Beginner Slow shutter speed with flash in Aperture Priority

Forkbeard

Forkbeard

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Jim
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(Canon 600D) I can't seem to get the built in flash to sync at a decent speed in Aperture mode when I'm shooting indoors in low light. If I use auto it chooses iso400 and a speed of 1/60, or I can use manual or Tv and use 1/200 at iso100. When I leave the camera in aperture mode though (which I normally use), it wants to use a shutter speed of at least 2.5 seconds, what am I doing wrong or what don't I know th that I need to?
 
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Forkbeard said:
(Canon 600D) I can't seem to get the built in flash to sync at a decent speed in Aperture mode when I'm shooting indoors in low light. If I use auto it chooses iso400 and a speed of 1/60, or I can use manual or Tv and use 1/200 at iso100. When I leave the camera in aperture mode though (which I normally use), it wants to use a shutter speed of at least 2.5 seconds, what am I doing wrong or what don't I know th that I need to?
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That's because in the semi auto modes Canon treat flash as fill.
When using flash as the primary light source, just shoot manual and leave ETTL to do it's magic.
 
Firstly, I would always encourage photographers not to use the built in flash. You can buy a decent speedlight from Amazon for £40. Something by Aperlite or Neewer will suffice. You'll get infinitely better results.

Anyway...

Ah, the joys of flash photography. To keep things simple, when I'm using flash, I break down the shot in to 2 parts - the ambient light and then the flash part on top.

Firstly, for me, is easier to shoot in manual when using flash. It gives you that control over the camera making strange decisions. Shooting handheld indoors means you'll want to be in control of your shutter speed yourself. Therefore...

Camera in Manual. First select a fast enough shutter speed. 1/200s is good. Then select your aperture. Wider (smaller F number) is better, as it allows more light through the lens. Then set your ISO to auto. Without flash, take a shot. It should produce a fairly good exposure, but your ISO will likely be quite high indoors. Then, pop up your flash and take the shot again. It should produce a similar exposure but your flash will do some of the work to light the scene meaning your ISO will be lower. Job done.

The problem with shooting flash in aperture priority mode is the camera will never know how to balance shutter speed with auto ISO to get an exposure. You could try aperture priority with a small F number, then manually select a high-ish ISO yourself (maybe 800) and see what shutter speed the camera chooses when you take a flash shot. But you're still not in control of your shutter speed, meaning it could easily drop to 1/50s or so, resulting in blurred shots.

When I shot weddings indoors, I always shot with a manual shutter speed and wide aperture and left ISO in auto.
 
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Oliver Pohlmann said:
When I shot weddings indoors, I always shot with a manual shutter speed and wide aperture and left ISO in auto.
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I always switch auto ISO off when using flash so I can control the ambient.

How do you predict the ambient when you're not in total control?
 
Forkbeard said:
(Canon 600D) I can't seem to get the built in flash to sync at a decent speed in Aperture mode when I'm shooting indoors in low light. If I use auto it chooses iso400 and a speed of 1/60, or I can use manual or Tv and use 1/200 at iso100. When I leave the camera in aperture mode though (which I normally use), it wants to use a shutter speed of at least 2.5 seconds, what am I doing wrong or what don't I know th that I need to?
Click to expand...
You arent doing anything wrong.
Canon have designed their cameras so that Aperture priority selects the correct shutter for the light it sees coming into the camera, it doesnt take into account the effect of the flash (inbuilt or not).
If you select a more manual approach when using flash light(s) i.e. select shutter speed, iso and aperture yourself and let TTL do its magic, you may find the background blacks out depending on its distance from subject (and camera), power of the flashgun and how light it actually is.
Tbh it's one area I really struggle with in terms of getting what I want, so dont feel too bad about it, there are many photographers out there struggling. :)
Fortunately with digital cameras you can experiment with little or no cost until you find what works for you, wasnt the case in the old film days.
Matt
 
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From your recent posts FB, your journey into the world of flash is progressing well. Keep going (y)

Some helpful comments above, but your basic question is answered in the handbook. Canons behave differently with flash according to what mode you're in. Suggest Av or manual, and remember that with flash you can have the camera in manual for the ambient exposure, with the flash on auto-TTL.

One of the reasons people struggle with flash is because it's not very intuitive and not WYSIWYG, so you have to have at least half an idea of the likely result before you start, in order to get initial settings there or thereabouts. Then you can tweak after a test shot or two.

Things to bear in mind when balancing flash and ambient light is that sunlight is very bright and the flash will often struggle even at full power. Indoors though, the opposite is usually true - normal room light light is weak compared to flash and you might have to drop the shutter speed a lot longer than you'd like. Push ISO and use low f/numbers to get a head start.
 
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