Tuesday, March 11, 2008

Digiscoping: Magnification?

What kind of magnifications can I get?

Digiscopers like Mike McDowell have come up w/ a formula for calculating the approximate magnifications capable with a given digiscoping setup:

EFL*=(FLc/35mm)*EPmag*50mm

where


EFL = Effective focal length of digiscoping rig
FLc = focal length range of P&S camera (mm)
Epmag = Scope eyepiece magnification
50mm = equivalent 35mm camera magnification (1X)

So, for example: a Nikon Coolpix P6000 w/ 24-112mm lens range at 112mm (4x) on a Zeiss 20-60x eyepiece at 20x would give EFL = (112/35)*20*50 = 3200 mm! The total range of magnification for this rig is ~800 - 9600mm!  or 20 - 240X!

With mirror less cameras becoming more popular with today's digiscoping rigs, one can get a magnification using this simple formula:

EFL* = EpMag * CFcamera * FLc

where CFcamera = crop factor of camera.

So, for a Nikon V1 w/ 10-30mm lens at 30 mm on a Zeiss 85T*Fl and 20-75X Vario Zoom eyepiece at 75X one can get an effective focal length of 75*2.7*30 = 6075 mm!

But do yourself a favor and work at the lowest magnifications on the camera (14-18 mm) and scope (20-30X) for sharpest images and most keepers.

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