Focal length 35mm equivalent, but not F-stop?

Started Jul 24, 2014 | Discussions thread
JBurnett Contributing Member • Posts: 835
Re: A Camera Club Perspective

Erik Magnuson wrote:

JBurnett wrote:

  • I would estimate that 35 of them purchased their APS-C cameras with the kit lens, and had no concept of equivalencies at the time.

YMMV. In my club 35mm equivalent focal lengths are mentioned often. If your members had compact cameras previously, I'll bet almost none of them could have told you the actual focal length of the lenses. If anyone said "mm" instead of "3x", they would have used equivalence.

A good point. In my former club in the big city, a larger percentage would be technologically savvy. The average age would be younger as well.

  • Maybe 10 understand that there is a difference in depth of field between their camera and cameras with larger or smaller sensors. Only 3 would know where to go to calculate that equivalence (or would ever care to do so).

Again, I'll bet most actually do know this intuitively -- it's obvious when they use their cell phone camera. Or when they compare the results to their previous compact camera.

Well, hopefully, there will be more, as I and another member are doing presentations on DOF and ISO this coming season. And the impact of sensor size will be addressed. The difficulty will be making the presentation short and entertaining enough to keep everyone awake.

  • Most members understand that if a light meter says f/4 at 1/60 at ISO 200 on one camera, they could use the same settings on a different camera

Since you say they mostly have similar cameras, that's reasonable. But would you tell the compact camera user to use ISO 3200 @ f/4 like the APS-C kit users?

Not at all. Given the relatively low light your example suggests, I would suggest shooting with the largest aperture and the lowest ISO possible. If a tripod could be used (assuming it was available and appropriate), then base ISO and use the camera's self-timer to release the shutter. If handheld, then I might ask about the need to capture action, the "equivalent focal length"; and the existence of image stabilization. From these I might suggest a reasonable shutter speed, and set ISO to give an appropriate exposure. Of course, there may be situations where the resulting image would be unsatisfactory (and a discussion about camera limitations/sensor size would ensue).

As I said, about half the members have already figured out the higher-ISO greater noise relationship (which I will cover in more detail this year). And we'll cover DOF in more detail in the coming season as well. But, in general, we don't speak about actual numbers when talking about pictures. There's more chat about "I used a wide aperture for a shallower depth of field" or "I used a fast shutter speed to capture the action" or "The image is noisier because I had to bump my ISO higher to get a fast enough shutter speed for hand-held. When someone says "Yeah, but why can't I get that shallow depth of field on my camera?", then it may be time to talk DOF and sensor size.

  • Only one person in the club really cares about equivalencies, because he shoots both full-frame and APS-C bodies at the same time.

Or if he has to talk to the APS-C users.

Nah. He only talks to me (a micro-4/3 user) about stuff like equivalencies. And when we do talk tech, everyone glazes over moves away.

  • The majority of time I've been drawn into a discussion about equivalencies, it has been a newer member who wants to move from a P&S to a DSLR or mirrorless. Equivalent focal lengths to what they see with their existing camera makes sense to them.

The differences in noise or DOF never comes up?

It depends. Often noise or the desire to have more control of DOF (eg. a shallow depth of field for portraits) is at the root of considering a larger-sensored camera. And, inevitably, the user wants a camera and lens(es) to cover the same range as the compact. And when that compact is a bridge superzoom, it's going to be a longer chat.

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