• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Is 8x32 or 8x42 the best Birding format? (1 Viewer)

8x32 or 8x42

[email protected] said:
What kind and size of spotter do you use? What 8x30's do you use?
Click to expand...
I have a Mirador merlin spotting scope had That back in march 1987, light and easy to use it was the first Instrument to Open up my eyes to seeing birds close up and still is it has a 60mm exit lens And two screw in lense,s one that go,s upto 47x and thee other lense upto 25x The 8x30,s are by Charles Frank of glasgow in scotland in the uk I had them as New in 1971 and in that time I have had them serviced once nothing wrong With them most of the birds I have seen have been through them not an Expensive binocular to buy but a good working one certainly.
 
coal tit said:
I have a Mirador merlin spotting scope had That back in march 1987, light and easy to use it was the first Instrument to Open up my eyes to seeing birds close up and still is it has a 60mm exit lens And two screw in lense,s one that go,s upto 47x and thee other lense upto 25x The 8x30,s are by Charles Frank of glasgow in scotland in the uk I had them as New in 1971 and in that time I have had them serviced once nothing wrong With them most of the birds I have seen have been through them not an Expensive binocular to buy but a good working one certainly.
Click to expand...
Definitely a nice spotter. Nothing like a bird @ 47x.
 
Swedpat said:
I would say that it does not need to be an alpha 8x32mm to provide an adequate clear image during low light conditions. Even mid-priced 8x32s provide a good image during dusk and dawn, and it is only when it gets even darker a larger aperture really make a crucial difference.
Click to expand...
You have a couple 6x32's. Would you say they are as bright at dusk as an 8x42?
 
Vespobuteo said:
just wondering, the twilight factor differs quite a lot,
14 for the 6x32
and 18 for the 8x42,
shouldn't that affect the low-light performance?
(coatings equal that is…)

:smoke:
Click to expand...

The twilight factor gives an idéa about how well a certain optics performs under low light conditions. But it has it's limits. Twilight factor is dependent of adequate brightness to have any importance. An 8x42 is better than a 6x32 when it comes to see details, but that's under all circumstances when you are able to see anything, not only at low light conditions.

What I mean is that 8x42 is better at low light conditions than 6x32 because the magnification is higher. Even an 8x32 has higher twilight factor than a 6x32 and can be better than a 6x32 at dusk and dawn despite the image is dimmer.
But twilight factor can't be used to measure the low light performance without taking the brightness in consider.

For example a 100x50 has twilight factor 70,7, while a 10x50 has the value 22,4. In this comparison the twilight factor has lost its importance at all, because at 100x the brightness is 100times lower than at 10x. Forget to see much details in low light conditions with 0,5mm exit pupil. Magnified darkness=darkness.

Therefore I mean the relative brightness is a more useful indicator of low light performance than twilight factor. All optics with same exit pupil provide the same image brightness(at a certain light transmission) and when using the twilight factor you need to take the exit pupil and the light conditions in consider.
 
etudiant said:
The STEREO coronagraph cross section is shown in this paper:

http://www.google.com/url?sa=t&rct=...uebZRSOjhkMfsBFBg&sig2=vGhE1UB2v9126JyVaK3x8g

It is baffled to the nth degree, no surprise as it looks directly at the sun.
Even with all that baffling, NASA still needs the light absorbing coatings to cut the stray light. So there is no magic bullet, even in space.
Click to expand...

Cool....although in binoculars you don't have the distance for all those
chambers. I see one clever new innovation there, though:
the two-opposed-blackened-saucers "light trap"...that is really wild!
Impressive that they made a very serious effort to model the scattering
ray by ray. I wonder if that lead to the 'light trap'.

=================

I see WSJ's Fujinon cross-section now.
Classic long-ribbed-tunnel and then just blackening the prism chamber.
There is a beveled iris before the prism that sends the stray rays into
the backside of the tunnel where is has a gap with the body. You get
that gap with a screw-on 2nd part to the tunnel.

The Tokyo Kogaku "SeeFar" 7x50 has a taper-step, taper-step-open-out
tunnel and has black-lined caps on the prisms. At the ultimate level
of suppression you want to block noise emission even from any little
bits of dust that may touch the prisms. Deep contrast has to have a plan
even for imperfections. (like that space design)
 
Swedpat said:
The twilight factor gives an idéa about how well a certain optics performs under low light conditions. But it has it's limits. Twilight factor is dependent of adequate brightness to have any importance. An 8x42 is better than a 6x32 when it comes to see details, but that's under all circumstances when you are able to see anything, not only at low light conditions.

What I mean is that 8x42 is better at low light conditions than 6x32 because the magnification is higher. Even an 8x32 has higher twilight factor than a 6x32 and can be better than a 6x32 at dusk and dawn despite the image is dimmer.
But twilight factor can't be used to measure the low light performance without taking the brightness in consider.

For example a 100x50 has twilight factor 70,7, while a 10x50 has the value 22,4. In this comparison the twilight factor has lost its importance at all, because at 100x the brightness is 100times lower than at 10x. Forget to see much details in low light conditions with 0,5mm exit pupil. Magnified darkness=darkness.

Therefore I mean the relative brightness is a more useful indicator of low light performance than twilight factor. All optics with same exit pupil provide the same image brightness(at a certain light transmission) and when using the twilight factor you need to take the exit pupil and the light conditions in consider.
Click to expand...

I guess more magnification would be a way of compensating
for the loss of detail the eye can distinguish in very low light, i.e. black and white/night vision.
And higher mag could be useful in that case.
But not at the expense of a too small exit pupil.
 
Vespobuteo said:
I guess more magnification would be a way of compensating
for the loss of detail the eye can distinguish in very low light, i.e. black and white/night vision.
And higher mag could be useful in that case.
But not at the expense of a too small exit pupil.
Click to expand...

That´s a good conclusion.
 
Just a caution, though: the shake at higher powers can eradicate the resolution.
IF binoculars or a monopod or tripod can keep the gains coming.
 
Swedpat said:
The twilight factor gives an idéa about how well a certain optics performs under low light conditions. But it has it's limits. Twilight factor is dependent of adequate brightness to have any importance. An 8x42 is better than a 6x32 when it comes to see details, but that's under all circumstances when you are able to see anything, not only at low light conditions.

What I mean is that 8x42 is better at low light conditions than 6x32 because the magnification is higher. Even an 8x32 has higher twilight factor than a 6x32 and can be better than a 6x32 at dusk and dawn despite the image is dimmer.
But twilight factor can't be used to measure the low light performance without taking the brightness in consider.

For example a 100x50 has twilight factor 70,7, while a 10x50 has the value 22,4. In this comparison the twilight factor has lost its importance at all, because at 100x the brightness is 100times lower than at 10x. Forget to see much details in low light conditions with 0,5mm exit pupil. Magnified darkness=darkness.

Therefore I mean the relative brightness is a more useful indicator of low light performance than twilight factor. All optics with same exit pupil provide the same image brightness(at a certain light transmission) and when using the twilight factor you need to take the exit pupil and the light conditions in consider.
Click to expand...
Good explanation of Twilight Factor. It does have limitations doesn't it?
 
[email protected] said:
Your right. Much over 10x and you lose resolution to shake.
Click to expand...

If we go by all the experiments with IS binoculars and tripods,
you start to lose handheld resolution even at 7x. If your acuity is OK,
there is the question of why you would prefer 10x. The detail might be there
at 7x, and even possible in your eye, but it takes a lot of time and
cortex work to dig it out, especially if it's a bird moving around a little,
not stripes or a font on a target. There is also less distracting information
at 8x or 10x, less field. I think that's one more reason I don't take out
the extra-wides. You look through these things to concentrate on something.
 
OPTIC_NUT said:
If we go by all the experiments with IS binoculars and tripods,
you start to lose handheld resolution even at 7x. If your acuity is OK,
there is the question of why you would prefer 10x. The detail might be there
at 7x, and even possible in your eye, but it takes a lot of time and
cortex work to dig it out, especially if it's a bird moving around a little,
not stripes or a font on a target. There is also less distracting information
at 8x or 10x, less field. I think that's one more reason I don't take out
the extra-wides. You look through these things to concentrate on something.
Click to expand...
I agree stabilization helps even at 8x.
 
Swedpat said:
The twilight factor gives an idéa about how well a certain optics performs under low light conditions. But it has it's limits. Twilight factor is dependent of adequate brightness to have any importance. An 8x42 is better than a 6x32 when it comes to see details, but that's under all circumstances when you are able to see anything, not only at low light conditions.

What I mean is that 8x42 is better at low light conditions than 6x32 because the magnification is higher. Even an 8x32 has higher twilight factor than a 6x32 and can be better than a 6x32 at dusk and dawn despite the image is dimmer.
But twilight factor can't be used to measure the low light performance without taking the brightness in consider.

For example a 100x50 has twilight factor 70,7, while a 10x50 has the value 22,4. In this comparison the twilight factor has lost its importance at all, because at 100x the brightness is 100times lower than at 10x. Forget to see much details in low light conditions with 0,5mm exit pupil. Magnified darkness=darkness.

Therefore I mean the relative brightness is a more useful indicator of low light performance than twilight factor. All optics with same exit pupil provide the same image brightness(at a certain light transmission) and when using the twilight factor you need to take the exit pupil and the light conditions in consider.
Click to expand...
I would say 8x42 is better in low light than a 6x32 because of the Twilight Factor.
 
[email protected] said:
I would say 8x42 is better in low light than a 6x32 because of the Twilight Factor.
Click to expand...

Yes, it is. But what I mean is that the twilight factor isn't some kind of magical addition to the brightness, but just a mathematical formula which has been formulated to provide a description of an optics performance under low light. The twilight factor tells that a larger image scale can be better despite the image is less bright providing the image does not become too dark.
A 6x32 actually is 3% brighter(which is barely perceptible) than a 8x42 but still an 8x42 wins because the larger image scale rules over the very slightly dimmer image(A 10x42 has even better twilight factor and can be better than the 8x42).
Consequently 8x42 is better than 6x32 under ALL circumstances providing the image is stable and the light is enough to see any details at all.
In my opinion it therefore actually has nothing to do with twilight performance in it self: the difference between 6x32 and 8x42 is simply the difference between observing an object with naked eye at 6 or 8 meters distance. You see better at 6m than at 8m, but you would hardly describe the reason to be that your eyes get better twilight performance at closer distance. The reason you see more details is that you are 2m closer the object.

Edited in red. Wrote magnification but meant brightness.
 
Last edited:
If we're talking actual twilight, the
time-to-best-acuity can run pretty long at 6x32 and be much quicker at 8x42, as I've found.
I believe the optic cortex is a factor there. The details are there but the mind works hard.

In OK light and for local views, I find 6x30 very relaxing and easy to pick up.
Less shake, easier for the eyes to adjust to the power, too.

I keep coming back to 7x more and more....the all-arounder. 7x35, 7x50.
 
Pileatus said:
I think if you compute the respective areas of 32, 42 and 50mm objectives you'll see that the same size exit pupil is not the determining brightness factor. A 6X32 and an 8X42 may generate nearly identical exit pupils (5.33/5.25 mm) but their light collecting objective areas are dramatically different...803 vs. 1384. The objective on a 10X50 has a whopping light gathering area of 1962 and a smaller 5mm exit pupil. And, my brilliant 80mm ED82 scope at 30X has an objective area of 5024 with an exit pupil of 2.66 mm.
Click to expand...

Still all configurations with same exit pupil provide same surface brightness: for example comparison between 6x30 and 10x50. 50mm objective gathers 2,78 times more light than 30mm. But with 10x the 2,78times higher light amount is spread out over 2,78times larger area. The result is that 10x50 will provide exactly the same perceived brightness as 6x30.

If you look at a light source, for example a street lantern, the light amount reaching your eyes will be 2,78 times higher through the 10x50 than the 6x30 but that does not mean it's brighter. It's just the same difference like if you are looking with the naked eyes at 6m compared to 10m distance.

But look at an even illuminated surface; a wall or something other even illuminated and stand at a distance that the object fills up the entire field of view in as well the 6x30 and 10x50. Then you will not notice any difference! The light amount reaching your eyes will be the same.
The same thing if you are out in the wilderness among the shadows. The perceived brightness will be the same, just that with different magnifications.
And yes; if you are able to see anything with 6x30 you will see it better with 10x50. But if it's too dark to see any detail with 6x30 you will not see anything with 10x50 either.
 
Last edited:
Swedpat said:
Still all configurations with same exit pupil provide same surface brightness: for example comparison between 6x30 and 10x50. 50mm objective gathers 2,78 times more light than 30mm. But with 10x the 2,78times higher light amount is spread out over 2,78times larger area. The result is that 10x50 will provide exactly the same perceived brightness as 6x30.

If you look at a light source, for example a street lantern, the light amount reaching your eyes will be 2,78 times higher through the 10x50 than the 6x30 but that does not mean it's brighter. It's just the same difference like if you are looking with the naked eyes at 6m compared to 10m distance.

But look at an even illuminated surface; a wall or something other even illuminated and stand at a distance that the object fills up the entire field of view in as well the 6x30 and 10x50. Then you will not notice any difference! The light amount reaching your eyes will be the same.
The same thing if you are out in the wilderness among the shadows. The perceived brightness will be the same, just that with different magnifications.
And yes; if you are able to see anything with 6x30 you will see it better with 10x50. But if it's too dark to see any detail with 6x30 you will not see anything with 10x50 either.
Click to expand...

And we must not forget the myths relating to "binocular summation."

Bill
 
Warning! This thread is more than 9 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Similar threads

D
Zeiss SFL 8x40 This Year's Best New Birding Binocular!
2
Replies
31
Views
5K
AlphaFan
A
N
Entry/Test 8x32 binoculars
2
Replies
38
Views
3K
Patudo
P
J
What binoculars are as good as Nikon Superior E?
2 3
Replies
46
Views
4K
Jaywalk
J
T
Zeiss SF 8x30 vs SFL 8x40
2
Replies
21
Views
1K
tian1227
T
Snuffleupagus
2nd Pair / Upgrade for Birder - Advise Needed
2 3
Replies
44
Views
3K
jring
J

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top