© 2006 KenRockwell.com
VR versus Fast Apertures
Which is sharper: a fast shutter speed from a fast aperture like f/1.4, or a longer shutter speed and VR?
VR in the 18 - 200mm VR claims a 3 - 4 stop advantage, which is exactly the advantage of f/1.4 over the f/4.8 of the VR lens at 50mm.
VR is of no help if your subjects are moving. Go for the faster lens.
What if you have a still subject and no tripod? Will the added depth-of-field of the slower lens add sharpness lost with the larger aperture?
The only way to see is to make some shots. Here is a full frame from the Zeiss f/1.4 at f/1.4 and 1/50 second, the slowest suggested speed from the old wives' tales with a 50mm lens. I also shot the same thing with the 18 - 200mm VR at 50mm, at 1/5 of a second.1/50 at f/1.4 is the same exposure as 1/5 at f/4.8.
Roll your mouse over to see the result with the VR lens.
Full frame comparison (roll mouse over image to see other lens)
100% crop comparison (roll mouse over image to see other lens)
The VR looks much better to me due to deeper depth of field and much better contrast. VR worked to get sharp shots at 1/5 of a second.
I shot each at the slowest speed at which I could get decent results.
I usually fire three rounds per burst in low light, but gave it five per lens to get a really sharp one. This technique comes from the fact that camera shake is a random event. Make enough shots if you're on the verge of shake and you'll get a sharp one. I usually fire three rounds and cherry-pick when shutter speeds get low. I leave my fire selector in AUTO, or Cs. Press once for one shot, hold for more. It's easy to sort out later, if you have the right software.
This process, best of five, is much fairer than making one shot each and hoping for the best. Shake is random, and this process gives me the most accurate representation of repeatable results in the field.
I got results with no motion blur for both lenses, hooray!
The differences I do see are the static results I would expect. The VR lens has better image quality wide open than any of the f/1.4 lenses. Every f/1.4 lens has a lot of veiling haze from spherical aberration. This lowers the contrast significantly. The VR is fairly sharp and very contrasty wide open, so it's sharper.
The VR at f/4.8 has much more depth of field than faster lenses at f/1.4. If I shot flat targets I'd be working in a library. In the real world things are 3-D, and the nonexistent depths of field of the f/1.4 lenses are big strikes against them. You can see this in both shots above.
In this case the VR is the winner. It's sharper, contrastier and has better depth of field. If the subjects were moving I'd opt for the f/1.4.
In brighter light the differences go away.
I didn't try in dimmer light. In dimmer light both lenses start to have visible camera shake. The VR lens probably starts to lose its edge as the exposures get closer to a full second or more. I didn't try it. It takes hours to line up and process results even from this crappy example shot of a fake elephant.
VR really works. It lets the 18 - 200 VR get the same or better sharpness for static subjects as an f/1.4 lens.
No, Nikon doesn't pay me anything or even loan me gear. This is what I've discovered trying this out for myself.
I spent almost two months shooting and writing this comparison of 50mm lenses. No one pays me for this. If you find this as helpful as a book you might have had to buy or a workshop you may have had to take, feel free to help me write more with a donation.
Thanks for reading!