Cassiopeia Observatory - Review - Celestron Cometron 12x70 Binoculars

Review - Celestron Cometron 12x70 Binoculars
Posted: 26 November 2013
Updated: 21 July 2014, 1 November 2016

Clouds returned on Tuesday, 19 November 2013. Sunset on Wednesday, 20 November, was pretty:

Cloudy skies, with periods of rain (1.68" total over two days), continued until Sunday, 24 November. With clear skies in the forecast for Sunday night, during the morning I went to the observatory and wiped rainwater off the dome. The sky started clearing after sunset, but then began clouding up again.

Monday, 25 November, dawned with a clear sky and frost on the ground (temperature 34°F). The observatory was opened at 1809 MST, 51°F. The sky was clear but there was a slight breeze. At 1816 MST, viewed Venus in the 8" telescope, 83X. The crescent phase was nicely visible.

On my 19 November 2013 report I discussed some initial tests with my new Celestron Cometron 12x70 binoculars (seen at the right), purchased from the OPT booth at the Arizona Science & Astronomy Expo. I noted that the eyepieces would "teeter-totter" on the focus shaft. I sent an inquiry to Celestron on 19 November about it; they responded on 20 November. I sent them a short video showing the rocking motion:

After viewing the video, Celestron responded on 22 November that the movement was normal with their binoculars. (Such movement does not happen on my old Orion 7x50 binoculars.)

During my first observing session with the Celestron binoculars on 18 November 2013, I had noted that they were lightweight enough for good terrestrial viewing while handholding them. However, astronomical viewing was slightly more challenging for steady handheld views due to the 12X magnification. Quoting in part from my earlier report:

"As I used the binoculars more I found I could get a steadier view. Bracing my elbows on the wall of the SkyShed POD also helped. Venus appeared elongated due to its phase. M13 (in Hercules) was definitely a large globular cluster. The Double Cluster looked very nice, as did the Pleiades. M31 (Great Galaxy in Andromeda) looked large even though the sky was not totally dark. I tried for M57 (Ring Nebula) but the sky was not dark enough. I did observe a very faint satellite passing through Cygnus. Although the satellite was faint to the naked eye, it appeared very bright in the binoculars. Having dual 70mm aperture lenses really helps with light gathering. There is some coma around the field-of-view (FOV) edge. The crispest view is at the center. I did some comparisons with my old Orion 7x50 binoculars. The 7x50 binoculars have crisp views across the entire FOV and a handheld steadier but fainter view. The FOV was also wider with the 7x50 (6°) vs the 12x70 (4.6°). The moon was gorgeous in the 12x70. There was a very slight color fringing around the moon but it was not objectionable."

While the handheld views were adequate for quick looks at astronomical objects, tripod mounting the 12x70 binoculars would be required for sustained viewing and to properly determine its optical quality. A photographic tripod adapter is included with the binoculars and I used it this night to attach the Cometron binoculars to a sturdy photographic tripod:

The Celestron tripod adapter is plastic (the one that was included with my old Orion 7x50 binoculars is metal). It securely holds the binoculars, although I did have to tighten its screw a lot to get a tight grip on the 12x50 binoculars to keep it from moving.

I began observing the night sky using the Celestron Cometron 12x70 binoculars at 1835 MST. The sky was dark as astronomical twilight had almost ended. I first viewed Venus; the collimation was way off. There were two Venus images which were widely separated vertically (the binoculars were horizontal, as seen at the right). Fortunately (or unfortunately), there was enough play in the eyepieces holder (allowing the teeter-tottering mentioned early) to move the holder in a vertical direction to correct the collimation. I focused the view to my left eye and then used the diopter adjustment on the right eyepiece to bring its view into focus. It was necessary to rotate the adjustment to the extreme "+" position; my Orion binoculars are in focus for both eyes with its diopter adjustment at "0". This is probably due to the play in the eyepieces holder. Fortunately, I was able to achieve a focus for both eyes. Some users might not be able to achieve a good focus since no further diopter adjustment is available to the "+" side.

With the collimation corrected and both sides of the binoculars focused for my eyes, I began concentrating on image quality. The right optics showed a slight coma on Venus with the planet centered. No coma was visible on the left side with Venus centered. I then viewed M45 (the Pleiades); this was a nice view, showing many more stars than were visible with the naked eye. Again, some slight coma was visible on the right optics, but it was not objectionable. The breezes were causing some movement of the image. A very sturdy tripod will be required if a wind is blowing.

Next viewed was M31 (Andromeda Galaxy). The galaxy was near the zenith, making the viewing straight up with the tripod mounted binoculars difficult. The galaxy extended nearly across the entire field-of-view (FOV). The Double Cluster was lovely in the 12x70 binoculars. I then turned my attention (and the binoculars) to the star Vega to check for coma. The left optics had very little coma visible throughout the entire FOV. The right optics showed a large coma at the left and top edges of the FOV; the rest of the right FOV was OK (Vega being fainter than Venus, which showed some coma when centered). I tried for M57 (Ring Nebula) but had no success in seeing it in the 12x70 binoculars. I was able to view M33 (Triangulum Galaxy) in the 12x70. As with M31, M33 was also high in the sky, making the view via the tripod neckbreaking.

At 1915 MST, I removed the 12x70 binoculars from the tripod and I relaxed on my recliner for some handheld tests. Using the 12x70 while reclining was actually very enjoyable. The Double Cluster and Pleiades were nice sights. Even the view of M33 while handholding the binoculars was good. M31 was impressive, with M32 and M110 galaxies visible. I then did a short tour of the Milky Way near and in Cassiopeia. NGC7789 (open star cluster) appeared as a very tight cluster of stars. I also viewed some open clusters in Auriga. I returned to the Pleiades for some long observing. Handholding the large binoculars was not tiring and the view was steady while I was reclining as I could brace my elbows on my chest. The Pleiades is definitely a showcase object for the Celestron Cometron 12x70 binoculars.

I ended observing using the 12x70 binoculars at 1949 MST. The humidity was just too high (57%) and the eyepieces began fogging up.

Bottom line: the Celestron Cometron 12x70 binoculars can provide some good views, even awesome at times. There are some optical and mechnical issues that can detract from the viewing pleasure, but for the low price some users may find these issues acceptable. If you want inexpensive large aperture binoculars with a higher magnification than your typical 7x50 binoculars, the Celestron Cometron 12x70 may be worth considering. If Celestron can improve the optical and mechnical issues while keeping the price low, the Cometron would be a recommended choice. But not yet.

In November 2013, I posted the above review of the Celestron Cometron 12x70 Binoculars that I had purchased at the Arizona Science and Astronomy Expo. As I noted in the review, I had contacted Celestron Support a few days after the purchase about the eyepieces "teeter-tottering", moving the optics into and out of collimation. At the time, the response was "that's normal". I never really believed that, but decided I could tolerate the problem when it occurred. Over the past few months of use, sometimes the views were excellent and sometimes they were lousy.

At the Oracle State Park "Star Party" on 21 June 2014, I had wanted to use the Cometron 12x70 binoculars on a tripod to show wide angle views of the night sky to Park visitors. However, the movement of the eyepieces was so large and the collimation was so bad that I quickly gave up using the binoculars. The next day I sent a followup message to Celestron, noting the very public problem with their product. I quickly received a followup that stated they would realign or replace the binoculars. A shipping label was provided by Celestron and the binoculars were shipped to them on 27 June. The replacement (covered under the original warranty) was received on 13 July.

An initial daytime test on receipt showed a dramatic improvement in collimation over the one I originally reviewed in November 2013. A quick night time test on 20 July 2014 showed that the collimation was definitely better, as was coma. Stars only showed some coma when very near the edge of the field-of-view. The diopter adjustment was more appropriate since collimation was good. Thank you to Celestron for replacing the binoculars. I can now thoroughly enjoy the views through the Cometron 12x70 binoculars.

The problem of the "teeter-tottering" eyepieces holder on the replacement Cometron binoculars had been worsening for the past few months, but was never so bad that I could not get the binoculars collimated. When they were collimated I was able to really enjoy the views through the 70mm binoculars over the past two years at my dark site observing location. On my observing report of 29 October 2016 I mentioned that I could not get the binoculars collimated on any objects I was viewing. Consequently, I decided to give up on the Celestron binoculars and will replace the Cometron with something better, which won't be from Celestron.