8x42 vs. 10x50 dawn/twilight (2 Viewers)

[ReinierB]

They most definitely are. Noticeably. A 50mm objective will gather more light than a 42mm objective. With power being a distant second factor.

It's just physics and no brand will override this. That is, an older 10x50 Leica Trinovid/Ultravid will outperform the latest-greatest Swarovski that's only 42mm. No coatings can be modified to overcome the laws of physics. Move to the 56mm and it's a different weight category, it will outpunch everything else.

I don't think I agree. It's the exit pupil that counts, isn't it? The exit pupil of the 8x42 is 5.25 mm versus 5mm of the 10x50. Light gathering will be greater with the 8x42. Maybe a 10x50 gathers more light, but it won't reach my eye because of the smaller exit pupil.

In reality I also see hardly any difference in brightness. Maybe the 8x42 is just a tough brighter. However, the 10x50 shows more details. I think that is the only advance besides the slightly larger AFOV.
I have decided to keep the SLC 8x42, because I see the advantage of less magnification in wooded areas. The DOF is larger, so less focusing and that is nice in twilight. Also more of the view is sharp and that contributes to the feeling that the view is brighter al well I think.
For open areas and far away the EL 10x50 is nicer.

However, it's at daylight the EL 10x50 really is a joy to use. The large exit pupil is really comfortable. I can move my eyes around and don't get blackouts. The view in the centre is also really sharp, also looking far far way (compared with my NL 10x32 even a bit sharper).

So I think it is quite true. The SLC is made mainly for hunters. It has something special in darker conditions. Maybe the contrast is higher as well. The colours of the EL are just a bit more vivid/nicer, so the EL is mainly for birdwatchers.

The NL 10x32 has quite a lot of glare. The EL 10x50 just a little and even less than the SLC. Probably also an advantage of a bigger exit pupil.

 

[Scott98]

I don't think I agree. It's the exit pupil that counts, isn't it? The exit pupil of the 8x42 is 5.25 mm versus 5mm of the 10x50. Light gathering will be greater with the 8x42. Maybe a 10x50 gathers more light, but it won't reach my eye because of the smaller exit pupil.

FWIW.....no, aperture is what "counts", not exit pupil. The 50mm is packing more focused light into the image.

Especially in low-light situations, exit pupil means nothing w/ regard to brightness....it's all aperture. Your pupils will dilate to 7mm, or maybe 6mm in an older person. This was easy to see looking for woodcocks with my 7x42's and 10x56. The smaller exit pupil 10x56 crushed the 7x42's in what I could see in the fading twilight. I was hoping the 7x42's would be more useful but no, the 56mm were the only ones giving me a chance to see them. They also out-performed my Dialyt 8x56...the updated coatings and glass in the 10x56 SLC pass more light than the Dialyts.

 

[Paultricounty]

FWIW.....no, aperture is what "counts", not exit pupil. The 50mm is packing more focused light into the image.

Especially in low-light situations, exit pupil means nothing w/ regard to brightness....it's all aperture. Your pupils will dilate to 7mm, or maybe 6mm in an older person. This was easy to see looking for woodcocks with my 7x42's and 10x56. The smaller exit pupil 10x56 crushed the 7x42's in what I could see in the fading twilight. I was hoping the 7x42's would be more useful but no, the 56mm were the only ones giving me a chance to see them. They also out-performed my Dialyt 8x56...the updated coatings and glass in the 10x56 SLC pass more light than the Dialyts.

Scott keep in mind , if I’m not mistaken you are comparing brightness in the 10x56 SLC to the Nikon 7x42 EDG. The Nikons are not known to be the brightest 7x42 roofs available for sure. Just about every other top so called alpha has a perceived brighter image and this has to do with the coatings Nikon uses, and for a specific purpose, I’d assume. The UVHD’s have a much perceived brighter image, and the Habicht’s are almost as bright as a 42 can get. I’ve had the Habicht’s side by side with the 10x SLC’s and they didn’t give up much in low light. As well as the SLC 56 has a much more neutral color hue which also helps with perceived brightness.

 

[ReinierB]

I don't understand it anymore. Some say brightness has all to do with the exit pupil and others say it's the lens diameter that counts...

🤷‍♂️

 

[William Lewis]

In the case above Scott's outlined, if his pupils aren't dialing to more than 5.6mm - which is perfectly feasible, then there won't be any gain from having the extra 0.4mm of exit pupil from the 7x42 and let's face it 0.4mm is going to make absolutely no difference anyway unless your talking of the difference between a 1mm exit pupil and a 1.4mm one for high magnification/astronomy use.

There will be gains from the extra magnification of the slc though as well as it's higher transmission, the subject will be 3x closer and just as bright so it's no surprise to have a better view.

Will

 

[ReinierB]

the subject will be 3x closer and just as bright so it's no surprise to have a better view.

So comparing the 10x50 with the 8x42, the view is just as bright, but the subject will be 2x closer. So the gain is that it is easier to see the details, but there is no gain in brightness...
If I understand that correctly.

 

[Patudo]

...easy to see looking for woodcocks with my 7x42's and 10x56. The smaller exit pupil 10x56 crushed the 7x42's in what I could see in the fading twilight. I was hoping the 7x42's would be more useful but no, the 56mm were the only ones giving me a chance to see them. They also out-performed my Dialyt 8x56...the updated coatings and glass in the 10x56 SLC pass more light than the Dialyts.

Magnification does play a part here - Zeiss attempted to take this into account with their "twilight factor" calculation. It would have been interesting to have seen how 10x50 or even 10x42 (even though the latter would definitely have not been as bright as 7x42) performed.

BTW, how dark were the conditions? This is something a lot of folks don't mention when they talk about "low light binoculars", yet there's a huge difference between say twilight and first light, and also if light is improving (morning) or failing (dusk) - and also whether light is affected by other factors such as tree cover.

 

[chill6x6]

So when "comparing" different objective sizes one needs to keep as many things constant as possible. For instance...use a binocular that is offered with different objective sizes such as Zeiss FL(32-56mm), Swarovski SLC(42-56mm), Leica UV(32-50mm) and Meopta Meostar B.1(32-56mm). So get you two or three of the same model, close to the same time of production, keeping the same magnification, and change only the objective size. Take all of them with you out in the field with a note book and document the time and what you see and don't see at fixed distances. Do it some starting before sunup and well after twilight. Several times.

Reading about binoculars and optics is very useful and like going to school it gives you something to work with. Facts however are a combination of study and hands-on experience.

"Twilight factor" is real.

 

[GrampaTom]

Didn't Harry Belafonte have a song about this?

 

[Maljunulo]

A larger objective will show fainter stars in a dark sky, but I do not believe that if the exit pupils are the same size, that a 50 mm will look any “brighter“ than a 42mm, In normal use on terrestrial objects.

 

[Paultricounty]

So comparing the 10x50 with the 8x42, the view is just as bright, but the subject will be 2x closer. So the gain is that it is easier to see the details, but there is no gain in brightness...
If I understand that correctly.

There are more factors that go into which optic will have an apparent brighter image. It’s not just exit pupil, objective size and magnification. In addition to those parameters there are multiple other factors that contribute to a binocular‘s perceived brightness difference. Of course there is the quality of the glass, the light transmission , where is peeks in the spectrum, and the coatings used all can have a big effect.

 

[Paultricounty]

Didn't Harry Belafonte have a song about this?

No , that was about daylight , The banana boat song. A classic 🤪.

 

[Scott98]

Scott keep in mind , if I’m not mistaken you are comparing brightness in the 10x56 SLC to the Nikon 7x42 EDG. The Nikons are not known to be the brightest 7x42 roofs available for sure.

The 56mm lens is gathering twice as much light. Any transmission difference, if there is one, would be like a percent or two. I should butt-out of these brightness talks...coming from astronomy, it's a different world. It's like we're speaking different languges....at night, aperture is only thing that matters. 42mm is simply a puny lens, barely useable for what we do

And remember....astronomers do it all night

 

[Paultricounty]

The 56mm lens is gathering twice as much light. Any transmission difference, if there is one, would be like a percent or two.

Also needed consideration is not just the number but how flat and where the peak is.

I should butt-out of these brightness talks...coming from astronomy, it's a different world.

Lol, definitely I understand exactly what you’re saying , aperture is king in astronomy. Although not to get into it to deep, but astrophysics 5 inch actually had better views on planets , sharper or more detail than my 8 dob. 🤪

It's like we're speaking different languges....at night, aperture is only thing that matters. 42mm is simply a puny lens, barely useable for what we do

And remember....astronomers do it all night

 

[GrampaTom]

No , that was about daylight , The banana boat song. A classic 🤪.

Well no, sorry, not that one. Its:

Man Piaba,

"… It was clear as mud but it covered the ground
And the confusion made the brain go 'round
I went and ask a good friend of mine
Known to the world as Albert Einstein…"

 

[Paultricounty]

Well no , sorry:

Man Piaba,
"… It was clear as mud but it covered the ground
And the confusion made the brain go 'round
I went and ask a good friend of mine
Known to the world as Albert Einstein…"

You don’t have to be sorry. Ya lost me there Tom, where’s the reference about twilight?

 

[GrampaTom]

You don’t have to be sorry. Ya lost me there Tom, where’s the reference about twilight?

There is none intended. If you jump in and read this whole, from #1 through #108, go back and forth between various understandings and opinions, I at least, smile and think, It is clear as mud...

 

[Paultricounty]

There is none intended. If you jump in and read this whole, from #1 through #108, go back and forth between various understandings and opinions, I at least, smile and think, It is clear as mud...

No way Jose I’m going back and reading 108 posts. It’s really not that important to me. I’ll concede I missed something ✌🏼.

 

[Hermann]

It is actually quite simple:

• Use a binocular with an exit pupil as large as or a bit larger than your eye pupil.
• Use a binocular with as much magnification as you can hold steady.
• But don't forget focusing gets harder in low to very low light. So using a binocular with a large depth of field (7x or 8x) may be advantageous.

BTW, I find I see more detail with the Canon 10x42 IS than with my Habicht 7x42 or my old Zeiss 8x50 in very low light, simply because the image is steady. Also makes it a lot easier to focus.

Hermann

 

[GrampaTom]

It is actually quite simple:

• Use a binocular with an exit pupil as large as or a bit larger than your eye pupil.
• Use a binocular with as much magnification as you can hold steady.
• But don't forget focusing gets harder in low to very low light. So using a binocular with a large depth of field (7x or 8x) may be advantageous.

BTW, I find I see more detail with the Canon 10x42 IS than with my Habicht 7x42 or my old Zeiss 8x50 in very low light, simply because the image is steady. Also makes it a lot easier to focus.

Hermann

Herman in case you were thinking of my 109,115,117, I get my attempts at humor are sometimes lost on folks here. In case not, after reading the whole one can I believe, see the confusion that exists among the various members trying to communicate. The confusion we sew in these conversations, relative to your old "smart people can make their own decisions thing," few weeks back, is a worry.

As to your point that its really quite simple, I'd direct you back up to Patudo's 107 and Chucks 108. The amount of light we see through a given binocular is dependent on more things than exit pupil. Admittedly this was a shock to me, but Ive come around. As a fan of 10, potentially of 12, and what my 18-54 scope with 77mm objective reveals, I agree with using the higher X one can hold for reasons I couldn't always explain so well. In the formulas described here one can see the role of magnification described by math, in case one doesn't have the various samples of binoculars with different Xs and takes the time to see. What is Twilight Factor and Relative Brightness and how do I Calculate | Celestron.

I dont have the problem with focusing you describe. Neither have I yet to appreciate the much promoted here, depth of field advantage of a 7X. Admittedly cuz I dont own one. And as a fan of 10 cannot figure why I would trade 3X for some improvement in the ability to focus. After 40 plus years of using 10, focusing is just something that happens between my finger, eyes and brain, almost automatically, certainly without thought. Nobody talks about that here though. I get it.

At to your IS equipped 10X Canon vs that 7X Habicht... check out that Celestron article above. Correlation is not causation as Im sure you know. Hard to say definitively whats contributing to your observation. According to it (above) at least though, 10X seems to provide some advantages even to light gathering whether IS or not.

Chuck's #108 inferring the complexity of the package each individual brand/model of bino provides, is a more inclusive explanation, I hope we all will think about.