Explore Scientific 24mm 82 degree Eyepiece

Posted in Hardware on July 9, 2015 – 5:56 PM
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Up until this week, my collection of eyepieces was mostly ones I got either with a telescope or through the Celestron beginner’s accessory kit which provided 5 plossl eyepieces and a barlow. I’ve picked up a few others along the way, particularly a couple TMB Planetary eyepieces, a couple inexpensive 2″ eyepieces, and an Orion Expanse 20mm which quickly became my go-to eyepiece for most things. For some reason over the past few months I’ve had the hankering to put together a set of nicer eyepieces at a reasonable cost – all my research led me to the explore scientific line.

Enjoying the view from the Orion Expanse was the key for me. While Plossl’s typically have a 50 degree field of view, the Expanse comes in at 66 degrees. So what would an 82 degree eyepiece do? And yes, 100 degrees (and even 120 degree) eyepieces are out there, but beyond what I’m willing to spend. But how does the FOV increase and keep magnification the same?

I decided to compare the Explore Scientific 2″ 24mm 82 degree eyepiece to a 25mm Celestron plossl. The comparison was done on my 10″ dob (fl 1200mm, f/ 4.7). I felt the ring nebula was a good target to compare magnification, image clarity, and color.

The Explore Scientific eyepiece is a pretty big and pretty heavy eyepiece coming in at about a pound and a half. I was also a little disappointed because fully seated in my stock focuser there was not enough travel to allow it to come to focus. I had to pull it out a bit and tighten down the screw which allowed it to focus. However, once in focus the view did not disappoint. Now at 50X magnification and an apparent field of 1.64 degrees I could still see M57 clear and the hole in the middle was evident. There was a slight bluish hue and crisp stars most of the way across the field of view which certainly looked large.

Switching over to the 25mm Plossl (48X, just over 1 degree apparent FOV) I immediately got my answers.
1. The wider field of view really does not impact the magnification. The plossl looked just about as good on the ring nebula, but the starfield is limited and the edge of the field now looks like you are looking down a long tube. Same magnification, but wider field viewed in the eyepiece.
2. The explore scientific had a crisper image at the edge of the field with only minor aberrations as you moved toward the edge of the field. The plossl wasn’t bad, but even with the narrower FOV, some lengthening of the point of light was noticable.
3. The color transmission was a bit better in the explore scientific, particularly looking at star colors, but the difference seemed reasonably small (perhaps under better skies it would look different).

Overall, I was impressed with the Explore Scientific 82 degree eyepiece – it performed as I hoped. There was good contrast, a very clean image, and the wide field makes viewing more enjoyable – and keeps the object in my eyepiece for longer. However, I was also impressed with the plossl I had been using for years. Sure, it doesn’t have the field of view, but considering cost, the view did not disappoint. It goes to show that you get what you pay for, but the inexpensive ame brand lenses offer great value.

Perhaps one day I will compare this eyepiece to a Nagler, Ethos, or similar – an eyepiece generally considered as superior… and will update this review.

This entry was written by matted, filed under Hardware.
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