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Originally posted by Aragorn
Mark are Orthos really worth getting ?been thinking of getting one for a while.
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I originally got mine for an f8 refractor and planetary work , which is there specialty , and while they work fine in a slower scope you might find them unsatisfactory for faster scopes, not sure on that though. Meaning stars may be unfocused or abberations towards the edge.
They work beautifully in my f6 newt but then I use the powermate which slows down the f number.
As there only a four element Ep they might not work well in a faster scope but I will, next time I see Saturn%25 (Graeme ) will try them in his f5 GSO dob and let you know.
Actually we did try them one night but with the Powermate on his Dob and they were fine in that configuration.
They have like only a 40-45deg field but that is not important on planets.
They do have a very natural and sharper view than multi element EP. The back ground appears blacker with less light scatter. They are favoured for planetary use and are quite cheap as compared to multi element eyepieces.
As I stated before eye relief is approxamtly 3/4 of the eyepiece focal length similar to a plossel , so with 3 and 4mm ones you have to glue your eyeball to the lens.
But with a barlow or Powermate and using 12mm and up, there a lot more comfortable to use.
Now you might say that what's the point if you have a four element Powermate and a four element eyepiece, thats eight elements.
I can only say that I tried a 6 and 7 element eyepiece only (no PM or Barlow) in my old refractor during the Mars event and the owner of those and myself found the Ortho Powermate combo sharper and clearer and were able to see more detail .
Mine are University Optics units and there are lots of reviews on these as well as a newer model of the same brand.
There are also other brands around for a higher price like Pentax.
It's really a good idea to try before you buy when it comes to eyepieces as they are such an important part of the optics and ever one has different tastes and expectations.
Mark