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Scope bodies versus scope eyepieces? Optical importance and upgrades... (1 Viewer)

mbb

Well-known member
I’ve seen many posts about forum members putting astro eyepieces on their spotting scope, or updating/upgrading their sometimes old spotting scope with new eyepieces. The latter either of the original brand (e.g.switching to recent wide field eyepiece with better coatings) or from other brands (e.g. putting an Opticron eyepiece on an older Kowa scope).
The appearance of wide angle zoom eyepieces (new optical formulas/design) probably has been one of the reasons, but I guess not the only reason or evolution in the last decades.

This has made me wonder :unsure: : how (much more?) important is the eyepiece as opposed to the scope’s body in defining the combined optical quality? Sharpness, contrast, brightness...?
Is there much less difference between bodies of different ages and price levels (excluding the cheapest or faulty ones) than there is between eyepieces?
If so, is this due to a higher optical complexity of eyepieces or their larger number of optical elements or glass-air surfaces, making them benefit more from technical evolutions (e.g.improvements in coating technology)?

Of course, a lousy/bad scope body won‘t allow a great eyepiece to really shine, it will depend on the specific body and eyepiece, and you cannot exactly quantify it, but can anybody share his/her knowledge and experience about this based on optical/technical knowledge and/or on hands-on experience with such upgrades and combinations of bodies and eyepieces, old and new, cheaper or more expensive etc.?

...
Or do we mainly talk more about putting new eyepieces on older scopes than we do about upgrading to newer bodies while keeping older eyepieces, just because new eyepieces are much cheaper than new bodies...? ;)
 

dannat

Well-known member
a good system/; lens set matched with body prism will last for ages, newer coatings might squeeze out an extra smidge of transmission - the nikon fieldscopes attest to this, their eyepieces are less sought after, and i’m sure people would jump at being able to fit new wide field designs to them.’
problem with eyepieces has been lateral colour, hard to design a big zoom eyepiece with wide field of view and control it..need lots of lens elements - look at the lens diagrams for some camera zooms up to 20-21 elements a few w ED glass

astro eyepieces are usually simpler designs, and wide fields of view are still relatively new-but many astro users still prefer and use 50 deg fov designs for their lack of aberration, but the eyepiece only accounts for a small % of the view here, prob only 5-10% of the overall system -a great astro telescope works as well with a $50 eyepiece as a $500 one, albeit with a narrower view usually (don’t look up zeiss abbe ortho prices) most astro targets though are essentially blk on white, apart from plants

spotting scopes have to cope w many more colours, hard to put a figure on it but i think their eyepieces account for a greater % of overall view, maybe 20% ..celestron regal 100 is a good lens set, but ep zoom comes with it is average, much lateral colour,swapping in astro eyepiece improves view greatly, when henry tested the nikon monarch he said that sample tested nearly perfect, eyepiece again had some lateral colour which baader zoom cleaned up
 

jring

Well-known member
Hi,

in general, as has been mentioned, modern wide field EPs (zoom or not) are virtually stacks of lenses with many glass-air surfaces. So improvements in coating tech will be very visible there - unlike with the 4 surfaces of the usual air-spaced doublet or the 6 of a triplet objective.

Also unlike with amateur telescope designs, which have not changed a lot for the last 50 years at least, with eyepieces there is still active development going on (although it is debatable if we really need 120 deg afov - I personally find everything over 80 deg or so to be only useful for an quite uncomfortable exercise in eye gymnastics).

Another factor is that EPs seem to have less sample variation than fast refractors (like our spotters) so if you have a known good body, there is not a lot of risk to try to make it even nicer with a new EP.
A whole new scope might be good - or not. Even worse, if you sold off your old cherry before to raise funds for the new toy...

You need a good objective and a good eyepiece for a good view.

Joachim
 

mbb

Well-known member
Thank you for the info!
I didn't even know that such huge AFOV's existed. My Swarovski ATX 65 has, I think, an AFOV of approximately 59-79° (if I calculated it correctly), which I thought was already quite a wide-angle view for a spotting scope.
I have read about star tests, but never tried it myself. Thus I don't know if my scope is a 'cherry' or not, but I can say I find it quite impressive :oops::)
 

Binastro

Well-known member
The Konig, Kohler 120 degree eyepiece was used in submarine periscopes about 1944.
Zeiss Jena manufacture.

Regards,
B.
 

mbb

Well-known member
The Konig, Kohler 120 degree eyepiece was used in submarine periscopes about 1944.
Zeiss Jena manufacture.

Regards,
B.
Interesting fact!
I can better imagine the relevance of such a large FOV for a submarine periscope than for a birder scope.
 

gcole

Well-known member
I’ve seen many posts about forum members putting astro eyepieces on their spotting scope, or updating/upgrading their sometimes old spotting scope with new eyepieces. The latter either of the original brand (e.g.switching to recent wide field eyepiece with better coatings) or from other brands (e.g. putting an Opticron eyepiece on an older Kowa scope).
The appearance of wide angle zoom eyepieces (new optical formulas/design) probably has been one of the reasons, but I guess not the only reason or evolution in the last decades.

This has made me wonder :unsure: : how (much more?) important is the eyepiece as opposed to the scope’s body in defining the combined optical quality? Sharpness, contrast, brightness...?
Is there much less difference between bodies of different ages and price levels (excluding the cheapest or faulty ones) than there is between eyepieces?
If so, is this due to a higher optical complexity of eyepieces or their larger number of optical elements or glass-air surfaces, making them benefit more from technical evolutions (e.g.improvements in coating technology)?

Of course, a lousy/bad scope body won‘t allow a great eyepiece to really shine, it will depend on the specific body and eyepiece, and you cannot exactly quantify it, but can anybody share his/her knowledge and experience about this based on optical/technical knowledge and/or on hands-on experience with such upgrades and combinations of bodies and eyepieces, old and new, cheaper or more expensive etc.?

...
Or do we mainly talk more about putting new eyepieces on older scopes than we do about upgrading to newer bodies while keeping older eyepieces, just because new eyepieces are much cheaper than new bodies...? ;)
Here is an example of a spotting scope eyepiece upgrade between two different spotting scope/eyepiece manufacturers. A Nikon EDG FEP 25W eyepiece permanently attached to a Pentax 65 EDAII spotting scope. In my opinion the Nikon EDG 25W eyepiece when compared to its Pentax’s premium XW20 eyepiece of comparable power definitely took this well known and very competent spotter to a next level optically. This is proof that eyepieces do and can play one of the most if not the most important factor in a spotting scopes overall optical view.
 

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