Telescope Reviews: BT 125 observing report

I was going to post this observing report in the eyepieces forum, but I think it really belongs here since we have quite a few owners of giant binos these days.
Last night I tried a pair of 16mm Nagler T5’s in my Vixen BT 125. I read many reports about these being great as a binoviewer e.p., so I bought a pair during Televue's recent sale

Starting around 8pm, transparency was excellent, with seeing fair to good. NELM was around 5.5.
The 16mm T5’s in the 125’s give 48x magnification, a 2.6mm exit pupil and a 1.7 degree true field, which I find more than adequate to find deep space objects using a red dot finder.
Eye relief is short at 10mm, but I found it to be okay since I don’t use glasses.

I like to use the Orion Nebula along with the four stars of the trapezium to test new eyepieces when it is visible.
The full sweep of the nebula was apparent, with both arms nearly making the connection at the bottom.
The depth and extent of nebulosity were both excellent at this magnification and field size. Color appeared a faint green/gray.
A 3D effect was apparent when using both eyes. Switching back and forth to a single eye reduced the visible portion of the nebula dramatically.
In the BT 125’s, the 16 T5’s have good light transmission and excellent contrast.

Next up was the Trapezium.
I use a pair of custom machined 100mm aperture masks to sharpen the image quality just enough to see fine detail at high powers.
The Trapezium was very sharp with large separation between A, B, C, and D.
“E” was clearly apparent when seeing would settle down, but remained an indistinct blur most of time.

Using OIII filters on the 16T5’s, I took a peek at the Horsehead Nebula while in the region.
For a moment I thought I caught a glimpse of it, but it could have been my imagination as the Horsehead has a way of playing games with smaller apertures.
I picked it off once in the 125’s last year using a pair of Series 5000 Meade 26mm Plossl’s from a mag 6.5+ location, but it pops in and out of view as you switch from direct to averted vision and can wear your eyes out pretty fast.

Mars was blazing overhead and had a nice light orange color. Being near opposition, the disk was large enough to see some dark surface features and a faint polar cap.

The prize of the morning was Saturn. Around 1:30am, Saturn was high enough to see. I was actually looking over my house so seeing was not at its best, but the image was still beautiful.
The rings were cleanly separated from the disk, with a hint of ring shadow seen on the planet itself. One band, whitish in color could be seen just above the ring.
The Cassini Division would appear momentarily when seeing improved, but the rings have become so close to edge on that it is almost impossible to see at this power. Three moons were visible, with Titan clearly the largest.

What really impressed me was the overall sharpness of the image quality. Stars are pinpoint to the edge of the field.
I didn't expect the 82 degree AFOV to be as comfortable in a binocular view as these are.

The 16mm T5’s are keepers for sure and are a good compliment to my 24 Panoptics.

Happy New Year and clear skies to everyone here at CN.

Mike

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AP 160 Starfire/AP 1200GTO
Stellarvue SV809D
Vixen BT 125 HFT-MA
Oberwerk BT 100/45
Tak 22x60 Astronomer
Nikon 10x70 FMT-SX
Leica 8-12x42 Duovid
WO 66mm SD