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Do you think an excellent 8x42 can be better than an alpha 8x32 optically? (1 Viewer)

[email protected]

Well-known member
Supporter
I have always wondered if you are better off buying a sub-alpha bigger aperture binocular like a 8x42 or 8x56 rather than an alpha 8x32 if you are just concerned about the view. The bigger aperture binocular even though it may not perform quite as well as the alpha given equivalent apertures if it has the advantage of a bigger aperture I think it could outperform the alpha. A 42 mm binocular brings in 72% more light than a 32 mm and has much more comfortable eye placement because of the bigger exit pupil, and it can be argued that the resolution and glare control are better with the bigger aperture. Will aperture size compensate for the quality of the optics?
 
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PYRTLE

Old Berkshire Boy
Impossible to answer........ what is the difference (or you're perceived difference) between an excellent and an "alpha" binocular?
Plus you're example of an alpha suggests an NL 42mm though the thread title is quoting a 32mm alpha. Come on Dennis.
 

jring

Well-known member
Hi,

if you are doing resolution tests with an additional magnifier - probably, given enough magnification.

For normal observation, I'm quite sure that the answer is no. Except for those maybe 15 minutes at dusk or dawn when an 8x42 pair really makes sense.

Eye placement in an 8x32 pair is quite easy as compared to really difficult sizes like 10x30, 8x25 or even 8x20.

As for glare and reflection tests, please take an alpha that is not flawed in that regard... so an EDG or a Zeiss FL and not an EL please.

Joachim
 

Pileatus

"Experientia Docet”
United States
I have always wondered if you are better off buying a sub-alpha bigger aperture binocular like a 8x42 or 8x56 rather than an alpha 8x32 if you are just concerned about the view. The bigger aperture binocular even though it may not perform quite as well as the alpha given equivalent apertures if it has the advantage of a bigger aperture I think it could outperform the alpha. A 42 mm binocular brings in 40% more light than a 32 mm and has much more comfortable eye placement because of the bigger exit pupil, and it can be argued that the resolution and glare control are better with the bigger aperture. Will aperture size compensate for the quality of the optics?
Dennis,
Please show your math for the 40%.
 

[email protected]

Well-known member
Supporter
Hi,

if you are doing resolution tests with an additional magnifier - probably, given enough magnification.

For normal observation, I'm quite sure that the answer is no. Except for those maybe 15 minutes at dusk or dawn when an 8x42 pair really makes sense.

Eye placement in an 8x32 pair is quite easy as compared to really difficult sizes like 10x30, 8x25 or even 8x20.

As for glare and reflection tests, please take an alpha that is not flawed in that regard... so an EDG or a Zeiss FL and not an EL please.

Joachim
Ok, if you did a lot of birding in low light which binocular would you prefer a Nikon Monarch HG 8x42 or a Zeiss 8x32 FL? Which one would perform better? remember the Nikon is pulling in 72% more light.
 
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John A Roberts

Well-known member
Australia
. . . A 42 mm binocular brings in 40% more light than a 32 mm and has much more comfortable eye placement because of the bigger exit pupil . . .

The area of a circle is pi times the radius squared (A = π r²) . . . So for the 32 mm it is 3.14(256)=804 square mm and the 42 mm is 3.14(441)=1384 square mm. So 804/1384 x100= 58%. The 32 mm only has 58% as much surface area to take in light as the 42 mm, so the 42 mm actually takes in 42% more light . . . A 56 mm binocular pulls in 68% more light than a 25 mm compact . . .

Hi Dennis,

It’s true that a 32 mm objective has only 58% of the area of a 42 mm one. However, that does not mean that the area of a 42 mm objective is 42% larger
I presume that you were somehow thinking in terms of: 58% + 42% = 100% ?

- - - -
If we want to know how much bigger the larger area is than the smaller one, we need to divide the larger figure by the smaller . . .

a) Comparing a 32 mm (804 sq mm) objective to a 42 mm (1384 sq mm) one: 1384 ÷ 804 = 1.72
i.e. the larger area is 1.72x the size of the smaller one: an increase of 72% (so neither 40% as in post #1, nor 42% as in post #9)

b) And the area of a 56 mm objective is 5x larger than a 25 mm one: 2464 ÷ 491 = 5 (500% being vastly different to 68%!)

- - - -
If we just want to know the relative area of two or more circles, we can greatly simplify things:
• as π is a constant we can eliminate it, and;
• then we can just square the diameter, without first dividing it

So again comparing 32 mm and 42 mm objectives: 32x32 = 1024 and 42x42 = 1764: 1764 ÷ 1024 = 1.72


John
 
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[email protected]

Well-known member
Supporter
Hi Dennis,

It’s true that a 32 mm objective has only 58% of the area of a 42 mm one. However, that does not mean that the area of a 42 mm objective is 42% larger
I presume that you were somehow thinking in terms of: 58% + 42% = 100% ?

- - - -

If we want to know how much bigger the larger area is than the smaller one, we need to divide the larger figure by the smaller . . .

a) Comparing a 32 mm (804 sq mm) objective to a 42 mm (1384 sq mm) one: 1384 ÷ 804 = 1.72
i.e. the larger area is 1.72x the size of the smaller one: an increase of 72% (so neither 40% as in post #1, nor 42% as in post #9)

b) And the area of a 56 mm objective is 5x larger than a 25 mm one: 2464 ÷ 491 = 5 (500% being vastly different to 68%!)

- - - -

If we just want to know the relative area of two or more circles, we can greatly simplify things:
• as π is a constant we can eliminate it, and;
• then we can just square the diameter, without first dividing it

So again comparing 32 mm and 42 mm objectives: 32x32 = 1024 and 42x42 = 1764: 1764 ÷ 1024 = 1.72


John
Your correct and I like your numbers even better! So a 42 mm binocular takes in almost twice the light of a 32 mm and a 56 mm binocular takes in 5 times the light of a 25 mm. That is a big difference.
 
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Royfinn

Well-known member
I am also interested of knowledge, if bigger aperture bin are better... At least 3 pro birders here have moved to Kowa 10x56 (2) or 12x56 (1) models, mainly used in migration watch for great distances, aided by finnstick. So I would be happy if someone would test big aperture bins against 32/42 bins.
 

jring

Well-known member
Ok, if you did a lot of birding in low light which binocular would you prefer a Nikon Monarch HG 8x42 or a Zeiss 8x32 FL? Which one would perform better? remember the Nikon is pulling in 72% more light.

Hi,

if I was doing a lot of low light observation, like mainly observing under a dense canopy, I probably would try to get a dedicated pair for that - with an exit pupil as large as my eyes will support it. So probably sth along the lines of 7x42, 8x56 or 10x60.

And maybe a pair of 8x32 for the occasions when I don't need the extra light (if any).

I probably would look for a good deal of sub-alpha bins in either case, or a used alpha if available.

Joachim
 

[email protected]

Well-known member
Supporter
Hi,

if I was doing a lot of low light observation, like mainly observing under a dense canopy, I probably would try to get a dedicated pair for that - with an exit pupil as large as my eyes will support it. So probably sth along the lines of 7x42, 8x56 or 10x60.

And maybe a pair of 8x32 for the occasions when I don't need the extra light (if any).

I probably would look for a good deal of sub-alpha bins in either case, or a used alpha if available.

Joachim
Who makes a 10x60? That would be interesting. A 7x50 kills a 7x42. It is like a 7x42 on steroids!
 

[email protected]

Well-known member
Supporter
I am also interested of knowledge, if bigger aperture bin are better... At least 3 pro birders here have moved to Kowa 10x56 (2) or 12x56 (1) models, mainly used in migration watch for great distances, aided by finnstick. So I would be happy if someone would test big aperture bins against 32/42 bins.
Bigger apertures are almost always going to be brighter, especially in low light, have easier eye placement, have better glare control, fewer aberrations on-axis and sometimes better resolution. Those pro birders aren't using a 56 mm for nothing! A 56 mm brings in almost twice the light of even a 42 mm. For long distance birding or Pelagics from a static position they have a lot of advantages.
 
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jring

Well-known member
Who makes a 10x60? That would be interesting. A 7x50 kills a 7x42. It is like a 7x42 on steroids!

10x60 is only a thing as an IF porro from the usual suspects in the astro market, e.g TS Optics or Oberwerk. 7x50 would be nice if I was 20 again and my pupils would still dilate to 7mm...

Joachim
 

[email protected]

Well-known member
Supporter
10x60 is only a thing as an IF porro from the usual suspects in the astro market, e.g TS Optics or Oberwerk. 7x50 would be nice if I was 20 again and my pupils would still dilate to 7mm...

Joachim
The advantage of a 7x50 are similar to a 7x42 except magnified. Greater DOF, steadier hold and easier eye placement. A 7x50 has even easier eye placement than a 7x42. Of course with IF the 7x50 is a nice format because you hardly ever have to focus with the great DOF. You just pop it up to your eyes and bam you have a great bright view with no fussing around with eye cups or focusing or worrying about black outs.
 

jring

Well-known member
The advantage of a 7x50 are similar to a 7x42 except magnified. Greater DOF, steadier hold and easier eye placement. A 7x50 has even easier eye placement than a 7x42. Of course with IF the 7x50 is a nice format because you hardly ever have to focus with the great DOF. You just pop it up to your eyes and bam you have a great bright view with no fussing around with eye cups or focusing or worrying about black outs.

Hi,

I have a ZOMZ 7x50 and a Leitz Trini 7x42... I actually prefer the Trini due to its wider FOV. DOF seems the same (that is huge) and theory says that given similar objective focal length the depth of field should be the same.

Joachim
 

Tringa45

Well-known member
Europe
Surely a 7x50 would have less DOF than a 7x42 due to larger aperture.
Depth of field is solely a function of magnification, unless the exit pupil is smaller than the eye's pupil; but then the view starts to get rather uncomfortable.
It is inversely prportional to the square of the magnification, i.e. for a given object distance, the DoF of a 7x binocular would be twice that of a 10x binocular.

John
 

yarrellii

Well-known member
Supporter
Here's my experience with exactly the two kind of binoculars you suggest: 8x32 alpha vs 8x42 "excellent-but-not-alpha".
My first "good" binocular was a Zeiss Conquest HD 8x42 (I guess it fits perfectly in your definition of "excellent 8x42"). Really very nice, but after a while I realised that it was a big mistake, because it was so heavy that I simply couldn't be bothered to carry it and started leaving it at home until one day I realised that it was pointless to have a great performer that it was too heavy for my use (I use it mainly while trekking or lots of walking involved), so I sold it.
Now my main binocular is a 8x32, sometimes I carry an "alpha" (Swaro ELSV), sometimes I carry an excellent one (EII or Traveller ED). Never a single second of regret for missing the view through the Conquest HD 8x42. Not a single second.

I don't know if this answers your question of whether or not a non-alpha 8x42 can provide an equal or better view than an alpha 8x32. I simply couldn't care less about what it provides, what matters for me is what I need most of the time, and this is an 8x32. I'm sure the Nikon WX 10x50 is an impressive device, its FOV at 9º is wider than most 8x42, even 7x42 out there. But even if I had the money I would not want one as a birding binocular, I'd still rather take a 8x32, even if it is a more mundane device like the Opticron Traveler 8x32 (of course I'd love it for astro, but this is BF, not CN ;) ).
This is actually the reason I'm 100 % sure I'd love the 8x42 SLC, but I don't think I want one, because is as heavy as the Conquest. So, even if I know it's an amazing device, I won't use it most of the days, and I simply can't justify spending +1000 € on something I won't be using (I don't mind having an ELSV or an ATS65HD, because I use them every day).

Like someone pointed out earlier. I'd rather have an 8x32 for everyday (at around 500 g) and then a dedicated but heavier low light (7x42, 8x56, even 10x50) than carrying 800 g every single day of my life, for the few times I need the extra punch in low light situations.
 
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