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More detail/resolution with 10x versus 8x? (1 Viewer)
- Thread starter Ostracod
- Start date
wdc
Well-known member
Thanks for those 'affordable' recommendations Chuck! I trust Zeiss at 18 and above, and Swaro at 20mm, if their specs hold true from model to model with varying objectives and magnification. For example, the Swaros in 8x32 and 10x42. The ER is spec'ed the same on paper, but does that hold true?
oldfortyfive
Well-known member
wdc
Well-known member
looksharp65
Well-known member
Well you know, the linear magnification is indeed 10/8 = 1.25x greater,
but the areal magnification is (10/8)^2 =1.5625x greater.
Thus, the image of an object viewed in two dimensions (width*height) is 56% bigger with a 10x binocular compared to 8x.
I still don't fancy the 10x anymore. I have explained this extensively in other threads years ago.
//L
oldfortyfive
Well-known member
Jack Speer
Well-known member
Thanks both for the explanation.
This reminds me of field of view. Looking at some "standard" numbers, a 115m FOV of a 10x versus a 133m FOV of an 8x (at 1000m) does not seem like a huge tradeoff, but that is only a linear measurement. Find the area of the circle for both of these diameters and it is quite a dramatic difference.
looksharp65
Well-known member
And to further complicate things, the FOV is not a circular disc viewed at 1000 meter, it's a cone and as such three-dimensional.
With a wider base comes a wider angle and hence a greater volume. Even what can be seen within the cones varies due to the difference in depth of field.
The depth of field is in this way a movable transversal slice of the cone.
It's not wrong to say you see more with lower powered binoculars!
//L
For astronomy often the 10x shows more than the 8x.
In the examples given, a 6.6 degree 10x field and a 7.6 degree 8x field the AFOV of the 10x is about 10% more linearly, 20% area.
In addition the 10x shows fainter stars assuming same apertures and transmission.
For birdwatching most seem to choose 6.5x to 8x although some use higher powers.
In the examples given, a 6.6 degree 10x field and a 7.6 degree 8x field the AFOV of the 10x is about 10% more linearly, 20% area.
In addition the 10x shows fainter stars assuming same apertures and transmission.
For birdwatching most seem to choose 6.5x to 8x although some use higher powers.
looksharp65
Well-known member
Here in Sweden, most hardcore birdwatchers seem to favorise 10x42 or SV 10x32. I can understand their appeal, but the features of 7x/8x (brighter or smaller, larger FOV, deeper depth of field, less shake) outweigh the wow effect of the 10x.
For astronomy, I understand it's different.
//L
looksharp65
Well-known member
B 
Hermann
Well-known member
Hermann
Well-known member
Over here it's 10x42. And yes, in some situations the difference between 10x and 8x (or 7x) can make the difference between getting an ID or indeed not getting it.
Hermann
