Bison Bud

Maybe yet another stupid question, but why is it that many, if not most, compact cameras with manual control features only allow one to stop down to around F/8. There are some exceptions with better lenses, but they too generally only stop down to somewhere around F/11. Is this usable F/stop range primarily restricted due to the quality of lens used or is there a physical/design issue due to the smaller overall size that limits this range? While F/8 is usable, does anyone else find this to be somewhat limiting? Thanks for the feedback and good shooting to all.

jerryc41 Loc: Catskill Mts of NY

I think it depends on the camera and the pricing. F/8 has generally been considered a good all-around aperture.

Actually, I don't think I've ever had a com pact camera that was limited to f/8.

mizzee Loc: Boston,Ma

My Tough TG6 offers 3 f-stops: 2.3, 3.2 and 9.

Bison Bud

Maybe I didn't make it clear that I am referring to minimum aperture settings here. Maximum aperture can be as low as F/1.2 and the range is adjustable through the F/8 cutoff. It's the F/8 limit that I find somewhat restrictive and wondered why the fixed lens can't be stopped down any further and if others found this to be rather limiting on their compact cameras.

Ysarex Loc: St. Louis

Just plain old practicality for one. What would you want it for? My compact Canon G7 will only stop down to f/11 as you noted. How many FF camera lenses do you have that stop down to f/32? I have a number of lenses for FF cameras and I just made a quick check of seven of them and f/22 is the smallest f/stop out of the bunch with a couple of them only stopping down to f/16. From the standpoint then of equivalent DOF my G7 compact stops down more than all seven of those FF lenses. Technically f/11 on my G7 is (DOF) equivalent to f/29 on a FF camera.

Now my G7 is a 1" compact which is a big small sensor. Move to an even smaller sensor and if the camera stops down to f/8 like my G7 it will be providing more equivalent DOF than most of what's commonly available for FF lenses.

The other limiting factor is diffraction. As the f/stop gets smaller diffraction kicks in and begins to degrade the image. Diffraction kicks in sooner with smaller sensors and shorter lenses and so we're better off avoiding those real small f/stops if we don't need them. On smaller cameras we need them less.

The photo below I took with my G7 and the f/stop was f/4. I got DOF in the photo I was happy with. To get the same DOF using a FF camera to take the photo I would have had to stop down to F/11. The smaller sensor cameras don't typically need such small f/stops.

(Download)

Bison Bud

Good answer, I guess I hadn't considered the "Equivalent F/stop" due to the smaller sensor. This makes sense as the relationship of the aperture size to the size of the sensor should be a major factor in this relationship. However, this also makes the difference between F/stops much bigger and less useful on the smaller cameras.

R.G. Loc: Scotland

The crop factor applies to the aperture as well as to the sensor, focal length etc, and f/8 is the limit below which diffraction becomes problematic. You'll also find that the lower f-stops provide lots of DOF but not much in the way of separation of the subject from the background.

Ysarex Loc: St. Louis

Or more useful -- depends on what you want to do. I just added a photo to my post above. My wife is a botanist and we're married nearly 40 years and I'm very much in the habit of photographing flowers and plants up close. When you get that close DOF can shrink to a few mm. I like using the smaller sensor cameras hand-held to take those photos. Stop a 1/1.7 sensor camera down to f/4.5 and you've got more DOF than a FF camera stopped down to f/22.

larryepage Loc: North Texas area

For small, short focal length lenses, the very small apertures required to result in f/stops smaller than f/8 or f/11 would be very difficult to achieve reproduceably and economically. And the difference between, say, f/16 and f/22 would be almost indiscernible. Making a mechanism to provide the very tiny adjustments which would be needed would be very difficult and very expensive...not very feasible on a small, comparatively inexpensive camera. So it ends up being mostly a question of what is reasonable and consistent to include on those cameras. Tiny apertures just don't make the cut.

BebuLamar

My Nikon Coolpix 5000 can only stop down to f/8 and that's with the lens zoomed to longer focal length. At maximum wide angle it's only f/5.4 or so.

Linda From Maine Loc: Yakima, Washington

I did controlled tests with my Canon SX50 around six years ago. At wider focal lengths, f/8 offered as much dof as you could possibly want. What negative aspects have you experienced with your compact camera in that regard, Bud? Or are you shopping for one now?

BebuLamar

Yup! f/8 on my little coolpix gives about the same DOF as f/32 on my FX camera.

User ID

You made it clear, no problem.

Tiny lenses just can’t stop down very far before the image suffers. Narrow gauge cine lenses actually close to f22 but IQ is nonexistent in those tiny formats anywho, and not ignoring their slow shutter speed.

I’ve seen early Leica lenses that ended at f11. Sheet film users that shoot at f45 or f64 don’t ask why 35mm lenses end at f16. Minox micros can’t close past f3.5. It’s just normal. Smaller is smaller and size really does matter.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Diffraction becomes an issue at smaller apertures.

PHRubin Loc: Nashville TN USA

As you seem to understand, physical aperture size for any given f/stop depends on sensor size. However diffraction depends on absolute size in inches or mm. So an f/8 on a camera with a small sensor may be as small a physical siza as an f/32 on a full frame. (I didn't calculate the exact comparison).