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First light with 16mm Nagler type 5's (1)

Started by tomhole, 07/06/2003 02:52AM
Posted 07/06/2003 02:52AM Opening Post
A friend of mine let me borrow his 16mm Nagler type 5's to try in my binoviewer. I was using them in the TV binos, 2x corrector, XT10. Seeing was a 4, transparency good. I was working 150x (2x tv corrector) and 375x (2x corrector into the 2x barlow and 2x powermate).

I was a little worried that I could not take in the entire 82 deg AFOV because of my daytime testing, but once I was dark adapted, it was awesome. Eye placement to take in the whole FOV was comfortable (er is listed as 10mm) and the sharpness and contrast were typical Nagler.

First target was the moon. It was still pretty light out and there was a thin overcast, but I was impressed with the fact that I could see the entire moon at 150x.

Next targets were some old friends from this past winter, Andromeda and its buddy M110. Wow. At 150x, Andromeda filled about 3/4 of the .55 deg TFOV. Went over to M110 and it was wonderful as well. I decided to do a quick light loss check. Nothing noticeable on M31, but M110 was noticeably dimmer. Comparison was pretty easy as the TV corrector is 2x so I just put the Nagler in the 2x barlow for comparison. This was alos a more fair comparison than the later ones with an extra set of glass in front of the corrector. I measured the 2x barlow at 2.2x, so I was probably getting a little higher mag on the cyclops mode(165x). But even at a slightly higher mag, the cyclops view was definitely brighter.

Now I needed to find a globular cluster. I usually only look at Mars early in the morning so I had to search around for one. M15 was nearby and visible through the trees. The widefield of the Nagler was more than ample to hold the entire cluster at 375x. I compared to cyclops at the same power and there was a noticeable light loss. Also, the cyclops image was sharper than the bino image. Not by a lot, but it was noticeable. I felt the comfort of binoviewing outweighed the loss of light and sharpness, but if you are trying to eek out every bit of performance on DSO's, the cyclops is better.

Mars was moving up so I could see it from the driveway, so I thought I'd end the morning there. As expected, the views were very good. The dust storm was showing up and it's bigger than it was yesterday. It looked almost as big as the south polar cap. I used the #21 filter on one eyepiece with very good results. I compared it to cyclops at the same power (375x) and found that the image was just a bit sharper in the cyclops view, but I could see more with the binos.

I compared using the 2x barlow and 2.5x powermate in front of the 2x corrector. Both give me 5x magnification (375x with the 16mm Naglers). I preferred the barlow over the powermate. I felt the powermate, in this role, gave a bit softer image on M15 and Mars.

Clear skies,