Thread: Swaro SLC W B 8x42 vs Leica Trinovid HD 8x42

Originally Posted by Moutere

I've had a pair of 8x30 WB SLCs for 20 years and been extremely happy with them.

I've had the same model for nearly 25+ years and have passed them down to my son as I went 10 x 42 EL if you buy quality they do last.

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Originally Posted by ebf

Tx Sarvo, looking at 8's because as I said mainly NI, I am keen to maximize FOV

8 power with 42 gives greater exit pupil, so by my thinking that is a plus for low-light compared to 10x42

Not sure if that is correct. The human pupil only dilates to 7mm, so if we divide the objective lens size by 7 we get the maximum magnification we should have to optimise the light from the objective. For example a 42 mm objective only matches with 6x mag. So most binos are a compromise and good poor light performance is more likely from better glass. The best binos I have used for poor light were 8 x 56 East German Zeiss. Pitch black could still see deer to 300 metres

Yes, the human pupil only dilates to a maximum of 7mm with a few rare exceptions greater than that. However, I doubt whether there would be too many middle age people who's eyes still dilate to 7mm.

An 8x42 will give an 5.25 mm exit pupil which is better than a 10x42 which will only give an 4.2mm exit pupil. Added to that of course is the quality of the glass.

Glass quality and coatings are probably more important that just the raw calc's

if you just use the raw calcs, then by that token a 1950's Zeiss, Swaro, lecia, whatever bino would be the same as a 2020 version.

Also depending what the manufactures are targeting with particular models will affect the performance at some end of the scale too such as last light - there is a huge market in the bird watching and nature markets which may affect how something is setup in a particular brand or model from that brand - Those targeting dusk (hunting) could use a coating with more light transmission, those targeting bird watchers will use a coating that helps with colour fidelity

Originally Posted by 10-Ring

Yes, the human pupil only dilates to a maximum of 7mm with a few rare exceptions greater than that. However, I doubt whether there would be too many middle age people who's eyes still dilate to 7mm.

An 8x42 will give an 5.25 mm exit pupil which is better than a 10x42 which will only give an 4.2mm exit pupil. Added to that of course is the quality of the glass.

I'll let you know in a couple of days. Got some decent 8x42's inbound

Originally Posted by ebf

I'll let you know in a couple of days. Got some decent 8x42's inbound

What did you end up getting?.

Regarding exit pupil for a given objective lens, it is something to keep in mind with vari power scopes, because we can adjust them to the correct mag for the objective size. A lot of scopes have a bump on the adjuster ring that lines up with objective diameter divided by 7 for the maximum magnification with a seven mm exit pupil, for those that don't it is worth putting a dab of white on the ring so we know where to set the scope as it gets dark.

@cameronjackwhite, went with the Trinovids, 8x42

Had a play with them today - low light performance is A for awesome