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Flash and Speed with Canon Rebel XT
I just bought a Canon Rebel XT and was wondering if I was having a 'blonde moment.' It seems that the flash won't work with anything over 1/200. Could that be true? Also, I don't seem to be in control as to when I want and don't want the flash to work. Granted there is the no flash mode, but come on, there should be more control than that. I take indoor photographs of gymnastics and sometimes I need flash with a fast shutter speed and other times not. Any help or advise would be greatly appreciated. Thank you. Cindy..

Comments (7)

Yes, you had a "blonde moment".

All SLR cameras, film or digital, have a max.flash sync speed, since SLR cameras were invented. It can range from 1/60 (for really old ones as the Pentax Spotmatic) to 1/500 as in in some Nikon models, but usually it's in the 1/200-1/250 range. This has to do with the 2 courtains shutter used in SLR cameras, because the 2nd courtain in higher than sync speeds start to close before the first one finish to open, so you never have the full frame open, so the very short burst of the flash cant light the whole frame. External flashes usually have a special mode to use higher speeds, at the cost of flash reach and recycle times, but internal ones arent powerful enough for those tricks.

Usually slow shutter speeds arent a problem even in fast action, as the ambient light is low enough to not affect the exposure, and the flash burst is really short (around 1/40000) so the effective shutter speed is 1/40000, more than enough to freeze any action.

Regarding flash control, as in all Canon SLRs, in Scene Zone modes the camera choses if the flash will be used or not. In Creative Zone modes (P, Tv, Av, M or A-Dep) the flash usage is left to the photographer criteria. You need to push the flash button to use it. Guillermo..

Comment #1

Thank you Guillermo for taking the time to respond. I went to your web site and was very impressed. I didn't find any way to contact you direct, so I hope you or someone else will respond to this. The Rebel XT has a max flash sync speed of 1/200 and most human motion can be captured at 1/250 or faster. So, when I am indoors,under fluorescent lighting, trying to take pictures of flipping kids (I mean that litteraly!) what can I do with no flash. I don't want some huge ISO, and the biggest apperature I have is f2.8.

Thanks again. Cindy..

Comment #2

Cindy:.

The Sony, as all digicams, use an iris shutter instead of a courtain shutter, so you have no sync issues. Courtain shutters allow faster speeds without flash but have the aftermentiones max sync speed with it.

Also Canon uses a full auto flash system in it's SLR line, so you can't select the intensity in a full manual way (except in the 550EX and 580EX external flashes), but you can change the amount of flash used via the flash exposure compensation (or FEC) in the same way you use exposure compensation for ambient light. In fact, you can use both settings to control how much ambient and flash light you want in the mix when flash is used as fill. Of course to use those settings you need to use Creative Zone modes. Regarding your question, why you are trying to capture high speed actions without flash? If you uses 1/200 or lower and some small aperture as f/8 and ISO 100 or 200, ambient light influence will be negligible, so the actual exposure time will be the flash burst (1/40000 sec or so). In fact, if you set 2nd courtain sync via Custom Functions, the use of a slow shutter speed and a somewhat large aperture will generate a "motion trail" behind the flash exposure, making the picture more natural. Of course if you don't want to use flash, or it isn't allowed, using ISO 1600 is a very viable option.

Even ISO 3200 is very usable. You can simulate it in the XT using RAW and a -1 exp. compensation and a +1 exp. compensation during conversion. BTW, my e-mail is in my profile here.

Guillermo..

Comment #3

Thank you again Guilermo for your time and knowledge. I obviously don't have your knowledge or understanding of cameras or photography, but I am trying I wasn't aware of the FEC at all, let alone how and when to use it. I will try and do some research on that today. As for my shooting conditions, I can't use a flash at gymnastic meets due to the dangers it posses to the athletes while they compete. They are always indoors with no lighting other than florescent lights. I am afraid to use a higher ISO because on my other camera anything over about 200 was nothing but grain.

I didn't know that I could use the higher ISO here, and not have as bad a problem as before. At gymnastic practice I can use a flash, but 1/200 isn't fast enough to stop the action, so the flash does me no good. I set the EV to +1, but the pictures are still underexposed. I didn't understand how taking pictures in RAW format could help. My other camera didn't have that capability, so I am not familiar with it.

I am trying to take better, more natural photos that don't need technical makeovers. Thanks again. Cindy...

Comment #4

Cindy:.

I took pictures indoors without flash in two occations, once with the Digital Rebel and once with the 20D. The first time it was a dance performance, so I wanted to keep the stage lighting, and the second time it was during a taekwondo practice. In both cases I used fast primes (Sigma 20/1.8 and Canon 35/2 and 50/1.8).

In the dance show, as the DRebel had a max. ISO of 1600, and it was noisier than the XT or 20D ISO 1600 (and even 3200 in the shadows), I used the lenses wideopen and ISO 800 as much as possible and ISO 1600 when absolutely needed. I was able to get 1/125-1/400 at ISO 800 when the light were good, and 1/25-1/60 at ISO 1600 when not. I applied some noise removal to the pictures, but 4x6 prints were flawless.

The Taekwondo practice was trickier, as light levels were very low (just some mix of fluorescent and incandescent lamps, a white balance nightmare) and the 35mm was only f/2, so I used f/2.5 and ISO 1600. I was unable to get anything above 1/125, and 1/60 most of the time, but I was able to take some decent pictures. Actually I was seeking the motion blur effect, so I used those settings instead of ISO 3200 and f/1.8 for example. This time I used no noise reduction and just a minimum amount of postprocessing in Photoshop. Those are examples of an ISO 800 and an ISO 1600 shot from the DRebel (using the 50):.

Http://gfreige.homelinux.org/gallery/photos/big/DR_2793.jpg.

Http://gfreige.homelinux.org/gallery/photos/big/DR_2809.jpg And a couple of ISO 1600 shots with the 20D (using the 50 and the 35):.

Http://gfreige.homelinux.org/gallery/photos/big/20D_3173.jpg.

Http://gfreige.homelinux.org/gallery/photos/big/20D_3265.jpg Guillermo..

Comment #5

Cindy:.

Regarding flash, EC has no effect (it only affect ambient light) so actually using it you can make the situation worse trying to use more ambient light, if the camera decides to use the flash as a fill. Just use FEC.

Probably the internal flash is too weak also. If distance is over 4-5m, a more powerful external flash is needed. You will able to use high speed flash also (with shutter speeds above 1/200), if needed. Guillermo..

Comment #6

Thank you once again Guillermo for taking the time to give such complete and thoughtful answers. I feel much better to hear that you didn't find taking pictures in those conditions a piece of cake. I really would have felt bad! Thank you for the extra effort of sharing some of the pictures that you have taken, as I found that very helpful along with the narration for each of them. If I could trouble you one last time, I promise (I hope) that I won't bother you any more Could you explain a little (in laywoman terms)about EC and FEC. The differences, the settings, and maybe some real life examples of when and how to use them. Other than that, I will try and use some of your earlier suggestions and see if I can get some photos that I can live with.

Cindy..

Comment #7

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