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El42/50mm real world light gathering at dusk? (1 Viewer)

matt green

Norfolkman gone walkabout
Looking for any opinions on the light gathering capabilities of the el42 vs 50mm models, for a very short time I had both 8.5x42 and 8x32 and made comparisons at dusk but the difference was never mind blowing, the 42mm had marginal improvements in micro contrast but very little difference in low light.

Currently 45 and have no idea how far my pupils open up at dusk to make full use of the larger exit pupil!

Matt
 

matt green

Norfolkman gone walkabout
Which binoculars do you now have?
Apart from a borrowed nikon monarch 8x36 nothing!

Just to clarify, particularly interested in 10x42 vs 10x50, reason being late model swarovision 10x50s seem to be quite reasonably priced..not likely to be looking at new or used fieldpro models seeing as the swarovisions are as I understand it are optically the same and benefit from a longer warranty period.

Matt
 

dries1

Member
Matt,

I much prefer the view of the 10X50 over the 10X42, including the larger FOV. Weight is the primary deterrent for many on the 10X50, therefore they opt for the 10X42. The 10X42 is fine for many in daily use, so my choice is purely subjective.

Andy W.
 

[email protected]

Well-known member
Supporter
Looking for any opinions on the light gathering capabilities of the el42 vs 50mm models, for a very short time I had both 8.5x42 and 8x32 and made comparisons at dusk but the difference was never mind blowing, the 42mm had marginal improvements in micro contrast but very little difference in low light.

Currently 45 and have no idea how far my pupils open up at dusk to make full use of the larger exit pupil!

Matt
A 50 mm binocular will pull in 40% more light than a 42 mm and will be brighter almost under any situation especially under lower light given similar magnifications. Even in daylight when you are looking into shadows or are under trees in a forest or a canopy the 50 mm will be brighter. The exit pupil and transmission on these is approximately the same, so it would not affect the brightness of either binocular. Also, if you are considering an EL 8.5x42 versus a EL10x50 you will also see more detail with the 10x50 under low light because of the higher magnification due to the "Twilight Factor". Twilight Factor is a mathematical formula that shows how both the size of the objective lens and the magnifying power contribute to a binocular's ability to show detail in dim light. The Twilight Factor is the square root of the product of the diameter of the objective lens and the magnifying power of the binocular. So the Twilight Factor of the EL 8.5x42 would be 19 and the Twilight Factor of the 10x50 would be 23. So the Apparent Brightness AND the Twilight Factor of the 10x50 would be greater than the 8.5x42 with the result that in anything but bright sunlight the 10x50 would kill the 8.5x42. Twilight Factor and Apparent Brightness are not to be confused because they are a different measurement but together they tell you how well a binocular will perform in low light. The EL 10x50 without a doubt is a better low light instrument than the EL 8.5x42.
 
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[email protected]

Well-known member
Supporter
Matt,

I much prefer the view of the 10X50 over the 10X42, including the larger FOV. Weight is the primary deterrent for many on the 10X50, therefore they opt for the 10X42. The 10X42 is fine for many in daily use, so my choice is purely subjective.

Andy W.
A bigger aperture will beat a smaller aperture every time. A 10x50 will always out perform a 10x42, especially in low light. Plus you have the advantage of a bigger exit pupil meaning more eye placement comfort. You give up performance for lighter weight with the 10x42.
 
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chill6x6

Well-known member
Looking for any opinions on the light gathering capabilities of the el42 vs 50mm models, for a very short time I had both 8.5x42 and 8x32 and made comparisons at dusk but the difference was never mind blowing, the 42mm had marginal improvements in micro contrast but very little difference in low light.

Currently 45 and have no idea how far my pupils open up at dusk to make full use of the larger exit pupil!

Matt
I think you have answered your own question... I have compared 32mm and 42mm like binoculars pretty extensively for meaningful differences while birding during low or poor light conditions. I have also compared pretty extensively the SV 10X42 and 10X50. Low or poor light conditions for each. As an avid birder, I really thought the differences were minimal.
 

matt green

Norfolkman gone walkabout
Many thanks for all of your replies,

Maybe an 8x58 for twilight owl/raptor viewing would be a better choice along with an everyday 7/8x42 for regular daylight hours, might aswell slip in a trinovid 32hd for summertime insect watching!!

I've never particularly desired a collection of optics but the longer I do this the more difficult it seems to choose a configuration that can satisfy all glassing situations! The pre legend el42 came pretty close before swarovski hacked the close focus.

Matt
 

dmcharg

Active member
My experience is that the differences between 32,40 & 50 is very minimal and other factors are likely far more significant i.e magnification, size, weight, ease of eye placement/exit pupil etc. For daytime viewing the 8x32 are exceptional I think.
 

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