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Battle of the 9s (again)

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#1 Peter Besenbruch

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Posted 12 January 2019 - 01:36 AM

This was the first night of the year where seeing was somewhat stable, so I hauled the 180mm Mak out into the yard for some lunar viewing. All views were with a Takahashi prism. At first the seeing held for the 16mm (169), then I tried my BST 58° 9mm (300), but that looked like too much power. After 20 minutes, the seeing appeared to stabilize, and that's when things got fun.

 

The BCO 10mm (270) always puts up lovely views if the seeing is anything near stable. Then I tried the Tak ortho 9mm, and it looked like it held.

 

I looked at several locations: The trio of Catharina, Cyrillus, and Theophilus began to offer a wealth of detail in the rough terrain. The seeing increasingly allowed this. The 1950s, 8mm (338) Brandon, while sharp, lacked the contrast of the Takahashi. I also explored the area from Aristotle (only the rim caught the sun) to the Lacus Mortis and the Burg complex of craters and rills, out past Hercules and Atlas. I tried the BST 58° 9mm again, and compared it with my BST Flat Field 27mm and 3x Barlow. Both were good. The 58° was better, with more neutral color. At this point I tried a 7mm BST 58° and found the atmosphere holding still. Catharina, Cyrillus, and Theophilus filled the field. The rubble fields were impressive. Again, contrast was superior to the Brandon 8mm.

 

Conclusion: Time and again, I cannot find anything that outperforms the BST 58° eyepiece series from 9mm on down. The Brandon gets retired (again), and a new 58° series 8mm is on the way. I needed something to fill the gaping hole between 9 and 7mm.


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#2 precaud

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Posted 12 January 2019 - 09:30 AM

I always find your compares informative and entertaining. I too find the short-FL BST 58's to be underappreciated and very comfortable to use.

 

But I thought you had an 8mm dual ED, yes? I'm curious why you've abandoned it.


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#3 Peter Besenbruch

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Posted 12 January 2019 - 01:05 PM

But I thought you had an 8mm dual ED, yes? I'm curious why you've abandoned it.

I never had one. My sequence went from 9 to 7mm. That was fine with shorter f-ratios, but at f15 that is right in the high power tweak range.


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#4 precaud

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Posted 12 January 2019 - 01:39 PM

So, once you get the 8mm, you'll be equipped to the nines...  ;)


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#5 JimV

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Posted 12 January 2019 - 06:01 PM

How do BST 58 UWAs compare to TV Delite, and UO orthos?



#6 Peter Besenbruch

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Posted 12 January 2019 - 10:22 PM

How do BST 58 UWAs compare to TV Delite, and UO orthos?

I don't have a Delite to compare it with. The U.O. orthos have been around for decades in various formats. They ranged from very nice to uneven at the end. I like the Takahashis a bit better, and find the BCOs a little more consistent. If you flock the interior tubing of the BST 58°, you get little or no difference in contrast, a wider field, greater eye relief, and better adjustments.



#7 Jon Isaacs

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Posted 13 January 2019 - 07:32 AM

How do BST 58 UWAs compare to TV Delite, and UO orthos?

I believe the BSTs trace their linage to the TMB Planetary series.  Many/most seem to find the TMB somewhat better.  I have a 9mm TMB planetary I purchased from Mike Hosea, many of you may remember Mike as a very knowledgeable eyepiece guy.  Mike had disassembled it and done a lot of blackening.  

 

I consider it a decent eyepiece but in a faster scope, it definitely shows astigmatism, Peter is using his at F/15 so that is not going to be an issue but my 9mm TMB definitely does not have the contrast and off-axis sharpness of my 9mm T6 Nagler in my scopes., 

 

Jon


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#8 SeattleScott

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Posted 13 January 2019 - 04:24 PM

On axis my 5lvw bests my 5 TMB at F9. The TMB does admirably well for a $67 eyepiece but is a little outclassed by a $250 one. Even on axis, at F9. Maybe blackening the inside would help.

Scott
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#9 precaud

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Posted 13 January 2019 - 06:51 PM

A couple years ago I compared 5mm DeLite, BST 58, and Paradigm in my dobs and ED127 frac. I spent three evenings doing it, because 5mm is an important planetary focal length with these scopes.

 

I liked the DeLite but it had worse scatter of the three. Not what one would expect for $250.

The Paradigm was just as sharp as the DeLite, had lower scatter and better contrast.

The BST 58 was comfortable to use, but had poor focus snap, middling scatter and contrast, and not as sharp as the other two. I found myself constantly fiddling with the focuser trying to optimize it.

 

I kept the Paradigm.

 

I have three other of the BST 58's. Two of them are better than the 5mm was. So maybe the 5 was a lemon. My 4mm is much like the 5mm was. But the 6 and 7 are very good.

 

Surprised that the quality is inconsistent through the line? I'm not. No different than any other line of eyepieces.



#10 Peter Besenbruch

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Posted 14 January 2019 - 01:10 AM

I consider it a decent eyepiece but in a faster scope, it definitely shows astigmatism, Peter is using his at F/15 so that is not going to be an issue but my 9mm TMB definitely does not have the contrast and off-axis sharpness of my 9mm T6 Nagler in my scopes.,

I also use it at f7.5, but not at f4.



#11 Jon Isaacs

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Posted 15 January 2019 - 12:35 AM

I also use it at f7.5, but not at f4.

I use the TMB Planetary's at F/7, they're reasonable eyepieces but the T-6s are better in terms of on and off-axis sharpness, scatter and contrast. 

 

No big surprise considering one costs $60, one coat $325 or so.

 

JOn



#12 Miranda2525

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Posted 15 January 2019 - 02:03 AM

How do BST 58 UWAs compare to TV Delite, and UO orthos?

Really? 



#13 precaud

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Posted 15 January 2019 - 08:33 AM

Really? 

 

Why not? You don't know until you try it. I did. And sold the Delite. (And the BST...)



#14 Miranda2525

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Posted 15 January 2019 - 06:47 PM

Why not? You don't know until you try it. I did. And sold the Delite. (And the BST...)

Well, Yea, I would expect the UO Ortho or the Delite to be a whole lot better than the BST, lol.



#15 precaud

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Posted 15 January 2019 - 07:01 PM

Well, Yea, I would expect the UO Ortho or the Delite to be a whole lot better than the BST, lol.

 

It wasn't a "whole lot better". Sharper, yes. But worse scatter. The Delite got sold too. It was bettered handily by a Paradigm.



#16 Peter Besenbruch

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Posted 17 January 2019 - 02:14 PM

It wasn't a "whole lot better". Sharper, yes. But worse scatter. The Delite got sold too. It was bettered handily by a Paradigm.

U.O orthos have been available for ages, and featured fully coated, multi-coated, and fully multi-coated models.The ones I'm familiar with are the fully coated ones, and a real turkey of a fully multi-coated 7mm.

 

A couple of additional comments: My experience of the BST 58° series is that they are superior to the original TMB Planetary series for sharpness, but worse in light control. It's easy to handle the light control issues, though.

 

That said, the 8mm I just received lacks the internal shininess. The manufacturer appears to have added very fine grooves to the main tube. I haven't had a chance to check it out yet.



#17 CollinofAlabama

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Posted 17 January 2019 - 05:09 PM

Peter, please check back and let us know how the 8 works with the 9's



#18 Peter Besenbruch

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Posted 16 March 2019 - 04:03 PM

I finally got a stable enough evening to try the 8mm on the moon. My suspicion that Barsta improved the interior was born out. There were no reflections of any kind. By comparison, the 9mm of the series, even with a flocked tube, showed in illuminated circle 3/4 of the way to the edge of the eye lens. The illumination does not affect the view of the moon, as it lies well outside the exit pupil. The 8mm simply shows the exit pupil. I suspect there is something at the Barlow end causes the ring of light in the 9mm, and to a lesser extent in the 7mm and 6mm. I hope the redesigned 8mm isn't the only one in the series that got the makeover.

 

I also tried another piece of hardware on my scope (a 180mm Maksutov), a GSO two speed focuser. Finally, a working fix to the not-so-hot moving mirror focus. For those wondering about whether to buy the single, or dual speed GSO for focusing at f15, the single is plenty.

 

As I mentioned above, the air was relatively stable. The terminator lay right across Laplace's Promontory. This put Plato in a good viewing position, with the craterlets nicely resolved. Also resolved were the many craterlets in the Alpine Valley, along with hints of the rille.


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