Atmospheric Dispersion Corrector - Have I been conned?

[WicklowSkies76]

I recently purchased what was listed as a used ZWO ADC on Ebay from a seller called ENS Optical from the U.K.

There is no bubble level on the ADC and without really knowing how to use it yet I am trying to ascertain if it's broken/defective. The ADC comes in a few parts. The central element which contains the 2 lenses with long thumbscrews is the bit I am concerned about. The two pieces of glass inside the element are loose, even when the thumbscrews have been tightened. The seller won't respond.

1. Have I been had?
2. Should the glass rattle around inside the element when it's tightened? Surely not.
3. Is there any way to fix this if it's an issue?
4. The top element seems to be fixed at an angle... maybe that's by design?
5. If I move the thumbscrews left and right it does move the 2 glass elements, I guess gravity is enabling it to do so but when I tighten it they can still move... won't that be an issue?

Thanks in advance!

[Freddie]

The original units didn’t have the level, this was a later addition for newer units.

[Frank the Troll]

Give Steve a call at ENS, number is on his fleabay

I have no qualms buying from ENS

[WicklowSkies76]

OK thanks will give that a try. Am trying to troubleshoot. When I tighten the top thumbscrew the top piece of glass doesn't move. 

It's the bottom piece that still can't be secured. Even tightened it still moves. I am assuming that is not OK. I don't know if the glass inside the ADC is symmetrical, in that it doesn't have any kind of calibration that has a different angle required at zero or a different width of glass that needs to be in a certain point... anyone know? What I am getting at, if I manage to get the two pieces of glass secured does it matter what position they are secured in? I can slide left or right on the top and bottom parts from the Zero position, but I don't know if it needs to be in a certain position to begin with?

[Ibbo!]

Did you get the pdf link with tit?

https://astronomy-imaging-camera.com/manuals/ADC Manual EN.pdf

 

[WicklowSkies76]

Hi there yes I got the link. I can figure out how to use it but the loose glass element bothers me and I was hoping someone would know if that's expected or not before I spend hours outside fiddling with it to no avail. 

[symmetal]

If you unscrew the adapters at each end of the ADC you can see two compression rings with four holes to insert a 'key' to tighten. I found one of the rings of mine wasn't pushing against the glass holder. When the glass thumbscrews were tight it still rattled when shook, which was the compression ring rattling. I just did the ring up half a turn pushing with my fingers until it felt resistance and the rattling stopped. I assume they're done up tight enough to stop the glass twisting but not enough to stop it rotating with the levers. When you have the tightness right a dab of silicone on the edge of the ring should keep it from un-doing again.

This might be your problem. 

Alan

[Cosmic Geoff]

I have looked at my ZWO ADC (which does have the bubble level).

No rattling, no parts at odd angles.  Just a black body with two levers (and the bubble level) sticking out. To adjust it, I move the two long screws in their slots, in opposition.  No need to tighten or slacken anything.

As I understand it, both the optical elements are thin wedges, and rotating them relative to each other creates some colour dispersion to counteract that from the atmosphere.  I hope that helps.