Problem focussing Baader Hyperion Zoom with SW 250PX

[peterbolson]

I have just changed my SW 200P for a 250PX. I had no problems focussing with the 200P but with the 200PX I'm unable to rack the draw tube in far enough to get it in focus. The problem is worse with the higher magnifications. All my other eps focus OK although even they have to be racked in almost to the limit.

I think the problem must be that the 2" and 1.25" adaptors supplied with the SW250 are just a few mm too long ( they are 58mm deep ). Both scopes have a focal length of 1200mm so presumably because of the greater diameter of the tube of the 250PX the focal point is nearer the scope ( does that make sense ? ).

The answer would seem to be a shorter adaptors. Have other people had the same problem & are such adaptors available ?

Thanks

Peter

[fredster]

Bit extreme but you could change the focuser for one of the low profile crayfords which allow the eyepiece to be slotted straight into the focuser. Or perhaps try and re-collimate the scope with the primary pushed up the tube a bit.

[Damo636]

One of these fitted to the zoom will gain you a few mm inward travel Peter....

http://www.scopesnskies.com/prod/scopeteknix/accessories/low-profile/eyepiece-adaptor.html

They semi permanently convert an 1 1/4" eyepiece into a 2" but only add a couple of mm to the length.

[John]

You are not using the 1.25" and 2" adapters together, as the same time, are you ?.

If so this does cause problems with bringing eyepieces to focus. You need to use either the 1.25" OR the 2", not together.

It's a common source of confusion with Skywatcher scopes !

[peterbolson]

You are not using the 1.25" and 2" adapters together, as the same time, are you ?.

If so this does cause problems with bringing eyepieces to focus. You need to use either the 1.25" OR the 2", not together.

It's a common source of confusion with Skywatcher scopes !

Hi John - no I'm not ! I've had my 8" for a few years so I've not been caught out by that one !

[peterbolson]

One of these fitted to the zoom will gain you a few mm inward travel Peter....

http://www.scopesnsk...ce-adaptor.html

They semi permanently convert an 1 1/4" eyepiece into a 2" but only add a couple of mm to the length.

Hi Damo

Looks good. I reckon that could be the answer. I'll give them a ring

Thanks

Peter

[John]

Hi John - no I'm not ! I've had my 8" for a few years so I've not been caught out by that one !

Thats good - hope you did not mind me mentioning it

I'm sure I've read reports on the forum of folks successfully using the Hyperion zoom with the 250PX so it must be feasible. I've owned both items but not at the same time so I've not had the opportunity to combine the two personally !.

That adapter that Damo links to might help. The same supplier has one for a few quid less in their discounted "Astroboot" section:

http://www.scopesnskies.com/AstroBoot

[peterbolson]

Hi John

I can't find it ! What 'filter' is it under ?

I spoke to the chap at scopes'n'skies & he said that the reason why some people have a problem & others don't is that it depends on how far the mirror is set up the tube when it is collimated. Apparently 1mm difference here make 2mm difference at the lens end. So I could do what Fred suggested.

Peter

[peterbolson]

I'm having second thoughts about the low profile adaptor. It only protrudes 2mm above the 2" ep holder which means that my ep would move 56mm towards the scope. This would be too much as I think I only a few extra mm ( I need to check this more accurately ) and it would mean that I have the draw tube almost fully out most of the time.

I think the Antares 1.25" to 2" ep adaptor with filter thread looks a better bet as it protrudes 10mm above the ep holder.

[gooseholla]

i use the adapter that was posted above. it allowed me to focus 1.25" eyepieces in my scope without a problem. There is one similar on the astro boot section for about £6, from what I remember.

[John]

Hi John

I can't find it ! What 'filter' is it under ?

If you use the 2" filter the adapter is in the 3rd row down, 2nd item in from the left.