canon – How to remove external flash stuck on camera body?

I’ve had the same problem recently with my Canon flash not budging when I tried to slip it off the hot-shoe of my Canon 40D body. I’m afraid I did use a lot of force to get it off… but I think it’s still OK. And I think I’ve figured out the problem.

After reading the answers here, I took the ring-flash and… while staring at the bottom plate… began turning the tightening-ring back-and-forth between the extreme “tightened position” and the extreme “loosened position”. In doing so, I could see the (forward-most, round) pin slowly go up and down. Seeing that, I now understand the (simple) mechanism that helps secure the flash to the body and keeps it from sliding off the hot-shoe.

When the circular tightening-ring at the bottom of the flash is fully loosened, the round pin is flush against the plate… and as the tightening-ring is tightened, the round pin begins to raise.

My mistake was not turning the tightening-ring to its fully (extreme) loosened position before attempting to slide the flash off the hot shoe! I was under the naive impression that the “cinching down” produced by the tightening rings is what held the flash in place. So, when removing the flash, if I turned the ring enough so that the flash looked and felt loosely-cinched against the hot-shoe, I figured I could slide it off. Not so!! Because the round pin only becomes flush with the base of my flash when its turned all the way to the completely loosened position.

Camera settings/features are disappeared

There is a Samsung A01 whose default camera settings are like this:

default camera settings

But for some reason, some camera settings/features located at top bar are disappeared. Does anybody know why? How can I restore it?

enter image description here

exposure – luminance range for camera

According to this article, luminance is proportional to pixel measurements via the following:
L=frac{N_d, f_s^2}{K_c, t, S}; ; (1)

N_d is pixel value
f_s is fstop
t is exposure time
S is ISO
K_c is a camera constant

If we shoot the same scene with same ISO and fstop, but change exposure, luminance is constant, and we can use a slope equation:
L=frac{Delta N_d, f_s^2}{Delta t, K_c, S}; ; (2)

From wikipedia, EV is related to Luminance like so:
EV=textup{log}_2left ( frac{L, S}{K_1}right ); ; (3)

Where K_1 is another constant.

Combining (2) and (3) yields the following:
EV=textup{log}_2 left (frac{Delta N_d}{Delta t}frac{f_s^2}{K_1, K_c} right )

If we were to take the difference of EV values, we would get the following formula:
EV_2-EV_1=textup{log}2 left (frac{Delta N{d_2}}{Delta t}frac{f_s^2}{K_1, K_c} right )-textup{log}2 left (frac{Delta N{d_1}}{Delta t}frac{f_s^2}{K_1, K_c} right ); ; (4)
We can use this property of logs:
textup{log}_ax-textup{log}_ay=textup{log}_aleft (frac{x}{y}  right ); ; (5)
From (4) and (5) we get the following:
Delta EV=textup{log}2 left (frac{Delta N{d_2}}{Delta N_{d_1}} right )
Equivalently, the following:
2^{Delta EV}=frac{Delta N_{d_2}}{Delta N_{d_1}}

For a pixel with 256 possible values, the max value of the right hand side approaches 256. My question is this: Since 2^8=256, for a given image, it seems like the maximum range we could theoretically see across it is 8 EV.

Is this correct? I realize that in equations 1 and 3, L is technically the average scene luminance, but if our scene were reduced to a single pixel, the math should be correct. Or am I applying something horribly wrong?

Thanks much!

Camera settings are disappeared

There is a Samsung A01 whose default camera settings are like this:

default camera settings

But for some reason the camera settings located at top bar are disappeared. Does anybody why? How can I restore it?

optics – tele lens for IP camera

I need to keep an eye for wild animals on a relatively small spot at 60ft distance. My plan is to gut an IP camera and construct an adapter for a tele lens, and a “birdhouse” housing. I am experienced with 3d design and printing, and in fact I have already made some prototypes (final designs will be made freely available on GrabCAD)
However, I need advice on which camera to use. My parameters are as follows:

  • Since I am going to gut the camera and keep only the sensor and
    circuitry, it should be inexpensive
  • Connection must be via Wifi
  • Video stream should be compatible with good, stable software
    (motion-triggering, scheduled recording, etc.).
  • I also need some advice on suitable software!

many thanks for any feedback you might have!

cam housing

cam adapter

unreal 4 – Make my Character face the same way as my Camera as I rotate the camera

Before posting, I’ve already tried parenting the camera to the Character mesh head and setting controller yaw, that didn’t work, in fact it invalidated my blueprint to set my Mouse X and Y for the pitch and yaw that allowed me to move my camera in the first place. So I need a different method to make my character follow the way my camera is facing whenever I rotate, otherwise when I turn around I just face my Character.enter image description here

camera settings – Do professionals use auto mode?

“Auto” can mean a wide range of things.

Most DSLRs offer a “full auto” facility that tends to manage shutter speed, aperture, ISO and more. But most of the modes on a DSLR that are other than absolute manual mode offer a substantial automated component. And even “Manual” may have auto features lurking in the shadows (literally in some cases).

Your friends are correct to the extent that you will definitely be missing out on achieving the most that a camera system can offer if you use auto always — and certainly so if you are unable to use any other mode — but there are occasions when auto or something close to it makes sense for many people.

Full Auto:

Some professionals use “auto” a large portion of the time. They would be in the minority.

Some use it occasionally, but seldom.

A hard core few would never use a full auto mode. You may well learn things from them but in most cases probably do not want to copy them — a Grand Master black belt 1st class may be wedded to the pure artistry of pure manual — but a top pro will use whatever tool does the job best/easiest/cheapest/quickest (choose some) and if that’s full auto in some cases, so be it.

A postcard photographer with a tripod mounted camera, who sells photos to tourists may very much be a true professional (by definition) and if the modern magic toy’s full auto mode invariably delivers the goods, then using full auto may be sensible.

A high profile web equipment reviewer and advice giver and shoots-photos-for-$ man (who I will not actually name) said some while ago that he always used auto mode as the cameras have got so good that they know best. I was very surprised, and this may not reflect his reality.


Most modes that a modern DSLR offer are semi-automatic, with some of the settings being adjusted by the system. If the camera can adjust at least something independently of the user’s actions then it is at least partially “auto” – see below.

Aperture priority mode allows the user to manually set the aperture and then adjusts the shutter speed to suit the required exposure. ISO may be set by the user or the user may specify a range of acceptable ISO values, allowing the system to adjust ISO within this range. Some systems also allow the minimum auto-settable shutter speed to be controlled. Your don’t-use-auto friends probably do not count all that as auto. It certainly is.

Similar applies to shutter priority where you set the speed and the system manages aperture and other settings.

“Manual mode” MAY allow dlighting or dynamic range optimisation to be carried out on a manual frame.

Sony’s top APSC camera – the A77, allows “dynamic range optimisation” in manual mode. (I just tried it to see). DRO is auto with a vengeance – comple signal processing is applied variably as required across the frame – that’s “auto”. The A77 it also allows in-camera 3 frame HDR — that’s also auto.

I bought a Nikon D700 yesterday 🙂 … quick check … You can adjust the DLighting setting on manually setting frames after the photo is taken — suggesting that they are indeed applied at the time.

Personal comment: I’d perhaps be described as semi professional — if you don’t count my time as worth anything then the obsession comfortably pays for the equipment. This does not make my wife too much happier :-). I take photos for my enjoyment and if others enjoy them too I’m pleased. If people enjoy what I do and how I do it enough to pay me to take them at an event etc for $ then I may agree. Works for all of us, so far.

So — I almost always use aperture priority mode — sometimes with auto ISO, but usually I prefer to have ISO under my control. It can be changed VERY rapidly on the A77. I also use memories for gross setting changes – which is also automation, even if the settings are manual ones, and then “play” around the memory produced settings. This allows eg rapid change during a wedding reception between ambient light no flash mode (large aperture, higher ISO, appropriate white balance) and flash photos (smaller aperture, lower ISO, white balance change.) Manually swapping between those memories is essentially an “auto” feature.

Very occasionally I try full-auto — usually “just to see what it knows” in a given situation.

I use AF largely but will drop into manual focus when apposite — either for one frame with AF/MF button or for a series of shots when needed. AF is “auto”.

I usually use multi segment metering but may swap to center weighted or spot if appropriate. All those are “auto”. The Sony Pellucid mirror cameras have the best live view in any DSLRs (the A77 utterly trounces my now 4 year old D700) and I frequently adjust lighting level on the fly with exposure compensation between shots based on the appearance of the live view screen. Sony make this extremely easy with control placement. Doing this is a MANUAL action standing on top of auto.

For critical focusing on the A77 I may swap to manual focus, then press the AF/MF button which autofocuses the camera, then release AF/MF so I am in true manual focus mode and use the focus magnifier to produce focusing as the lens is capable of – a superb capability. All that is a true manual MF mode sitting on top of an auto AF platform.

I’ll use full manual mode on occasions when nothing else works. Occasionally things change so rapidly in a complex way that the brain is best at keeping up – and sometimes things change so little that manual is best. (Tripod and portraits.) Some years ago we did a large amount of driving in Europe. With several drivers in the car I was able to spend most of the time taking photos of the sights. We could not stop at all the places I would have liked to take photos of – this was a practical necessity in a most enjoyable situation. SO even when driving through eg a small German village that was not on our can-stop list I had to make the best I could of the situation. I had a top camera with the equivalent of a live view LCD AND an electronic EVF (and in real terms then cost more than the top ADSC DSLR now!). In the countryside I’d use aperture priority semi-auto. In villages I’d use full manual – aperture, shutter speed (and sometimes focus). Delve (optically) down a dark alley way – shutter speed to minimum safe, aperture to suit, zoom into alley, click, cafe table in sunlight – go on shutter up, aperture down, zoom back, click click, next …

A mix of manual and auto used to advantage. You want to get to know your camera well enough to do this. Then use it on full full auto mode when it suits 🙂

mac – Show icon to indicate microphone and/or camera are being used

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unity – How to set off Cinemachine camera shake during an explosion

From the docs:

Use the Cinemachine Impulse Source component to generate impulses on events that are not collisions or Collider triggers. This is a generic Impulse Source that exposes a family of GenerateImpulse() API methods. These methods generate impulses at the specified locations and with the specified velocities and strengths. Call these methods directly from your game logic, or use them with UnityEvents.

So, place an Impulse Source component somewhere in your scene. It can be part of the explosion effect prefab you spawn on demand, or a persistent scene object that you trigger at the same time you spawn the explosion.

Make sure its range/dissipation distance is quite large, so your camera can “hear” the explosion from a long distance away.

To cause the shake, call one of this component’s GenerateImpulse() methods, or GenerateImpulseAt(position of explosion, Vector3.up) if the component is attached to an object away from the actual explosion site.

FaceTime HD camera stops transmitting live video in Catalina — how to fix?

At some point in Catalina’s evolution (10.15.5+ ?) situations started recurring where there’s no video with the Thunderbolt Display attached and the MacBook Pro in closed clamshell mode when attempting a videoconference via FaceTime or other videoconferencing app (Skype, Zoom, etc). What is strange is that the Display FaceTime HD camera is selected and the green LED is illuminated. I also tried disconnecting the Thunderbolt Display to see whether the MacBook Pro’s built-in FaceTime would transmit live video — and it did. But then there was no audio! I was able to reconnect the Thunderbolt Display to regain audio, but of course there was no live video.

The workaround for this problem is to restart the computer.

Has anyone else seen this problem, and is there a fix besides restarting?