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$25 VS $125 Short Focal Length Eyepieces - A Review

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#1 ayadai

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Posted 27 September 2021 - 08:15 PM

Back in March of this year, I bought a collection of Orion Expanse (6mm, 9mm, 15mm, & 20mm) eyepieces for ~$120. On the C8 SCT, and more recently, the Orion ED80T CF (f6/480mm) refractor, I found them very clear, sharp to the edges with good contrast, comfortable to use and with nice wide views.

 

Having read how well a good triplet refractor can handle extreme magnification, I decided to test it out while viewing bright objects like the moon, Jupiter and Saturn. I found good deals on a clean Orion Shorty Plus 3-Element barlow ($60; great performer, BTW) and a new Explore Scientific 4.7mm 82 degree eyepiece ($125). I've always wanted to try "less than budget" eyepieces and this seemed a good opportunity.

 

Last night marked our first clear night in several weeks, so I broke everything out to try it for the first time. A principle goal, other than testing the limits of the refractor, was to compare the Orion Expanse 6mm to the Explore Scientific 4.7mm and see if a $125 eyepiece delivered better views and/or was more comfortable to use than a $25 eyepiece. Here are my impressions:

  • Clarity/sharpness: Both are equally very clear; in terms of sharpness, the Explore Scientific may be a little bit better around the edges where stars are visible, but it’s negligible. Clarity and sharpness of the central bright object is indistinguishable between the two.
  • Contrast: No discernible difference between the two. Both allow the refractor to do what it does best.
  • Eye relief/blind spots: No discernible difference between the two.

The Explore Scientific 4.7mm provided more magnification and was a bit dimmer, as one would expect given the 1.3mm difference in focal length. Performance of both eyepieces was as described both with and without the barlow.

 

Overall, as a test of the ability of the Orion ED80T CF to handle magnification, last night was a success! It had views that rivaled those of my C8 with excellent sharpness and contrast. I’ll be keeping the Explore Scientific 4.7mm, as I find it has the perfect minimum focal length for the Orion ED80T CF when combined with the Orion Shorty Plus 3-Element barlow.

 

As far as $25 VS $125 eyepieces go, the argument could be made that a 1.3mm difference in focal length with no difference in eye relief/blind spots means that the Explore Scientific 4.7mm is superior, but that may be stretching things; whether it's worth $100 is subjective. Perhaps a longer focal length eyepiece would be a better object for comparison on a f6 refractor, or perhaps my eyes and/or brain are just incapable of discerning fine differences.


Edited by ayadai, 27 September 2021 - 08:27 PM.

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#2 SeattleScott

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Posted 27 September 2021 - 08:33 PM

The 6mm is reportedly the best in the series.

F6 isn’t especially demanding.

The ES is 82 AFOV instead of 66, so there’s that. Does that make it worth 5x as much? To some, sure.

Scott

#3 ayadai

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Posted 27 September 2021 - 08:42 PM

The ES is 82 AFOV instead of 66, so there’s that. Does that make it worth 5x as much? To some, sure.

True. Since any difference in AFOV could only be assessed between eyepieces of the same focal length, it would have been apples-to-oranges for me to compare AFOV between a 6mm and a 4.7mm, so I did not go there.


Edited by ayadai, 27 September 2021 - 08:45 PM.

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#4 teashea

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Posted 28 September 2021 - 07:19 PM

Back in March of this year, I bought a collection of Orion Expanse (6mm, 9mm, 15mm, & 20mm) eyepieces for ~$120. On the C8 SCT, and more recently, the Orion ED80T CF (f6/480mm) refractor, I found them very clear, sharp to the edges with good contrast, comfortable to use and with nice wide views.

 

Having read how well a good triplet refractor can handle extreme magnification, I decided to test it out while viewing bright objects like the moon, Jupiter and Saturn. I found good deals on a clean Orion Shorty Plus 3-Element barlow ($60; great performer, BTW) and a new Explore Scientific 4.7mm 82 degree eyepiece ($125). I've always wanted to try "less than budget" eyepieces and this seemed a good opportunity.

 

Last night marked our first clear night in several weeks, so I broke everything out to try it for the first time. A principle goal, other than testing the limits of the refractor, was to compare the Orion Expanse 6mm to the Explore Scientific 4.7mm and see if a $125 eyepiece delivered better views and/or was more comfortable to use than a $25 eyepiece. Here are my impressions:

  • Clarity/sharpness: Both are equally very clear; in terms of sharpness, the Explore Scientific may be a little bit better around the edges where stars are visible, but it’s negligible. Clarity and sharpness of the central bright object is indistinguishable between the two.
  • Contrast: No discernible difference between the two. Both allow the refractor to do what it does best.
  • Eye relief/blind spots: No discernible difference between the two.

The Explore Scientific 4.7mm provided more magnification and was a bit dimmer, as one would expect given the 1.3mm difference in focal length. Performance of both eyepieces was as described both with and without the barlow.

 

Overall, as a test of the ability of the Orion ED80T CF to handle magnification, last night was a success! It had views that rivaled those of my C8 with excellent sharpness and contrast. I’ll be keeping the Explore Scientific 4.7mm, as I find it has the perfect minimum focal length for the Orion ED80T CF when combined with the Orion Shorty Plus 3-Element barlow.

 

As far as $25 VS $125 eyepieces go, the argument could be made that a 1.3mm difference in focal length with no difference in eye relief/blind spots means that the Explore Scientific 4.7mm is superior, but that may be stretching things; whether it's worth $100 is subjective. Perhaps a longer focal length eyepiece would be a better object for comparison on a f6 refractor, or perhaps my eyes and/or brain are just incapable of discerning fine differences.

interesting comparison




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