[ChrisMarshallNY]

That does a fairly good job.

I'm sure that image nerds would poke holes in it, but it seems to work pretty much exactly the way it does IRL.

The noise at high ISO is where it can get specific. Some manufacturers make cameras that actually do really well, at high ISO, and high shutter speed. This seems to reproduce a consumer DSLR.

[arghwhat]

With the disclaimer that I am comparing to the memory of some entry-level cameras, I would still say that it's way too noisy.

Even on old, entry-level APS-C cameras, ISO1600 is normally very usable. What is rendered here at ISO1600 feels more like the "get the picture at any cost" levels of ISO, which on those limited cameras would be something like ISO6400+.

Heck, the original pictures (there is one for each aperture setting) are taken at ISO640 (Canon EOS 5D MarkII at 67mm)!

(Granted, many are too allergic to noise and end up missing a picture instead of just taking the noisy one which is a shame, but that's another story entirely.)

[einr]

Noise depends a lot on the actual amount of light hitting the sensor per unit of time, which is not really a part of the simulation here. ISO 1600 has been quite usable in daylight for a very long time; at night it's a somewhat different story.

The amount and appearance of noise also heavily depends on whether you're looking at a RAW image before noise processing or a cooked JPEG. Noise reduction is really good these days but you might be surprised by what files from even a modern camera look like before any processing.

That said, I do think the simulation here exaggerates the effect of noise for clarity. (It also appears to be about six years old.)

[kqr]

The kind of noise also makes a huge difference. Chroma noise looks like ugly splotches of colour, whereas luma noise can add positively to the character of the image. Fortunately humans are less sensitive to chroma resolution so denoising can be done more aggressively in the ab channels of Lab space.

Yes, this simulation exaggerates a lot. Either that, or contains a tiny crop of a larger image.

[ChrisMarshallNY]

Yeah, I don't think that it's easy to reproduce noise (if it was, noise reduction would be even better). Also, bokeh/depth of field. That's not so easy to reproduce (although AI may change that).

[JKCalhoun]

I think it is excellent as well—that it also demonstrates aperture and shutter priority is a bonus.

I do feel (image nerding now) that its shutter/ISO visual for showing the image over/under-exposed is not quite correct. It appears they show incorrect exposure by taking the "correct" image and blend (multiply) with either white or blend with black (on the other end of the exposure spectrum) to produce the resulting image.

I suppose I am expecting something more like "levels" that pushes all the pixels to white (or black) until they are forced to clip. (But maybe I am too trained in photo-editing tools and expect the film to behave in the same way.)

[kqr]

No, you're correct. I would have expected the highlights to blow out much sooner (for digital) and the shadows to block up much sooner (for analogue). The simulation doesn't portray this accurately, but it gives the general idea!

[1e1a]

Video showcasing ISO noise behavior of a few different cameras: https://youtu.be/iiMfAmWbWSg?t=94s

[nayuki]

Excellent presentation and explanation. I agree with ~90% of it except the small part at 4m54s where he tries to give an answer about the existence of noise. Yes, sensor readout noise and A/D quantization noise exist, but he forgot the big elephant in the room: photon shot noise ( https://en.wikipedia.org/wiki/Shot_noise ). Light is inherently quantum mechanical, and the lower the brightness of a scene, the more that the discrete nature of light shows up in captured images.

Lately I've been researching cameras for astronomy, especially for deep-sky objects (DSOs) like nebulae that require hours of exposure time. The marketing material for these cameras go into a lot of detail: quantum efficiency (the percent chance that a photon converts into an electron), dark noise at different temperatures (fractions of electrons per second), readout noise (usually around 1 electron), and well depth (usually around 10k electrons). Compared to general photography, the astro community much more motivated to explain and keep track of all the sources of noise. Random product example: https://www.zwoastro.com/product/asi585mc-mm-pro/

[ChrisMarshallNY]

That's a pretty good demo!

Very limited camera choices, though.

[1e1a]

Yeah, it would be interesting and useful to see this across many more cameras.

[asdff]

dpreview is good for that. They shoot a test image of every camera on the market, and you can compare specific iso values on the same subject side by side.

[ChrisMarshallNY]

Some of the new Nikon cameras have excellent high-ISO performance. Also, they now own RED, so we should see some interesting stuff, down the road.

[sneela]

I recently bought a film camera (Minolta X-700) and I wasted a whole roll because I inverted the aperture (i.e, 2 = sharp, 32 = blur)...

I'm interested to see how the roll turns out - gave it for development the other day, had a good laugh with the employees though.

I now have a mnemonic for it: Blor - a (somewhat) portmanteau of Blur and low. So low aperture = blur.

Edit for clarification: I mean low number (2 vs 32) = blur

[Toutouxc]

Note that both very high or very low aperture settings also bring their own optical issues. At very low values (big hole) you’re getting hurt by different aberrations (essentially too many paths the same rays can take to the sensor) and at very high values you’re getting hurt by diffraction. At the low end, it’s good to go a little higher than the lens advertises, and at the high end anything over F13-F18 (depending on the gear) is usually quite bad.

[4gotunameagain]

The larger the entrance pupil is, the narrower the depth of field is.

The smaller, i.e. the closest to an ideal pinhole camera, the wider the depth of field is. A an ideal pinhole camera has infinite depth of field.

Unfortunately the aperture f numbers are the wrong way round; larger numbers correspond to smaller diameters.

[tiagod]

High aperture = Blur

Unfortunately the lower number actually means bigger aperture.

[sneela]

And that's what exactly confused me :)

With my mnemonic, I say low *number = blur

I should have been more specific

[Filligree]

The aperture size is usually described as e.g. f/32, where f is a camera-specific constant.

Denominator, not numerator. That's why larger number = smaller aperture.

[armadsen]

To be a little more precise, f is not a camera-specific constant. It's the focal length of the lens. It's a formula that tells you the diameter of the entrance pupil. So at a focal length of 50mm, an aperture value of f/2 means an entrance pupil diameter of 25mm.

But photographers generally just say "f2", meaning an aperture value of two set on the dial of the camera/lens. It's one stop faster (twice as much light) as f/2.8. It'll give you a relatively shallow depth of field, but not as shallow as e.g. f/1.4.

[zokier]

Camera ISO and noise can be really complicated and even contentious topic. One complication is that some cameras are "ISO invariant" and on those cameras afaik it is beneficial to stick to the one or two native ISO values. There is also the whole discussion around ETTR etc

[turnsout]

It needs to be updated to do its calculations in linear light, but it's probably useful for getting an intuitive sense of what the different levers of photography do to an image.