Review - Tele Vue 2" 4X Powermate
Posted: 24 July 2018
2" 4X Powermate
While doing some planet astrophotography tests with my Nikon D850 DSLR I came to realize that the images I was getting from a 1.25" 9mm eyepiece (271X eyepiece projection) were not as good as I wanted. In 2013 I purchased a Tele Vue 2" 2X Powermate and have liked imaging with it at prime focus. I also have a Meade 1.25" 3X TeleXtender, but I decided I wanted even more image scale for planet imaging.
Based on my visual and astrophotography experiences with the 2X Powermate I purchased a 2" 4X Powermate from B&H Photo Video in early July 2018. (And as is frequently the case when you get a new telescope or accessory, the sky was cloudy for several nights after it was received.)
As seen in the photo on the right, the Powermate comes in a box and includes some info on Tele Vue Powermates and Eyepieces. Both the 2" 2X and 2" 4X Powermates include a 1.25" eyepiece adapter.
Here are my 2" 2X and 4X Powermates side-by-side:
This is a Meade 2" 24mm UWA eyepiece + 4X Powermate on the Meade 2" diagonal:
I tested views of a crescent Moon through the 4X Powermate on my 12" f/8 LX600 telescope (using the 2" diagonal) with the following eyepieces:
|2" 50mm||195X||Good, very long eye relief|
|1.25" 40mm||244X||Good, long eye relief|
|2" 30mm||325X||Good, long eye relief|
|2" 24mm UWA||406X||Good|
|1.25" 9.7mm||1005X||Good, dim|
|2" 9mm 100°||1084X||Surprisingly good, dim|
|1.25" 5.5mm||1773X||Fair, very dim|
|2" 8-24mm Zoom||1219X-406X||Good entire range, dim at 8mm|
|Binoviewers 1.25" 20mm||488X||Good|
Note that the theoretical maximum magnification for a 12" telescope ranges from 600X to 720X. The views were all good and bright until the maximum magnification was significantly exceeded, when the image became dim. I also viewed Venus and Saturn with the 24mm UWA + 4X Powermate (406X); the views were nice and crisp when seeing allowed. Once the theoretical maximum magnification is exceeded, the views would be too dim on planets to be useful. Views of the Moon at magnifications near 1000X (with the 12" telescope) will be nice.
Planet Astrophotography Tests
My main reason for purchasing the 4X Powermate was for planet astrophotography. Here is my Nikon D850 at prime focus + 4X Powermate:
With my 12" (305mm) f/8 focal length 2438mm telescope, using the 4X Powermate yields f/32 and focal length 9752mm.
Here are comparison photos (uncropped) of the Moon taken with the D850 DSLR under less than ideal seeing conditions:
Prime Focus (f/8, FL 2438mm)
Prime Focus + 2X Powermate (f/16, FL 4876mm)
Prime Focus + 4X Powermate (f/32, FL 9752mm)
Prime Focus + 4X Powermate (f/32, FL 9752mm)
The 4X Powermate will be ideal for lunar imaging.
iPhone 8 Plus afocal 406X image of Venus (NightCap Camera, handheld):
Single image photos of Saturn (D850 DSLR full-frame), prime focus + 4X Powermate:
1/30sec, ISO 4000
Saturn moons, 1 second, ISO 6400
The 4X Powermate will be useful for imaging the moons of Jupiter and Saturn to show their changing positions.
Some planet astrophotography (poor seeing); DX, 1080p, 60fps videos stacked using Lynkeos; prime focus + 4X Powermate:
Venus (1/400sec, ISO 400, 43 frames)
Jupiter (1/100sec, ISO 1600, 362 frames)
Saturn (1/60sec, ISO 4000, 398 frames)
Once seeing improves I hope to get better planet images. But the larger image scale is nice.
The Tele Vue 2" 4X Powermate is a nice addition to my telescope accessories. For convenience, using it with my most frequently used 2" eyepieces (24mm UWA and 9mm 100°) will provide good high magnification views of bright objects. For iPhone afocal imaging, it increases the usable magnifications available. When imaging with the DSLR at prime focus + 4X Powermate, image scale is twice that of the 2X Powermate, making for potentially better images (when seeing allows). I will be doing more planet imaging, including Mars, and will report the results on my Cassiopeia Observatory reports.
As is expected with a Tele Vue product, the quality of the 2" 4X Powermate is excellent, both in material and optics. More information on the 1.25" and 2" Powermates is available on the Tele Vue web site.
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