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Eyepiece advice needed.


silentrunning

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Glad you got sorted with some wider angle eps. :thumbsup:

 

Good luck with all those tuning rings. ;)

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Try and set the focal lengths you think you'll need in advance. You don't really want to be changing the rings in a dark field. Especially opening up the glass to moisture, it's killer.

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The 8mm Hyperions and rings have arrived. Picture shows them without and with both extension rings. Pretty big but no so much as some monster WA EPs out there!

 

get.jpg

Edited by silentrunning
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I had a quick look through the 8mm Hyperions last night and the experience was good and bad.

 

The EPs are quality and work well although the eye relief is not as comfortable as the 21mm requiring the eye to be closer to the eye lens and in a narrower range. The bad news is that the higher magnification shows up severe mirror pinch which is completely undetectable at lower mags. This is result of the design of the mirror cell which has nothing but very tight brass clips pressing down on the mirror in 3 places with three radial screws attached to the brass supports, see picture. The good thing is the pinch appeared 'perfect' without any other aberrations superimposed on it. A PM to Graham might be in order :)

 

Another thing is alignment of the barrels at high mag requires tiny adjustments to the main mirror collimation screws that took me about 15 minutes to do, having an assistant would reduce this time enormously. Another issue is that each eyepiece holder is rotated to achieve individual focus and at higher mags assymetry caused by the basic locking nut mechanism of the EP/EP holder means the individual  images can be seen to rotate whilst focusing which then pushes them out of alignment. Makes alignment necessary after each refocus which is a pain even if just one observer is present. With a group of observers it be a royal pain in the proverbial!

 

Nevertheless I had a splendid view of the M57 and M27 through the 8mm hyperions which gave x187,  M27 all but filling the FOV. Even with the above issues this increased mag gave a much improved view of these relatively bright PNs.

 

get.jpg

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M57 and 27 must have been a marvellous sight.

 

I think you need to back off the pins poking in to the mirror edge and the vertical clamps from the surface by the tiniest little bit. Make them barely touch the mirror. You could try screwing it all back lightly to a piece of paper between the metal and the mirror, then remove the paper. Check again at high power and see if that solves the pinching.

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2 hours ago, Tweedledee said:

M57 and 27 must have been a marvellous sight.

 

I think you need to back off the pins poking in to the mirror edge and the vertical clamps from the surface by the tiniest little bit. Make them barely touch the mirror. You could try screwing it all back lightly to a piece of paper between the metal and the mirror, then remove the paper. Check again at high power and see if that solves the pinching.

 

Thanks Baz, that's what Graham has suggested.

 

I've just emailed one of the guys who built it just to check there's no reason why there shouldn't be a gap between the clamps and the mirror. My only concern is that the mirrors are up side down during installation and removal and I don't want them to wobble around and cause me to drop them!!

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Well that was simplicity itself. There are three knurled nuts under the main mirror holding each of the 3 triangles for the 9 pin support. I just loosened the radial screws, loosend the aforementioned bolts slightly and then adjusted them with a waver thin bit of paper under each clamp. Also the mirror is beveled so as  it's impossible for it to fall out - as long as the radial screws are not completely removed! :-)

 

Thanks to Graham and Baz!

 

get.jpg

 

get.jpg

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