Each pixel basically takes a weighted average of all the light that travels from a pixel-sized area in the world to the lens. As the picture with the dark area shows, this makes the debris form a dark area over a large part of the image. As the f number increases, the weighting gets stronger until 100% of it is a single line from scene to lens to pixel. At this theoretical f/infinity, you'll see all the lens's imperfections in perfect detail since the camera is essentially a pinhole.
The DoF when shooting macro can be fractions of a millimetre.
There is a diffraction limit calculator at the bottom of this page, https://www.cambridgeincolour.com/tutorials/diffraction-phot...
Optics are modeled by differential equations. They describe a massively parallel phenomenon, light waves passing through and being modified by layers of media that, essentially, performs calculations using them. Warps and scales and so on. Clearly these particular differential equations are highly robust to architectural changes.
There's a parallel there to something else I've read about on Hacker News... what are those things called? Oh yeah, deep networks.
Are there any deep nets out there that attempt to mimic optics? or is anyone applying ideas from robust differential equations to deep nets?
Effectively, the lens computes a Fourier Transform for you
One can probably compute a FT with NN, but we already have FFT :)
Our deep SELL offers several possibilities for analog physical implementation. Given
the great demand for fast low energy neural networks, the possibility of harnessing physical phenomena to perform efficient computation in deep networks is worthy of consideration.... (see paper)
See the eighth paragraph of the "An Algorithm For Logarithms" section.
Not really. There's an incredible amount of redundancy on the information received by the lens, because the exposure time needs to be short. The person writing the article purposefully didn't take pictures at higher apertures and different focus distances. Optics aren't modeled by differential equations, and if you want to model optics you need to choose a model that depends on your application. Modelling lens optics with quantum mechanics alone would be a massive pain in the ass, but completely ignoring them would also give you horribly wrong ideas. Also I don't really get by what you mean with "mimicking optics". Mimic which functions exactly?
I learned my lesson and will often use an air spray squishy thing to get rid of dust from the lens.
I don't use lens caps either, but put a clear filter on the lens. Resale value is hurt with scratches...
UV filters though degrade image quality. Why buy nice glass just to put a “protective” filter on it that gets in the way of the image?!
The real concern is decentering the lens by dropping it, but no filter will protect it from that.
I've been saved by an ND0 filter when I bashed the lens against a rock. It destroyed the filter's screw thread but the len's wasn't damaged.
I also once while whale watching got 'steam blasted' by a humpback whale that exhaled while scratching it's back on the boats keel. I was able to quickly unscrew the steamed-up filter and carry on photographing.
Edit - This is also why I religiously use the lens hoods - if nothing else they form a sacrificial protector.
Clear filters can’t hurt IQ other than introducing flare or ghosts in backlighting. It’s possible to crack or scratch your front element with minimal to no effect on your picture; a clear piece of glass isn’t going to do anything.
Or causing fringing, or reducing sharpness, or reducing contrast...
The absolute _best_ that a filter can do to IQ is nothing. But that's basically impossible. Every air/glass interface causes reflections, and no piece of glass is optically perfect. So it's going to hurt your IQ, the question is merely how much, and whether it's worthwhile.
I used to use them. Then I decided I was probably never going to get much of anything reselling my lenses, so I might as well just use them instead of trying to baby them. Haven't had a problem with that decision, but YMMV.
Make sure you wipe the lens with your t-shirt every once in a while.
For some reason, I have almost been 'conditioned' to adopt a 'Everything that we manufactured is really crappy' philosophy---maybe this comes from working too much with software---so it is really nice when you learn about these things.
Also, as an owner of a DSLR, this is news to me, making me less anxious about now having the best equipment for cleaning everything with me all the time.