Explore Scientific 52 LER Series Eyepieces
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Explore Scientific 52 LER Series Eyepieces

  (5 Reviews)
✓ 2 year warranty


1x in stock shipped 1-2 working days

About this product

Model:  es_52_4-5mm
Part Number:  0219504

Comfort, Quality, Value. The Explore Scientific 52° Series™

Very nice flat-field eyepieces with an apparent field of view of 52 degrees and a minimum of 15mm eye relief. 

Fully multicoated edge-blackened optics deliver high contrast, maximum light transmission and freedom from ghosting. Resolution and edge-to-edge field correction are both impressive!  

All Explore Scientific 52° eyepieces are Argon purged (the air inside is replaced with Argon, an inert gas) and sealed so the inside will never suffer from condensation. The interior optics will remain clear, bright and dust-free, year after year. 

The nosepiece includes a milled safety undercut (to prevent the eyepiece slipping out of the focuser) and is threaded to accept astronomy filters. 


  • High quality fully multicoated glass elements. 
  • Excellent resolution and field sharpness, even with fast optics. 
  • 52° apparent field of view. 
  • Minimum of 15mm eye relief.
  • Blackened lens edges for enhanced contrast. 
  • Sealed Argon-purged body (waterproof & fog-proof). 
  • Stainless steel barrel with milled safety undercut. 
  • Threaded for astronomy filters. 
  • Patented EMD-coating to maximize contrast.

Eyepiece Field of View Simulator


Model 3mm 4.5mm 6.5mm 10mm 15mm 20mm 25mm 30mm 40mm
Product Code 0219503 0219504 0219506 0219510 0219515 0219520 0219525 0219530 0219540
Apparent Field of View 52º 52º 52º 52º 52º 52º 52º 52º 52º
Eye Relief 15mm 15mm 15.9mm 16.6mm 16.3mm 15mm 16.4mm 19.9mm 27.1mm
Barrel Size 1.25” / 31.7mm 1.25” / 31.7mm 1.25” / 31.7mm 1.25” / 31.7mm 1.25”/ 31.7mm 1.25”/ 31.7mm 1.25”/ 31.7mm 1.25”/ 31.7mm 2” / 50.8mm
Height (From End of Barrel) 97mm 89mm 109mm 89mm 93mm 76mm 74mm 82mm 103mm
Weight 192g 185g 220g 185g 200g 175g 155g 200g 390g

Customer reviews

Average Rating (5 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Explore 30mm LER
04 May 2023  | 

First light highly professional excellent service
Very pleased optical contrast is good, good value for money

Rating (max 5):  
New eyepiece
03 December 2021  | 

Just received my new Explorer scentific eyepiece from FLO. Again a very good service from these people. The eyepiece came in a very nice box, which was well packaged. I'm not shore when I will be able to try it out, as the weather hasnot been great.

Rating (max 5):  
Excellent optics
28 July 2020  | 

Bought this as a replacement for the standard 10mm eyepiece supplied with the scope. The image was dramatically sharper and brighter. Was able to see much more detail on the moon and Jupiter and it's inner 4 moons were much clearer and sharper. A cost effective upgrade, will so get the matching barlow and replace my 25mm eyepiece too.

Rating (max 5):  
Well worth it
26 May 2020  | 

Total novice here, bought this with my first "proper" telescope. Absolutely lovely bit of kit for the price. I only have the budget Celestron and Skywatcher eyepieces to compare to, but this is hugely better, with a similar comfort level/ease of use to a low power 25mm or 20mm and brighter than the cheapo 10mm I got. I had a hunch that the bundled EPs wouldn't be enough by themselves, and I was right. The brightness of this is very good considering the magnification - dimmer than looking through 50mm binoculars, similar brightness to the 20mm cheapo EP, which for something over twice the magnification is impressive. (It'd be great on a mounted spotter scope for extreme distance daytime use.) Tried it with a Barlow in daytime in my 600mm telescope and I could easily see individual flies buzzing round the leaves on the tip of a tree about 250-300 yards away across a field, which blew my mind a bit compared to all other optics I've used. That was a total magnification of 184x and it was still not much dimmer than regular 26mm binoculars.

Using it in such extreme daylight conditions also revealed how well made the internals are in terms of image - really flat, hardly any distortion. After reading online a lot I knew to look for edge distortion, but could barely see any. Couldn't get it quite sharp enough but I can tell with some swapping bits that this is due to my not having collimated properly yet.

Stuck it in my budget 400mm kids telescope for a laugh and quickly stopped laughing because it was actually not too bad. Dark, obviously, but it did an incredible amount with such a cheap piece of equipment.

Best of all, compared to a normal simple EP in a short length, the apparent field of view and eye relief are amazing, it's more like looking into a binocular eyepiece. Huge field of view, really comfortable. I'm probably going to replace all my cheapo EPs with equivalent lengths from this range.

Note, though, it's big and heavy compared to cheap EPs. Feels really well made and solid, gorgeous CNC'd metalwork and detailing, but much heavier, like a D cell battery. Worth remembering if you plan to carry around several in your pocket.

Overall: I hovered indecisively, wondering if it was worth spending over 50 on an EP when cheap ones are around 15. It absolutely is. A couple of great EPs like this are definitely better than a huge range of cheap, dull EPs with uncomfortable eye relief and tiny exit pupil. Whatever multifaceted wizardry goes into these chunky things is worth the extra money.

Rating (max 5):  
Very good quality
07 March 2020  | 

I bought the 3mm variant and have put it to use for the past couple of weeks. Using my Orion Skyscanner 100mm newtonian, I was amazed at the detail I was able to see on the Moon at 133x magnification, not to mention the comfortable eye relief; I certainly did not have to squint to look into the eyepiece. I was immersed in the eyepiece's field of view. It was as if I could reach out and touch the surface of the Moon! For the price I seriously recommend buying one of these lovely gems especially if you have a short focal length telescope and want to use higher magnifications while still having a comfortable eye relief. You can't go wrong with these eyepieces!


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