Video – Android: Capture the front and back of the camera and save them in separate files

As a title, I would like to record both the front and the rear camera simultaneously and then save them in separate files. I'm writing code based on the Android example Camera2VideoJava. Instead of using MediaRecorder, I use MediaCodec to encode to a h.264 file. Then I read the file and decode it into the mp4 format. The preview of both cameras was fine, but when I tried to start coding, the application ran for a while and then crashed. The errors appear in the logcat:

A/libc: Invalid address 0x7e9d4ec880 passed to free: value not allocated
A/libc: Fatal signal 6 (SIGABRT), code -6 (SI_TKILL) in tid 20876 (CameraBackgroun), pid 20843 (id.camera2basic)

My question is: Is there still the possibility to record both cameras and save them in separate files?

Thank you very much.

repair – Olympus OMD 5 mark I: The camera is frozen when focusing during macro shooting. Can not switch it on anymore

I have an old Olympus OMD 5 Mark I which is in perfect condition. I use it to practice my photography and look cool.

I tried to take a macro shot. with the target a bit too far, so I got involved until it could focus.

The camera then froze with a picture in the viewfinder. After that, no button would work anymore. So I decided to turn it off and turn it back on.

Nothing, no sound, no lights, nothing. I tried to remove the lens and the SD card and turn it on, no luck. I tried to insert, remove and replace the battery but no luck. I went home, recharged the battery overnight, and put it in the morning. Also no luck.

So I went to a camera shop, they put in a new battery to test, no luck. You put my battery in another camera and this camera is on, so definitely not the battery.

At this time, it is most likely a stupid idea to send the camera for repair, as it costs more than it is worth. So, is it possible to fix it yourself if someone has an idea of ​​where the problem might be? I mean, if I destroy the camera while trying to fix it, there's no problem because it's a sitting stone as it stands (useless).

Any ideas, what could have broken, if reparable, and how to do it?

Light modifiers – How can I reduce the flash output of my camera so that my subjects are less disturbed?

I know this seems like a stupid question, but I wanted to know how to literally weaken the light of my lightning. I make photos of a prayer group at night, and generally it's very dark, but people are also moving quite a bit, so a short shutter speed is required. So I have to resort to lightning, even if there is a danger that the people who pray will be disturbed. So I was looking for a diffuser, like an octabox for the flash, but I'd like to hear from you, is there a way to make the flash weaker, so as not to bother people so much? At home I put a piece of paper in front of the flash – but is there a more professional way to do it? Thank you very much.

This is an approximate human translation of the original question in Portuguese. The original can be found in the processing history.

software – How can I find out which camera mode I used for a digital photo?

You can use an Exif reader (like exiftool) to find out this information. For example, I check a picture of myself and I can see

Shutter speed: 1/250

F number: 8.0

Exposure program: Program AE

ISO: 200

The program automation has aperture priority. A quick Google search (for Exposure Program Exif) provides the following values ​​(taken from this link):

  • 0 = not defined
  • 1 = manual
  • 2 = normal program
  • 3 = aperture priority
  • 4 = shutter priority
  • 5 = creative program (biased towards depth of field)
  • 6 = action program (set to fast shutter speed)
  • 7 = portrait (for close-ups with a blurred background)
  • 8 = landscape mode (for landscape photos with a sharp background)

Note, however, that you do not necessarily need the name of the mode to know what worked and what did not. What is really important is the combination of ISO (the so-called exposure triangle or better tricycle as @mattdm clearly explained), shutter speed and aperture (and exposure compensation …).

The different camera modes will only help you to set these values: but in the end, you have to say, "Look, I really would like to have more exposed for this part of the photo and less for that other part …".

You'll find that some modes are more useful in certain situations and others in other situations (for example, when you try to freeze an action, the shutter priority is much more useful than the aperture priority). But it's the final combination of values ​​that really matter to you.

White balance – How to correct yellowish images in neon light on a digital camera?

Your camera can adjust the white balance manually. In most cases, auto white balance will work fine, but since it is highly likely that you will be recording JPEG images, the image quality may be slightly affected if the cause of the error is resolved. In any case, see page 90 of the English version of the manual for your camera for instructions on setting white balance. This is necessary because the white under the lights seems white to us, but this is not the case. Therefore, the camera needs to have an idea of ​​how far it is from that state, and sometimes it has to tell.

You may also need to learn to shoot in another mode (eg with shutter priority) to control it. I'm not sure what the manual has to offer (I shoot Nikon, so it's different). In any case, I recommend that you learn to shoot with sports lock priority, have better control, and have less blurry pictures. You can always switch back to Auto for other purposes.

Keep in mind that if you change the setting, do not forget to reset it to Auto when finished.

canon – What camera settings should I use for ice hockey?

The best way to do sports indoors is to manually adjust the exposure. You have the most complete control over shutter speed, aperture and ISO.

Note that manual exposure is more accurate than automatic exposure metering of flickering lights found in most indoor sports venues and outdoor stadiums used at night. The meter often measures the lights at their peak and then the shutter opens when in the valley of its cycle and vice versa. If you set the manual exposure for the middle of the light cycle, you will be closer to the overall picture.

If you want to get close to freezing the action, all you have to do is live with the flickering of the lights. In order to eliminate most of the flicker, you would need to use shutter speeds of at least 1/125 second, which is not the case with ice hockey. When you get the shots you want to take in raw mode, you have more latitude to correct the color and exposure of the light peaks and valleys during post-processing. (The linked question refers to the processing of hockey photos taken under constraints, which gives an example of the strength of raw post-processing compared to JPEG.)

Of course, the number of frames that you can record in a burst is reduced before the buffer fills and the frame rate drops. With the 6D, you can record about 17 raw images continuously before slowing down. At 4.5 fps (theoretically), this corresponds to a four-second burst. Normally you should avoid filling the buffer completely. Try to limit the number of outbreaks to half, so you have a few shots in reserve when a key moment occurs.

You can set a custom white balance by shooting directly onto a solid white piece of ice. Underexposure one or two apertures intentionally, set the focus switch on the lens to "MF" and defocus either on the MFD or at infinity. If the lights on the venue are flickering (they probably will – our eyes can not tell the difference, but our cameras can!), Take multiple shots and use a shot that's roughly halfway between the brightest and the darkest to set the custom white balance.

Custom White Paper Note: When you are taking raw pictures and want to use a custom white paper in the post by using Canon Digital Photo Professional raw conversion software you Got to When you take the picture, load that custom white balance and set the white balance to Custom. You can still change the white balance to another available setting (Auto, Color Temp, White Balance, and so on). However, if the WB setting in the camera is set to a value other than Custom, you can not apply the custom WB value generated from another shot of a meaningless white object under the lighting conditions in question. You can probably get very close with the Click WB tool and WB Fine Tuning along the blue-yellow and magenta-green axes, but it will not be exactly the same.

Do not forget to set the lens back to "AF" when you have adjusted the white balance. Set the image stabilizer to "On", the IS mode to "2" (panning mode) and the focus limiter to "2.5 m – ∞" (unless your subjects are closer to you than 2.5 meters at points in action).

With a 6D full screen and the superb EF 70-200mm 1: 2.8 L IS II you will only get a lot of close shots if the players are on the parts of the ice you are on. If you want to trim footage from players at a greater distance, your maximum shutter speeds will need to be shorter to control the subject's motion blur than would be the case with uncropped footage.

With the 6D's AF system, you probably want to manually select and leave only the center AF point. Set the AF mode to AI servo AF, You must leave your main subject in the center of the picture. When shooting remotely, you're probably going to trim a little anyway, so you can customize the composition if you wish by cropping off-center. When you set the AF point to automobile You will end up with the next thing in the frame (usually a Plexiglas support) instead of your intended subject in focus. When filming I prefer the AF ON Button to activate the AF and disable the AF associated with the shutter, but it takes some getting used to. YMMV.

Set the drive mode continuous,

Set the aperture to 1: 2.8, set the shutter speed to 1/1000, and then set the ISO value until you see a decent histogram on the back of the camera when you review your shots. Avoid the ISO settings for +1 / 3 stop on Canon DSLRs. Remember to move the histogram slightly to the right when shooting at a downward angle where most of the frame is white ice. If you are photographing from a very low angle, such as the team bench, and much of the frame has a dark background (such as dimly lit seating areas), you want the histogram to be displayed farther left. If you are forced to a higher ISO value by 1/1000 second than you are willing to accept, reduce the shutter speed to 1/800, 1/640 or 1/500 second and check your results. When you check your shots on the LCD, you zoom in to see if motion blur is occurring.

Do not be afraid to take many pictures. Under the best of circumstances, the "keeper" rate in sports is lower than most other types of photography. But that does not mean that you should not plan your recordings, instead of just "praying and spraying". It just means that you should accept that the action sometimes develops differently than expected. Sometimes the AF will miss something. Sometimes it will miss a land mile. Sometimes another player (or, more likely, a referee with his back to you) comes in between the moment you and your subject with the shutter open.

Change the TPS camera angle in Unity

It's a bit tricky to find a specific solution without seeing a screenshot or a graph of current or desired behavior. However, looking at your script, I can suggest two general approaches to expanding your camera behavior:

1) Moving the destination point

2) Moving the camera position or rotation

I've added the following two approaches to your script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CameraFollowPlayer : MonoBehaviour
    GameObject target;
    //Offset variables
    Vector3  targetOffset;
    Vector3  rotationOffset;

    // Start is called before the first frame update
    void Start()
        target = transform.parent.gameObject;

    // Update is called once per frame
    void Update()
        // adding position offset to target
        transform.LookAt(target.transform.position + targetOffset); 

        //adding rotation offset to transform
        transform.rotation += rotationOffset;

By changing these variables, you should be able to control the camera position and angle so that you can hopefully get the view you want.

Compatibility – Is the X brand flash compatible with the Y camera brand?

If the camera's flash and the flash are both ISO compatible, you can use the flash of one system on the flash shoe of another system, and the flash fires in sync with the exposure. But that is the only function you will have. No TTL, no high-speed sync (FP), no menu command for the flash, no flash exposure compensation, no waking from hibernation, possibly no second curtain, no adjustment of the zoom to the focal length of the lens – everything that requires communication between the flash and the camera body except the "fire!" Signal is not transmitted.

If you look at the camera's hot shoe and the flash foot, you'll see why.

Pictures of hotshoes for various camera brands

Almost every camera manufacturer adheres to the ISO standard for flash hotshoes (from 1985 to 2012, Sony did not use the old Minolta iISO hotshoe, but since the NEX6 has been switched to the ISO-compatible (sorta) multi-interface hotshoe). The ISO standards for foot and shoe footwear indicate the physical dimensions of foot and shoe and indicate that the rails on the shoe are ground and that the contact in the middle of the "square" of the foot / shoe is synchronous.

Everything else is protected by copyright. For example, Canon and Nikon have their non-synchronized contacts / pins in different places. So if the flash sits properly on the hot shoe, there is no electrical contact and no communication.

However. The four-thirds, four-thirds, Fuji X and Canon hotshoe contacts all use the same placement (though not necessarily the same number of pens). So if you mix brands under these three pens, there is the possibility of crosstalk. And since each brand uses a completely different signal protocol, it can lead to errors and possible damage (although the risk is low). So, if you are very paranoid, it may be a good idea to tape contacts or remove pens. I pulled the TTL (fully reversible) pins on a Nikon SB-26 to use on my Canon hotshoes.

Positive, however, is this similar placement also means you can also use Canon TTL cables for MFT and Fuji (ie you can connect a MFT flash to an MFT camera and a Fuji flash to a Fuji camera with a Canon TTL cable and full function with Have TTL and high-speed synchronization); However, this only works with passive cables that only carry out the signal transmission.

It does not work with TTL-capable wireless releases that can perform some sort of signal manipulation. Newer versions of the MFT and Fuji X flash units now provide power to the accessory flashes with an extra contact that the Canon hot shoe does not own or use in this way. Therefore, the TTL cables from Canon do not work with these flash units (such as the Fuji EF) -X8) because they have no other power source.

Although Nikon and Pentax have separate pin arrangements, the wake-up signal is strangely identical in both the contact placement and the electronic signal, so that something like a Nikon Yongnuo RF-603II can actually trigger Pentax flashes, but There is also no TTL / HSS cross-fire with Nikon equipment on Pentax.

Synchronization voltages should not be a problem when using flash models for the digital age. All digital flash units typically have sync voltages of <10V, and most Canon / Nikon flash units have a limit of 250V, while mirrorless cameras have a limit of about 20V. The 6V limit you often see in Web references applies to the first generation of Canon DSLRs. If you have a Canon camera model made after the original dRebel (300D), the limit is 250V.

If you really need cross-brand TTL / HSS compatibility with older flashes, consider the Cactus X-TTL triggering system.

Flash – Can an off-camera flash be used to learn the basic lighting outside the camera?

I have a pretty old Nikon D60 camera (which is sufficient for now) and a couple of lenses. I'd like to get more control in demanding lighting environments, so think of a combination of remote control and flash (such as the Godox TT350 and X1T (Quadralite brand)) or a basic studio set that consists of two lights and softboxes.

I am very aware that a simple studio set and a flash are two very different things that are meant for different situations. I tend more to the flash / command combination because it gives me more flexibility: I can hold the flash, trigger the camera remotely and make a portrait, but I can also use it for various other types of photography. B. in low light or traveling. The studio set seems to be much more specialized and cumbersome, although it gives you the advantage of seeing your lighting in advance, and the basic entry-level sets are a bit cheaper than the combination of lightning and commander.

I would like to buy both, but my budget is currently pretty close. So I just want to know if the combination of lightning and commander can be useful for experimenting with a somewhat controlled lighting environment.

Game Maker – Problem displaying the path drawing in the camera / in the viewport

I have an ADM object that draws the path in space as follows (Object ADM – Draw Event):





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I've created 2 viewports to show specific cars:

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And this problem happens, parts of the circuit in the view of these cameras are wrong / faulty:

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The reason I know (or at least suspect) is that I take part of the room and double its display.

Any ideas on how to handle this?