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Old 01-02-2014, 08:07 PM
skysurfer's Avatar
skysurfer
Dark sky rules !

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Eyepiece with Powermate better than another EP alone ?

I recently got a 2nd hand TMB Planetary 3.2mm just for its lightweight for using in the Televue Genesis.
Due to cloudy skies I did a test run in the garden using a test sheet consisting of a photo frame with a USAF-1951 sheet in it (with black and white bars of different sizes) and 20 and 50 euro banknotes for contrast test.
I compared the TMB 3.2mm (156x) and the simple 20 years old Vixen LV 6mm with the TV Powermate 2.5x (210x) both with the Genesis from 10m distance from the target, using the Everbrite 2" diagonal provided with the Genesis.

What was the result ? Surprising !

The LV6+Powermate performed better ! More contrast in the small lines on the banknotes and the black bars on the USAF 1951 remained black. Using the TMB I could not get rid of the blue tinge in the black bars.

Strange, a *higher* power yield *more* contrast and better image quality ???
Can somebody explain why ?
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  #2  
Old 02-02-2014, 11:49 AM
bytor666
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Sure, I will explain:

The 6mm LV has better glass in it. Many have reported that the TMB planetaries are a bit "mushy" in views. Plus you are using a premium TV Powermate with the Vixen LV.


I asked a buddy of mine ages ago about getting a TMB planetary. He told me to pass on any of them altogether.

Cheers,
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  #3  
Old 02-02-2014, 01:36 PM
brian nordstrom (As avatar)
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I had a full set of the Vixen LV's and they are ( were ) very good but I found that the Circle 'T' Orthoscopics I owned at the same time to be sharper on the moon and planets , both set were from the 3mm-24mm range .
Of course the 20mm eye relief was much easier than that of the Ortho's .

The LV's seemed to impart a slight dimming in comparisim , but it was invisible without direct side by side comparisim between these 2 sets .

I have a 2x , 2 inch Powermate and use it a lot in my Tak sky90 for the same reason Skysurfer uses his in his Genesis , with only 500mm fl to play with its hard to acheave higher powers with eyepieces alone so I use my Powermate often when wanting 200x plus in my Takahashi when using my smaller TV Radians , these I kept over both the LV's and circle 'T's , I find the Radian's have all the good quality's of both the LV's and Ortho's in one eyepiece , hence these are what I now own a full set 3mm-18mm .

The Powermate does not add anything to the view in my opinion except make it easier to use say my 3mm Radian and PM as a 6mm alone , nice bit of gear , but expensive .

This is my own opinion , oh yes I find the Radian's perfect in my 127mm f8 Istar achromat as well , these just work in that scope as well for some reason . Refractor's perhaps ?

Hope this helps ,
Brian.
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  #4  
Old 02-02-2014, 01:39 PM
bytor666
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Quote:
The LV's seemed to impart a slight dimming in comparison , but it was invisible without direct side by side comparison between these 2 sets.
Brian,

You are right about this. I also noticed some dimming of views when I once tried a 9mm LV myself.

Cheers,
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  #5  
Old 02-02-2014, 01:47 PM
brian nordstrom (As avatar)
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Thanks Bytor666 , it might not be so important in larger scope say 150mm + but with only 90mm to play with I need all the light I can get .
Not to take anything away from the LV's tho , they are a very nice eyepiece and its a shame these and the TV Radians ,,, and Oh yes the circle'T' ortho's are not made any more .
What a depressing thought for a sunday morning .

Brian
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  #6  
Old 02-02-2014, 01:51 PM
bytor666
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So true.
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