Advantages with 7x binos

[gorank]

Why doesn't more birders use 7x binos?? Though I own a pair of 8x binos, I just can see advantages with a little less magnification:

Easier to hold steady a whole birding day (in windy conditions).
Greater field of view.
Better for scanning the sky.
Less eye-strain.
Larger exit pupil = better in low light.
Larger exit pupil = better eye comfort.

If you don't have a scope I can understand that you might want 10X binos but since most birders also uses a scope I am a bit puzzled.

Is this a psychological matter, 8 is bigger than 7 and thus better, are we so afraid of losing some detail? But do we, really? Maybe it is stability and not magnification that makes the difference.

At least here in sweden the 7x42 Zeiss BGAT were rather popular 10-15 years ago among the "fanatic birders". And still I see rave reviews of people who praise this classic binos.

So should I leave the main stream birding community and choose 7x binos instead of the 8.5 status magnifiers ??
Or even dare to buy the old 7x42 zeiss, instead of a contemporary ultra shiny pair with a red dot?

I'm eager to hear your thoughts!

[scampo]

I think your train of thought is rather individual (as it should be I suppose). As in Sweden, 7x were popular in the UK about a decade and more ago (this was well before people had evolved sufficiently to hold their hands steady) - more for their twilight viewing abilities. Now we tend to go to bed earlier, so do not need such a bright glass (or could it be that the likes of Swaro, Leica, Zeiss and Nikon have made their 8/10x brighter...?).

Let's be sensible - 10+x is what we need as it gives us more of what we want a binocular for but for many of us such a magnification is more difficult to hold still and cannot offer such a natural width FOV.

[Art Thorn]

I think it just comes down to personal preference. I have 8 and 10 power glasses, and I prefer the 10 power most of the time. I was surprised that my wife, who has not used binoculars in the past, also prefers 10 power. She still has difficulty finding the bird right away, so I thought the 8 power, with a 7.5 degree field of view, would be better for her. Not so. She finds birds more quickly with the 10 power 6 degree glasses. I don't understand why, because there is no other real difference (same quality Nikon superiors).

[Tim Allwood]

What you need depends what you do....

in a rainforest say 7x bins are wonderful....a little extra light goes a long way.The slight drop in magnification is not an issue but the extra filed is very useful.

the old zeiss 7s have incredible resolution too and are very good when seawatching or trying to pick up raptors etc. 10x in a binocular is way too much for me.

I use 8x mostly but often take my old 7x instead.

[Art Thorn]

Everyone is different, and situations are different. I like to see the detail of a bird, and I don't shake too much (yet) so I use 10 power. But if I go into a dense forest looking for warblers, I take the 8 power (not because of brightness but for the field of view). The same with scopes. My three eyepieces give me 42,67 and 120 power. I prefer the 120, because I am at the shore and like to see the ducks, etc., close up. I try the other eyepieces when I am seaching through a flock for something unique, but switch back to 120 as soon as I find 'that' bird.

[laika]

Is there a big difference in depth of field in a 7x roof bino vs a 10x roof bino?
Or in a roof bino vs a porro in the same magnification? I know a porro bino have better 3D view,(at least in theory ) because of the longer distance between the objective lenses.More correctly I'am asking is there a difference roof vs porro even if yoy close one eye? The reason for asking this is my left eye which is almost blind.I can only read the biggest frontpageletters in the newspapers.
When i use my Leica Ultravid 10x42BR i must use the focusingwheel very often ,compared to a Swarovski 7x42 Classic or my Fujinon 7x50,but the Fuji has IF and not comparable to CFbinoculars.

When i compare my Leica to my brothers Swarovski 8.5x42 EL,i must admit i don't like the EL's focus at all.Too slow for me. Leica is much quicker ,but perhaps not in the same class as Nikon 10x42 HG which i also have tested.

[deboo]

Is there a big difference in depth of field in a 7x roof bino vs a 10x roof bino?
Or in a roof bino vs a porro in the same magnification? I know a porro bino have better 3D view,(at least in theory ) because of the longer distance between the objective lenses.More correctly I'am asking is there a difference roof vs porro even if yoy close one eye? The reason for asking this is my left eye which is almost blind.I can only read the biggest frontpageletters in the newspapers.
When i use my Leica Ultravid 10x42BR i must use the focusingwheel very often ,compared to a Swarovski 7x42 Classic or my Fujinon 7x50,but the Fuji has IF and not comparable to CFbinoculars.

When i compare my Leica to my brothers Swarovski 8.5x42 EL,i must admit i don't like the EL's focus at all.Too slow for me. Leica is much quicker ,but perhaps not in the same class as Nikon 10x42 HG which i also have tested.

Good Evening Laika,

I don't know about a difference in depth of field in 7x or 10x bins.
I borrowed a pair of red Leica 8x32 BN's and there was a massive difference in depth of field compared to my 8x42's....I could not get on with the smaller Leica's and took 'em back to the shop after 3 days.
As regards the bins you mention....Swarovski, Nikon and Leica...they are all very good in my opinion. Try them out and decide for your self...As the old saying goes......" You pays your money and you takes your choice".

Dave.

[iporali]

Why doesn't more birders use 7x binos?? Though I own a pair of 8x binos, I just can see advantages with a little less magnification:

I would compare the binos and the eye to a digital camera with a zoom: the more resolution ("megapixels") there is in the sensor, the less you need magnification (focal length) to "see" the same thing. If your eyes are very good at seeing the details 7x binos deliver, then you can enjoy its advantages. Quite many of us however feel more comfortable with slightly larger image - maybe partly because our megapixels are not enough to resolve the details that a great 7x can bring in the eye.

If I am mainly using the scope to id the birds, 7x would probably be better for me than my 10x, but knowing how many times I have to struggle with just binos, I would not dare to trust myself with 7x magnification.

Ilkka

[satrow]

The 'old' Zeiss 7x42's are a very good binocular still. The ability to pick up movement by eye and see it clearly, as soon as you lift the bino, without having to focus, is a great asset in many circumstances. They are a little 'quicker' in use than anything else that I have tried.

With a fleeting bird, it is sometimes better not to try to use binoculars; a second or two by eye is better than half a second or so of a shaky blur.

It comes down to the way that you do your birdwatching.

Zeiss always said that the 7x42 had better resolution than their 10x40.

Andy.

[Tim Allwood]

agree totally Andy
ace bins

[Art Thorn]

Depth of field has been clearly identified in the photo world, and can't be disputed. A long lens (higher magnification) has a shorter depth of field. With a wide angle lens (very low magnification) everything is in focus. And a lens used wide open has a shorter depth of field than when the lens is closed down. The same happens with the human eye. I use reading glasses, but often forget them when I go out to eat. In a dimmly lit restaurant my pupils dilate (open to their max) and I can't read the menu. A bit more light and my pupils start to get smaller and suddenly I can read. Now if I could only figure out how all of that relates to binocs.

[Doug Greenberg]

I use Nikon Superior E 10 x 42 binoculars, and I love them, I've never found anything better for looking at birds. To me seeing birds at 10x is simply better than seeing them at 7x. The Nikons are reasonably lightweight, they are bright, and they are pin-sharp from edge to edge. As someone who never liked the feel of roof prism binoculars, these porros are absolutely ideal.

Obviously, binoculars are a matter of personal preference. I guess that I would be able to hold 7x bins slightly more steady than 10x, but this is not an issue for me when I am in the field. And I certainly don't have any issue with "depth of field" with binoculars. Usually I am looking at only one bird at a time, and I manage to get it into focus.

[Jane Turner]

I've never been a fan of big magnificaton... my eyes can resolve a lot of detail as long as I have a bright, sharp shake free image. That said, I've always used 8x by choice, but there is nothing wrng with the Zeiss 7x

Was seawatching off a rocking boat in bad light a few years back and I swear I picked up about 30 Storm Petrels before the people around me saw one. They were all using 10x.

I have once looked through a pair of 15x60 Zeiss Porros... I think if I ever find a good condition second hand pair I'll pick them up and use them instead of a scope. I'd need a bearer though!

[Art Thorn]

Jane and Doug have just summarized it all nicely. We are all different and all find what works best for us, given an opportunity to experiment. I've come to the same point as Doug - I will pick the 10x42 SEs almost every time. I'll add that I like the two barrels to get my hands around, probably the same idea as those 8.5x42 Swarovski's at an incredibly good price (I paid $375 U.S. for a brand new pair!!!). Time to go look at some birds.

[Grousemore]

Interesting point about different magnifications.
I was speaking to the manager at an optics retailer last week and he was showing me the new Leica Ultravids. He opined that "80 to 90% of birders prefer 8x rather than 10x mag"
This surprised me as I've always seen a fair mix of both when out and about and have always used 10x myself.
However there have been times recently in woods/forests where I wondered if the better depth of field of 8x may have been a better bet.

[scampo]

I would compare the binos and the eye to a digital camera with a zoom: the more resolution ("megapixels") there is in the sensor, the less you need magnification (focal length) to "see" the same thing. If your eyes are very good at seeing the details 7x binos deliver, then you can enjoy its advantages. Quite many of us however feel more comfortable with slightly larger image - maybe partly because our megapixels are not enough to resolve the details that a great 7x can bring in the eye.

If I am mainly using the scope to id the birds, 7x would probably be better for me than my 10x, but knowing how many times I have to struggle with just binos, I would not dare to trust myself with 7x magnification.

IlkkaI can't easily accept this idea. Top quality modern optics all exceed the resolving ability of the human eye - they also offer a contrast that creates an appearance of extreme sharpness close to what the unaided eye achieves.

Isn't the point of binoculars and scopes that birds tend to fly away as we approach them? So we have found a clever way of getting "nearer" by the use of an optical illusion - clearly we would surely choose the most powerful magnification we could to get the bird as apparently near as we needed.

But, depth of focus diminishes as magnification increases - so a 7x bino gives a greater DOF than does a 10x bino. This means the 7x is far easier to a) focus and b) look through...

Also field of view decreases as magnification increases (for the same diameter objective, so again, 7x is easie to use than 10x on that basis...

Similarly, brightness decreases as magnification increases, so again, 7x is easier to use...

Finally, it is more difficult to hold a high magnification optic still and a shaking image is next to useless...

At 7x the image is rarely satisfyingly close enough to (most?) people in bringing the object "close enough". So that's why most people go for 8, 8.5 or 10.

Quite logical (for a change!) to my mind.

[gorank]

I would compare the binos and the eye to a digital camera with a zoom: the more resolution ("megapixels") there is in the sensor, the less you need magnification (focal length) to "see" the same thing. If your eyes are very good at seeing the details 7x binos deliver, then you can enjoy its advantages. Quite many of us however feel more comfortable with slightly larger image - maybe partly because our megapixels are not enough to resolve the details that a great 7x can bring in the eye.

If I am mainly using the scope to id the birds, 7x would probably be better for me than my 10x, but knowing how many times I have to struggle with just binos, I would not dare to trust myself with 7x magnification.

Ilkka

Very interesting theory, of course there must be differences, and as we are getting older we need more glasses. The resolution in the human eye is also dependent on how much light there is, and in gray and rainy whether the colors fade away as quickly as in a pair of bad binos...the megapixels in our sensors is reduced. And I guess thats why the twilight factor says that magnification increases resolution in low light..at the same time the binos apperture is getting smaller...and when the light is so low that the eye pupil is bigger than the binos exit pupil you are loosing light...and you get the opposite effect instead.
BTW our friends the eagles don't have any binoculars and still they can spot prey on several kilometers, due to greater resolution in their eyes.
I found this "basic" binos theory link rather interesting at eagle optics (a coincident):
http://www.eagleoptics.com/Default/Buying+Guide/pid2388

[iporali]

...
BTW our friends the eagles don't have any binoculars and still they can spot prey on several kilometers, due to greater resolution in their eyes.
I found this "basic" binos theory link rather interesting at eagle optics

Thanks gorank :clap:! You helped me to understand myself.

Ilkka

[Leif]

The Zeiss 7x42 BGAT seem to have quite a sizeable fan club. Many amateur astronomers adore them for their wide field and large exit pupil. When I picked a pair up I was astonished at how comfortable they felt, and they looked very well made too. I have briefly looked through some a few times, and I am always struck by how bright they are, compared with top grade 8x40 glasses. Is this simply the result of the 7x magnification? The only thing I have against them is the rubber eye tubes which are a right royal pain to fold up/down. Also they are not waterproof and nitrogen filled and that puts many people off.

Some years ago I would borrow a friends 10x50 Opolyths and they gave a wonderful bright contrasty view. Views of a local marsh with ducks and the like were glorious. Sadly I found them useless for general birding due to the narrow field of view. I guess it is very much a personal thing, but I prefer ~8x glasses with a wide field of view. I've never tried a 7x glass apart from peeking through some. I suspect most people haven't. I also prefer the large exit pupil of a 8x glass: it makes it easier to align the optics with my eyes.

Having said that, the Swift Kestral 10x50 have a good field of view albeit they are a tad heavy and bulky. The Leica 10x32 BA have a field of view as wide as many top 8x40 bins, and they are marvelous, albeit with very little eye relief, and limited in low light.

[Jane Turner]

The large exit pupil is the single most important factor I think... it means that you can handle much more shake. If you do most of your birding with your elbows planted on the ledge of a hide it won't matter.. but out in wind, following a flying bird, you really notice a difference.

[scampo]

I'm a bit confused by that. I thought - perhaps wrongly - that the 'exit pupil' of a lens system is the apparent size of the image as it leaves the final eyepiece lens before it meets the eye. It is always equal to the size of the objective lens divided by the magnification, so for the Swarovski binos 8.5x42, it would be about 5mm.

But if the diameter of your eye's real pupil is greater than this a larger exit pupil, I understood that it a larger exit pupil would be irrelevant - and only in very dim light would a person's eye pupil be, say, 5mm in size.

In daylight, the eye's pupil is ~1.5mm, I would guess, so a larger exit pupil would not be noticeable.

[Jane Turner]

Its less about the brightness and more about the tolerance of movement of the bins in relation to your eyes I think. Like looking though a drainpipe as opposed to a tube of smarties.

[scampo]

[QUOTE=satrow]
With a fleeting bird, it is sometimes better not to try to use binoculars; a second or two by eye is better than half a second or so of a shaky blur.
QUOTE]

Very good advice - I've lost more sightings than I care to admit to taking my eye off the bird!

[scampo]

Got it!

[Tero]

Would the field of view be that different for 7x vs 8x?

If I can see as broadly, wide field, I would pick 8x40 over 7x35 any time.

[dogfish]

Would the field of view be that different for 7x vs 8x?

If I can see as broadly, wide field, I would pick 8x40 over 7x35 any time.


The Zeiss Dialyt 7x42s (are they called Classics now?) have a field of view of 150m at 1,000m. I've not seen an 8x advertised with a FoV quite that wide. They are brilliant bins.

[Jonathan B.]

The Zeiss Dialyt 7x42s (are they called Classics now?) have a field of view of 150m at 1,000m. I've not seen an 8x advertised with a FoV quite that wide. They are brilliant bins.

Hi, dogfish

The Nikon 8x30 E II (not Superior E) has a field of view slightly greater than the Zeiss Dialyt's. This Nikon is a fine binocular and is one of the best buys on the market (at about $300 US). The view through the Zeiss is very natural--as if viewing with your own eyes--while the Nikon exhibits some distortion, especially while panning. But at 8x, the 460-foot FOV of the Nikon is very impressive.

[Leif]

Its less about the brightness and more about the tolerance of movement of the bins in relation to your eyes I think. Like looking though a drainpipe as opposed to a tube of smarties.

I agree. I have Nikon 8x32 SE with a 4mm exit pupil which is not as comfortable as I would like due to the small-ish exit pupil. Otherwise great bins.

[dogfish]

Hi, dogfish

The Nikon 8x30 E II (not Superior E) has a field of view slightly greater than the Zeiss Dialyt's. This Nikon is a fine binocular and is one of the best buys on the market (at about $300 US). The view through the Zeiss is very natural--as if viewing with your own eyes--while the Nikon exhibits some distortion, especially while panning. But at 8x, the 460-foot FOV of the Nikon is very impressive.

Impressive indeed, and the first I've heard of that beat my Zeiss 7x42s. I wonder why Nikon didn't give the SEs the same FoV as the EII. Perhaps pushing FoV that far in an 8x reduces the optical quality slightly.

[gorank]

In daylight, the eye's pupil is ~1.5mm, I would guess, so a larger exit pupil would not be noticeable.

no, probably not when it comes to the apparent brightness of the view in daylight (when comparing equal binoculars in quality).

But still the view would be more comfortable due to the larger exit pupil.

In twilight/low light (or a typical gray day November to January here in the cold north), the eye pupil will adapt and increase in size.
And I suspect that the eye will lose sharpness of the same reason that a photo lens does when increasing its aperture*??

Maybe there is an optician out there who could explain this??

*The sharpness of a photo lens is usually better at smaller apertures.

[Tim Allwood]

Wow! a bin that beats the Zeiss 7 x 42 for field of view....
So easy to find a bird with.....especially in a dark wood or jungle
I must have a look thru these Nikon SE bins

[scampo]

There's doesn't seem much point in having a field of view that is wider than that of the human eye so there must be a limit to what is useful.

[dogfish]

Wow! a bin that beats the Zeiss 7 x 42 for field of view....
So easy to find a bird with.....especially in a dark wood or jungle
I must have a look thru these Nikon SE bins

It's the E11s (the cheaper ones, amazingly) that have the very wide field. SEs are pleasantly wide, would think c.130-35m

[scampo]

I think the eye's own fov is no more than 130-140 yards at 1000 yards so that would explain why they seem so good maybe?

[Tim Allwood]

It's the E11s (the cheaper ones, amazingly) that have the very wide field. SEs are pleasantly wide, would think c.130-35m

cheers Scampo
will check em out sometime soon

[Jonathan B.]

Impressive indeed, and the first I've heard of that beat my Zeiss 7x42s. I wonder why Nikon didn't give the SEs the same FoV as the EII. Perhaps pushing FoV that far in an 8x reduces the optical quality slightly.

I'm a bit out of my territory with this reply, and perhaps Leif or another more experienced person can set me straight if I'm wrong....

I am pretty sure that the field of view in the E II, and the flatness of field and incredible resolution in the SE, are determined principally by the design of the eyepiece. I think your assumption is correct--that the distortion is a by-product of the extreme field of view. I think if Nikon could make a porro-prism binocular that could perform as amazingly as the SE and also have a field of view as great as the E II, they would do it.

[iporali]

I'm a bit out of my territory with this reply, and perhaps Leif or another more experienced person can set me straight if I'm wrong....

I am pretty sure that the field of view in the E II, and the flatness of field and incredible resolution in the SE, are determined principally by the design of the eyepiece. I think your assumption is correct--that the distortion is a by-product of the extreme field of view. I think if Nikon could make a porro-prism binocular that could perform as amazingly as the SE and also have a field of view as great as the E II, they would do it.

I'm with Jonathan. There is really not that much you can do with a 30 mm porro-objective in terms of fov. The eyepiece of SE is the optical masterpiece.

Ilkka

[Art Thorn]

Field of view is a complex function of the objective lens, focal length and the eyepiece. That is prettty clear when you look at astro scopes. A particular scope, without eyepieces, will have a maximum field of view. Then you can purchase various eyepieces that, with increasing complexity, give you wider, flatter fields that are sharper from edge to edge. And I do mean complex - the best eyepieces cost upwards of $500, for one! Binoculars, even the best, are cheap by comparison. Could they be better? Of course, but no one would pay, and the weight and size would increase as all of the important factors increased. My 85 mm scope is one of the best small refractors out there, as most amateur astronomers would say, but it costs $2500 with a good eyepiece, and that is a mass produced product.

[scampo]

$500-00 eyepiece? That's the cost of a Swarovski 20-60 zoom isn't it?

[Art Thorn]

Don't know what the Swaro costs - mine came with the scope when I bought (and sold) it. But Naglers (and Pentax) top of the line long focal length, wide field eyepieces can go as high as $900 CDN. What is that in pounds or eurodollars? ANyway, I know that I wouldn't be buying anyone's binoculars at that rate. My Nikons are the bargain of the century, by comparison.

[scampo]

I think you perhaps meant $5000 rather than $500 then, Art?

[Swissboy]

I think you perhaps meant $5000 rather than $500 then, Art?

900 Canadian Dollars are about 366 British Pounds.(According to FXConverter)

[Art Thorn]

900 Canadian Dollars are about 366 British Pounds.(According to FXConverter)
Thanks. Anyway, before we get too mired in details, my point still is that if binoculars were expected to be really great, on the level of APO astro scopes, they would have to cost far more than they do. And it isn't directly related to high power either. In fact the eyepieces with the longest focal lengths (hence lowest power) are the most expensive. The bottom line, for me, is that I get to see, clearly, the birds that I want to see. And for that, I have three binoculars, all Nikon, each suited to a particular situation. Waterproof 10 power at the shore, wide field 8 power in the woods, and the best, brightest image 10 power for general birding. And all for the price of a Swaro 8.5x42 (on eBay anyway). I'm happy!

[CDK]

I'm with Jonathan. There is really not that much you can do with a 30 mm porro-objective in terms of fov. The eyepiece of SE is the optical masterpiece.
Ilkka

Ilkka. What difference does the objective lens make to fov? Is it not the case that the fov is something to do with the eyepiece design (as mentioned in your post regarding the SE), and nothing to do with the objective lens, which gathers the light.
I thought that a good Porro prism binocular will give a wider fov than a roof prism binocular.

I heard that some cheaper Porro prisms, might not actually give the magnification, as stated, I certainly am not saying that about the Nikon, but someone purchasing a cheaper Porro might not be getting the magnification that they are expecting. Is this correct?

[scampo]

I have found that with cheaper binos, it's almost always the field of view that is most obviously lacking.

[iporali]

CDK: I may not be the best person to answer but I think Art Thorn put it very well: "Field of view is a complex function of the objective lens, focal length and the eyepiece... A particular scope, without eyepieces, will have a maximum field of view."

The focal length and the objective lens diameter determine the "window" size, through which you look at the world (or a bird ;)) and which is magnified by the eyepiece. You can increase the field of view by shortening both the focal lengths of objective and eyepiece, and keeping the front lens diameter constant - this is why some "wide angle" binoculars are so short. When I said that you can't do very much with the 30mm objective in terms of fov, I meant that the physical dimensions of the binocular and the prism system determine approximately the useful focal length of the objective. And this determines the f of the eyepiece - and then the eyepiece designers decide how much of the maximal fov they are willing to show. The more fov they "open", the more difficult it is to maintain a good image quality. Nikon EII has a very wide field but you can see the decrease of the edge-to-edge sharpness. SE has quite a wide field, but still it is very sharp and well corrected at the edges. Some manufacturers (as Steve said) eg. Olympus (I have heard - take it with a grain of salt) prefer sharp edges over the fov.

All I know about porro vs. roof prism is - as you mentioned - that porros usually do have a slightly larger fov, maybe their objective focal length is shorter?

Re differences in magnification - I believe the observations, but I have absolutely no idea why this is the case.

Ilkka

Steve: We Finns have no ear for (the?) definite articles, sorry ;)