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Looking for the best widest field 2" eyepiece


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  • 2 weeks later...

No one has mentioned Pentax XW's so I will....30mm and 40mm.  Currently only available on the used market.  I did a grand face-off contest between the TV offerings and these two - 41mm and 35mm Panoptics, 31mm Nagler.  The XW's are a bit lighter which was the first reason to try them.  They weigh about the same as the 35mm Panoptic, which is lighter than the 41mm Pan and 31mm Nagler.

After many comparisons I became a big fan of the XW's.  Under careful examination I got the impression that all 3 TV eyepieces imparted a yellowish tone to the stars, where the Pentax appeared pure white.  Also the XW's do not employ rectilinear distortion, so the stars appear normal when panning around, instead of visibly bending as the FOV moves across the sky.

Because there is no rectilinear distortion, the 40mm doesn't work so great at lower f-ratios typical of big Newts - you see the field curvature at the edges where the Tele Vue keep the stars as points to the edge.   However the 30mm XW has better edge correction and it's worked well for me at f/5.6.  Between the two of them you have a great high-contrast eyepiece that works well on long & short f-ratios.  I've avoided the ES eyepieces because of heavier weight.

Edited by Scott42
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43 minutes ago, Scott42 said:

No one has mentioned Pentax XW's so I will....30mm and 40mm.  Currently only available on the used market.  I did a grand face-off contest between the TV offerings and these two - 41mm and 35mm Panoptics, 31mm Nagler.  The XW's are a bit lighter which was the first reason to try them.  They weigh about the same as the 35mm Panoptic, which is lighter than the 41mm Pan and 31mm Nagler.

After many comparisons I became a big fan of the XW's.  Under careful examination I got the impression that all 3 TV eyepieces imparted a yellowish tone to the stars, where the Pentax appeared pure white.  Also the XW's do not employ rectilinear distortion, so the stars appear normal when panning around, instead of visibly bending as the FOV moves across the sky.

Because there is no rectilinear distortion, the 40mm doesn't work so great at lower f-ratios typical of big Newts - you see the field curvature at the edges where the Tele Vue keep the stars as points to the edge.   However the 30mm XW has better edge correction and it's worked well for me at f/5.6.  Between the two of them you have a great high-contrast eyepiece that works well on long & short f-ratios.  I've avoided the ES eyepieces because of heavier weight.

Have you tried comparing the 30mm Pentax XW to the 30mm APM UFF?  areyoukiddingme on CN claims the latter is optically better than the former, but he still prefers the former due to the sharper field stop.

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It looks good - not too heavy - and the price is right, I'd like to try one....the body looks similar to the TMB Paragon series.  Only 5 elements and 80 degrees, sounds interesting.   I did like the XW40mm better than the Paragon 40mm but the XW40 is far heavier.

https://www.apm-telescopes.de/en/eyepieces/more-74-ultra-wide-angle/apm-lunt-eyepieces/apm-eyepiece-uw-30-mm-80.html

Edited by Scott42
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7 hours ago, Scott42 said:

It looks good - not too heavy - and the price is right, I'd like to try one....the body looks similar to the TMB Paragon series.  Only 5 elements and 80 degrees, sounds interesting.   I did like the XW40mm better than the Paragon 40mm but the XW40 is far heavier.

https://www.apm-telescopes.de/en/eyepieces/more-74-ultra-wide-angle/apm-lunt-eyepieces/apm-eyepiece-uw-30-mm-80.html

Wrong 30mm APM.  That's the much older Widescan III clone.  It has severe field curvature leading to blurry edges.

This is the 30mm APM UFF I'm referring to.  It has 9 elements in 5 groups:

spacer.png

I did compare it to the Agena Astro version of the 30mm Widescan clone in this thread.  If you page down, I have several comparison reports.  Here's what they look like side by side.  The 2nd eyepiece from the left that says 20mm is really a 30mm Widescan clone that comes with a removable barlow element to make it 20mm.  The 3rd eyepiece from the left is the APM UFF.  The leftmost one is a decloaked original 30mm ES-82 when they had a twist-up, mushroom shaped eye guard.  The 27mm Panoptic on the far right is self-explanatory.

260682456_27mm-30mmEyepieces2.thumb.jpg.5b13327dc0a0c9ab6e2334116989806d.jpg

1942740858_27mm-30mmEyepieces1.thumb.jpg.702935a98f7effa00974ee1d22fce1af.jpg

And this field of view comparison image includes all of the above eyepieces:

647478535_27mmto42mmCrops.thumb.jpg.2b1030a8597f50bd1ee01ca37ede1f57.jpg

Edited by Louis D
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On 01/08/2019 at 20:46, Louis D said:

Wrong 30mm APM.  That's the much older Widescan III clone.  It has severe field curvature leading to blurry edges.

This is the 30mm APM UFF I'm referring to.  It has 9 elements in 5 groups:

Thanks for setting me straight!  I've used the WIdescans-types before.  So the UFF has some more lenses to flatten things out.   I see that there is no "safety groove" on the APM which is fantastic.   Weight is very reasonable at 19 ounces.

Edited by Scott42
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1 hour ago, Scott42 said:

Thanks for setting me straight!  I've used the WIdescans-types before.  So the UFF has some more lenses to flatten things out.   I see that there is no "safety groove" on the APM which is fantastic.   Weight is very reasonable at 19 ounces.

It's actually an entirely new approach to lens design to keep it slim enough for binoscope usage as well as being flat field.  The lowest elements actually form a telecompressor instead of the more typical Smyth or Barlow tele-extender.  The physical field stop (30.4mm as shown in the lens diagram) is smaller than the effective field stop (36.4mm as I measure it based on the above photo) as a result.

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  • 2 months later...

Thought I would post an update to this saga.

 

Having tried the 41 Panoptic and ES 40 for some time I conclude I like the Panoptic 5% more than the ES. This sounds pretty arbitrary but I have tried to put a figure on it and there is no area where I can say the ES is better through my eyes and my telescopes. To be honest the ES has a slightly larger field despite having a shorter focal length and the same declared angular field.  If it were a question of finance alone I would opt for the ES, but this is astronomy and once you have gleaned a 1% improvement that clinches any decision. I am therefor probably going to sell the ES.

Having said all this I find I use the 31mm and 26mm Naglers more often than the big Panoptic. Indeed the old 20mm Nagler still sees many more outings.

For those who said for wide ,flat, fields you are using the wrong telescope I can agree that a decent short frac has the right credentials and to that end have added a FLT132 to my burgeoning scope collection (and overloaded mount!)

Now I have my widefield eyepieces sorted I am looking at the other end. I have found myself using my old Ortho's on planets even though I have Naglers down to 7mm, since the crispness of Ortho eyepieces surpasses that of any other eyepiece I have ever owned (had a monocentric a long time ago  but it went walkabouts before I had a decent enough telescope to appreciate it).

After comparing recent acquisitions to my ancient Meade RG ortho's (7mm and 16.8mm) I once again I find myself looking for the best. I don't need higher powers for my long SCT's but for the FLT I need to fill the gap in fl's less than 7mm. I have 1970's volcano top orthos in 6mm and 5mm fl, but they just aren't as crisp as the 7mm RG Meade.  I acquired a 10mm BCO, which to be honest does not give the crispness of the Meade RG's followed by a 12.5mm Fujiyama HD-O  to fill in the 16.8mm to 7mm gap, but am looking for 4mm, 5mm and 6mm to use with the FLT to get the best out of that scope on planets and doubles. I have been put off the BCO's as they appear no better than my 40+ year old volcano tops.  I believe I have sourced a 6mm BGO but also need a 5mm semi-premium ortho at least. I am also trying an old 4mm from the volcano top days to see if that is usable and if so will need the best 4mm Ortho I can source.

I find it very odd that there are no mid price range Ortho's out there today with the plethora of short apo's on the market. To get the best out of your 4-6 inch apo on planets there seems to be nothing better than a decent ortho and today they are as rare as hens teeth new and about the same on the s/h market. The BCO's and Kson examples are available, and are cheap, but no better than the ancient volcano tops despite the improvement in coatings there has been in 40 years. I also note the BCO range now stops at 6mm, which seems an odd marketing move.

I really hope the weather picks up soon so I can get out there observing as getting my astro fix through buying kit is getting expensive!

 

Ian B

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7 hours ago, astronomer2002 said:

Thought I would post an update to this saga.

 

Having tried the 41 Panoptic and ES 40 for some time I conclude I like the Panoptic 5% more than the ES. This sounds pretty arbitrary but I have tried to put a figure on it and there is no area where I can say the ES is better through my eyes and my telescopes. To be honest the ES has a slightly larger field despite having a shorter focal length and the same declared angular field.  If it were a question of finance alone I would opt for the ES, but this is astronomy and once you have gleaned a 1% improvement that clinches any decision. I am therefor probably going to sell the ES.

Having said all this I find I use the 31mm and 26mm Naglers more often than the big Panoptic. Indeed the old 20mm Nagler still sees many more outings.

For those who said for wide ,flat, fields you are using the wrong telescope I can agree that a decent short frac has the right credentials and to that end have added a FLT132 to my burgeoning scope collection (and overloaded mount!)

Now I have my widefield eyepieces sorted I am looking at the other end. I have found myself using my old Ortho's on planets even though I have Naglers down to 7mm, since the crispness of Ortho eyepieces surpasses that of any other eyepiece I have ever owned (had a monocentric a long time ago  but it went walkabouts before I had a decent enough telescope to appreciate it).

After comparing recent acquisitions to my ancient Meade RG ortho's (7mm and 16.8mm) I once again I find myself looking for the best. I don't need higher powers for my long SCT's but for the FLT I need to fill the gap in fl's less than 7mm. I have 1970's volcano top orthos in 6mm and 5mm fl, but they just aren't as crisp as the 7mm RG Meade.  I acquired a 10mm BCO, which to be honest does not give the crispness of the Meade RG's followed by a 12.5mm Fujiyama HD-O  to fill in the 16.8mm to 7mm gap, but am looking for 4mm, 5mm and 6mm to use with the FLT to get the best out of that scope on planets and doubles. I have been put off the BCO's as they appear no better than my 40+ year old volcano tops.  I believe I have sourced a 6mm BGO but also need a 5mm semi-premium ortho at least. I am also trying an old 4mm from the volcano top days to see if that is usable and if so will need the best 4mm Ortho I can source.

I find it very odd that there are no mid price range Ortho's out there today with the plethora of short apo's on the market. To get the best out of your 4-6 inch apo on planets there seems to be nothing better than a decent ortho and today they are as rare as hens teeth new and about the same on the s/h market. The BCO's and Kson examples are available, and are cheap, but no better than the ancient volcano tops despite the improvement in coatings there has been in 40 years. I also note the BCO range now stops at 6mm, which seems an odd marketing move.

I really hope the weather picks up soon so I can get out there observing as getting my astro fix through buying kit is getting expensive!

 

Ian B

I suggest you start a new thread on the very important topic of premium, short focal length eyepieces to focus the discussion.  Until then, I suggest you look into the Takahashi TOE and Vixen HR eyepiece lines.  They are probably the best high power eyepieces currently available new.

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11 minutes ago, Scott42 said:

IMO, Takahashi and Fujiyama are the best orthos out there today.  Between the two of them you should be able to cover all the focal lengths.  Beware the 4mm and 5mm orthos have extremely tight eye relief

The 4mm Tak TOE is supposed to have fairly comfortable 10mm of eye relief as an alternative.

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I’m fortunate to have the 4mm TOE and the Vixen HR 3.4 - both are exceptional optically and in overall build. There have been discussions around this in the forum to which I’ve contributed along with others in some detail. Someone commented along the lines that at last he’d found an eyepiece (think it was the Vixen) that could show what his scope (100mm Tak?) could really do. That summed it up perfectly I thought. My main eyepieces are Tak orthos, the point being that I have those to draw comparisons with - to my eye and in terms of what’s currently available, both the Vixen HR and the Tak TOE are about as good as it gets. And, yes, given their short focal lengths, I find both remarkably comfortable to use. 

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A new planetary comparison review of the 4mm Tak TOE versus the 4mm TMB Supermono was posted on CN yesterday.  The reviewer could see no appreciable difference other than the TOE having a warmer tone.  I'm guessing it uses at least one rare earth element that causes it.  To quote the summary here:

" Conclusion: The only obvious difference between the two is the warmer tone of the TOE. This does not translate into perceived planetary detail. It’s a matter of taste or preference. Every detail that was seen in the TMB was also seen in the TOE and viceversa.
The Tak TOE 4 is very likely the best 4mm planetary eyepiece on the market available today. In the past I have compared the TOE 4 with a DeLite 4, a XW 3.5, a TAK Abbe Ortho and many mid-range orthoscopics and found the TOE to be a step above, specially when it comes to sharpness in lunar observation. An instance in which I was able to glimpse the separation between Rima Dawes and Dawes with the TOE in the TV-102, but not with Delite, XW 3.5 or others comes to mind. TOE 4 is in the same class as discontinued premium glass (Pentax SMC Orthos, TMB Supermonos etc). "

Thus, a very good alternative to run of the mill orthos at 4mm.

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I suppose if we wanted to read CN we'd be logging in there instead of this site.  

I've got the TOE 4mm and it's very nice but it's a 6-element eyepiece.  6 element eyepieces cannot perform like 3 and 4 element eyepieces on contrast, scatter, and clarity.  The pure whiteness of a 3 element eyepiece is exactly what I would expect versus a 6 element eyepiece, along with a subtle improvement in contrast.  You can't pile a bunch more glass into the eyepiece and expect the same clarity.

I keep Tak LE 7.5mm, 5mm, and the TOE 4mm in my case and use them most of the time for high power because of the wider field and increased eye relief over orthos.  But if seeing is good and I"m not sharing the views with clumsy people at outreach events (!) I will break out my AP SPL 4mm, 5mm, and 6mm.   The difference between them and eyepieces with a barlow inside is like the difference between getting fresh bread at a bakery versus bread in a plastic bag at the supermarket.  It's like removing a veil from covering the planet's disk in terms of clarity.

However, the SPL's have better eye relief than abbe orthos.  The tiny eye relief of 4mm and 5mm orthos is nearly intolerable for me and difficult to use on undriven mounts.  FWIW, I think using a quality barlow like the AP Barlow with longer orthos is also superior to eyepieces with a barlow inside.   I suspect it's because of the larger diameter lens in the barlows - the negative lens in the TOE is absolutely tiny.

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Read a test a while ago where they measured light transmision of the latest High end multi element eyepieces and found no difference betwenn those with six or seven and those with just a few elements. They pointed out it’s not the number of ekements that is important but the coatings used. Coatings are so good now that the old belief that the fewer the elements the better no longer applies. It’s the quality of the eyepiece. 

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  • 1 month later...

Just a follow up note:  The 40mm Pentax XW has been reintroduced and will be at dealers at the end of December.  US price $399.95.

Depending on the scope, this is a very viable alternative to the 41mm Panoptic.

My personal preference is the Panoptic, but a lot of people go the other way on that choice.

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On 27/10/2019 at 18:45, johninderby said:

Read a test a while ago where they measured light transmision of the latest High end multi element eyepieces and found no difference betwenn those with six or seven and those with just a few elements. They pointed out it’s not the number of ekements that is important but the coatings used. Coatings are so good now that the old belief that the fewer the elements the better no longer applies. It’s the quality of the eyepiece. 

Agreed. The XWs in my mind perform like 70 deg FOV 20mm eye-relief orthos. The fact that my eye can relax as I view the image means I can tease out more detail than when I need to strain my eyes by glueing my eyeballs to the eyepiece. Note that the number of elements was never the most deciding factor for light scatter and internal reflections, it was the number of groups. Scatter at glass-glass interfaces is far lower than that at glass-air interfaces. There is also an upside to more glass-air interfaces, i.e., more degrees of freedom in the design of the optical surfaces, so better correction of other aberrations over a wider FOV.

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