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Bargain Budget Spotting Scope Recomended (1 Viewer)

Ridge Walker

Well-known member
Bargain Budget Spotting Scope

Hi all Info. for anyone looking for an excellent quality cheap spotting Scope? I just bought A 20-60-x80 off the bay for £38 posted. That, because of the good feedback left by everyone who bought it.. There back on now for £44 posted a bargain. I didn't expect much for that price but very surprised at the quality. Sharp edge to edge image. up to around x40. That could be down to the quality of the zoom eyepiece??. What I didn't expect was a removable eyepiece. It's an external 42mm thread, similar to the Opticron type scope. I have bought a HDF to HR adapter for £5 just to see if it's the same size, and correct thread pitch. See pic. Link https://www.ebay.co.uk/itm/ENKEEO-W...d-20-60X80-Multi-Coated-Lens-NEW/114294439580
 

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jring

Well-known member
Hi,

congratulations about getting an ok example from the lottery... As it is a plain glass scope, image degradation is to be expected beyond 40x, regardless of the zoom EP quality.

If you can, get a wide angle fixed EP with 30-40x and enjoy!

Joachim
 

Ridge Walker

Well-known member
Hi,

congratulations about getting an ok example from the lottery... As it is a plain glass scope, image degradation is to be expected beyond 40x, regardless of the zoom EP quality.

If you can, get a wide angle fixed EP with 30-40x and enjoy!

Joachim

I'm not sure what you mean by a plain glass scope. BTW the front lens is fully coated??? Hopefully if the adapter does fit, it will give a good choice of fixed mag eyepieces.
 
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jring

Well-known member
Hi,

plain glass as in non-ED glass... so probably an achromatic doublet with a crown and flint element. These can work great for high magnification astro scopes at focal ratios above f10 for small apertures and up to f15 at larger apertures.

For fast instruments like your spotter at f5 these show a lot of CA (aka chromatic aberration) at magnification beyound 40x or so, even if they are otherwise a perfect piece of optics.

And longitudinal CA means that not all colors of the light get to focus at the same point, which results into the inability to find a well defined point of best focus at higher magnifications - you then get rather a wide area of least fuzziness.

Joachim
 

dwatsonbirder

Well-known member
Sounds very good for such a modest outlay, I agree with Joachim, if you can get an Opticron fixed lens to come to focus (between 25x - 35x would be ideal) then it seems to be an excellent buy. I wonder if it is the same scope as this one? Certainly looks very similar...
 

Ridge Walker

Well-known member
Hi,

plain glass as in non-ED glass... so probably an achromatic doublet with a crown and flint element. These can work great for high magnification astro scopes at focal ratios above f10 for small apertures and up to f15 at larger apertures.

For fast instruments like your spotter at f5 these show a lot of CA (aka chromatic aberration) at magnification beyound 40x or so, even if they are otherwise a perfect piece of optics.

And longitudinal CA means that not all colors of the light get to focus at the same point, which results into the inability to find a well defined point of best focus at higher magnifications - you then get rather a wide area of least fuzziness.

Joachim

Thanks for that info. Still learning. Looking through the scope at dark edge . There's no CA at x40. From x40 up to to x60 There is a tiny bit of CA but only in certain areas. Then you have to look for it. But the image does start to get darker and not as clear, and loses some the sharpness the around the edges, around 30% in all
 

jring

Well-known member
Thanks for that info. Still learning. Looking through the scope at dark edge . There's no CA at x40. From x40 up to to x60 There is a tiny bit of CA but only in certain areas. Then you have to look for it. But the image does start to get darker and not as clear, and loses some the sharpness the around the edges, around 30% in all

Hi,

what you generally know as CA (purple/yellow fringes at hard contrast image parts) is known as lateral CA - it means that light of different colors ends up in different places in the focal plane - just like when the sun shines through a simple prism to show a rainbow - this is mainly dependant on eyepiece design.

Longitudinal CA means that light of different colors comes to focus in different positions along the optical axis - this does not show the fringes but results into general fuzziness at higher magnification (and will show as colored diffraction patterns when doing a star test).

The loss of edge sharpness at higher magnification could be either due to field curvature (in that case you can refocus a bit to get the edge sharp) or other aberrations (when you can't refocus).

Joachim
 

Ridge Walker

Well-known member
To jring. Thanks for that vey interesting information. Which BTW I have copied and saved for future reference
Cheers
 

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