what magnification

[granddad john]

Hi All, This is a really basic question which I feel I should really know the answer to ( terrible grammar, I know) but somehow I don't. I have binoculars, 10*40, and a scope *25-*50 on a 65mm objective. Fine. How do you work out the equivalent magnification on a camera lens. I remember that 55mm is about equal to our normal field of view, but is this relevant in this equation? If someone can help me or point me in the right direction I'd be grateful. thanks John:bonk:

 

[HoppyUK]

Hi All, This is a really basic question which I feel I should really know the answer to ( terrible grammar, I know) but somehow I don't. I have binoculars, 10*40, and a scope *25-*50 on a 65mm objective. Fine. How do you work out the equivalent magnification on a camera lens. I remember that 55mm is about equal to our normal field of view, but is this relevant in this equation? If someone can help me or point me in the right direction I'd be grateful. thanks John:bonk:

Hard to compare exactly, as you have to take viewfinder magnifcation into account and things like field of view.

But roughly, a 50mm lens on a DSLR usually presents about a life-size image to the eye, ie 1x magnification.

The binoculars are 10x magnifcation, and it looks like you have a zoom scope with 25-50x magnifcation. So a 500mm lens to match the binoculars, and a 1,250-2,500mm lens to match the scope (assuming I've understood your numbers correctly).

 

[granddad john]

Thanks Richard, I sort of thought that might be it, but that makes a hell of a lens to equate to even the lowest mag on a telescope and if these huge Canon lenses I see machine gunning away when out birding now only give the eqivalent of my binoculars, then there must be a fair amount of cropping going on! Thanks again John

 

[Alastair]

Hard to compare exactly, as you have to take viewfinder magnifcation into account and things like field of view.

But roughly, a 50mm lens on a DSLR usually presents about a life-size image to the eye, ie 1x magnification.

The binoculars are 10x magnifcation, and it looks like you have a zoom scope with 25-50x magnifcation. So a 500mm lens to match the binoculars, and a 12,500-25,000mm lens to match the scope (assuming I've understood your numbers correctly).

Sure there isn't an extra zero in the second set of figures?

10x 50mm = 500mm

25x 50mm = 1,250mm
50x 50mm = 2,500mm

 

[HoppyUK]

Thanks Richard, I sort of thought that might be it, but that makes a hell of a lens to equate to even the lowest mag on a telescope and if these huge Canon lenses I see machine gunning away when out birding now only give the eqivalent of my binoculars, then there must be a fair amount of cropping going on! Thanks again John

Yes, often a bit of cropping. It's the only option when you've run out of lens focal length. But the trick with birding is to get close. Field craft, and patience, are at least as important as heavy weapons.

Edit: crossed posted with Alastair. Haha! Yes! thanks for correcting. I've edited my original post

 

[Alastair]

Never underestimate fieldcraft, you can get quite close to even timid birds* with a bit of thinking and if you're putting the time into just one shot rather than tickboxing a county in a day.

*anyone for Jays with an 85mm.. ..

 

[SLRUser]

Never underestimate fieldcraft, you can get quite close to even timid birds* with a bit of thinking and if you're putting the time into just one shot rather than tickboxing a county in a day.

Best advice ever...

...a few years ago I was speaking to a pro wildlife photographer and he said that the most important thing is to focus on getting one really good photo instead of lots of mediocre photos.

 

[hollis_f]

How do you work out the equivalent magnification on a camera lens.

It depends on how big you print the final image.

When using a 420mm lens I get an image that's about the same as through my 8.5x bins - similar to the image on the left below. But I can take that image and blow it up to virtually any size - like the one on the right.