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7mm eyepiece, looking for people who own these

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33 replies to this topic

#26 Greg77

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Posted 14 August 2020 - 02:52 AM

7mm XW...great eyepiece...
 
https://www.astronom...e-eyepiece.html

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#27 25585

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Posted 14 August 2020 - 05:40 AM

Pentax XW 7mm & Baader Morpheus 6.5mm TFOV, virtually the same.

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#28 Murff

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Posted 14 August 2020 - 12:07 PM

For those of you who like the Pentax, the description says it does not have blackened lens edges.  Does that make a noticeable difference to you?

I am leaning towards the Pentax, and that is my only remaining question.


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#29 j.gardavsky

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Posted 14 August 2020 - 12:41 PM

For those of you who like the Pentax, the description says it does not have blackened lens edges.  Does that make a noticeable difference to you?

I am leaning towards the Pentax, and that is my only remaining question.

Some manufacturers (Docter, Leica, Nikon, Pentax, Swarovski, Zeiss, ...) don't paint the lens rims to avoid chemicals in the lens cell.

They put anodized baffles inside,

and the concept of mounting the lenses with the light rays stopping rings makes the lens rims blackening unnecessary.

 

Best,

JG


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#30 jakecru

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Posted 14 August 2020 - 02:19 PM

Personally, i'd look at a 7 XW or 6.5 Morpheus. 


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#31 Murff

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Posted 14 August 2020 - 02:31 PM

Some manufacturers (Docter, Leica, Nikon, Pentax, Swarovski, Zeiss, ...) don't paint the lens rims to avoid chemicals in the lens cell.

They put anodized baffles inside,

and the concept of mounting the lenses with the light rays stopping rings makes the lens rims blackening unnecessary.

 

Best,

JG

Thank you


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#32 BillP

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Posted 14 August 2020 - 02:36 PM

For those of you who like the Pentax, the description says it does not have blackened lens edges.  Does that make a noticeable difference to you?

I am leaning towards the Pentax, and that is my only remaining question.

True that some sites do not mention blackened lens edges, Astronomics site says they are.  Their features:

https://www.astronom.../pentax/xw.html

  • 20mm Eye Relief
  • 70 deg AFOV
  • Lanthanum ED glass
  • Adjustable eye guards
  • Rubberized external housing
  • Removable top guard exposing accessory threads (43mm 0.75 pitch) for top of eyepiece accessories
  • Computer optimized internal light baffling
  • Air-glass surfaces multicoated & cemented surfaces partial coatings instead of the typical no coatings for a transmission of 96% at 550nm
  • JIS Class 4 weatherproof construction (no issue if rained on and also keeps dust out from internals)

Edited by BillP, 14 August 2020 - 02:42 PM.


#33 j.gardavsky

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Posted 14 August 2020 - 03:34 PM

 

True that some sites do not mention blackened lens edges, Astronomics site says they are.  Their features:

https://www.astronom.../pentax/xw.html

  • 20mm Eye Relief
  • 70 deg AFOV
  • Lanthanum ED glass
  • Adjustable eye guards
  • Rubberized external housing
  • Removable top guard exposing accessory threads (43mm 0.75 pitch) for top of eyepiece accessories
  • Computer optimized internal light baffling
  • Air-glass surfaces multicoated & cemented surfaces partial coatings instead of the typical no coatings for a transmission of 96% at 550nm
  • JIS Class 4 weatherproof construction (no issue if rained on and also keeps dust out from internals)

 

Just a fast check on the Pentax XW 7, which has happened to be within the reach of my right hand:

The only lens rim visible through the eye lens is the doublet, and it is not blackened but very bright scattering the beam of the laser pointer.

 

In a smart optics design, the light rays will be stopped by the baffles and oversized mounting rings from becoming refracted into the lens rims within the light rays cone of the designed numeric aperture.

In plain language, the light rays passing the focus plane of the telescope, won't hit the lens rims, so far the eyepiece is mounted in the telescope.

 

Best,

JG

 

PS: Lanthanum and blackened lens rims are the mantras of marketing, ha, ha

 

 

 

 

 

 



#34 Jon Isaacs

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Posted 14 August 2020 - 05:24 PM

I have a 7 mm Type 6 Nagler. I use it in scopes ranging from F/4.7 to F/7.5. it's my best double-star/DSO/planetary eyepiece at this focal length.  It's sharp-sharp across the field in a fast Newtonian with a Paracorr or a Refractor with a flat field.

 

At one time I used it a great deal on doubles, I'd double Barlow it in my 10 inch to get 820x but once I got the 3.5 mm Nagler, it use the 5 mm and 3.5mm with a 2X Barlow if needed.

 

It does take good seeing for such magnifications to be worthwhile.

 

Jon




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