Can Popper
Well-known member
Various eyepiece reviewed with PF-100ED
I recently tested my whole eyepiece collection plus a binoviewer on my Pentax 100ED. The goal was to get what I will term the "Ultimate View" for a reasonable price. I like to use my scopes for astronomy, long range target shooting and birding so I purchased the 100ED as the scope that could be used for all 3.
The day I tested the eyepieces was a bit humid so high power views at long range may show atmospheric degradation and not reflect the true performance of the scope and eyepiece. I also had my wife look through the various eyepieces for a second opinion. For reference comparisons, I have a 114mm Bushnell Voyager Newtonian rich field (Edmund Astroscan knockoff), 90mm Konus OEM Maksutov, and 60mm Meade Kestrel refractor spotter.
The eyepieces tested were:
40mm GTO plossl (purchased off ebay)
32mm GTO plossl (ditto)
26mm GTO plossl (ditto)
20mm 65 degree William-Optics (came with binoviewer)
20mm SWA (purchased off ebay from Smart Astronomy)
15mm SWA (purchased off ebay from owl1)
11mm UWA (purchased off ebay from Smart Astronomy)
10mm GSO Superview (purchased directly from Smart Astronomy)
Pentax SMC zoom (8mm to 24mm)
Orion Ultrazoom (7mm to 21mm)
Scopetronix Zoom (7mm to 21mm)
Plus I tested a William Optics binoviewer, with and without the 1.6x barlow nosepiece.
Here are the results:
40mm GTO plossl - results in about 16x mag. Very long eyerelief (25mm+). Clear and bright views. Around 6.3mm exit pupil. Probably great for digiscoping. Eyepiece is clean with no dust between lenses.
32mm GTO plossl - results in about 20x mag. The very best, bright view out of all eyepieces tested. Long eyerelief. Exit pupil around 5.1mm. An absolute delight. Eyepiece is clean with no dust between lenses.
26mm GTO plossl - results in about 24x mag. Nice bright view with good eyerelief. Brightness not perceived to be as bright as 32mm plossl probably because of smaller exit pupil of 4.2mm. Eyepiece is clean with no dust between lenses.
20mm William-Opt Widefield eyepiece. - results in 32x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece is clean with no dust between lenses.
20mm SWA - results in 32x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece contains some dust between lenses which detracts from the "being there" experience.
15mm SWA - results in 42x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece contains some dust between lenses which detracts from the "being there" experience.
11mm UWA - eyepiece does not come to focus in 100ED, an F6.3 system. Also doesn't work in my Voyager a F4.3 system. Simply not enough "in-focus" on the two scopes. Only scope it works on is the F12.3 Maksutov.
10mm Superview - results in 63x mag. Atmospheric conditions that day probably resulted in more degraded view. Less dusty than SWA's but not as clean as plossls and Williams eyepieces. Eyerelief is decent and field of view is still pleasant.
Pentax SMC zoom - variable mags from 26x to 79x. One big mother! Not as heavy as it looks (whew!) Good eyerelief though eyes are harder to position due to such a big eyepiece. Very good color, as good as the plossls. View at higher mags resemble the 10mm Superview probably because of slight haze due to atmospheric conditions. Like all zooms, less field of view at low mags and wide field of view at high mags.
Orion Ultrazoom - variable mags from 30x to 90x. I love this eyepiece on my Bushnell Voyager, clear, bright and widest views of all zooms tested but it just isn't appropriate for the Pentax 100ED. Eyerelief is too short to use as a spotting scope eyepiece. Also works poorly on my 90mm Maksutov.
Scopetronix Zoom - variable mags from 30x to 90x. I hated this eyepiece on my Bushnell Voyager because its field of view was quite narrow in comparison to the Orion Ultrazoom but it really redeems itself on the Pentax 100ED. Has longest eyerelief of all zoom eyepieces tested. I can see why Scopetronix sells it as a solution for zoom digiscoping. Fairly clear, clean, and bright due to it being fully multicoated. Atmospheric degradation to image at high powers. Smallest zoom out of three tested. A decent zoom spotting scope eyepiece and only $60 to boot. People with the smaller Pentax spotters should seriously consider this as a substitute to the SMC if they want to save on weight and money.
Now onto the binoviewer....
When I plugged the binoviewer in, it didn't look out of place at all. Probably because the Pentax SMC was such a big eyepiece. I tested it using the two included 20mm Williams-Optics eyepieces.
First without the 1.6x barlow nosepiece, the binoviewer config would not come to focus at all. Second with the included 1.6x barlow attached, would only come to focus on objects out to 10ft. Had the same problem on my Bushnell Voyager as well. The only scope the binoviewer would come to focus on is the F12.3 Maksutov and this is without the 1.6x barlow nosepiece. However, the Maksutov's focal length is 1200mm so with the 20mm eyepieces, I get 60x mag and an exit pupil of 1.5mm which makes it difficult to align both eyes with the eyepieces.
I felt frustrated and went checking on the CloudyNights website for a solution and found people recommended using Seibert Optics OCA's to get the binoviewers to come to focus with any scope, even spotting scopes. After looking through Seibert's website, I ordered the 1.25x OCA which are guaranteed to bring any scope to focus. I chose the 1.25x because I didn't want the OCA's adding too much to the eyepieces' magnification. I will post a review when I get the Seibert OCA and test them with the various eyepieces.
I recently tested my whole eyepiece collection plus a binoviewer on my Pentax 100ED. The goal was to get what I will term the "Ultimate View" for a reasonable price. I like to use my scopes for astronomy, long range target shooting and birding so I purchased the 100ED as the scope that could be used for all 3.
The day I tested the eyepieces was a bit humid so high power views at long range may show atmospheric degradation and not reflect the true performance of the scope and eyepiece. I also had my wife look through the various eyepieces for a second opinion. For reference comparisons, I have a 114mm Bushnell Voyager Newtonian rich field (Edmund Astroscan knockoff), 90mm Konus OEM Maksutov, and 60mm Meade Kestrel refractor spotter.
The eyepieces tested were:
40mm GTO plossl (purchased off ebay)
32mm GTO plossl (ditto)
26mm GTO plossl (ditto)
20mm 65 degree William-Optics (came with binoviewer)
20mm SWA (purchased off ebay from Smart Astronomy)
15mm SWA (purchased off ebay from owl1)
11mm UWA (purchased off ebay from Smart Astronomy)
10mm GSO Superview (purchased directly from Smart Astronomy)
Pentax SMC zoom (8mm to 24mm)
Orion Ultrazoom (7mm to 21mm)
Scopetronix Zoom (7mm to 21mm)
Plus I tested a William Optics binoviewer, with and without the 1.6x barlow nosepiece.
Here are the results:
40mm GTO plossl - results in about 16x mag. Very long eyerelief (25mm+). Clear and bright views. Around 6.3mm exit pupil. Probably great for digiscoping. Eyepiece is clean with no dust between lenses.
32mm GTO plossl - results in about 20x mag. The very best, bright view out of all eyepieces tested. Long eyerelief. Exit pupil around 5.1mm. An absolute delight. Eyepiece is clean with no dust between lenses.
26mm GTO plossl - results in about 24x mag. Nice bright view with good eyerelief. Brightness not perceived to be as bright as 32mm plossl probably because of smaller exit pupil of 4.2mm. Eyepiece is clean with no dust between lenses.
20mm William-Opt Widefield eyepiece. - results in 32x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece is clean with no dust between lenses.
20mm SWA - results in 32x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece contains some dust between lenses which detracts from the "being there" experience.
15mm SWA - results in 42x mag. Nice wide bright clear contrasty views. Decent eyerelief. Eyepiece contains some dust between lenses which detracts from the "being there" experience.
11mm UWA - eyepiece does not come to focus in 100ED, an F6.3 system. Also doesn't work in my Voyager a F4.3 system. Simply not enough "in-focus" on the two scopes. Only scope it works on is the F12.3 Maksutov.
10mm Superview - results in 63x mag. Atmospheric conditions that day probably resulted in more degraded view. Less dusty than SWA's but not as clean as plossls and Williams eyepieces. Eyerelief is decent and field of view is still pleasant.
Pentax SMC zoom - variable mags from 26x to 79x. One big mother! Not as heavy as it looks (whew!) Good eyerelief though eyes are harder to position due to such a big eyepiece. Very good color, as good as the plossls. View at higher mags resemble the 10mm Superview probably because of slight haze due to atmospheric conditions. Like all zooms, less field of view at low mags and wide field of view at high mags.
Orion Ultrazoom - variable mags from 30x to 90x. I love this eyepiece on my Bushnell Voyager, clear, bright and widest views of all zooms tested but it just isn't appropriate for the Pentax 100ED. Eyerelief is too short to use as a spotting scope eyepiece. Also works poorly on my 90mm Maksutov.
Scopetronix Zoom - variable mags from 30x to 90x. I hated this eyepiece on my Bushnell Voyager because its field of view was quite narrow in comparison to the Orion Ultrazoom but it really redeems itself on the Pentax 100ED. Has longest eyerelief of all zoom eyepieces tested. I can see why Scopetronix sells it as a solution for zoom digiscoping. Fairly clear, clean, and bright due to it being fully multicoated. Atmospheric degradation to image at high powers. Smallest zoom out of three tested. A decent zoom spotting scope eyepiece and only $60 to boot. People with the smaller Pentax spotters should seriously consider this as a substitute to the SMC if they want to save on weight and money.
Now onto the binoviewer....
When I plugged the binoviewer in, it didn't look out of place at all. Probably because the Pentax SMC was such a big eyepiece. I tested it using the two included 20mm Williams-Optics eyepieces.
First without the 1.6x barlow nosepiece, the binoviewer config would not come to focus at all. Second with the included 1.6x barlow attached, would only come to focus on objects out to 10ft. Had the same problem on my Bushnell Voyager as well. The only scope the binoviewer would come to focus on is the F12.3 Maksutov and this is without the 1.6x barlow nosepiece. However, the Maksutov's focal length is 1200mm so with the 20mm eyepieces, I get 60x mag and an exit pupil of 1.5mm which makes it difficult to align both eyes with the eyepieces.
I felt frustrated and went checking on the CloudyNights website for a solution and found people recommended using Seibert Optics OCA's to get the binoviewers to come to focus with any scope, even spotting scopes. After looking through Seibert's website, I ordered the 1.25x OCA which are guaranteed to bring any scope to focus. I chose the 1.25x because I didn't want the OCA's adding too much to the eyepieces' magnification. I will post a review when I get the Seibert OCA and test them with the various eyepieces.
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