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Nice review of Explore Scientific 9mm 100º UWA 2" telescope eyepiece

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#1 astrocanito

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Posted 12 April 2021 - 11:39 AM

This is my point of view about this great eyepiece and why it's an excellent 1st choice for a beginner, I use it with a 12" f/5 dobsonian newtonian reflector telescope with a 2" focuser.

 

https://www.youtube....h?v=6Eulm0qze3I


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#2 RLK1

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Posted 12 April 2021 - 12:46 PM

I like the eyepiece and I use it in either a 12" f5 dob or in my 16" f4.5 dob. It's well corrected for edge aberrations and is a comfortable eyepiece to use for observations of DSOs. It does, however, exhibit significant lateral color on the planets. Unless you're fixed on having a 9mm 100A FOV eyepiece, a 10mm Ethos is superior in every regard.



#3 astrocanito

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Posted 12 April 2021 - 02:13 PM

Mine doesn't have lateral color on planets. Are you sure is the eyepiece?



#4 RLK1

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Posted 12 April 2021 - 02:13 PM

Mine doesn't have lateral color on planets. Are you sure is the eyepiece?

I'm sure...



#5 astrocanito

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Posted 12 April 2021 - 02:17 PM

I'm sure...

What's your latitude?



#6 RLK1

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Posted 12 April 2021 - 02:22 PM

What's your latitude?

34N. My findings on the 9mm 100A FOV are similar to starman1's comment on the ES25MM 100AFOV: "lateral color. Star images become prismatic near the edge, and moving the eye only partially eliminates this. Holding the eye in the wrong place with an Ethos can do this too, but changing the position of the eye eliminates it. In this case, it can't be eliminated, AND the blue ring at the edge is very noticeable on the Moon; otherwise not at all.

Suggestion: Experimenting with eye placement is essential to reduce this effect."



#7 Dave Mitsky

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Posted 12 April 2021 - 02:25 PM

I also own a 9mm Explore Scientific 100-degree eyepiece and really enjoy using it for DSO observing.


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#8 Spikey131

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Posted 12 April 2021 - 03:00 PM

I like mine as well. When I got it used a few years ago, it cost less than 1/3 of what a new Ethos costs. The views compare favorably to those in my Ethos EPs.
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#9 rowdy388

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Posted 12 April 2021 - 03:16 PM

The ES 9 100 was one of my favorite eyepieces for a few years. I sold off its siblings, the 14 and 20 before letting go of the 9. After getting the 8 & 10 Ethos

plus 9 ES120 & 9 Morpheus it was finally time for the 9 ES100 to leave. I'm sure it is loved in its new home.



#10 astrocanito

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Posted 12 April 2021 - 07:13 PM

34N. My findings on the 9mm 100A FOV are similar to starman1's comment on the ES25MM 100AFOV: "lateral color. Star images become prismatic near the edge, and moving the eye only partially eliminates this. Holding the eye in the wrong place with an Ethos can do this too, but changing the position of the eye eliminates it. In this case, it can't be eliminated, AND the blue ring at the edge is very noticeable on the Moon; otherwise not at all.

Suggestion: Experimenting with eye placement is essential to reduce this effect."

I'm a curious guy. Would be nice to know if more people note that in this 9mm EP to understand the cause. Next planet i will carefully pay attention and test with different situations to try to see that. But until now i didn't see nothing but coma on the edges.



#11 RLK1

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Posted 12 April 2021 - 08:05 PM

I'm a curious guy. Would be nice to know if more people note that in this 9mm EP to understand the cause. Next planet i will carefully pay attention and test with different situations to try to see that. But until now i didn't see nothing but coma on the edges.

Here's one in a review of the 9mm 100 AFOV:

"Also, the edge of the field of view in the ES100 is not colour-free."  "There is a slight amount of false colour to be seen"

https://stargazerslo...egree-eyepiece/

I'm seeing a bit more than this guy reports but he's using a smaller apo refractor and I'm primarily using a 16" f4.5 dob.


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#12 explore19

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Posted 12 April 2021 - 09:26 PM

Has anyone compared the 9mm ES with the 9mm APM XWA?

#13 SeattleScott

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Posted 12 April 2021 - 09:32 PM

Has anyone compared the 9mm ES with the 9mm APM XWA?

Many have and the APM is pretty much universally preferred. The day of the ES 100 has passed. They made sense when they were 1/3 the cost of an Ethos. They make no sense at 80-90% of the cost of Ethos.

Scott
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#14 havasman

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Posted 12 April 2021 - 09:50 PM

Has anyone compared the 9mm ES with the 9mm APM XWA?

Yes. I had both and found the APM optically purer and preferred it pretty easily. The difference was more pronounced with the ES100 20mm and APM HDC 20mm. Both the ES100's had this very slight haze to the presentation that was seen in direct comparison of the eyepieces. Once that became apparent color didn't matter. The ES100 14mm had the least of it but I also preferred the APM HDC 13mm. The 14 and 13 were the only ones I didn't have simultaneously for direct comparison in 16" f4.49 Starmaster/CZO.

Later circumstances allowed me to replace the APM's with Ethos and that's what I use. I think them better than the others but of course they're pricey. The APM HDC's are, IMO, great buys.


Edited by havasman, 12 April 2021 - 09:54 PM.

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