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astrorg

Skyliner 250PX and reducer or tube shortening ...

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Hi experts
I recently resuscitated my old [the very first one], but in New conditions Skywatcher Skyliner 250PX.

I put it for sale many months ago and had a couple of interested buyers, but never sold.

I had second thoughts in selling it and the main reason was - it is getting too heavy for me.

Mine has: added fan to keep mirror dewless, although I managed years ago to better original focuser steadiness, I replaced it with the lowprofile [good for DSLR I still happily use] 10:1 - which also has extension for use with more modern CCD + added secondary mirror Dew-heater [when needed].
The whole thing is fit on a EQ6-ascom driven mount.

I always wanted to either reduce tube length [i.e. saw it] or use a reducer.
Either ways: what would you recommend as reducer or/and cutting tube shorter?

I currently am using [not much yet !] its matched Skywatcher Flattener [0.9x] with my DSLR Canon 100D and I am happy with it.

Looking forward to get back to it - I was sick for 2 weeks [nothing bad] then I was busy, then holidays etc. I skipped at least a month of Deep Sky imaging.

Personally I guess the best way is to shorten tube but, I need to take account of:

1. I do need to use its flattener
2. I both wish to use DSLR + CCD and 'eventually' use filter wheel [which takes about 45-50mm at least].

All the above needs to be considered.

One obviously wishes to shorten tube as much as possible without loosing resolution or creating new problems - i.e. trying to make a faster and also less heavy tube [not much!]

 

Thank you in advance experts
Mauro

PS I know easy way is to have a decent  Newtonian and buy the Quattro Carbon one [much lighter] + expensive flattener!

 

Edited by astrorg

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addition, just rememberedI now have the 10:1 and if I shorten tube I will also need either put old focuser back or move secondary [too much to do]. Maybe also Primary mirror curvature might get involved as focusing angle will change.

mmm

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Mauro, I'm a little confused. Shortening the tube still leaves you with the same focal length mirror, so you can end up with all sorts of issues doing this, and your image scale is still the same etc.

What are you planning exactly?

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Yes, I realised I said a stupid thing! Disregard the tube cutting ...

1. Mainly only try and reduce F/4.7 to something much lower if possible and use DSLR minly and eventually an Altair 178C.

I do have a coma corrector that works well - only tested once and coma seems 99% gone!
I have not yet done a proper night imaging yet, since I have fixed all small problems I had and added coma corrector and already thnking 'faster' - I must be mad!
Just trying to make it faster.

2. I really wish to reduce its weight to half!
I thought to do a scheleton and add strong clothing around and get maybe 30% weight off - I am getting older!

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ADDITION
Just remembered - of course - the shortening of the tube was only to get the focus point outer than it was as DSLR did not reach it even with all focus in [old focuser] - reason I did replace focuser - I forgot - as mentioned I only re-hesumated this telescope, which I still love - mirrors are as new!

Tried them sometime ago and I was so surprised [I did forget] how fast it is at F/4.7.
 

Edited by astrorg

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