Recommendations for Ultra Wide Binoculars

[Stonius (Markus)]

Hey all,


I'm looking for something with a TFOV in the area of 10 degrees while maintaining the biggest light grasp possible. These are to be constellation binos.



I've come to think maybe 7x35 might be in the right area, and the 5mm exit pupil appeals to me (I don't think they make 10x50s with ultra-wide fields of view?).



My understanding is they don't make them like they used to (why *is that?) so I'm not afraid to go vintage.


But, I've heard the Nikon ACTION EX 7x35 is pretty good, and I like the idea that it benefits from modern coatings. Is there anything else I should be considering?


Hopefully something without too much chromatic aberration?


Many Thanks for any advice.


Markus

[sheeny (Al)]

G'Day Markus.


What you're looking for I'd hardly call ultra wide especially when it comes to binoculars.


For light grasp you need the biggest objective you can afford. A full dark adapted eye is 7mm diameter pupil (when young!), so 49mm2.


35mm binos will capture 25x more light than your naked eye.
50mm binos will capture 51x more light than your naked eye.
80mm binos will capture 130x more light than your naked eye.
100mm binos will capture 204x more light than your naked eye.



You also want the largest usable exit pupil you can get. there's no point having an exit pupil bigger than the pupil of your dark adjusted eye, so choose binos with an exit pupil as close to 7mm as possible - better under than over.


Obviously you want the biggest field of view you can get once these 2 criteria are met.


My Pentax 7x50s have an exit pupil of 7mm and a field of view of 7.1°. They are excellent to hand hold.


My AOE 20x80s have an exit pupil of 4mm and a FOV of 3.4°. While they can be handheld, they are much better on a tripod. 11 x 80's would be better for what you want if you want to go this big. They would have an exit pupil of 7.3mm.


Al.

[sheeny (Al)]

Sorry, I re-read to see you want to view constellations, not deep sky. In that case aperture is less important and FOV is most important so, you'll probably find the best FOV in small binos like the 35mm you mentioned. Perhaps even in 20mm objectives.


Al.

[sheeny (Al)]

Originally Posted by Stonius

Hey all,
I've come to think maybe 7x35 might be in the right area, and the 5mm exit pupil appeals to me (I don't think they make 10x50s with ultra-wide fields of view?).

As a rough guide the FOV in degrees will be roughly the same as the exit pupil in mm, so 10 x 50s would have about 5° FOV. It will be slightly different due to optics and any obstructions in the light path inside the binos, etc usually slightly less.


Al.

[Tinderboxsky (Steve)]

I am a big fan of my Vixen S6.5X32WP astronomy binoculars.

They were designed from the ground up for astronomy use. They have one ED element in the objective and have dedicated astronomical telescope coatings, not the usual coatings designed for daytime terrestrial use. They have a 9 degree true field of view. The FOV is aberration free right to the edge of the field and no chromatic aberrations that I can pick up. They have very accurate individual eyepiece focusing.

They are ideal for broader scanning of constellations etc. They are easily held steady for long periods.

They have 20mm eye relief and are the only binoculars that I have found that allow me to wear glasses comfortably with the eyepiece caps retracted.

The views are noticeably brighter than my Nikon Action 7X50 binoculars.

I always have then on hand when visual observing, and even EAA observing, to give me context to the observations

[astro744]

Nothing wider than Orion 2x54 binoculars designed for constellation viewing. See https://www.bintel.com.au/product/or...le-binoculars/

36 deg. true field of view!

There is also SvBony 2.1x42 giving 26 deg. true field of view. I have both and prefer the Orion for the wider field.

The optical design differs from 'standard' binoculars and there is no need to be concerned about exit pupil restrictions. The binoculars simply make things brighter at slightly greater magnification. It is almost like looking at a Tirion Sky Atlas 2000.0. Pleiades show many more than 7 stars! Read the blurb on Bintel web site under the 'add to cart' button.

There was a discussion about these on this forum recently.

[Stonius (Markus)]

Originally Posted by sheeny

What you're looking for I'd hardly call ultra wide especially when it comes to binoculars.


For light grasp you need the biggest objective you can afford. A full dark adapted eye is 7mm diameter pupil (when young!), so 49mm2.

[...]


You also want the largest usable exit pupil you can get. there's no point having an exit pupil bigger than the pupil of your dark adjusted eye, so choose binos with an exit pupil as close to 7mm as possible - better under than over..

Thanks for your reply



Hey, I'm happy to take the biggest light grasp (objectives) I can get! - it just seemed from my reading that they dont actually make them that big - maybe I'm wrong! I currently have some Saxon 20x80's, but i find their TFOV too narrow. I had a Pentax XW40 that delivered a, 8mm exit pupil with my dob and the results were not good and so i have avoided larger than 7mm exit pupils ever since. I figured that once the exit pupil touched the edges of my pupil something happens (maybe on account of getting my eyes lasered years ago?) and I've avoided it ever since - hence looking more at 5mm. But does that limit my choices?


The light grasp is important because it would be good to be able to perhaps see a faint smudge of a target where it is supposed to be before i train the scope on it. But yes, that is secondary to having a wide field.

[Stonius (Markus)]

Originally Posted by Tinderboxsky

I am a big fan of my Vixen S6.5X32WP astronomy binoculars.
[...]
The views are noticeably brighter than my Nikon Action 7X50 binoculars.

Oh, that's good to know! Thanks!

[Stonius (Markus)]

Originally Posted by astro744

Nothing wider than Orion 2x54 binoculars designed for constellation viewing. See https://www.bintel.com.au/product/or...le-binoculars/

36 deg. true field of view!

Yes, I've seen these, and they're pretty cheap, but with a 24mm exit pupil it just seems you're basically looking through 2x14 binoculars since you can only ever use 7mm of that massive exit pupil. So I'm thinking I'd rather compromise on the field of view in that instance for some more light grasp.

[astro744]

Originally Posted by Stonius

Yes, I've seen these, and they're pretty cheap, but with a 24mm exit pupil it just seems you're basically looking through 2x14 binoculars since you can only ever use 7mm of that massive exit pupil. So I'm thinking I'd rather compromise on the field of view in that instance for some more light grasp.

NO. Exit pupil limits do not apply to this optical design. Read the Bintel info. Images are bright and the field is wide.

[Stonius (Markus)]

Originally Posted by astro744

NO. Exit pupil limits do not apply to this optical design. Read the Bintel info. Images are bright and the field is wide.

Okay, I did, but I'm still not quite sure how they circumvent the laws of physics. Light that falls outside the pupil can't really end up on the retina, can it?


I can imagine it's cool of they presumably have a really wide AFoV as well - real starwalk kind of stuff.



However, they say it adds a further 1.2 magnitudes to the naked eye, whereas a 50mm pair of binos would add 4.4 magnitudes which I think might be more useful than the incredibly large field of view.


Look, I'd love to try them - 36 degrees TFoV sounds amazing! Heck, maybe I'll even get some one day, but I'm looking for something to help me see enough of a constellation to star-hop to targets.


Cheers


Markus

[OzEclipse (Joe Cali)]

A friend of mine has a pair of 10x42 Bushnell Forge binos. Stunning crisp clear images on astro and terrestrial. ~$700.
https://www.tradeinn.com/trekkinn/en...E&gclsrc=aw.ds

Only 6.5 degree field. You will find it hard to find a 10 degree field with high quality.

I am thinking about getting a pair myself even though I have a pair of Orion 9x63 and a quite good old pair of Carl Hoffer German 7x35's. The Bushnell Forges leave them all for dead.

They also make 56mm version for about $1500. Hmmm?

[dannat (Daniel)]

nikon wx 7x50, 10deg and excel ep's,

the old 10deg binos had 50% usable, terrible views anywhere near edge of field

[astro744]

Originally Posted by Stonius

Okay, I did, but I'm still not quite sure how they circumvent the laws of physics. Light that falls outside the pupil can't really end up on the retina, can it?


I can imagine it's cool of they presumably have a really wide AFoV as well - real starwalk kind of stuff.



However, they say it adds a further 1.2 magnitudes to the naked eye, whereas a 50mm pair of binos would add 4.4 magnitudes which I think might be more useful than the incredibly large field of view.


Look, I'd love to try them - 36 degrees TFoV sounds amazing! Heck, maybe I'll even get some one day, but I'm looking for something to help me see enough of a constellation to star-hop to targets.


Cheers


Markus

I thinks it’s something you just have to try for yourself. The Galilean optics mean the exit pupil behaviour is different and of no concern. There have been some discussions on CN and post #3 in this thread answers it well. https://www.cloudynights.com/topic/7...an-binoculars/

I first bought the SvBony 2.1x42 when on sale and was pleasantly surprised just how many extra stars I saw over a large field. I then bought the Orion 2x54 and these take this type of viewing up a notch with their massive 36 degree true field of view.

Basically you see more stars at very low power. The Pleiades is wonderful in its full context in the sky amongst Taurus with so many extra stars showing yet still looking like an unaided view. The 2x54 are a nice complement to the Orion 9x63 mini giant which are great for getting in closer giving nice bright images but only 5 deg. true field.

Your other option is some retro 7x35 which used to give 10 or 11 deg. but we’re short on eye relief. Not sure if there’s anything more modern giving the same. Out of all of them I would only call the Orion 2x54 true constellation binoculars. Taking Orion and all of Canis Major in one field gives another wonderful view.

[OzEclipse (Joe Cali)]

I used a borrowed pair of the Vixen ultra-wide binos at Astrofest. In a dark sky, they gave me at most 2 magnitudes advantage over naked eye, commensurate with 10-15mm binoculars. Looking at the three stars 10' from the SCP, I could easily see the mag 6.8. Barely see the 7.8 and not see the 8.7 mag star. As I've aged, my pupils now only dilate to about 5.5mm last time I measured them about a year ago. A teenager with 7mm dilation could do about one magnitude better.

The big aperture on wide binos is used to drag in the wide field of view. Look backwards through a regular pair of binoculars and you'll see a similar effect but you are never using more than a small aperture. The older your eyes are, the smaller your dilation, the smaller the effective aperture.

For star hopping, you will do better with a pair of standard binoculars and a narrower 6 deg field as the standard binos will let you see stars that are:-

35mm - about 4 mags fainter than naked eye mag 9-10 in a dark sky
50mm - about 5 mags fainter than naked eye mag 10-11 in a dark sky

I have based the above mag estimates on average middle age vision limits of naked eye mag 5-6 in dark skies.

So it's really a question of what you need, a wide field with fewer hop stars, or a narrower field and many more hoppers.

In my experience, it's pretty easy to point, centre, and view anything in a 6-degree binocular or finderscope field.

Joe

[Stonius (Markus)]

Well, for $50 I ended up getting a vintage pair of 7x35 10 degree binoculars from an estate sale. They were Mechanically and optically great, and still in the box. So I guess I'll see how they fit in to my observing.

I looked them up. Aparrently the optics were made by Sanyo Koki. Not sure if that's good or bad, but they cost $50 and they work well.