Swarovski NL 8x32 vs Leica Duovid 8+12x42 Brightness Mystery (4 Viewers)

[ticl2184]

Recently had the chance of testing my 8x32 NL vs my Duovid 8-12x42 on the Stars and misty gloomy conditions on the Isle of Wight..

The results were really odd so I wanted to pass it by you guys ...

I'll get straight to it... Basically in all conditions the Swarovski either matched or beat the Duovid in brightness and resolution.
This doesn't make any sense whatsoever. The 42mm objective should collect 75% more light than the 32mm objective.. Even you take into consideration the 150 metre fov of the NL over the 118 of the Duovid which should bring more light to the eye, I can't understand why 32 mm objective would match or beat a 42mm.

Have attached some images for your comparison..

Would be really interested in anyone's explanation for this anomaly.

By the way I used the same settings on my phone camera to take the photo by useing
manual.

The Red crosses mean Duovid and Blue Swarovski.

PS
I believe Gijs van Ginkle measured the light transmission of the Duovid and would be interested to know what he found to be the overall light transmission.


Cheers

Tim

 

[pppppvvvv]

A few years back, I bought a Zeiss Victory Pocket 8x25 to complement my Duovids, (mainly for close focus survey work).
On inspecting the two, side by side, there was little, if anything in favour of the Duovids.
I couldn't think of any reason to keep the Duovids, and subsequently sold them.

 

[ticl2184]

A few years back, I bought a Zeiss Victory Pocket 8x25 to complement my Duovids, (mainly for close focus survey work).
On inspecting the two, side by side, there was little, if anything in favour of the Duovids.
I couldn't think of any reason to keep the Duovids, and subsequently sold them.

Exactly.......
Wtf is goin on mate... Doesn't make any sense.

There is 11 optical units in the Duovid..... There light transmission would have to be less than 60% or less to compete with a 32mm aperture....

Thanks for your reply....


Cheers

Tim

 

[Owlbarred]

Excellent photos. The quote below is from Optics Trade Blog regards inherently poorer light transmission in zoom than non-zoom binoculars.

• Poor Light Transmission Rate

Due to an added number of optical components, the light transmission rate in zoom binoculars is generally poor. The light rays entering through the objective lenses have to pass through additional optics elements in zoom binoculars. Every time light strikes an optical component, such as a prism or lens, some part of it is lost due to scattered reflection.

Therefore, images that are viewed through a set of zoom binoculars usually lack sufficient brightness and sharpness even in daylight. Therefore, binoculars with variable magnification cannot be effectively used during low-lighting conditions.

Zoom Binoculars VS Fixed Magnification Binoculars - Optics Trade Blog.

 

[ticl2184]

Excellent photos. The quote below is from Optics Trade Blog regards inherently poorer light transmission in zoom than non-zoom binoculars.



Zoom Binoculars VS Fixed Magnification Binoculars - Optics Trade Blog.

Thanks Owlbarred

Appreciate the import..

Cheers

Tim

 

[Gijs van Ginkel]

ticl2184, post 1,
Yes, we measured the light transmission values of the Leica Duovid 8 and 12x42:
8x: 81% at 500 nm and 84% at 550 nm
12x: 77,9% at 500 nm and 81% at 550 nm
The transmission curves are not flat but gradually incline from 425 nm to 675 nm
Gijs van Ginkel

 

[ticl2184]

ticl2184, post 1,
Yes, we measured the light transmission values of the Leica Duovid 8 and 12x42:
8x: 81% at 500 nm and 84% at 550 nm
12x: 77,9% at 500 nm and 81% at 550 nm
The transmission curves are not flat but gradually incline from 425 nm to 675 nm
Gijs van Ginkel

Thanks Gijs....
Appreciate your reply ...

I imagined there was a 20% loss of light transmission but can't understand why the 42mm aperture of the Duovid hasn't compensated over the 32mm of the NL..


PS ... What was the average light transmission also known as "mean" value of the Duovid?


Cheers

Tim

 

[henry link]

The 700 pound gorilla in the room is the "effective aperture" of the binoculars when combined with your iPhone or your eye.

Phone camera apertures are only around 2-3mm depending on the model and which lens on the phone camera you chose to use. If we just assume 2.5mm that means that both of your binoculars would be operating as if they were 8x20s in the photos, so no significant difference in image brightness should be expected. The difference in light transmission would be a small fraction of an f-stop, so not that significant in a photo.

Visually, your eye would need to be dilated to more than 4mm before any difference at all in image brightness would start to become noticeable and even if your pupil diameter equaled the Leica's 5.25mm exit pupil (unlikely even in dull daylight) you might find the difference underwhelming.

A test you might try is to make a 4mm stop down mask for one side of the Leica and compare the image brightness between the masked and unmasked sides under the same conditions as in the photos above. I think you'll see no difference at all in either the dull landscapes or night scenes in iPhone photos and only a small difference visually in the night scenes.

 

[ticl2184]

Thanks Henry ...

I'll do that ....Only problem is that what you see on those images is exactly what I see through my eyes ....
I've been doing this a long time my friend.
I'll try a larger imaging source but I doubt it will make any difference...
Plus I'll try what you suggested

Thanks for the input Henry..

Cheers Tim

 

[dmcharg]

With 2 such high quality optics I would expect the differences to be relatively small. I have compared my 8x25 CL to 8x32 FP whilst there is distinct difference in the FOV etc when it really comes down to telling the difference in detail between them its much closer then I would have expected. But I carry the 8x25 far more often simply because of their size. I guess it comes down to can your eye make use of that additional aperture during normal conditions.

 

[William Lewis]

Hi Tim

It's just transmission - the nl has 10% higher transmission, give or take, than the duovid. The nl's going to appear brighter unless your pupil's dilated to more than 4mm, or, as Henry says, your phone camera has a larger than 4mm aperture - which it doesn't.

Think of a torch shining through a keyhole, the nl's a brighter torch, the duovid (at 8x) is a bigger keyhole.

I'm all in for a 6mm exit pupil in a birding bin but brightness isn't the main advantage until it's got very late (or early) in the day and even then its only a marginal difference at best compared to an 8x32.

 

[ticl2184]

Hi Tim

It's just transmission - the nl has 10% higher transmission, give or take, than the duovid. The nl's going to appear brighter unless your pupil's dilated to more than 4mm, or, as Henry says, your phone camera has a larger than 4mm aperture - which it doesn't.

Think of a torch shining through a keyhole, the nl's a brighter torch, the duovid (at 8x) is a bigger keyhole.

I'm all in for a 6mm exit pupil in a birding bin but brightness isn't the main advantage until it's got very late (or early) in the day and even then its only a marginal difference at best compared to an 8x32.

Thanks for your reply...

So your saying its my pupil size. That doesn't make sense because my 10x42 EL used to be brighter at night than my 8x32 NL ?

A 42mm objective collects 75% more light than a 32mm. Even with the increased transmission rate of the NL the Duovid should be brighter..


I'll let my eyes adjust to the dark so my pupil is maximally dilated and report the findings ...Plus I'll get a larger camera to take some more photos..

Many thanks for your input though William..

Cheers
Tim

 

[William Lewis]

So your saying its my pupil size. That doesn't make sense because my 10x42 EL used to be brighter at night than my 8x32 NL ?

Your EL would have had an exit pupil of 4.2mm, the NL 8x32 would be 4mm - it would be a marginal difference at best and one I doubt you (or most people) could detect - but it does make sense given they have very similar transmission values.

 

[ticl2184]

Your EL would have had an exit pupil of 4.2mm, the NL 8x32 would be 4mm - it would be a marginal difference at best and one I doubt you (or most people) could detect - but it does make sense given they have very similar transmission values.

Gijs said the transmission of the Duovid was around 80% overall if you take the mean value...
NL transmission has around 92 % apparently...

The difference is noticable...Wish you could see for yourself...

I'll test again when my eyes have been fully dilated plus with a bigger camera ..


Cheers

Tim

 

[William Lewis]

Hi Tim. I'm quite familiar with the difference between high and low transmission and exit pupil effects - a trinovid 8x20 vs SLC 7x42 vs habicht 8x30 is an interesting comparison.

It's worth considering what those larger objectives are doing with all the extra light - if the magnification stays the same they're just projecting it over a larger area making a larger exit pupil.

 

[DrewskiMT]

Great topic and line of questioning. It really is all about transmission. Comparing my own low 80s % transmission 42mm's to a low 90's % transmission 32mm, I also perceive a significantly brighter view in the 32mm in daylight conditions. I think this is why many serious optics users now carry high transmission 32s in place of their older less transmissive 42s. I would be curious to hear your impressions of brightness when looking into shadows at dusk.

 

[John M Robinson]

So, bottom line, your ELs are brighter than your Duovids and it’s not even close. In normal daytime light, the size of the exit pupil means nothing. I have a pair of 7x50 Fujinon marine binoculars which are excellent for low light, nighttime use, but they are considerably dimmer than my 7x21 Curios, even looking into shadow area during the daytime. A 3mm vs 7.1mm EP. The newer Curios have much better glass and coatings than my 40 year old Fujinons.

Comparing new to new, my Curios are noticeably brighter than my 7x35 Retrovids, though they are close enough for other attributes to outweigh the slight difference in brightness.

 

[ticl2184]

Great topic and line of questioning. It really is all about transmission. Comparing my own low 80s % transmission 42mm's to a low 90's % transmission 32mm, I also perceive a significantly brighter view in the 32mm in daylight conditions. I think this is why many serious optics users now carry high transmission 32s in place of their older less transmissive 42s. I would be curious to hear your impressions of brightness when looking into shadows at dusk.

How do your 32vs42 binoculars compare at night-time....

Be interested to know..


Cheers Tim

 

[ticl2184]

Great topic and line of questioning. It really is all about transmission. Comparing my own low 80s % transmission 42mm's to a low 90's % transmission 32mm, I also perceive a significantly brighter view in the 32mm in daylight conditions. I think this is why many serious optics users now carry high transmission 32s in place of their older less transmissive 42s. I would be curious to hear your impressions of brightness when looking into shadows at dusk.

But how is possible that a 32 can outperform a 42 mm...
Looking into the shadows is better in the 32 which doesn't make sense...

Cheers
Tim

 

[John M Robinson]

But how is possible that a 32 can outperform a 42 mm...
Looking into the shadows is better in the 32 which doesn't make sense...

Cheers
Tim

Hi Tim,

I posted earlier about my little 7x21 Swarovski Curios being brighter than my 8x42 Pentax and 7x50 Fujinons. The larger exit pupils are only relevant when it gets dark enough for your eyes pupils to open up bigger than the binoculars ep, and even then the difference in coatings, quality of glass and general design can offset the larger EP. One more thing, as we get older, our eyes become less flexible and don’t open as wide as they used to.