I was checking out photo camera lenses since Canon has extended their range of RF lenses. I thought it would be interesting to get a macro lens, which was followed by me looking up 'what actually is a macro lens', which seems to include a minimum focusing distance of under 30cm. Turns out the two lenses I do have, which are not marked as macro lenses, are as good or better at macro than lenses especially marked as macro (30cm for the 50mm one, 17cm 12cm for the 18-150mm RF-S one). So I'm getting an ultra wide angle instead (10-18mm RF-S), because that is something I'm missing with buildings and stuff being too big or the streets next to them too narrow. A lens which btw will also out-macro the macros, focusing at 12cm I think 8cm in MF. #Photography
The film X with Jenna Ortega is going to be in cinemas again for one day only in a nationwide fan event on the 18th of June. They don't specify which nation, but I can guess. See their insta post. You're also going to get a sneak peak at the third film in the trilogy, MaXXXine. #JennaOrtega #X instagram.com/reel/C7y28UVsUkF…
Kiran Sonia Sawar is an actress who let's you feel the emotion of the character and the situation so deeply. She's been underrated for so long, it's good to see her in TrueLove doing a major character for a change. Just saw the final episode. #KiranSoniaSawar #TrueLove
As an urban landscape photographer concerned with architecture, I make a extensive use of what are called "shift movements", which are supported by certain cameras/and or lenses. Shift movements are used to avoid introducing geometric distortions (particularly of rectangular objects) that would otherwise be caused by the camera's position with respect to the subject
Suppose we want to make a photograph of a building. We set up our tripod on the sidewalk across the street (which is as far back as we can go) and select a lens for a composition that fills the frame with the building's facade.
We find we have to tilt the camera up in order to get the subject fully in the frame.
In this example, I'm using a 40mm lens (on a 645 format sensor, so that's about like a 26mm lens in 35mm terms).
The subject is the Russian News Agency office near DC's Dupont Circle, a mansion built in 1912. It's not a particularly interesting building, and there's a car annoyingly parked in front, but it will do for our purposes here.
You'll notice the building seems to be falling backwards. The two sides of the building, which are parallel in real life, are converging toward the top. 3/
What happened here? Why doesn't the front of the building look rectangular, the way it does to our eye (and is in reality)?
The problem is we had to tilt the camera up, so it's not parallel to the building. That means the lens projected a distorted image of the building onto the sensor. The top of the building is effectively farther away from the (tilted) camera than the bottom is, and the image correctly reflects that. But it's almost certainly not what we want.
So what can we do to make a photo that correctly reflects the true geometry of the building? We have four options:
- Correct the image in post-processing.
- Move. In particular, move UP, so we can point the camera straight at the building, centering it fully within the frame. This may require being improbably tall, and using a gigantic tripod. Probably not practical.
- Use a wider lens, so we can point the camera square to the building and still show all of it.
Post processing to fix the distortion seems like an attractive option. Modern image software like Capture One and Lightroom have the ability to do geometric transformations on the frame that can correct this kind of distortion.
I used the Capture One "keystone" tool here. It effectively squeezed in the sides of the frame from the bottom, leaving the top as it was.
It's pretty close to the geometry of the actual building.
There are two problems, however. The geometry isn't quite perfect, because the original camera position wasn't actually parallel to the building. The transform can't fix that. It's very close, however, and probably not something someone would notice.
The bigger issue is the transform discarded over 30% of the pixels in the original frame. We have a smaller image than what we started with. Notice how the image looks cropped compared with the original.
Our next option is to move the camera up, so that we can aim the camera parallel to the building (avoiding distortion), but still keep the whole building in the frame.
This would be great if we could do it. Maybe put the camera on a drone. Or hire a bucket lift. Or just be really tall.
this would also provide a dramatically different perspective on the ground level, showing more of the (top of the) car, the sidewalk, etc. But that might actually make it easier to crop out the car from the shot.
Our next option is to use a wider angle lens, so we can keep the camera aimed straight at the building (again, avoiding distortion) and capture the whole subject.
Here, I replaced our original 40mm lens with a 23mm lens.
The building looks good, but what a crappy composition. The big street in front is really distracting.
Since the wide angle image (with the crappy composition) includes a perfectly good undistorted view of the building, we can simply crop it to create a better composition.
Unfortunately, this is less than 40% the size of the original frame. We got a much smaller, lower-resolution image this way.
Our final option (saving the best for last here) is to use our original 40mm lens, but keep the camera parallel to the building and compose the frame by "shifting" the sensor away from the center.
Shift movements require a special camera (or lens mount) as well as a lens that projects a larger "image circle" than required to fill the sensor. For example, 645 (medium format) sensors need about a 66mm diameter image to cover the frame. Lenses for shift project a larger circle than that. 11/
View cameras (the kind with a bellows that make the photographer look like they're from 1890) and "technical" cameras (like the Phase One XT that I use) have shift movements built in. Most other cameras don't, but a few DSLR/mirrorless lenses from Canon, Nikon and others have shift controls built in.
Here, I used the original 40mm lens, but I shifted the sensor down from center by 12mm. This had the effect of moving the frame up, centering the now undistorted building.
There are two disadvantages to using shift. The first is that lenses tend to be sharpest near the center, and so by shifting the sensor you may be recording a less sharp image. Very good lenses designed for shift have to meet very stringent performance requirements.
Which brings us to the second potential disadvantage. Cameras and lenses that support shift cost a ton compared with those that don't. They also weigh a ton and take up a lot of space, and are designed to be used on a tripod.
Whether it's worth using a system with camera movements, as opposed to correcting in postprocessing, is a balance of tradeoffs. These photos took about an hour to make, requiring careful setup (and I could have done better with more care). The equipment is expensive, heavy, and cumbersome.
It's only worth using this kind of gear if you need the particular qualities that camera movements provide. For most photography, it's likely to just get in the way.
Thank you for the thread. In theory I understand the technical side, but in practice it always feels a little bit like magic that moving a lens by relatively little physically (eg, 12mm in your photo) has much of the same image effect as moving the camera much more to be high up on a giant tripod.
(And I guess that a higher camera position would make it so that the photograph was looking down on the parked car, instead of being relatively level with it.)
Production notes: I didn't aim the 23mm image (that got cropped) quite as carefully as I might have; the camera was vertical, but slightly off-axis with respect to the building.
Because we're only concerned with geometry here, I didn't spend much time fiddling with the contrast or exposure. I'd probably make them a hair brighter if I were actually making a serious photo here. And also wait for that damn car parked in front to move.
The building, at 1706 18th St NW in Washington, DC, is an annex to the Embassy of the Russian Federation (and so it's a diplomatic property). The building was originally a private residence, but was sold to the Soviet government in the 1950's. It's currently mostly unoccupied as far as I can tell, but has been used to house state media offices (such as Soviet Life magazine, back in the day).
Addendum: If you're interested in "formal" photo composition, especially for architecture, it's EXTREMELY useful to understand the concepts of zero, one, two, and three point perspective used in drawing and painting.
Students of painting and drawing have to work hard to master using more points of perspective convergence in their compositions. Students of photography, on the other hand, have to work hard to master using fewer.
I’m reminded that there was a time (my time, but who’s counting) when it was routine, for boys, anyway, to be taught mechanical drawing in high school, including isometric and perspective views. My sense is that this is no longer the case, except perhaps tech-specialized schools. And even then, there’s something about working it out yourself with T-square and triangles…
A couple people have asked about my camera setup and how I travel with it. Warning: Long equipment-centric thread follows.
I mostly use the Phase One system, which is built around a very flexible medium format (54x40mm) interchangeable-back sensor mount. This allows me to use a variety of different cameras (DSLRs, technical field cameras, or full view cameras) and lenses. I usually shoot with the “XT”, which is a small (as these things go) field camera with horizontal and vertical movements.
For a while I considered getting the Canon EF-mount tilt/shift lens, but my vision is really not good enough to focus manually and I realized I wouldn't use it enough to be worth the expense, since most of the photography I was doing at the time was either radio towers or the cramped interiors of transmitter buildings. There are only a few transmitter sites that are architecturally interesting, and fewer every year.
i do like your phrasing "shifting" the sensor, in comparison to the normal lens shift. You're selecting where within the lens's image circle the sensor sits.
Obviously use shift. Post looks odd, moving upward would be fine if you had a helicopter, a wider lens includes the photographer's toes, while shift just moves the image circle. This is assuming of course the circle of "good" quality is big enough. imho
“the way it does to our eye (and is in reality)” bothers me. The top of the building is after all farther away, and *should* look narrower, no? (how much narrower depending on how far away we’re standing). A fully shift-corrected image from very close feels a bit wrong to me, the building looming in a way that it does not IRL (again, this is highly dependent on distance from subject). (Huh, digression: interesting ambiguity of “subject” here.)
@profdc9 The Scheimpflug principle has nothing to do with shift. It's used to calculate angles for tilt and swing to keep things in focus on planes that aren't parallel to the sensor.
@mdwray Swing and tilt movements, also found on view cameras, are used to solve a different problem (maintaining focus on across a different plane) from shift movements. Shifts are used to allow you to maintain the geometry of the subject. That's what the thread discusses.
@brooklyn11211 The reason shifting lenses are so expensive (compared with an equivalent non-shifting version) isn't so much the shift mechanism, which is fairly simple, but demands on the lens itself. A lens designed for shift has to project a larger "image circle", so that the sensor can be moved around the projected image. A regular lens only has to project a circle that covers the sensor from the center.
A shift adapter will only work with lenses that already have a large image circle.
@brooklyn11211 You'll notice that most of those shift adapters take medium format lenses (Hasselblad, etc) and allow them to be mounted on 35mm format cameras. Medium format lenses have a large image circle compared with 35mm format, so this allows room for shifting.
@maco that’s a related, but slightly different technique, involving the use of a high perspective and reverse-tiling the lens to create an artificially shallow apparent depth of field. Interestingly, exactly why this works to create the appearance of a miniature scene is not entirely understood.
Dafne was on The One Show (BBC) promoting The Acolyte. I caught only the last minutes of it (and the on demand viewing is geoblocked), but the show posted these pictures to prove it. I did learn that Dafne got an especially small light saber because she's short and kept hitting the ground with the normal sized one. #DafneKeen #TheAcolyte
I thought I had recorded the 1990 version of The Witches, but it turned out to be the newer 2020 one. Having watched it, I'd still much rather would have watched the older one... #TheWitches
She posted the short caption "Instagram", so I repost similarly... Apparently she had a day off from filming and posted some scenic shots of Ireland. Link above. #JennaOrtega
But anyway, we need more things with Stephanie Leonidas in a leading role. She's way too good an actress for all that supporting role, guest role stuff. And then they need to actually release the films to all countries instead of keeping it in the UK/US. #StephanieLeonidas
Stephanie Leonidas posted some photos of an upcoming film of hers on Twitter and Instagram. The posts don't say which film, but she captioned it "Donna", which according to imdb is her character in 5lbs of Pressure. #StephanieLeonidas #5lbsOfPressure
Ok, got a message from Instagram that they are going to put my data into AI (presumably to decrease the I). There's a link somewhere in the message that you have the 'right to object'. Obviously the link is a dead link.
The form now works. That is, the link to the form works. You need to enter (required) how being ingested into AI affects you, so I wrote some stuff. Then you also need to enter your country and email. They send a code to the email, which you need to enter. Then they tell you your country doesn't exist.
After many tries I found the trick: don't pick the name of your country from the auto complete. Fill in the abbreviation like NL. It does accept that. Full force dark patterns... #Meta #Instagram
I was trying to look into a minor issue with my mother's wifi router, but not remembering the password I attempted to log in a bit too much. When it stopped connecting to the internet at all I had apparently broken it completely and I tried to fix it for quite a while. Two resets and reconfiguring later we had finally internet back. Then we read on that internet that there had been a big outage with several service providers where their routes to Google had been broken, many people reporting problems.
So the conclusion is clear: Google's routes run through my mother's wifi router.
This weekend I built a prototype of using FedCM for IndieAuth! This gets rid of the need to enter your domain when logging in to websites using IndieAuth! Demo video and notes here: aaronparecki.com/2024/05/12/3/…
This weekend I built a prototype of using FedCM for IndieAuth! This gets rid of the need to enter your domain when logging in to websites using IndieAuth! Demo video and notes here: aaronparecki.com/2024/05/12/3/…
IndieWebCamp Düsseldorf took place this weekend, and I was inspired to work on a quick hack for demo day to show off a new feature I've been working on for IndieAuth.
Since I do actually use my website to log in to different websites on a regular basis, I am often presented with the login screen asking for my domain name, which is admittedly an annoying part of the process. I don't even like having to enter my email address when I log in to a site, and entering my domain isn't any better. So instead, I'd like to get rid of this prompt, and let the browser handle it for you! Here's a quick video of logging in to a website using my domain with the new browser API:
So how does this work?
For the last couple of years, there has been an ongoing effort at the Federated Identity Community Group at the W3C to build a new API in browsers that can sit in the middle of login flows. It's primarily being driven by Google for their use case of letting websites show a Google login popup dialog without needing 3rd party cookies and doing so in a privacy-preserving way. There's a lot to unpack here, more than I want to go into in this blog post. You can check out Tim Cappalli's slides from the OAuth Security Workshop for a good explainer on the background and how it works.
However, there are a few experimental features that are being considered for the API to accommodate use cases beyond the "Sign in with Google" case. The one that's particularly interesting to the IndieAuth use case is the IdP Registration API. This API allows any website to register itself as an identity provider that can appear in the account chooser popup, so that a relying party website doesn't have to list out all the IdPs it supports, it can just say it supports "any" IdP. This maps to how IndieAuth is already used today, where a website can accept any user's IndieAuth server without any prior relationship with the user. For more background, check out my previous blog post "OAuth for the Open Web".
So now, with the IdP Registration API in FedCM, your website can tell your browser that it is an IdP, then when a website wants to log you in, it asks your browser to prompt you. You choose your account from the list, the negotiation happens behind the scenes, and you're logged in! One of the nice things about combining FedCM with IndieAuth is it lends itself nicely to running the FedCM IdP as a separate service from your actual website. I could run an IndieAuth IdP service that you could sign up for and link your website to. Since your identity is your website, your website would be the thing ultimately sent to the relying party that you're signing in to, even though it was brokered through the IdP service. Ultimately this means much faster adoption is possible, since all it takes to turn your website into a FedCM-supported site is adding a single <link> tag to your home page.
So if this sounds interesting to you, leave a comment below! The IdP registration API is currently an early experiment, and Google needs to see actual interest in it in order to keep it around! In particular, they are looking for Relying Parties who would be interested in actually using this to log users in. I am planning on launching this on webmention.io as an experiment. If you have a website where users can sign in with IndieAuth, feel free to get in touch and I'd be happy to help you set up FedCM support as well!
TL;DR there is a significant amount of context at the start of this issue before we get to the proposal, here is a google doc version for an alternative form. Background The origins of many federat...
Doctor Who series 1 (yeah, I don't know either, second reboot I guess) starts tonight at 18:20 UK time, 19:20 CEST, on BBC One, with two episodes. #DoctorWho
Great interview with Miranda Cosgrove in Bustle magazine, with great photos by Kat Slootsky. She talks about her life and fame and how her life as a celebrity has been somewhat different than others. Miranda's film Mother of the Bride is out now on Netflix.
Apparently I still have an account at Dell, because of ordering a pc several decades ago, so I received their notification of a breach. I'm sorry to say to the hackers that accessed this customer information, that none of it is actual anymore.
Dafne Keen will executive produce and star in a new film called Night Comes. The film's description looks very interesting, being a horror thriller that is both action and character based, set in a world without rules and gender roles. It is further produced by the people behind Get Out.
The two actresses playing sisters trying to survive the horror also rather look like they could be sisters. This explains Dafne's Instagram story of yesterday, where she posted an extreme closeup of her with another young woman, but they looked so alike and it was so closeup, that you couldn't tell who's who. Dafne must have known the announcement was coming today and wanted to skirt around the edges of what the embargo would allow... #DafneKeen #NightComes
Wow. I've had this personal clevo laptop for four years, it's great, the only disappointment is that it doesn't have a display signal over its USB-C connector, meaning I need a separate mini-Displayport cable to my monitor, where all other work laptops can just use the USB-C cable. It not supporting a video signal over USB-C is confirmed both in practice by my monitor, as well as by rereading the specs on the website which I didn't do properly before buying it.
Turns out, four years later, that I just need to turn on this feature in the BIOS? It could do this all along?
The setting is called "DDI to Thunderbolt" which was set to "DDI to mDP". This disables the mini-Displayport (you can't have it both ways) but sends the 'digital display interface' over the Thunderbolt/USB-C connector. This should also allow me to use my MHL cable to watch Netflix on my mother's tv (USB-C to HDMI), which previously involved a more complicated screen mirroring setup with my tablet.
Memory errors in consumer devices such as PCs and phones are not something you hear much about, yet they are probably one of the most common ways these machines fail.
I'll use this thread to explain how this happens, how it affects you and what you can do about it. But I'll also talk about how the industry failed to address it and how we must force them to, for the sake of sustainability. 🧵 1/17
First of all let's talk briefly about how memory works. What you have in your PC or phone is what we call dynamic random access memory. That is memory that stores bits by putting a minuscule amount of charge into vanishingly small capacitors (or not putting it in if we're storing a zero).
These capacitors continuously leak this charge, so it needs to be refreshed periodically - every few milliseconds - which is why it's called "dynamic". 2/17
This design is *extremely* analog in nature. When your machine needs to read some bits the capacitors holding them are connected to a bunch of wires. The very small voltage difference that happens in the wire is detected by the use of a circuit that turns it into a clear 0 or 1 value (this is called a sense amplifier). 3/17
So how can this fail? In a huge number of ways. Circuits age with time and use. The ability of the individual capacitors to hold the charge goes down slowly over time, the transistors in the sense amplifiers degrade, points of contact oxidize, etc... Past a certain point this can make the whole process end up outside of the thresholds required to reliably read, write and retain the bits in memory. 4/17
This can lead to different failures: a very common one is a stuck bit, which ends up being always read as 1 or 0, regardless of what was written into it. Another type is timing-dependent failures, which cause a bit to flip but only if it's not touched in due time by an access or a refresh. More catastrophic errors can affect entire lines - which is what happens when a sense amplifier starts to fail. 5/17
Either way, even a single bit error which happens once in a blue moon is catastrophic to a consumer machine. Sometimes it will cause a pixel to slightly change color, but sometimes it will affect an important computation and lead to a crash. Or worse: it'll cause some user data to be corrupted before it's written to disk, and when it is, the damage has become permanent. 6/17
If your machine exhibits rare but hard-to-explain crashes, or if you're forced to reinstall programs - or even the operating system - because of mysterious failures, or experience random reboots or BSODs, then it's very likely that your memory is failing and you need to replace it. 7/17
Diagnosing it is hard. Windows has a memory diagnostic tool which will catch the worst offenders and is easy to use: microsoft.com/en-us/surface/do…
It's not enough though, some errors can only be caught with more extensive testing. I recommend the open-source memtest86+ (memtest.org/) tool or the closed source memtest86 one (memtest86.com/) 8/17
Optimize your PC performance and prevent slowdowns with Windows Memory Diagnostic and RAM tools. Learn how to test RAM and improve performance with Windows Memory Diagnostic.
Naturally what happens on PCs also happens on phones, network devices, printers, TVs, etc... but you can't test them. This is a disaster because these failures are common, and they become more and more common as the device ages. If we want to have repairable devices that last for a long time, the industry will have to change its practices, but more about this later. 9/17
Now you might wonder: how often does this actually happen? The common wisdom on this topic is that hardware failures are so rare that software bugs will always dwarf them. As I found out this is demonstrably false.
While investigating Firefox crashes I've come to the conclusion that several of the most common issues we were dealing with were likely caused by flaky hardware. This led me to come up with a simple heuristic to detect crashes potentially caused by bit-flips. 10/17
Deploying this heuristic to Mozilla's crash reporting infrastructure has been eye opening: if I take the 10 most common crashes on Windows, 7 are out-of-memory conditions - that is, not bugs - and 3 are likely caused by bad memory.
You've read that right, three out of the ten most common reasons why Firefox crashes on Windows are caused by memory that's gone bad. 11/17
Now there's a few things that are worth mentioning: users with bad hardware will be over-represented in this category, their machines will crash far more often than others.
The second thing is that Firefox is exceptionally stable, we've driven down its crash rate by more than >70% in the last few years. But Firefox is also a 30 million-lines-of-code monster. There are bugs in there, but they're less common than hardware failures! 12/17
Plotting these types of crashes against time yields interesting trends: the more machines age the more likely they are to encounter hardware-related failures. You might think that's obvious, and indeed it is, but until now the industry has looked the other way, based on the hand-wavy excuse that hardware failures were less common than bugs. 13/17
So what needs to change? First of all, error detection and correction must become commonplace. You can already build a desktop machine with ECC memory (en.wikipedia.org/wiki/ECC_memo…), but it's uncommon in laptops, even mobile workstations, and completely absent on phones and other consumer appliances. This will measurably lengthen the usable life of these devices. 14/17
Really depressing that we've reached the physical limits of creating "memory we're confident that actually will store it's value reliably" :(.
We've went from PARITY CHECK 1/2 to "memory works fine without detection or correction" to "oh now not even parity check is enough". In that sense, it's WORSE than 40 years ago :P.
Note that detection is more important than correction. The user needs to know that there's something wrong without having to run a memory testing program. Think of the lights that turn on in cars if something's malfunctioning, or the error beeps that your washing machine makes when it thinks it's leaking water. These are extremely common, they need to be on computing devices too. 15/17
Finally hardware design must change to make devices repairable and prolong their useful life. Yes, I'm looking at non-ECC memories soldered on the motherboard or worse, on the same substrate as the CPU. 16/17
To end the thread I'd like to thank my colleagues Alex Franchuk and @willcage who did the implementation work and my boss Gian-Carlo Pascutto who plotted crashes against machine age. I'd also like to point out that we've got preliminary data on the topic, but I fully intend to write a proper article with a detailed analysis of the data. 17/17
Also many of the machines just had simple software. Something like AppleSoft BASIC was just easier to keep bug-free (ish) than the giant software of today.
The same size/complexity software is more reliable today, but what they actually shipped was much smaller and simpler.
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Gidi Kroon
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