Binoviewer edge performance?

Does anybody have experience using a binoviewer using the Nagler 13T6 and 9T6 eyepieces? I was wondering if they maintain there edge performance in a binoviewer? I am currently trying out a DeepSky Bino. I don't have the 1.2x corrector yet so I am using a Powermate 2.5x to get to focus. I am experiencing some loss in edge performance with this setup. Is this normal in a Bino? The reviews on Bino's that I've read only discuss image brightness, vignetting/no vignetting, and planetary performance-no mention of edge performance.

Thanks,

David

Hi Dave. The 2.5X Powermate and a 13mm or 9mm eyepiece may be creating mega amplification (4X plus). The Binoviewer should not contribute to any downfall in edge performance. I tested our Deepsky Binoviewer in a 20 inch F5 with the 1.2X OCS and found that the performance of 24mm plossls were improved on the edge over a single non-bino view with said eyepieces. I used 19mm panoptics to test for edge performance with this same setup. I let Epsilon Lyra drift from center to edge and then out of the field. The components remained beautifully divided throughout with no aberrations created.

I would recommend that until you recieve the OCS, you try a standard barlow if you have one and see if matters improve. It would be interesting if you could estimate the true amplification factor that the powermate is creating with these combinations. I have a suspicion that the 9mm may be acting like a 2mm and the 13mm like a 3mm. Do you see this field edge deterioration in other longer FL eyepieces? I have heard from someone using a 16mm Nagler type 5 plus the 1.2X OCS and the performance is said to be wonderful. Again, the 19mm panoptic field edge is close to immaculate. Seems like the extraordinary high power is the wildcard here.
Russ/ Denkmeier Optical

I have both those eyepieces and find no deterioration in edge performance when used in the AP/Baader/Zeiss binoviewer.

Not sure about the design specifics of your binoviewer, but it's possible that the corrector is needed. In the AP the 1.25x corrector is designed to eliminate slight chromatic aberration introduced by the prisms. In a slow scope, I see little difference with or without the corrector, but in fast scopes it makes a more noticeable difference.

Gus