Last updated on
4/11/
2006

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My Eyepieces

The eyepieces I use, are these (with the magnification and Actual FOV listed for a 8” f/10 SCT):



The Panoptic is a 2” eyepiece; the rest are 1.25” EPs. Note that a 1.25” EP with a wide field of view, has a big advantage over 2” EPs when you start to look at the price of specialized narrow-band (nebula) filters.

The Televue 27mm Panoptic is a wonderful eyepiece for lower-magnification viewing, at a price lower than comparable Naglers. (I’ve never tried the long focal length Naglers, on the philosophy that it’s not wise to try an eyepiece you can’t afford, just like it’s not wise to look into a large-aperture telescope you can’t afford <grin>. But there are a lot of amateur astronomer who feel that Naglers are worth the price.)  I have used the 27mm Panoptic a lot and would recommend it to anyone. 

For medium magnification viewing I use the Pentax XW 20mm and the Pentax XL 14mm.  (An alternative is an Orion Lanthanum Superwide (LSW) 17mm - I do believe that the Orion [Vixen] LSWs are unfortunately often overlooked by observers. They are rarely reviewed or discussed but their long eye relief, wide field of view, ability to fit 1.25” or 2” diagonals, and price make them very attractive for low- to medium-power viewing in my experience.)  At 200X magnification I’ve settled on the Pentax 10.5mm eyepiece because it provides very good contrast.  Televue Radians are regarded by many as also providing high contrast by I never really liked the view I got from the 14mm Radian I had - I suspect that each of us have eyes with particular idiosyncrasies, which some eyepiece designs help to mitigate and others don’t.  The 14mm Radian never worked for me and it doesn’t for some other folks, although there are many observers who really like Radians.  On the other hand, I’ve never heard of anyone who doesn’t like Pentax (or Takahashi) eyepieces, at least for medium-to-high magnification viewing. Above 200X I like the Takahashi 7.5mm eyepiece and if viewing conditions permit it, the University Optics 6mm Orthoscopic which I have found to be a good eyepiece at a substantially lower price than a comparable Brandon; the Brandon design has somewhat better contrast but it is pricey, especially at magnifications that viewing conditions don’t allow you to use very often. (I do have an 8mm Brandon but for my eyes the 7.5mm Tak is a better eyepiece.)

When I first started using my scope I tended to use the 27mm Panoptic most of the time.  After gaining observing experience I found that I now tend more to use higher magnifications (the 14mm Pentax).  Deep-sky objects tend to be more easily found or recognized at lower magnifications, but show more detail at higher magnifications. As I came to understand better what I was looking for, I didn’t need the lower magnification and I found the detail in the view at higher magnifications to be more satisfying. So, based on my experience don’t be surprised if your “favorite” eyepiece evolves over time to a higher -magnification EP. (Of course there are some deep-sky objects, especially open clusters, that require a lower magnification because they are just too large to fit in the field of view of any higher-magnification EP.)
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A very wide-field (low-magnification) eyepiece is really useful for some of those deep-sky objects (such as the Pleiades, the Perseus Double Cluster, some other open clusters, and views of the Milky Way itself) which are really large.  However the rear-cell opening in an 8” SCT is 1.5” and this limits the maximum actual field of view you can see without substantial vignetting, to 1.07°. Such vignetting is gradual as you exceed the maximum actual field of view limit, and manifests as a darkening of the stars at the edge of the field of view.  The severity of this problem is subjective - many observers find this objectionable while others do not.

Here is another table you may find helpful, comparing most of the wide-field eyepieces available that are usable in an 8” SCT (the widest-FOV of these are, and of necessity need to be, 2” eyepieces).  These eyepieces are sorted by descending Actual Field of View for an 8” f/10 scope:

Those eyepieces listed above that have actual FOVs above 1.07° will start to exhibit vignetting but as I noted above, not all observers find this to be a problem.  I haven’t personally used any of the very-wide -field eyepieces in this list except for the Televue Panoptic 27mm.  Of the eyepieces currently available the Meade SWA 32mm, the Edmund Optics RKE 32mm, and the Orion DeepView 42mm would provide the widest usable field of view in an 8” SCT without substantial vignetting. Although the Orion DeepView is significantly less expensive than the Meade or the Edmund, the Edmund or the Meade would provide about the same FOV as the Orion at a 33% higher magnification, which is more desirable.
 

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