Are Skywatcher binoviewers worth the money?

[gazza63]

Hello, to you all

Are 1.25" binoviewers worth buying?  Are there any advantages( probably the use of two eyes, are one) and disadvantages.

Is there anybody on here that uses them?

Here's the link:

http://www.cameracentreuk.com/skywatcher/skywatcher-125-binoviewer-with-2x-barlow-lens-dual-eyepiece-50989-1460-261-1496.php

[gazza63]

Maybe I should have put this in the Eyepiece- discussions category?

Admin..... please move, if you think it should be?

Thanks

[mitchelln]

The main problem with them is they add a lot of length to the optical path. So you might not be able to achieve focus, especially with a Newtonian. Best check they are compatible with your scope before buying!

[laowho]

The main problem with them is they add a lot of length to the optical path. So you might not be able to achieve focus, especially with a Newtonian. Best check they are compatible with your scope before buying!

Yeah, have a gander at Cloudy Nights BVer forum. Seems there's a lot to take in/consider this way. We BV and swear by it, but we went the simpler route of just using two of everything. As for your 1.25" question, different brands/models have different size prisms which will determine the size of your field stop before vignetting of your low-power-wide-field EP sets in.

[Adrian]

I have the same as those you have listed (mine are AstroEngineering branded) that I got second hand. They work well and are great for planetary, subject to the in-focus caveats.

But for slightly more than the price of those, you could get these:

http://www.firstlightoptics.com/binoviewers/william-optics-binoviewer.html

Which are very well regarded and come with a pair of eyepieces to get you started.

[angusb1]

I have the AstroEngineering branded ones too.  They are excellent and have the selfcentering EP holders.  I would definitely go for this feature over the ones with a locking screw.  Also look at the "supercharged" ones Harry Siebert does - if I hadn't got mine at such a bargain price second hand they are what I would have bought.  http://www.siebertoptics.com/SiebertOptics-Binoviewer%20Upgrade.html I think he sells them already supercharged - worth asking him.  You can use much larger focal length EPs to get wider views than otherwise. His website is hard work to navigate around but he really knows what he's talking about.

[faulksy]

wow what a interesting web page, those super charged binoviewers look great

[acey]

Binoviewers split the light between two eyes so the image is dimmer in each, which is why people don't use them for deep sky, though they're appreciated for lunar/planetary viewing. You also need to double your eyepiece collection.

Focuser travel would be the main thing to consider, though a reflector in which it's easy to alter the distance between primary and secondary (e.g. a flextube) shouldn't have a problem. Some binoviewers solve the travel problem by incorporating a barlow, thus raising the magnification - so don't offer the low-power, wide-field experience of binoculars.

[AlexB67]

I recall watching this interesting video regarding the topic and their merits. quite informative 

http://www.youtube.com/watch?v=r6dCwBStZXw

[Northern Soul man]

Hi Gazza, I use the William Optics Binoviewer with my 11" Celestron and find them very nice to use.  They work perfectly in an SCT scope, but with a Newt, you need to have a lot of travel in your focuser to bring them to focus.  

In this price range (under £200), I think they are all very similar and are a nice introduction into using 2 eyes, a couple of things I have noticed is that, when set up, its a little tricky to look through the finder on the SCT when they're in place - being wider than a single EP, you can't get your eye "into" the finder, its a straight through finder, a RA finder would eliminate this.  The next thing is that they split the available light through them, so for the same mag as a single EP, it gives a darker image, some say that if you lower the powers in the Binoviewer, this will give a brighter (but smaller) image - so you can compensate with longer focal length EP's.

In the 11" SCT, the Moon and planets are fantastic, the brighter Messiers are also fine - but not really any good for faint galaxies/DSO's, but the brighter Planetary Nebulae seem to hold up well in them.

But you have to remember that the aperture your using has a lot to do with the brightness of any image - the larger apertures allow you a much BRIGHTER image, it would be nice if you could take your scope to a star party, or if a friend has a set you could try before you buy, its a pity your not near me - you could have a crack with mine mate, but you really need to try them before you buy them.  Regards    Paul.

[laowho]

The video is interesting, only because I've never heard the "seeing more" phenomenon explained this way. Usually it's done with math...reduce the original aperture as per the light loss from beam-splitting, then re-supply the loss by way of a (standard 1.4x probability) binocular summation gain. It's too bad there isn't better info out there. Most anywhere you look you'll find this 1.4x binocular summation gain as the expression for what you'll get back after the initial light loss--but this is an old and obsoleted probability summation model. They've been doing much better psychophysics research since the 70s on NEURAL binocular summation--the physical processes and dynamics of actual binocular summation. Brightness gains for point source resolution do fall around a 1.4x gain (or even lower) with two eyes as against one, but contrast sensitivity and detection for faint extended objects, especially at low thresholds, enjoys gains of as much as 1.7x over that of one eye. However, given the scant light available from DSOs, perhaps these gains aren't realized after the initial loss of light. And it may be why users choose to BV only bright planets, clusters and planetary nebulae. But there IS one other aspect...thus far the talk has been about differences in degree or equivalence, but there's also a difference in kind...users swear by the sense of "presence" that BVing affords and something for which they're willing to invest, even for a narrower range of targets. So yeah...I'd have to agree with those who suggest you try before you buy.

[Northern Soul man]

Great Point laowho, with a larger aperture, your fine, under 8" aperture your going to struggle due to the "light loss" inherent in the optical path when BViewing, but then, using 2 eyes, I find, a much more relaxed experience - there's nothing better than being relaxed at the EP's - doing exactly the same thing with both eyes as opposed to "squinting" down the EP with one eye and blinking, twitching and scrunching the other eye up when searching for that "steady" seeing WOW moments. 

[laowho]

True that. Another benefit I failed to mention but which the video maybe covers. We don't use BVers but we do binoview with a double scope/big bino. We only ever had binoculars to begin astronomy with, but we wanted to see more and the prospect of giving up one eye seemed counterintuitive. Pretty sure that one-eyed viewing will some day be a thing of the past.