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Bright eyepieces?

Started by Jeremiahcole, 12/31/2014 09:15AM
Posted 12/31/2014 09:15AM Opening Post
I have recently purchased several Nagler eyepieces due to the wide field of view and impressive reviews. However, I have seen in some reviews that they tend to be "darker" due to the amount of lens pieces. while I am definitely happy with the Naglers I have (3.5mm T6, 7mm T1, 9mm T1) My scope is a 120mm refractor so I definitely need something that also maximizes what little light does get through.

What recommendations do people have regarding the brightest eyepieces? Price is only somewhat of a consideration, if I can't afford it I'll look for it used or save up....
Posted 12/31/2014 03:14PM #1

Jeremiah:
Some of the brightest are not necessarily the best optically, but the Edmund RKE EPs are bright, easily obtained and inexpensive.. Most of the Japanese orthoscopic EPs with 4 or 5 elements are fairly bright. Although they are only available used, the Pentax XO series is excellent in every category except FOV and eye relief. The Brandons are pretty good with excellent contrast. Having said all this the best EPs I have are the 10 element Nikon HW 12.5mm. With modern glasses and coatings it's not simply the number of elements.

George
Posted 01/04/2015 08:03AM #2
Any dimming due to more lens elements is extremely minor due to modern coatings. Also, your eyes will not easily detect anything less than a 10% decrease in brightness. The key is not looking for a "brighter" eyepiece, but learning to use what you have. Which is appropriate for viewing what, etc. Your 5-inch delivers plenty of light for many, many objects, BTW. wink

Uncle Rod

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Posted 01/04/2015 12:40PM #3
Hi Jeremiah, Before my retirement from aerospace work a few years ago, I enjoyed the luxury of doing self-directed independent research as an ITT Tech Fellow. Among that was a 16p unpublished paper, "Photometric Throughput of Visual-Use Astronomical Telescopes." I measures the VRGB transmittance of a bunch of eyepieces to 0.2% accuracy or better and also the performance of the coatings. Here are some of the (V-only throughputs and coating loss per surface) results: old Orion Big Barlow 97.3/1.2%, old TV Paracorr 95.0/1.1, TV Dioptrx 98.5/0.7, old UO 55mm Plossl 88.0/3.0, old Celestron 26mm Plossl 95.5, 1.0, old UO 24mm Konig 90.6/2.3, old UO 12mm Konig 92.3/1.9, old TV 13mm Nagler 90.2/1.2, old TV 9mm Nagler 90.7/1.1, old TV 20mm Nagler T2 88.4/1.1, TV 13mm Ethos 93.8/0.6, old Zuiko SLR lens 50mm f/1.4 92.7/0.6, old Zuiko SLR lens 100mm f/2.0 93.5/0.5. I traced the surprisingly high loss in the 3 old UOs to the coatings...they cheated by only MARC-coating the one outside surface toward the eye. The only really superior coatings were the Ethos and (old!) Olympus camera lenses! The old Naglers and (surprisingly!) the old Celestron were decent. I also did papers on mirror coatings and 20 commercial Star Diagonals (wavefront, throughput, alignment). A new Antares "Dielectric 99%" measured a pathetic 88% and was horribly misaligned! The (reputable) dealer didn't want to hear about it, just the middle-man but did offer me a refund. I kept it as an example of a really crappy defective diagonal. I also did a very ambitious paper on scatter and one (long time ago) "Telescope Quality - How Good is Good Enough" wherein esteemed co-author Daniel Malacara and I did a performance analysis of telescopes suffering (among other things) Primary Spherical Aberration. That was pre-launch of Hubble and damned (negatively) auspicious, considering the later-discovered Hubble SNAFU! Most of these (and a couple hundred other) tech papers are available. I usually incorporate such material into presentations, many in the amateur astronomy community.

But back to your question, I agree with Rod that it hardly matters. But the TOTAL throughput of your system will affect your ability to see such subtle stuff like remote galaxies. Oh yeah, most coatings measured deficient in the blue = spiral galaxies! For wide-field DS, nothing beats a good fast APO or Giant Newt with modern WF eyep (Delos, Nagler, Ethos). For high-mag resolution, nothing beats a slow-feed scope with a nice Ortho! That's just my opinion part...

Bio: The vast majority of my work was professional aerospace and put bread on the table. Satellite docking, Hubble-Class imagers, Keck 1&2, KPNO (light pollution), Night Vision, GPS...myriad others. But I've always been an amateur astronomer at heart and now enjoy that in retirement - 36-inch scope! Woo Hoo! And my eyes still work...?! Tom Dey

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 10/01/2020 02:41AM #4
Originally Posted by Jeremiah Cole
I have recently purchased several Nagler eyepieces due to the wide field of view and impressive reviews. However, I have seen in some reviews that they tend to be "darker" due to the amount of lens pieces. while I am definitely happy with the Naglers I have (3.5mm T6, 7mm T1, 9mm T1) My scope is a 120mm refractor so I definitely need something that also maximizes what little light does get through. <br><br>What recommendations do people have regarding the brightest eyepieces? Price is only somewhat of a consideration, if I can't afford it I'll look for it used or save up....
I use to work for EPOI which back in 1970's owned Nikon and many other companies like Bronica, Fuji...etc.
I asked their Head Salesman if I could purchase some Demo Nikon Microscope eyepieces. He went to the lower level
of the building and searched for a series of Nikon Microscope eyepieces. He found a Nikon 5x, Nikon 10mm WF, Nikon HKW 10mm with 
cross-hair reticle, Nikon HKW 15mm and a Nikon K20x. I also got a FM (Early model to EFM) and more all for $50!
I at that time had a Lafayette Galactic 70mm refractor. That scope had a 0.965mm eyepiece holder. In the 1980's, I had access to
a professional Metal Lathe. I was able to produce 3, 0.020" aluminum sleeves that I turned down from a 1.0" Aluminum round stock. 
I made these, so I could put these Nikon Microscope eyepieces to use with my Lafayette Galactic.  
   I sold off the Lafayette Galactic and every scope from that point had either a 1.25" or 2.0" eyepiece holders. I basically, mothballed
those Nikon Microscope eyepieces.   
   Currently, I own a Questar Duplex and a 10" Meade LX850 OTA. I recently remembered that I had the Nikon Microscope Eyepieces
and I saw on eBay a Seller(China based) that offered a 0.965" to 1.25" eyepiece adapter for $7.95. It also include a 1.25" to 0.965" 
adapter too.
    I have accumulated quite a few Televue eyepieces. I own a 4mm & 10mm Televue Radians and a Televue Type 2, 16mm Nagler.
The Questar came with 2 Brandon's 16mm & 32mm. Those were Erfle designs. 
    Up to that point, my 16mm Nagler was my prized possession and there are Many review about this particular eyepieces performance. Then that Chinese 0.965" to 1.25" eyepiece adapter arrived and I could finally use my Nikon eyepieces.
    The Questar Duplex's views are incredible to start with. When I dropped in the Nikon's into the eyepiece holder my mind
was absolutely blown away. These eyepieces were brighter, had more contrast and Detail than ANY eyepiece I own!!
     The Nikon K20x was very close in magnification to my Televue Type 2, 16mm Nagler. This little K20x blew the doors off the
Nagler! In fact, I noticed by comparison of view of Jupiter as my test bed, that the Nagler had a warm and unnatural tone.
The Nikon K20x had just as good eye relief and offered more detail and contrast.
      Now I'm not going to get into a debate with Televue Owners but I will ask Anyone who would like to perform a simple test.
These Nikon eyepieces are going for Dirt cheap on eBay. You could buy the same set and pay probably less than $160 for them all.
   Of course you will need that 0.965' to 1.25" adapter and a friend of my used some flexible Stainless Steel tape to increase the
Nikon's 0.913" OD up to the 0.965" OD.  These eyepieces will completely change your mind on what a Telescope Eyepiece will
deliver as far as imaging. So, if you are looking for a cheap but totally affordable way to improve your viewing, do what I did.
So far, to friends of mine, purchased these eyepieces and did the same test as I did. They were totally blown away too.
Posted 10/06/2020 05:57PM #5
Jerimiah,
You did not indicate the f-ratio of your 120mm refractor.  I'm assuming it's something like f/8.  If that's the case, the 3.5mm Nagler is yielding 274x, which is pushing it quite a bit for that scope.  Your view is guaranteed to be dark w/ that eyepiece.  The 6mm would yield 160x, which is likely closer to the practical limit (for nice views) but may still be a bit dark.   Unless you have a $6,000 scope and pristine dark skies I would ignore the old guideline of 50x per inch of aperture.  In practice it's more like 25-30x per inch of aperture for acceptable views.
Jim
Posted 10/11/2020 03:57PM #6
Originally Posted by Thomas Dey
Hi Jeremiah, Before my retirement from aerospace work a few years ago, I enjoyed the luxury of doing self-directed independent research as an ITT Tech Fellow. Among that was a 16p unpublished paper, "Photometric Throughput of Visual-Use Astronomical Telescopes."<br>

Hey Tom - I know this post is several years old now, but I'm wondering if your eyepiece and diagonal studies are posted anywhere online?  I'd love to read those papers.  Thanks,

-Scott