Flash and shutter not synchronized

greenspun.com : LUSENET : Canon EOS FAQ forum : One Thread

I have a Canon EOS Rebel G with a Tamron 28-200 lens. When I take pictures at night using the automatic setting and flash, the pictures come out blurry or even look like triple exposures. When I photographed some dancers under these conditions, the same subject would appear multiple times in the frame as ghost images. An interesting effect at times, but not what I had intended! Am I doing something wrong, or might the camera be defective?

Thanks for your suggestions.

Kristin Barendsen

-- Kristin Barendsen (kristin@barenedit.com), August 24, 2001

Answers

I'm far from an expert but a very logical computer person. If the subject is far away the flash will not reach it. Let's assume the subject is within 15 feet of the camera. What was probably happening is that the shutter speed was being slowed way down. Try setting the camera to Shutter priority and set the speed to 1/125th second. This will give you a fast enough speed speed to get ensure clear photos. Let the camera select the aperture. Let's now assume the Auto Focus is working fine. Now your only problem should be photos the are too dark (under- exposed) if the flash isn't strong enough for the distance. If this is what happens you now know the answer. Too far away for the strength of the flash.

-- Myer Kwavnick (kwavnick_fla@compuserve.com), August 24, 2001.

Kristin- because camera names differ between the U.S. and the U.K., I'm not certain of your camera model. But I bet you are managing to put the camera in a mode where it combines a long shutter speed to take advantage of ambient light with the correct aperture for flash.

I rather like doing this in medium-low light with a fairly fast film, as it comes out a great deal more 'natural'- certainly more visually appealing- than using flash with the shortest shutter speed that shutter synchronization will permit!

But in very low light you will get excessively long shutter speeds leading to the effects you describe.

Go back to your camera manual and try whatever setting you need for 'straight' flash exposure!

Cheers JIM

-- Jim Cross (iamacamera@hotmail.com), August 24, 2001.


Kristin,

I concur with Jim. You say you are "taking pictures at night using the automatic setting and flash" -- I assuming you are using the full program mode that has an icon depicting a person and a crescent moon. That would be the mode that Jim refers to. You would want to use the icon of the person running, or the green box (Full Program mode, non- shiftable). "P" will also work for you (Full Program, shiftable) but you would have to remember to manually raise the flash (are you using the built in flash or a shoe mounted one?). Are we correct in this? I look forward to your response.

-- Hung James Wasson (HJWasson@aol.com), August 24, 2001.


My apologies, Kristin, the program mode icon I was thinking of depicts a person with a star over their shoulder, not a crescent moon (I should have looked at a camera instead of relying on faulty memory)! In any case, is that the program mode you were using for your night/dark scenes?

-- Hung James Wasson (HJWasson@aol.com), August 25, 2001.

Thank you Myer, Jim, and Hung for your replies. Yes, I do remember that the shutter speed was extremely slow. And the subject may have been too far away. As Hung guessed, I was using the full program mode with the icon of the person and the star at night. I will try using shutter priority (person running) or full program mode (green box). If I understand you correctly, the person/star icon treats aperture as a priority to take advantage of low light (leading to excessively long shutter speeds), while the person-running mode will use a shorter shutter speed. But in very low light, will that short shutter speed be enough? I suppose this is why real photographers use tripods and separate flash units. Under what conditions would you use the person/star mode?

Thanks!!

Kristin Barendsen

-- Kristin Barendsen (kristin@barenedit.com), August 26, 2001.



> If I understand you correctly, the person/star icon treats aperture as a priority to take advantage of low light (leading to excessively long shutter speeds)

The program algorithm assumes that gathering background lighting is the most important factor, and adjusts aperture & shutter speed to achieve this. It is truly meant to be used on a tripod. The idea is that if you use standard program, the camera will only be concerned with the foreground subject – your person will be properly exposed (well, maybe over-exposed … nothing’s perfect) while the background ends up being almost completely black. Using the Night Scene mode, the camera tries to set the exposure up so that you still get good exposure on your foreground portrait subject, but you will also have a more properly exposed background (i.e. a lighted building, fountain, bridge, etc.) to add more detail to the scene. It all depends on your creative mood. You get ghosting because the flash outputs the proper amount of light to expose the foreground subject, but the shutter stays open long enough for ambient light to produce a visible image.

>while the person-running mode will use a shorter shutter speed.

Yes, it will use a faster shutter speed (up to the flash sync speed)

>But in very low light, will that short shutter speed be enough? It all depends on how far away your subject is. The built in pop-up flash is very convenient, but not very powerful (otherwise you’d have even more problems, like truly serious red-eye, and sucking your camera batteries dry). Dedicated flash units move the flash tube farther away from the lens -- reducing red eye, are more powerful (allowing to properly light subjects farther away), often have a zooming head (to further extend the range of the flash), and use their own batteries. This doesn’t even list all of the cool features the more advanced units have.

>I suppose this is why real photographers use tripods and separate flash units. Under what conditions would you use the person/star mode?

Yes. :-) Even we serious amateurs find the need for tripods in our art, let alone the pros. If you find a tripod just too bulky or inconvenient, try bean bags or a monopod (basically, a single leg of a tripod – with you to provide the other two)!

The Night Scene mode is good for capturing some details of the background in addition to your portrait subject (while using that tripod ;-) ). Picture the model/one you love leaning against a decorative pillar while the moonlight plays across the beach & shimmering ocean behind, capture the sweat on a steel worker’s face while the red hot glow of the furnace and molten steel create a hell- like setting – get the idea? It is just one simple tool to allow you to try other creative paths.

Use up lots of film! Have fun! That’s what this is all about!

PS You are very welcome!

-- Hung James Wasson (HJWasson@aol.com), August 26, 2001.


Minor point correction:

Yes, it will use a faster shutter speed (up to the flash sync speed) - - this is if the flash head is up (or a flash unit is attached & on). Otherwise the program can select higher speeds.

-- Hung James Wasson (HJWasson@aol.com), August 26, 2001.


Kristin,

My sincerest apologies! I did get your direct e-mail, but I wasn't able to reply right away (and forgot it until I was going through my e-mails to purge). So, here I am! In case you haven't found the answer to your questions already:

  • So when photographing the model in heaven or the steelworker in hell, would you actually disable the built-in flash?
  • It depends on whether or not you have a cooperative subject willing to stand very still for long enough, and the effect you are going for.

    Disabling the flash & going with ambient lighting lends an entirely different tone to the image, and has it’s own entirely different set of complications: what speed film?, what exposure values, how much light to add how much detail to the face, etc., etc.

    Enabling flash will give you plenty of detail of your foreground subject ( perhaps too much, depending on the effect you want), it may wash out your foreground or completely darken the background so no details can be seen [thus, the night mode setting on your camera, to allow more ambient lighting to come in]. You can use many different techniques to change the quality & intensity of light coming from your flash ( wrapping/draping it with thin cloth, using gelatin filters, diffusion/bounce heads, etc.). Your pop-up flash is limiting due to its low power, and lack of direct controls (that doesn’t mean that you can’t experiment & achieve pleasing effects), and you will want to eventually invest in a dedicated flash that gives you some control.

  • How do you do this? [disable the flash]
  • The night mode is a “full program” mode, so the flash will pop up whenever it thinks it ought to (and to assist with low light AF). You may be able to push it back down again while keeping your finger slightly depressed on the shutter button (I’ve never owned the G). You may leave it up, and try gelatin filters or thin translucent fabric to reduce the output of the flash. Or, you may switch to a non-full program mode (even, dare I say it, “manual exposure”)

    This is the very essence of the art of photography! To explore what your camera, film, lighting & YOU can do. You will make plenty of mistakes, use lots of film, but in doing so hopefully achieve the vision you aspire to. You will definitely reach a point when all the program modes that have provided you convenience simply can’t handle what you are trying to achieve, and you are just going to have to wing it. Bracketing exposures can help. So can a multitude of other things. I suggest you take some creative photography classes at your community college or parks & recreation division. They can give you far more pointers than I can cover here (although I’m more than willing to continue to respond to your questions). You may also then have access to a dark room if doing black & white photography. I always loved being involved in the entire process, from taking photos, developing the film, cropping & printing the print, to mounting the finished product. You can also learn from books, but they actually work better as a supplement, rather than a primary education.

  • I hope you'll forgive my ignorance, but my manual is in a box somewhere.
  • There’s nothing to forgive! :-) I hope that you continue to enjoy photography, and share that joy with others. The manual may tell you how to operate functions, but it won’t tell you how to be a photographer (that’s why you’re here, isn’t it?)!

  • Thanks so much for your detailed answers -- you've helped a lot.
  • You are most welcome!

    -- Hung James Wasson (HJWasson@aol.com), September 03, 2001.


    Moderation questions? read the FAQ