REVIEW OF SUMERIAN OPTICS ALKAID 16” TRAVEL SCOPE
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Televue 31mm Nagler and TeleVue 27mm Panoptic Eyepieces
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This review contains; 1) a short review of the 31mm Nagler, 2) a second short review of the 27mm Panoptic, and 3) a comparison review. The review was conducted over several weeks and includes comparisons based upon several different observing sessions in different conditions. Three different telescopes were used during the review including: the TMB92SS, a 92mm APO refractor, the TeleVue TV101, a 101mm APO refractor, and an AstroPhysics AP130EDF Gran Turismo, a 130mm APO refractor.
The TMB92SS with the 31mm Nagler; at 16x and with a 5 degree field, provides one of the most remarkable rich field views obtainable in portable telescopes available today. The views simply have to be seen to be believed. This scope and eyepiece give one a celestial window through which to experience the Universe that is, quite frankly, breathtaking in extent. The winter clusters in Auriga are unbelievable. The region of Orion’s belt is just incredibly rich and one can spend hours there. When Sagittarius and the North America Nebula complex in Cygnus are high in the summer sky this combination is perfect for their exploration from a dark-sky site! In my opinion, the TMB92SS and the 31mm Nagler compliment each other perfectly. Both are somewhat spendy, but hey how often do you get the chance to really experience the Universe up close? It’s worth every penny. My only issue with the whole setup is that the 31mm Nagler tends to reveal my astigmatism quite obviously. This most likely is due to the large exit pupil at f/5.5. As a result, you may find it necessary or desirable to use a corrective lens. I find I can comfortably view with my glasses or use my left eye which is not astigmatic.
One of my favorite ways to use the 31mm Nagler is in a rich-field instrument such as the TMB92SS mentioned above, or the TV101 on a simple alt/azimuth mount. I begin low on my summer southern horizon in Sagittarius and just conduct a sweep in azimuth followed by moving up one field in altitude then sweeping the opposite direction. I can spend hours like this. The innumerable clusters and scattered nebulae of summer (or, in the winter Milky Way) are immediately obvious in a combination like this. Once I encounter a cluster (or more often, a group of clusters), in the extreme wide field of this eyepiece at these short focal lengths, I just spend time examining them in their natural setting. The 31mm Nagler is perfect for this type of observing. It is useful at times to use medium to high power to examine the details of star clusters, particularly globular clusters. But, I really enjoy seeing these clusters against that incredibly rich and wide-field stellar background. The 31mm Nagler provides a perspective quite unlike anything else in astronomy. Lovely is the best adjective. And, you can become consumed by the views. The 31mm Nagler is quite simply an incredible eyepiece. It does not, however, ‘get out of the way’ and let you observe in my opinion. It is simply too bulky and heavy for that. You are always conscious of its presence in the diagonal and it can cause significant balance issues depending upon your choice of mount and telescope.
One evening last summer I was using the 31mm Nagler as described above. I found that when changing from the 31mm Nagler to my 19mm Panoptic I had the distinct feeling of optical claustrophobia! The Nagler view is so incredibly large that the 19mm Panoptic just seemed narrow and limited by comparison. However, this effect is drastically reduced when switching from the 31mm Nagler to the 27mm Panoptic. The eyepiece provides a very large field of view, and it provides incredibly sharp views and wonderfully contrast. In fact, the Panoptic exceeds the image contrast of the Nagler by a quite readily detectable margin. I love using the 27mm Panoptic in my smaller aperture refractors such as the AT66ED. I specifically bought the Panoptic for use in that and other short focus refractors. Its weight of only 18oz. compared to the incredible mass of the Nagler at 35oz. makes it much more user-friendly and pleasant in these smaller instruments. I appreciate that. And, this eyepiece does ‘get out of the way’, and lets you observe the night sky. And, you may disagree but I actually prefer an eyepiece in which you can see the field stop. It provides a certain reference plane that makes sense to my brain. Much of the time with the Nagler, I am not aware of the full extent of the field or the presence of the field stop. Some people may prefer this perspective, however I am not one of them. The contrast in the Panoptic is simply remarkable. In the AP130 telescope I have viewed M38’s companion cluster NGC1907, an 8th magnitude tiny wisp of a cluster at nearly full moon from my suburban backyard! Only an eyepiece and telescope combination with contrast could show such a low surface brightness object under those conditions. I credit the Panoptic. This is just a wonderful eyepiece for picking out subtle detail in those faint fuzzies although at limited magnification. As with the Nagler, it is quite simply at its best as a rich field observing tool in a short focal length instrument. It has become my go-to eyepiece for that wide field experience under most circumstances.
So, how do the two compare directly? I have reached the conclusion that both of these eyepieces have a permanent place in my observing plans. I reach for the 31mm Nagler when I want the widest, most incredible rich-field experience. It gives you a floating through space perspective, simply awesome in a short focal length refractor. The 27mm Panoptic though, has an advantage in everyday use. It is light in weight, (well, okay, lighter in weight) provides just that little bit more magnification and hence a slightly darker sky (important when viewing from suburban areas) and it is simply one of the highest contrast wide field eyepieces I have ever used. And, with the Panoptic, one still can get that wonderful rich field experience at ½ the cost, and ½ the weight as well. I must admit to a slight bias, I am a true Panoptic fan. I own the 27mm, a 24mm TeleVue Widefield (the Panoptic predecessor) and the wonderful 19mm Panoptic (probably my favorite eyepiece). I like the 27mm Panoptic best in my AP telescope and I suspect that it has a lot to do with the longer focal length and slightly higher magnification in that scope as compared to the others. It also works very well in the AT66ED with an exit pupil of 4.5mm. When using my DSCs I slip the 27mm Panoptic into the diagonal and I always can find the object in a field of view over 2 degrees wide. I have yet to use or even view through the 35 or the 41mm Panoptics but I would love to see them! You will also notice from the table below that the field of view of the Panoptic is quite a bit less than the Nagler. Is this a noticeable difference in practice? Well, yes it is. But, is it a difference I can live with? Yes, again. I would not choose an eyepiece based solely upon this single criteria. The Nagler has a remarkable field of view, but it is not practical for use in smaller instruments. It is simply too large and bulky. But I do have the luxury of owning both eyepieces so I can choose. If I were to buy only one I would have a difficult choice. But, keep in mind that the Panoptic is about ½ the price and ½ the weight of the Nagler, two significant advantages.
Oh, and by the way, if you own one of the wonderful AT66ED telescopes or a similar instrument with a focal length of around 400mm, the 27mm Panoptic will provide a remarkable 4.59 degree field at 15x. And, if you could make it work in a practical sense….the 31mm Nagler in that same telescope would provide an unbelievably large 6.36 degree field at 13x and with a 5.1mm exit pupil. Incredible!
|TMB92SS 506mm f/l|
|31mm Nagler||16x||5.02 degree field|
|27mm Panoptic||19x||3.63 degree field|
TV101 540mm f/l
|31mm Nagler||17x||4.71 degree field|
|27mm Panoptic||20x||3.40 degree field|
AP130EDF GT 830mm f/l
|31mm Nagler||27x||3.06 degree field|
|27mm Panoptic||31x||2.21 degree field|
I have been an amateur astronomer for nearly 50 years. My first telescope was a 60mm Tasco on an alt/azimuth mount. I still use and prefer alt/azimuth mounts. I own several telescopes, mostly refractors. My interests are in deep sky observing with small refractors and lunar studies.