Light transmission comparison...

[PPP]

I have picked some new bingos but I don’t know whether to go for 8x or 10x

Of my current binos (different grades of same brand) I think I prefer 10x over 8x to give me more detail.  I’m going to be spending quite a bit more on a better set but can’t decide on 10x42 or 8x42, my hesitancy is light transmission... How much more light will I lose through 10x all other things being equal? Thanks!

[oldypigeonpopper]

hello, light transmission is on the size of front lens, the higher the magnification you need to hold more still like 10 x 50s that is why some have a tripod thread, saying that some quality makes in 8 x 42 are better than cheap 10 x 50s, i have 2 pairs, 1 pocket type, other is a quality Japanese 8 x 40 i keep in motor, bought second hand, these i bought 20 plus years ago for bird watching PYSER -SGI Eagles 10 x 42. very good binos  

Edited March 31, 2020 by oldypigeonpopper

[JohnfromUK]

6 hours ago, PPP said:

How much more light will I lose through 10x all other things being equal?

As in so many things, the answer isn't simple or clearcut! 

First - if you are talking the same make and model type - the 'goodness' of the glass and coatings will be in effect the same - so that is not a factor.  (This is where very expensive makes using very high grade glass and superior coatings can be better than cheaper types).

The '42' is the objective diameter.  The 8x or 10x is the magnification.  The major light parameter is the 'exit pupil size', found by dividing the objective size by the magnification, so it is 4.2 (mm) for the 10x and 5.25 (mm) for the 8x.

Now it is the exit pupil size that is important in low light situations; it is the size of the light circle that comes out from the eyepiece into the pupil of your eye.  Under bright conditions, your pupil closes up to reduce the light input to the eye.  If the actual pupil size of your eye is less than the exit pupil size of the binoculars - you will capture as much light as possible and your eye is the limiting factor.  However - if the exit pupil of the binocular doesn't fully fill the pupil of the eye - then then binocular is the limiting factor.

Typically - the maximum pupil size can vary a lot - see https://en.wikipedia.org/wiki/Pupil

So - what is the answer?  IF you intend to use the binos in low light (i.e. near twilight/dawn) a lot, you should try and compare under those conditions - because IF your pupil can open to 5.25 mm - you will capture more light from the 8x - which may be an advantage.  However if (and many of us older types are like this) your pupil doesn't open up as much as it once did - you may find little difference in low light.

IF you rarely use them in low light - you may find the slightly greater magnification an advantage.

I know this doesn't really help a lot, but I hope it does explain why it really has to be a personal choice based on trial under (especially low light) various conditions.

[Dougy]

What make are you looking at, a 10 x swarovski for example will very likely be 10x better than say a pair of ebay costing £20, so really not all things may be equal. 

 

If its possible compare both pairs at the same time, late evening when the light is fading, thats going to be the only way you would be able to tell which one suits your needs. 

Woodland stalking for example with lower light would also be a deciding factor, what is your most common scenario ? 

[PPP]

Hi Guys

They will be identical models, sorry if not clear, that’s what I meant by ‘all other things....’ 

Thanks this is really helpful! I won’t be able to try them sadly but I may ask my optometrist to measure my pupil at next eye test (couple of weeks) if they can..

1 hour ago, JohnfromUK said:

As in so many things, the answer isn't simple or clearcut! 

First - if you are talking the same make and model type - the 'goodness' of the glass and coatings will be in effect the same - so that is not a factor.  (This is where very expensive makes using very high grade glass and superior coatings can be better than cheaper types).

The '42' is the objective diameter.  The 8x or 10x is the magnification.  The major light parameter is the 'exit pupil size', found by dividing the objective size by the magnification, so it is 4.2 (mm) for the 10x and 5.25 (mm) for the 8x.

Now it is the exit pupil size that is important in low light situations; it is the size of the light circle that comes out from the eyepiece into the pupil of your eye.  Under bright conditions, your pupil closes up to reduce the light input to the eye.  If the actual pupil size of your eye is less than the exit pupil size of the binoculars - you will capture as much light as possible and your eye is the limiting factor.  However - if the exit pupil of the binocular doesn't fully fill the pupil of the eye - then then binocular is the limiting factor.

Typically - the maximum pupil size can vary a lot - see https://en.wikipedia.org/wiki/Pupil

So - what is the answer?  IF you intend to use the binos in low light (i.e. near twilight/dawn) a lot, you should try and compare under those conditions - because IF your pupil can open to 5.25 mm - you will capture more light from the 8x - which may be an advantage.  However if (and many of us older types are like this) your pupil doesn't open up as much as it once did - you may find little difference in low light.

IF you rarely use them in low light - you may find the slightly greater magnification an advantage.

I know this doesn't really help a lot, but I hope it does explain why it really has to be a personal choice based on trial under (especially low light) various conditions.

Brilliant thank you!

[Smokersmith]

I tend to use 8x42 as you see a wider field of view, and they’re less susceptible to wobbly viewing.

[Robertt]

If you're searcing/hunting for something 7x,  7 x 50's for example, are verg good.

They have a massive field of view and depth of field, which, allows you to look at close or distant objects without changing the focus.

8x and 10x are good for studying things.

8x are more stable than 10x.

Sometimes less is more and thats why I prefer 7x.

 

[barbel]

opticron 10x42 bga water proof use most days had a long time, never felt the need to change, more you pay generally better the glass, weight is a factor when stalking as well, most people I know have  the 40 - 42 due to weight etc.

[Cawdor118]

I had a set of Swarovski EL Range 10x42 binoculars, they were fantastic with what i would class as a warmer sight picture and optical clarity. I would however say they were harder to stabilize free hand as 10x is quite extreme. I have since moved to 8x54 Zeiss Victory RF and find the 8x much better to stabilize and actually are nicer to look through for my eyes with a colder sight picture.

If you use sticks you can use them to glass off. I would honestly reccomend you try as many makes as you can and try both 8x and 10x to see what you like. I woodland stalk and hill stalk and 8x is more than sufficient. 

[PPP]

28 minutes ago, Cawdor118 said:

I had a set of Swarovski EL Range 10x42 binoculars, they were fantastic with what i would class as a warmer sight picture and optical clarity. I would however say they were harder to stabilize free hand as 10x is quite extreme. I have since moved to 8x54 Zeiss Victory RF and find the 8x much better to stabilize and actually are nicer to look through for my eyes with a colder sight picture.

If you use sticks you can use them to glass off. I would honestly reccomend you try as many makes as you can and try both 8x and 10x to see what you like. I woodland stalk and hill stalk and 8x is more than sufficient. 

Thanks, this is great. I’m wondering whether the 8x image quality on my current binos is the limiting factor at 200m rather than magnification ..

[Cawdor118]

Honestly, without bragging... i suspect i get to stalk in the best ground in the UK with respect to diversity. Hill stalking, woodland stalking, moor stalking and forest stalking and i cant exaggerate how much i prefer the 8x. If you were closer, you would be welcome to a look. 

I was 100% a "more is better" guy until i bought the 8x. Its a shame wisdom doesn't come cheaper!

Edited April 3, 2020 by Cawdor118

[Loki]

Hi

Some useful (in my opinion) information......

Link: https://www.allbinos.com/binoculars_reviews.html

L

[oliver90owner]

I think 8 x 56 is about the ideal for a lot of applications.  The pupil exit diameter is 7mm , so the average eye will get the best image, the light gathering capability is over 50% better than 42mm objectives (particularly for use in dim lighting) and the magnification will a) provide easier handling (steady image) and a wider field of view.

As your question is only about light transmission, clearly the larger the objective the more light entering the optics is an advantage.  Quality of the optics can, however, make a huge difference to how much of that light reaches the retina of your eye(s).

Neither option is using the full potential of your pupil size.

[PPP]

Guys, this is brilliant! 8x wins!

[Kalahari]

The thing that many people ignore is resolution. This is the ability to "separate" detail. Often this is what you pay for but is not clearly stated. A really high quality 8x bin with high resolution often shows more detail than a cheaper 10x bin although this can only be shown in a side by side test.

 

David.

Edited April 4, 2020 by Kalahari

[PPP]

43 minutes ago, Kalahari said:

The thing that many people ignore is resolution. This is the ability to "separate" detail. Often this is what you pay for but is not clearly stated. A really high quality 8x bin with high resolution often shows more detail than a cheaper 10x bin although this can only be shown in a side by side test.

 

David.

Thanks, makes sense to me.  All of this shooting stuff is a minefield and it’s expensive getting it wrong ...

[JohnfromUK]

I note that 7 or 8 x 50 or 56 are well liked.  There is no doubt that they will be very good (in fact the better makes are pretty much as good as you can get of any type) - and especially so in low light where they are unrivalled. 

What I would question is whether they are suited to most people's normal usage.  Under reasonable or better light conditions, a smaller objective lens will be virtually as good - but much lighter, much cheaper, and more convenient.

I bought an expensive pair of 10x50 some years ago - and they are superb .......... but don't get used a lot as they are so bulky and heavy to carry.

[Kalahari]

One other point is that young people can accomodate a 7mm exit pupil. ie. objective size in mm divided by magnification. So a 7 x 50 or 8 x 56 fulfil this criteria perfectly and you get the best your eye can cope with. However, as you get older your pupil won't actually open to the full 7mm so a 6mm exit pupil might be fine so 7 x 42 would suit or even a 5mm exit pupil in a 8 x 40/42. So have a look through a few at dusk if you can. Also the very big binoculars with high magnification are heavy to carry, harder to hold still and show the resultant wobble better and generally have a narrower field of view.

 

I am sorry if this has only muddied water for you.

 

Best wishes,

 

David.