Svbony 3-8mm Zoom

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WilliamPaolini United States of America
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Svbony 3-8mm Zoom

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Post by WilliamPaolini »


IMG_2207 (web).jpg

Received a Svbony 3-8 Zoom yesterday and took it out for a daytime spin today as well as did some bench test measures. Been inactive for more than a year as nothing really new or interesting in the marketplace IMO. But this little zoom, especially for under $150 USD caught my eye as it has what I feel is a perfect focal length range to be a one eyepiece show for planetary. Used my Vixen 81S f/7.7 Apo for the cursory test. Here are my results:

1. External build quite nice. Good fit and finish.

2. Zooming is not too tight or loose, so just right amount of friction. The "feel" of the mechanism as it zooms is just a bit rough, so not buttery smooth. Will probably work itself smooth over time. Nothing bad, just could feel the internals working to move the zoom.[/list]

3. Rubber eye guard easily comes off so nice. Otherwise, at 8mm setting my face was just lightly touching to top of the eye guard when observing. At 3mm setting had to press in a little to see the entire AFOV as the ER tightened. Bench test measures were 10mm optical ER at 8mm setting (i.e., from top center of eye lens). 8mm ER at the 3mm setting. Eye lens top surface is flat and nearly flush with top of metal housing. Inset probably no more than 1/4mm.[/list]

4. AFOV varied slightly, getting slightly larger as one zoomed to the 3mm setting. Measures showed 57.5 deg AFOV at 8mm setting and 60.5 deg AFOV at 3mm setting.

5. Eyepiece is parfocal throughout the zoom range

6. Field Stop visually remains sharp at all settings.

7. No perceivable Field Curvature from center to edge across the zoom range.

8. Slight vignetting of the AFOV at the far edge near the field stop at the 7-8mm settings. No noticeable dimming of the AFOV at the field stop daytime test though.

9. Determined this by observing an out of focus airy disk pattern and could see the circle get truncated by a little less than a half as it reached the field stop. Only happened again at the 7-8mm settings. Given that it needed to be almost at the field stop do not think this will show any dimming in the field at night, but need to do a night time test to verify. Similarly, the out of focus airy disk stayed perfectly round when in or out of focus near the field stop so does not appear to have any astigmatism present. For note, the airy disk view was using the sun reflecting off a convex surface on a car in the distance.

10. Rectillinear distortion was very well controlled, much better than in any modern Plossl I have tested. Virtually nonexistent at the 7-8mm setting, slight at the 5-6mm setting, and approaching something less that what I would call moderate at the 3-4mm setting (probably on par with the TV DeLite if memory serves).

11. Image contrast appeared quite good, but a daytime test cannot mimic IME contrast performance for planetary observing, so will reserve judgement until a good planetary test, but expect it will probably turn out to be perfectly acceptable if not better.

Quite impressed with this little eyepiece so far, but night time is where the rubber hits the road of course. And it is affordable as well! The focal length range is IMO perfect for all planetary observing needs, so nice to finally have a single eyepiece brought to market that can serve the typical range of planetary magnification needs. Examples: in 10" f/4.7 or 8" f/6 Dob magnifications would be 150-400x (40-50x/in), in my 4" f/8 TSA Apo 102-272x (68x/in), in my Vixen 81mm f/7.7 Apo 78-208x (65x/in).

Happy New Year!
-Bill (1/2023)
-Bill

U.S.A.F. Veteran - Visual Amateur Astronomer since 1966 - Fully Retired since 2019
8" f/5 Newt - Lunt 152 f/7.9 - TSA 102 f/8 - Vixen 81S f/7.7 - P.S.T. - Pentax 65ED II - Nikon 12x50 AE
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
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Re: Svbony 3-8mm Zoom

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Post by Lady Fraktor »


Thank you for the interesting report Bill.
I was interested in how it would perform since nobody has done one of these since the TeleVue 2-4mm and 3-6mm.
Looking forward to reading your report on night time observing with it.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
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Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
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Re: Svbony 3-8mm Zoom

#3

Post by WilliamPaolini »


Skies were clear, cold (38 deg F / 3.3 C), and a little breezy tonight so gave the Svbony 3-8mm Zoom a try on Jupiter, Mars, Betelgeuse, and M42/43 tonight to see how it would perform. Used my Vixen 81S f/7.7 Apo with Baader Zeiss 1.25" Prism Diagonal, and brought out a 5mm Tak LE, two excellent performing Volcano Top Abbes in 4mm & 6mm (single coated - Celestron from the 1980s). Scope was fully acclimated prior to observations

Light Artifacts -- observed no light artifacts (flare, ghosting, etc) on any of the objects as I moved them through the FOV and positioned them just outside the FOV.

Scatter -- was on par with the Tak LE, and the Abbes were perhaps just very slightly less scatter.

Background -- showed as dark as the Tak LE; Abbes just a bit darker probably due to their only being single coated.

Field Curvature -- Shows just a very slight bit of field curvature requiring about 1/8 turn of the fine focus know between center and edge at the 8mm setting, and just a hair of a turn at the 3mm setting. Only seen when the object was right at the field stop.

Astigmatism -- none observed on any star points, even at the field stop.

[EDIT 1/10/2023] Lateral Color -- I also noted very minor lateral color when a star was at or very near the field stop at the 8mm setting. I did not test this at other zoom settings.

Parfocal -- perfectly parfocal from 3mm to 8mm range and no focus adjustment needed.

Betelgeuse -- Beautiful orange hue shown in all the eyepieces. Other than the slight Field Curvature already mentioned no astigmatism or other star point aberrations visible at any setting of the zoom at any location in the FOV of the Zoom.

Nebula (M42/M43) -- On par with the 5mm Tak LE (did not test against others). Extent and brightness of nebula appeared the same, mottled structure and dark lanes just as visible in both, Trapezium glimmering nicely in both, nebulocity of M43 also appeared same in both. Basically a dead heat.

Planets -- On Mars Syrtis Major, Mare Cimmerium, and Sinum Sabaeus, all nicely visible and perhaps a hint of the polar cap as well (or limb clouds). On Jupiter the NEB, SEB, NTB, and the North and South Polar regions clearly visible with nice boarder details showing on NEB and SEB. As I was observing the Io was just beginning and Ganymede was just exiting occultation. Both of those happening at once was a treat to see. Contrast and sharp rendition of the planets and their features was similar in all the eyepieces so all winners with the Svbony performing as well in the planetary role as the premium Tak LE and keeping pace with the classic Abbes.

Ergonomics -- The click stops made it easy to determine what setting I was on in the dark and enjoyed that not a lot of force was needed to turn the mechanism, much less force than the Nagler 2-4 and 3-6 zooms I used to own. Having such a nice range in the focal length was also much appreciated as with the larger almost 60 deg AFOV and at 8mm there was more than enough TFOV (3/4 degree) for the Orion Nebula to be generously framed and at the 3mm setting was nice to get the image scale of Mars satisfyingly large. So for an 80mm class scope this is a perfect 1 pony show for higher magnifications. I brought out an 18mm LE (1.5 degrees) also to use as a finder, but ended up not needing it as the 8x50 finder scope on my rig did that job just fine. I also appreciated the Svbony's longer ER when I switched from the Abbes, and its more generous AFOV when switching from any of the others, even the 52 deg AFOV of the LE.

Overall really enjoyed this eyepiece as it both worked and performed quite well. It is not a replacement for the very top tier planetaries like the Baader/Zeiss ZAOs or Pentax XOs, but holds its own just fine with other well made Abbes and the premium 5 element Tak LEs. Will make a valued addition to my eyepiece stall.
Last edited by WilliamPaolini on Tue Jan 10, 2023 6:11 pm, edited 3 times in total.
-Bill

U.S.A.F. Veteran - Visual Amateur Astronomer since 1966 - Fully Retired since 2019
8" f/5 Newt - Lunt 152 f/7.9 - TSA 102 f/8 - Vixen 81S f/7.7 - P.S.T. - Pentax 65ED II - Nikon 12x50 AE
Pentax XWs - Baader Morpheus - Takahashi LEs - Edmund RKEs - BST Starguiders - 6ZAO-II/5XO/4Abbe
PM and Email communications always welcomed
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Re: Svbony 3-8mm Zoom

#4

Post by messier 111 »


thx , for the nice report .
I LOVE REFRACTORS , :Astronomer1: :sprefac:

REFRACTOR , TS-Optics Doublet SD-APO 125 mm f/7.8 . Lunt 80mm MT Ha Doublet Refractor .

EYEPIECES, Delos , Delite and 26mm Nagler t5 , 2 zoom Svbony 7-21 , Orion Premium Linear BinoViewer .

FILTER , Nebustar 2 tele vue . Apm solar wedge . contrast booster 2 inches .

Mounts , berno mack 3 with telepod , cg-4 motorized , eq6 pro belt drive .

“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won't come in.”
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Re: Svbony 3-8mm Zoom

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Post by pakarinen »


WilliamPaolini wrote: Tue Jan 10, 2023 1:35 am Skies were clear, cold (38 deg F / 3.3 C), and a little breezy tonight so gave the Svbony 3-8mm Zoom a try on Jupiter, Mars, Betelgeuse, and M42/43 tonight to see how it would perform. [...]

Overall really enjoyed this eyepiece as it both worked and performed quite well. It is not a replacement for the very top tier planetaries like the Baader/Zeiss ZAOs or Pentax XOs, but holds its own just fine with other well made Abbes and the premium 5 element Tak LEs. Will make a valued addition to my eyepiece stall.
:think: I have some funds left on an Amazon gift card...
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AT50, AT72EDII, ST80, ST102; Scopetech Zero, AZ-GTi, AZ Pronto; Innorel RT90C, Oberwerk 5000; Orion Giantview 15x70s, Vortex 8x42s, Navy surplus 7x50s, Nikon 10x50s
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