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CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.
Parks Gold Series Eyepieces
I recently had the distinct opportunity to test out the complete line of Parks Gold Series 1.25” Eyepieces. Yes, all nine of them, generously supplied to me by Sam “The Man” Sweiss, Store Manager at Scope City in San Francisco, California. Sam is very friendly and also has a very helpful staff, all of whom have assisted me in my past telescope eyepiece purchases. As I spied the Parks Gold Series one afternoon, Sam asked what I was interested in looking through, and, without much hesitation I asked to “borrow” a couple of his Parks Eyepieces and evaluate them. Sam told me to wait just for a moment, got out a big box and put all in all nine of the Gold Series Parks Oculars! Elated, I told Sam I’d take good care of the eyepieces and bring them back after evaluating them on the Moon and Saturn.
The Parks Gold Series Oculars can be describes as follows: Fully Multicoated eyepieces consisting of 5 to 7 elements ranging from 35mm focal length to 3.8mm focal length. The apparent field of the 35mm eyepiece is 49 degrees while the apparent field for the other eight eyepieces(30mm, 25mm, 20mm, 15mm, 10mm, 7.5mm, 5mm and 3.8mm) is 52 degrees. The prices of the Gold Series Oculars ranges from $189.95 for the 35mm to $99.95 for the 15mm, 10mm and 7.5mm eyepieces.
I decided to use my Celestron WideView 102mm f/5 fast Achromatic Spotter(about $330) to evaluate the Parks Gold Series Oculars, rather than my Televue 102mm f/8.8 Apochromatic Scope(about $2200), because I wanted to test out these eyepieces using a relatively inexpensive type of telescope that is more commonly owned by amateur astronomers. The two objects selected, the Moon and Saturn, represented modestly challenging and severely challenging objects, respectively, for the Celestron Wide View Spotting Scope, especially at the low power end and the high power end of viewing. On a fast f/5 scope, and at the low powers, under about 20X magnification, my vision, just cannot handle the larger eyepiece exit pupils because of the inherent problems I have with astigmatism in my right/viewing eye. In my younger days, as I am now 52 years old, I could handle lower powers with even 7mm to 8mm eyepiece exit pupils. Exit pupil is defined as the telescope objective diameter divided by the power of the object being viewed through a particular eyepiece. Also, at the high power end, many factors tend to come into play such as atmospheric distortions from less than ideal seeing conditions. Overall, I would say my intrinsic visual acuity is excellent at medium to high power except at the previously mentioned low power end of the viewing spectrum. Just for reference, I can still read about half the letters on the 20:15 row of the eye chart at the optometrist’s office, and maybe a couple of the letters on the 20:10 row.
The diagonal used with the Wide View 102mm Spotter was a 2 inch Meade Mirror Diagonal of reasonably high quality. In a previous Cloudynights article, I mentioned CEIBS and IPDTEFE as parameters for testing eyepieces, but will redefine them here:
CEIBS - Central Eyepiece Image Brightness & Sharpness. A measure of how well the object viewed looks at the very center of the field of view within the eyepiece, with a rating from Zero(0) - lowest/worst rating, to Ten(10) - highest/perfect rating.
IPDTEFE - Image Point Degradation Towards Eyepiece Field Edge. Estimated, in percent, with 80% or higher being excellent, which is a measure of how “sharp” the eyepiece optics are as the stellar object gets closer and closer to the field edge.
The testing on the Moon was done on the evening of October 14, 2002, while the testing on Saturn was done on the morning of October 15, 2002. The overall sky conditions were good to very good with a “seeing” rating condition ranging from around 7 to 8 out of 10. I live in a suburban area, San Ramon, California with moderate to severe light pollution as the overhead limiting magnitude is 4.0 to 4.5 under normal conditions.
The object on the Moon chosen for viewing/testing was the fairly dark crater, Plato, with a nicely defined and picturesque totally encircling rim. I chose to concentrate on how clear the rim looked as well as to see how well the encroaching dark “shadow”, from the crater wall blocking off sunlight, looked within the crater, itself. Of course Saturn is arguably the most beautiful of planets with the magnificent Cassini Division and moon Titan, known to hold an atmosphere.
Keep in mind that my ratings are defined with my own CEIBS subjective rating - yours may differ somewhat. Also, IPDTEFE was estimated as I “eyeballed” the recorded percentages.
Here are the testing results for the moon viewed with the Parks Gold Series Eyepieces, Table 1.
|Eyepiece||CEIBS (1-10)||IPDTEFE (%)||Remarks|
|35mm 14x||9||95||Ver sharp Image|
|30mm 17x||9||80||Crisp Image|
|25mm 20x||9||85||Crisp Image|
|20mm 25x||9||80||Crisp Image|
|15mm 33x||9||95||Very Sharp Image|
|10mm 50x||9||75||Crisp Image|
|7.5mm 67x||9||75||Sharp Image|
|5mm 100x||9||90||Very Sharp Image|
|3.8mm 132x||9||95||Very Sharp Image|
Table 1 Object Viewed: Moon
Here are the testing results for Saturn viewed with the Parks
Gold Series Oculars, Table 2.
|Eyepiece||CEIBS (1-10)||IPDTEFE (%)||Remarks|
|35mm 14x||8||75||Rings and Titan|
|30mm 17x||8||75||Rings and Titan|
|25mm 20x||8||80||Rings and Titan|
|20mm 25x||8||75||Rings and Titan|
|15mm 33x||8||70||Rings and Titan|
|10mm 50x||8||75||Cassini's Division glimpsed|
|7.5mm 67x||9||75||Cassini's Division glimplsed|
|5mm 100x||9||75||Cassini's Division seen directly|
|3.8mm 132x||9||95||Cassini's Division seen directly|
Table 2 Object Viewed: Saturn
I found the Parks Gold Series Oculars to be especially outstanding in performance at the high power end of the series, namely at 5mm and at 3.8mm offering powers on the Wide View of 100X and 132X respectively. On Saturn(see Table 2), the 5mm eyepiece at 100X clearly showed me Cassini’s Division, as did the 3.8mm ocular at 132X.
Generally, from my own experience, most fast achromatics will show some degree of image breakdown, sometimes marked breakdown, especially on a planet, like Saturn, at around 30 times to 35 times per inch of aperture. I was pleasantly surprised that in using the 3.8mm Parks Gold Series eyepiece at 132X, nearly 33X per inch aperture, Cassini’s Division was still viewed with direct vision; not bad for a fast scope like the Wide View 102mm f/5 spotter.
When using the Parks Gold Series Oculars ranging from 25mm to 7.5mm, at fairly low(20X) to medium powers(67X), respectively, the eyepieces provided very good to outstanding details on the lunar crater Plato(see Table 1) as the shadow and crater rim were well defined. In addition, at the highest powers used, 5mm eyepiece at 100X and 3.8mm eyepiece at 132X, very sharp views of Plato were obtained through the Wide View scope.
If you want excellent fully multicoated performance in 5 to 7 element eyepieces strongly consider the Parks Gold Series set of eyepieces. Their performance on the Moon(Crater Plato) and gas giant, Saturn(Cassini’s Division) is outstanding. If you’re in San Francisco, consider dropping in to say hello to Sam “The Man” and his staff and also to take a look-see through his many optical offerings both inside his shop and even on the sidewalk directly outside the front doors.
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