diagonal or even the Baader Quicklok which is also supposed to be 2". I also have difficulties fitting some 2' filters to 2" eyepieces. Anyone else get this? I was wondering if differential expansion/contraction might be the reason. It's very frustrating on a cold night when I have to almost force the eyepiece in and sometimes upsetting the scope alignment in the process.

Any thoughts? WD40 on the eyepiece perhaps?

Kerry, I think you're on the right track, observing in cold weather, as the scope with diagonal usually have been out and cooled for a couple of hours, while the 2" finder EP has been in the cosy EP case, the contraction of the diagonal´s EP holder can very well cause the issue.

[Reeny]

Turtle wax or car polish might be less destructive than WD40 spray.

I normally coat the top of our curtain poles with car wax to help the rings slide along more smoothly.

If the problem is expansion, I don't know what you can do apart from clean up any sharp edges - and polish the high spots off the barrel.

[kerrylewis]

Interesting comments and although Steve has escaped I am obviously not alone. I will try to note which combination cause trouble and then have a look in the daylight with all the bits at equal temperature. It could be, as YKSE suggests, that with the scope and diagonal etc out in the cold and the eyepieces being returned to a relatively cosy foam lined case then they are not contracting as much as the diagonal or Clicklok. I could try leaving the troublesome eyepieces out in the cold for a while (that'll teach 'em!) and see if they then behave.

Btw I wasn't serious about the WD40 but I could try something else as suggested by Reeny 

Cheers

Kerry 

[rwilkey]

Yes I have a problem getting my Baader Hyperions in and out of my 2" diagonal - it's really annoying. I was thinking of applying some very light lubrication around the barrel and wiping off again and seeing if this improves matters. If not I may revert to the 1.25" fitting (the Hyperions have both) which unfortunately slighly defeats the point of a 2" diagonal.

Hi Robert, I can see no benefit in using the Hyperions in 2" mode as you are altering the focal length by doing so, making it longer.  I find the Hyperions are better used with the 1.25" nosepiece as there is no increase to the 68 degree view, you need dedicated widefield ep's for that.

[RobertI]

Hi Robert, I can see no benefit in using the Hyperions in 2" mode as you are altering the focal length by doing so, making it longer.  I find the Hyperions are better used with the 1.25" nosepiece as there is no increase to the 68 degree view, you need dedicated widefield ep's for that.

Thanks Robin, I do actually keep the 1.25" nosepiece attached to the eyepiece as normal, but I fit it to the 2" opening of the diagonal using the 2" part of of the eypiece barrel, so eyepiece sits lower inside the diagonal. Seemed like a good idea as it seemed more secure, but unfortunately it's a tight fit!

[John]

I'm not 100% sure how the Baader Clicklock works but I'd guess it's through some type of compression collar. Is it possible that, either through cold weather or extended use, that the collar is not fully returning to it's non-compressed form ?

[russ.will]

I have issues with my Delos and a wide range of 2-1.25" adaptors. I also have trouble finding one with a brass compression ring that mates with the weird TV undercut. They're secure, but always seem to lifta touch and wobble unless you do it up double tight.

Russell

[Owmuchonomy]

I'm not 100% sure how the Baader Clicklock works but I'd guess it's through some type of compression collar. Is it possible that, either through cold weather or extended use, that the collar is not fully returning to it's non-compressed form ?

Yes, a ratcheted nylon insert. In my case, and I have the same issue as the original poster, it's down to old age and incompetence. My daughter has no problem! Personally I wouldn't put lubricant near any of my precious optics.

[YKSE]

Yes, a ratcheted nylon insert.

Have you or me got a special made one? Mine looks and feels all metal.

[Owmuchonomy]

Oooh now you have me wondering. Mine looks the same as yours but the insert 'feels' like nylon or similar. I guess it could be soft metal.

[kerrylewis]

I did a wee experiment: I put all the relevant bits - diagonal, Baader Clicklok, 2" adapter and some 2" eyepieces in the same temperature (actually an unheated room) and, guess what, they all fitted perfectly well! So, it does seem that differential contraction (it usually happens in the cold) may be the culprit.

I will have to get into the habit during an observing session of removing my most used eyepieces from their foam bed and perhaps putting them in the lid of the eyepiece case and see if that cures the problem. 

[YKSE]

Great that you get it sorted out.   Actually, looking át the thermal expansion coefficients, brass expands/contracts almost twice as much as steel/iron.

And  a side note, undercut in EP's barrel can cause some minor nuisance too.