Canon 420EX and Shutter Speed

[Lyssi]

I was trying to shoot some neat mushrooms in a light woods today with a Canon 100mm Macro lens and wanted to do them hand-held. Thus I wanted to maintain a shutter speed of at least 1/100 so I didn't have to worry about camera shake.

I haven't much experience with my Canon 420EX but I decided to use it, thinking it would get me a faster shutter speed without having to up the ISO so much.

Well, that didn't happen - I still had to use ridiculously high ISO (800-1000) to get a speed of 100, using f2.8. It didn't seem to make any difference in the resulting shutter speed if I used the flash or not, and in fact with the flash the exposure was too light in colour than the reality. With or without a flash I had to use a really high ISO and actually preferred without the flash because the mushrooms were the actual darker brown rather than the lighter flash version.

So, I'm really off in my thinking that a flash would result in faster shutter speeds??? :roll: Or was I doing something wrong with the flash? What I thought was that the subject would be better lit with the flash and therefore not require the higher ISO for a reasonably higher shutter speed. I'm really confused as to why this didn't work so your comments would be much appreciated.

Haven't used my macro in awhile either and I'm very disappointed at the amount of noise with the Canon 30D at only 400 ISO !!! I guess I'm noticing more as I progress along the learning curve.

edit: I did try different modes, i.e. Manual, AV, P and TV with the same results.

Thanks / Pat

[rhys]

Put your camera into manual mode. Set shutter and aperture as you wish then take the photo. Within its limitations, the flash will illuminate all. You can get clever then and set the shutter speed so that it's slightly faster than indicated by the meter and the flash will balance the exposure so you get partial daylight and partial flash, giving a nice exposure. Canon's flash metering sucks anyway but that's the best you can get with Canon.

[Moppie]

Sample photos would help a lot here :)

[Lyssi]

Sample photos would help a lot here

OK - I'll try to figure out how to post some pics, have to learn sometime. It may take awhile. I don't know how to include exif data but will manually put it in.

Thanks.

[jra]

Remember that your camera will always meter for ambient light. If you're using flash, flip over to M mode and set your shutter speed at your max sync speed and your choice of ISO and aperture. disreguard what your camera's light meter is telling you. This will allow your flash to be the primary light source and also give you a faster shutter speed. When using flash...it's important to remember that you're actually making 2 seperate exposures in the same frame....one for ambient light and one for flash. Use your shutter speed, aperture and ISO to eliminate or introduce ambient light into your pic.

[Lyssi]

disreguard what your camera's light meter is telling you

Jason,
Looks like I was doing everything wrong... here's what I did

- manual mode
- the flash I set on High sync and flipped between that and the normal setting, not knowing quite what to do.
- set AV at 2.8 (just so it was wide open, didn't really want that)
- adjusted shutter speed until the indicator pointed at centre on the exposure index strip
- the s. speed was always too slow so I kept boosting the ISO until I got a higher shutter speed (which took me very high 800-1200 to get to 1/100)

I read the camera and flash manuals again afterwards but they didn't help much. Certainly I see that I don't understand much of how the flash and camera work together and will have to find some good articles online - I think I'm going to have a hard time grasping this but I'm sure going to try.

Edit: this link from another thread looks good in case anyone else is interested: http://super.nova.org/DPR/#Canon

Thanks...

[Lyssi]

Here's a couple of pictures, with and without a flash. I also have a diffuser on it. Not sure what you can tell from them since they are attached files and small.

Sorry the pics are so bad but I wasn't even trying for an image, was just caught up in trying to figure out the flash; the woods are in my yard so I knew I could get them again if I get this figured out. Always thought my first posted images would be my best sucessful ones. :oops: However, I am looking forward to your thoughts and advice regarding this flash and high ISO business - surely it doesn't have to be that high!! (I didn't even get near the 1/100 shutter speed I needed with flash and high ISO)

Now that I'm viewing them on the screen, I see a creepy-looking face toward the back of the larger mushroom - eek!

Taken WITH the flash:
Manual AV: f3.2 TV: 1/40 ISO: 1250 Metering: pattern 0EV Focal length: 100mm

208252


Taken WITHOUT the flash:
Manual AV: f3.2 TV: 1/40 ISO: 1250 Metering: pattern 0EV Focal length: 100mm

208253

[Moppie]

Ah, looks like jra spotted the problem :)

When using the flash here are two separate exposures, but your cameras meter only shows you one of them.
Because you had the exposure set for the ambient light, the flash only provide a very small amount of light.

Try it again, and ignore the meter.
Set a shutter speed of 1/250, at say F8 because you are nice and close to the subject. ISO 100.
Ignore the meter, and take the picture (with the flash) :)

[rhys]

Just a thought... Are your flash batteries fresh?

I used my 420EX and the batteries were somewhat flat. The LED worked for focus assist. The flash would not fire though.

[René Damkot]

Here's a couple of pictures, with and without a flash. I also have a diffuser on

Nice fill flash ;)

The shutterspeed the meter is telling you to use is determined by aperture, ISO, and amount of light.
In this case, there was little light, so you needed a high ISO and wide open aperture to get a decent shutterspeed.

Using flash has *no impact whatsoever* WRT the ambient lighting, or shutterspeed you need to use, unless you want the flash to be the main light source... (Then you can set however fast a shutterspeed you want, up to the sync speed. ETTL will take care of the proper exposure (or at least try to ;))

In the example you posted, if you would have set the camera to ISO 100, f/8 and 1/100 (for example), what would have happened would be that a) There would have been (almost) no ambient lighting in the image (black BG), b) The flash would have flashed a lot harder, and so c) The mushroom would have only been illuminated by the flash: Totally different image.

Best way to take an image like this is to use a tripod IMO. The mushroom will stand still for a few seconds, so you can set ISO 100, f/8 (for more DoF), 2 seconds. (Same exposure if I counted right).

You could use the flash for fill (lightening the shadows a bit), but I would then use a bit of -FEC to get it to output a bit less: It's a bit too much now IMO.

[Lyssi]

Thank you all so much for taking the time to respond; your insight has been so helpful! I'll continue to reference this as I try to make sense of all that I've read in the sticky resources.

It felt really good to have a starting point today, except that I hadn't received yours yet Rene and you are right - I need to use the tripod; absolutely that mushroom will stand still for a few moments! And it was great to have your description of what would have happened as I could relate it to what I took today as soon as I read it.

Alas, my mushrooms were crumpled, the wind or perhaps the small critters/ birds. I was so disappointed but there were other subjects and I proceeded to take a methodical series of images in various modes and settings with the flash, which I can also reference as I read along. I'm definitely suffering from a "dent" in the brain tonight after swimming in all this information today.

Tried to upload a couple of images from today with the suggested settings but was unable to. I'm so appreciative, thanks again.