Quote:
Originally Posted by Somnium
A 14.5 iDK on a paramount MX
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Hi Aidan,
I suspected that from your original post, but I just wanted to be sure there were no other different telescopes involved. As you would be aware this telescope is designed and optimised as an imaging platform and not as a visual telescope. It has a secondary obstruction of 7.5" (51.7%) which will cause major issues with some aspects of visual optical performance. The large secondary obstruction does not impact its performance as an imaging platform.
For visual use the large secondary obstruction causes significant diffraction and will have a major effect on the MTF curves, which will result in poor performance at higher powers, which you might normally use on a 14.5" telescope for lunar, planetary and double star work. Consequently, I wouldn't be spending a lot of money on high quality eyepieces for high power work. As a telescope for low to medium power work on DSO's and other extended objects the telescope will do a fair job. The 7.5" secondary obstruction will reduce its light gathering power to be the equivalent of an unobstructed 12.4" telescope. Whilst the large secondary obstruction does not affect the resolving power of the telescope itself, it will limit your ability to run higher powers and take advantage of the resolution capabilities of the telescope.
All of the above having been said the telescope warrants "decent" eyepieces IMO for low to medium power use. The telescope has a focal length of 2.47 metres (fairly long). I would be aiming to get an eyepiece which gives around 100X to 130X for general Deep Sky use in this scope, which means about a 20mm to 25mm eyepiece. Two good ones which immediately come to mind are the 22mm Vixen LVW and the 24mm Televue Panoptic. The Panoptic can still be sourced new, but the 22mm Vixen LVW would have to be sourced 2nd hand, but they are reasonably available on the used market. With patience you should be able to find either eyepiece for under $300 second hand. These eyepieces generate about a 3.5mm exit pupil which is ideal for use with visual deep sky filters like UHC and OIII also.
Cheers,
John B