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MotoCroz
7th April 2010, 06:42 PM
Just wondering if anybody knows what the lens equivelent of 10x binoculars is/are in 35mm terms. Or if there is a conversion equation.
*chr Paul

Dogcow
7th April 2010, 08:14 PM
You should do the conversion trough the FOV (field of view).

So if you know the FOV of the binoculars, you can find the corresponding FOV for a 35 mm lens

JerryE-1
8th April 2010, 07:09 PM
I'm pretty sure 10x bins equate to a 500mm lens in 35mm terms.

Jerry

David M
8th April 2010, 09:45 PM
I'm pretty sure 10x bins equate to a 500mm lens in 35mm terms.

Jerry

I seem to think 45mm equates to 1x so 10x bins equate to a 450mm lens in 35mm terms.

That meant my 8x bins had roughly the same magnification as my 350mm OM Zuiko (8x45=360) in my 35mm film days.

crimbo
9th April 2010, 04:08 PM
250mm on my 70-300 gives the same FOV as my 8x42 binos so empirically in 35mm terms I would say 500mm is about 8x

JerryE-1
9th April 2010, 05:52 PM
Sorry Paul, now you've got three different answers so you'll be even more confused than before:confused:

Jerry.

David M
10th April 2010, 12:31 AM
Sorry Paul, now you've got three different answers so you'll be even more confused than before:confused:

Jerry.

I was comparing magnification not FOV. The FOV between different bins can vary greatly.

JerryE-1
10th April 2010, 12:41 PM
Sorry David, I wasn't implying that my answer was the correct one, just that it seems to be a bit tricky coming up with a chapter and verse way of equating 35mm lens focal length to binocular magnification.

As I understood it, 50mm was the rough equal of 1x magnification irrespective of the field of view, and the FOV just gave an indication of light gathering ability, with 7x50 bins being better for low light than say, 10x40.

Having had a search on the net, I now realize there is more interaction between magnification and FOV than I realized, and the subject is quite a complex one. All I know is that my 7x50s are better suited for use on a small boat than higher magnification bins.

Jerry.

David M
10th April 2010, 01:19 PM
Sorry David, I wasn't implying that my answer was the correct one, just that it seems to be a bit tricky coming up with a chapter and verse way of equating 35mm lens focal length to binocular magnification.

Jerry.

I realize that.

I was just making the point that comparing FOV can be misleading given that 6 different pairs of 8x bins could all have different fields of view.

As I understood it, 50mm was the rough equal of 1x magnification irrespective of the field of view, and the FOV just gave an indication of light gathering ability, with 7x50 bins being better for low light than say, 10x40.

The 50 or 40 in the bins specs give the indication of light gathering ability. Combined with the mag it also gives you your exit pupil diameter, 10x40 giving you a 4mm exit pupil diameter and 7x50 a 7.14mm exit pupil diameter.

MotoCroz
12th April 2010, 07:30 PM
Definatly sorry I asked. We where out walking using the misses binocs and just wanted to get a rough idea. It seems as if 500mm it is or a 250 in my case.
Thanks anyway :)