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2/14/2013

Eyepieces and Which Wide Field: 24mm Explore Scientific 82 degree vs 27mm Pantoptic 68 degrees


   27mm TeleVue Panoptic or 24mm Explore Scientific 82 degree as a 2" finder eyepiece




  For some time now I have been using the 27mm Panoptic as my finder eyepiece in my 14 inch dob.  The 27mm Panoptic offers a good dark background, solid magnification of 61x in my 14" dob with a field of view of 1.11 degrees and a 19mm eye relief. It weighs 18 ox or 1 lb 2 oz.

Over the holidays Explore Scientific had their promotion going on where they sent a piece of the asteroid Campo del Cielo from Argentina with a ten percent discount.  So I ordered the 24mm Explore Scientific 82 degree eyepiece. I had heard many wonderful things about this eyepiece and I wanted to try out my wide field experience.  This 2 inch eyepiece weighs in at 1 lb 6 oz. (4 oz. more than the 27mm Panoptic).  The listed eye relief is 17mm and it seems to be close, about 16.5mm as I reckon. This eyepiece gives a magnification of 69x and a field of view of 1.19 degrees.

So now I'll compare the stats of these two eyepieces.

                    TeleVue 27mm Panoptic 68 degrees                                 24mm Explore Scientific 82 degrees

Field of View                 1.11 degrees                                                                 1.19 degrees

Eye Relief                       19mm                                                                             16.5mm

Weight                             1 lb 2 oz                                                                      1 lb 6 oz.

Magnification                     61x                                                                             69x

To see how the eyepieces show a field of view I used Starry Night Pro to show the differences.  Here are some of those images.


Here is Messier 95 & 96 and Messier 105 in the same field of view. In all of these images, the green will be the TeleVue 27mm Panoptic and the 24mm Explore Scientific 82 degree is the yellow.  It is easy to see that the ES 24mm gives the better overall field of view here.


Here you can see the field of view for the Leo Triplet, Messier 65, 66 and NGC 3628 in Leo.  Again, all three objects are in the field of view of both eyepieces, with the 24mm Explore Scientific giving a wider field of view.

Well, I wanted to show Messier 42 and the Double Cluster but my program isn't saving correctly. So I'll have to use the two images above.  In trying to decide which eyepiece will be my finder eyepiece, I have several things to consider. First, my 14 inch dob can get top heavy and though balanced to work with a Paracorr, a 30mm ES 82 degree eyepiece, a 9x50 finder and a Telrad, I prefer not to run that much weight too often. So with weight being a concern, the Panoptic has the edge so far. Next if I look at the actual field of view and can see that for the most part, the slightly larger field of view of the 24mm ES 82 degree isn't enough to really over come the field of view of the 27mm Panoptic.  So with weight going to the 27mm Panoptic, I looked at other factors. The 24mm ES 82 degree has a lot of coma without the Paracorr in.  The coma is a good 30 percent out from the edge.  The Paracorr cleans it up but with the 27mm Panoptic coma is not really an issue with the Paracorr and the pincushion issue is resolved for me.  Edge here goes to the 27mm Panoptic.  Magnification is relatively close so that isn't an issue, and I like the lower power of the Panoptic 27mm.  Last is eye relief.  I do wear glasses and though my astigmatism isn't bad, and I can observe easily without my glasses, I usually leave them on as I need them to look at constellations and align the Telrad.  So here the Explore Scientific has a 16.5mm eye relief vs the 19mm of the 27mm Panoptic. Edge for me has to go to the Panoptic.

So in weighing these factors my final decision is that the 27mm Panoptic will remain my wide field eyepiece of choice. I like the 24mm Explore Scientific 82 degree and to be quite honest for the $179.99 I paid made it an excellent choice for someone who cannot afford the $370.00 for the 27mm Panoptic.  Now I need to come to a decision on what to do with the 24mm Explore Scientific 82 degree eyepiece. Do I sell it for my cost of $179.99, which is cheaper than the cost of a current new one? Do I hold on to it and use it from time to time in my 10 inch dob? I'll probably keep it for awhile and use it for outreach and for in case an observing friend needs a wide field eyepiece to use.  I may end up selling the eyepiece in the next couple of months on Astromart or on CloudyNights.

I hope someone benefits from how I went about evaluating the two eyepieces from the field to here. I wouldn't lose using either eyepiece and so in the end, if I didn't own the 27mm Panoptic and hadn't purchased it for $270.00 new a couple of years ago, I would be just as happy with the 24mm Explore Scientific 82 degree eyepieces.

I did some more comparisons to ensure I have what I want.  Here is the chart I put together using my 1650mm 14 inch dob.

Cost                  EP                  ER                   Mag                 FOV                         Weight
$299.99         ES 20mm 100    14.5mm          83x                     1.21 degree              2lbs 2oz

$199.99         ES 24mm 82      17mm             69x                      1.19 degree              1lb 6oz

$29.99         ES 30mm 82       21mm            55x                       1.49 degree              2lbs 2oz

 $119.00        ES 24mm 68      18mm            69x                       0.99 degree               11.2 oz

$99.00            ES 20mm 68       15mm           83x                        0.82 degree              8.8 oz

$370.00        27mm TV Panoptic   16mm        61x                        1.11 degree              1lb 2oz

I did this an experiment to see if I have really found my wide field eyepieces. This may sound crazy as I spend money for land to observe on, spend money on a premium mirror etc. but I would prefer not to spend $600.00 to $1000.00 per eyepiece for TeleVue's.  So what does the table show me? Yes, I have the eyepieces I need. I was thinking of the 20mm ES 100 degree EP again but decided not to. The 24mm ES 82 degree and the 27mm TV Panoptic will work for me.  I put the 24mm 68 degree to compare it to the 24mm ES 82 degree I have and no, that is not the eyepiece I want.  I'm happy with what I have.