This auction is for a 1990 Celestron (Focus Optech Co. of South Korea) 8x20 finder scope assembly. This is complete to code with the original cast aluminum bracket system, original rubber O-ring to stabilize the finder in the rings, the original (3) oversized setscrews, and both original dust caps.
**Please notice that the images shown through this finder (photos 13 + 14) are crisper and better resolved than as you see them in the photos. The soft edges seen is an effect given from my cell phone's camera lens and I cannot get it to show an image as good-resolved as I see with my own eyes. Even though the amici prism has some coating loss (see photo 12), the finder is still more than capable of producing both excellent images and has been tested to work for targeting brighter deep sky objects; like M45 and Orion's Sword region**
It should be noted this finder scope assembly comes from Korea, BUT has the heavy-duty, dome brass setscrews; making this one of the earliest era examples of the 8x20 finder.
The 8x20 finder scope first appears with the 3rd generation Celestron C90 in black gloss in January of 1989. This generation of the C90 had already been a few years in production, but it is December of 1988 that we see the C90 coming with the 5x24 finder scope for the last time. The 8x20 was created for the all-new C90 Rubber Armored; even though the very 1st half year of the C90 Rubber Armoreds never came with the ability to have a finder scope (they did not have drilled holes!). Like the 5x24, this finder will reside in the very same, black cast aluminum, low profile finder brackets. They will always share the same bolt pattern and utilize the same rear-holds setscrews, front-hold-O-ring format.
By 1992, the 8x20 would go on to serve its only other telescope as an inclusive finder; the C5 Spotter in white-and-black, but not the C5 Tabletop Observatory and C5+; those featured the rare 5x24 in white-and-black.
Right around November-December of 1997, the 8x20 finder will enter its 2nd and final generation; sporting a grainy-black paint textured body that was highly prone to sunlight fading and coming from China. It is funny to think about it, but the Chinese variant is quite rare to come across.
December of 1999 is the final year of the C5 Spotting Scope, yet the C90 will live on up until about March of 2000.
So it is March of 2000 as the very last time these little 8x20 finders were carried by Celestron. The small finder will return, but not until early 2004 with the all-new, Suzhou Synta-made C90 (now f/13.8 instead of f/11) in which it is now the 8x21.
It is interesting that one of the ways to date these finders pretty accurately is with the type of setscrews their finder brackets came with. As discussed, the 8x20 finder itself can only come in (2) guises; in milled, anodized black gloss from Korea and granular black texture from China; and of the Korean models, the very first 1.5 years featured the thin crosshairs, not the thicker, graduated crosshairs.
And during the entire time from the black gloss C90 with the 5x24 finder scope in 1985 until the final year of the C90 with the 8x20 finder scope in 2000, the cast aluminum bracket format and its color NEVER change. However, the setscrews do.
Keeping in mind the setscrews have NOT been replaced and have been kept original, the following can nearly fully accurately date the 8x20 finder scope assembly:
1989: polished brass (only ever on the C90 Rubber Armored)
1989-1991: domed, chrome-plated brass
1991-1992: steel with allen wrench head
1992-early 1995: steel with allen wrench head and with green nylon contacts
1995-2000: domed, black nylon
Furthermore, there are (2) variants of the cast aluminum finder brackets. The 1985-1992 years will almost always have perfect circular holes; the 1993-2000 years will have elongated holes. The elongated versions are particularly desirable since they do not require absolute measurement for fitment. The elongated spread allows a fitment allowance between 1.08-inches to 1.32-inches. With the older circular hole models, fitment must be nearly precisely 1.08-inches to 1.09-inches.
In all, only (2) telescopes ever came with these 8x20 finder scope setups:
* C90 Spotter (1989-2000)
* C5 Spotter (1992-1999)
And though many do not know it, though the finder scope brackets could not be purchased separately, the actual 8x20 finder scope could, which fell under mpn 94103. I only know this code to be available with the Korean models.
*Concerning the finder*
Model: 8x20 finder scope
Aperture: 20mm
Magnification: 8x
Design: doublet objective and kellner eyepiece with amici prism
Optics: fully coated objective and eyepiece
Image: correct upright
Eye relief in eyepiece: 9mm
Exit aperture: 9.1mm
Total body length: 3.56-inches
Main body width: 1.02-inches
Materials: milled anodized aluminum, rubber eye guard, rubber O-ring, glass
Weight: 2.4 ounces
*Concerning the bracket*
Model: 8x20/5x24
Inside diameter of rings: 1.10-inches
Rings to fit: nearly any finder scope with 18mm to 24mm clear aperture
Bolt pattern: (2) #8-32 screws from 1.08-inches
Curved to fit: optical tubes up to 6-inches in diameter
Materials: solid cast aluminum, brass set screws
Weight: 1.3 ounces
Total weight of finder scope assembly: 3.7 ounces
The finder scope WILL FIT into any Celestron gray cast aluminum finder bracket assembly that came on the orange C90s (1978-1984) and orange C5s (1971-1983). If the finder in those brackets was/were for a 5x24 model, then it will fit this finder because both those finders had the same main body diameter.
You can also fit this little finder onto your Meade 97-series maksutov finder brackets as it used the same brackets. And yes, this finder will fit into the brackets of your Meade 2040 and 2045 (also the final 2045D) as their 5x24 finder scopes shared the same finder body diameter.
This finder will also fit with the Meade ETX 8x21 finder scope's hard plastic finder brackets.
Quality on this finder is very high and one of the very best mini finders on the planet period. In the late 1993-onward models, the cross hairs are graduated at the center for very precise targeting of the object. Images are correct image; so the STOP sign will read "STOP". And unlike many 6x30 finders, images are crisp and resolved to the edge field of view. In its size class only the Takahashi 5x25 has it beat, which makes the finest optical finders known (not open to argument).
To focus the finder, simply twist the eyepiece end of the finder till the images are in focus and it will stay. The helical threads are very fine and hold firmly without the need of a set screw or lock ring.
VERY pleasing for daytime targeting and great for bright nighttime targets like the Moon, Jupiter, Mars, Saturn, Vega, M45, and Arcturus. +3.0 mag will be about as dim as you can sight with an aperture this small.
And because this was for large aperture spotting scopes, the finder is designed with a built-in amici prism for upright correct images at the eyepiece. This means the "STOP" sign will be seen as "STOP". What makes this special is that when following a target with the finder (like bird, squirrel, or a ship), that object will be moving in the same directional orientation as it will in the telescope (given you are using a 45 degree prism in the telescope). And so aiming will be VERY straight forward.
As for the finder scope bracket system, the rings will accommodate virtually ANY finder scope in the 18mm to 24mm aperture size, particularly the Towa, Carton, and Vixen of Japan era 5x24 finder scopes. Maximum diameter of your finder scope's main body should NOT exceed 1.03-inches.
For steady results, a small, rubber O-ring is usually needed to keep alignment spot on during transportation. You can also use electrical tape or a rubber band on the end of your finder-in-use, should the rubber O-ring break over time; a safe option which will not harm the paint on the finder.
The brackets' bolt pattern WILL IMMEDIATELY FIT to all orange C90s (1978-1984) and orange C5s (1971-1983) from. It will likely fit to the C8 from the Great Polaris years and Celestar Classic years (1993-1999) because they shared the same bolt pattern for finder scopes and the white-and-black era C5. However, because the holes on this model predate that era, you need to check my measurements beforehand. Remember, that MOST C8s by 1993 were coming with finder scopes whose holes were the elongated variant; meaning they had a wider range of 2-hole bolt patterns they could mate to.
This bracket assembly will also fit will fit to ALL the Meade 97-series 90mm maksutovs (97d and 97e). It WILL NOT work with any of the ETX line. It will NOT FIT on the Chinese-made C90 models or the Orion Apex/StarMax maksutovs because their finders mount into a dovetail saddle and are not held in with actual screws.
There is a STRONG possibility these brackets will work with the classic Meade 4-inch schmidt cassegrains; the 2040, 2045, 2045D, and their spotter version; the 1022 and 107D. But to be safe, check that bolt pattern first.
This auction ad was completely, organically written by Veradale Mobile Observatory, not an A.I. software device; an actual honest-to-goodness, real human with over 20 years experience with now over 1000 telescopes made from today and all the way back to 1948.
Packed with great care.