Quote:
Originally Posted by firebox40dash5
You need to check your math. Aperture is not linear, and going from f/4 to f/1.8 is actually 2 1/3 stops. That means a shutter speed over 4 times as fast to keep the same exposure.
As for getting adequate DOF, that depends on the distance you're shooting at. A 35mm at f/1.8 and 8' from the subject has >1' of DOF, which is plenty as long as you can focus quickly.
Edit: The max aperture with the 18-105mm (or 16-85mm, and probably 18-200mm also) is f/4.5 @ 35mm, and f/5 @ 50mm. So the actual difference is 2 2/3 stops for the 35mm, and 3 stops for the 50mm, assuming you're comparing the f/1.8 versions.
|
The post still stands; from my experience with similar subjects and the kit the OP has I find the flash more valuable and the benefits of a prime negligible at best.
A prime gives you more light but at the cost of framing flexibillity and DOF, both of which you need in spades. Once you've stopped the prime down you're at the apertures you had in the zoom, only without the capability to zoom any more and no VR. Flash isn't without it's drawbacks (you have to learn to use it properly), but off-camera the speedlight is going to be a heap more value than the glass.