TV Mode Shutter Speed

canon400d

I have been using a Canon 40D with the 17-85mm lens. I usually shoot 'M' mode but I decided to shoot 'TV' mode to get a fast shutter speed when I was taking a waterfall shot.
Can you please explain to me that when I select a high shutter speed of around 1/800 or 1/1000 or more and once I start to depress the shutter to take the shot I notice the shutter speed drops to say 1/200 and stays there until I take the shot. Does this meean I have taken the shot in 1/200 rather than the 1/800 I selected.
Kind regard
Bob

ziggy53

Bob,

It sounds like you have "Exposure Safety shift" enabled. (Custom Function menu number "1, Exposure", item number 6.)

With that menu item enabled the camera will override the exposure if the selected settings aren't within an acceptable exposure range.

If you had increased the ISO a couple of stops you might have achieved the faster shutter speed you desired.

In full "Manual" mode the safety shift does not engage so you can also use that mode for total control and just use the built-in exposure meter to determine a suitable exposure.

canon400d

ziggy53 wrote:

Bob,

It sounds like you have "Exposure Safety shift" enabled. (Custom Function menu number "1, Exposure", item number 6.)

With that menu item enabled the camera will override the exposure if the selected settings aren't within an acceptable exposure range.

If you had increased the ISO a couple of stops you might have achieved the faster shutter speed you desired.

In full "Manual" mode the safety shift does not engage so you can also use that mode for total control and just use the built-in exposure meter to determine a suitable exposure.

Thanks Ziggy the Safety Shift is on Enabled. Do you think in future when using TV mode I should change the Safety Shift. The shots I have been taking have been with a 40D and Sigma 50-500 of birds on feeding hoppers about 10' away. I get fabulous close ups but a lot of motion blur. I normally shoot manual.
Regards
Bob
Regards
Bob

PixNW

You may want to give AV mode a try for the birds. Decide how much depth of field you want, set the ap and see what kind of shutter speed the camera shows. Adjust the ISO to get a fast enough shutter speed to freeze the action to the extent that you want to.

canon400d

PixNW wrote:

You may want to give AV mode a try for the birds. Decide how much depth of field you want, set the ap and see what kind of shutter speed the camera shows. Adjust the ISO to get a fast enough shutter speed to freeze the action to the extent that you want to.

Yes thanks ever so much. In actual fact I used AV all the time until I was able to use Manual. I will give AV a go and see how it goes, as from what you say it could be the answer. However, to short cut the situation I would really like to know if I disabled Safety Shift would that be detramental to the other shooting modes ie: M which I use all the time?
Regards
Bob

Robinivich

canon400d wrote:

However, to short cut the situation I would really like to know if I disabled Safety Shift would that be detramental to the other shooting modes ie: M which I use all the time?
Regards
Bob

It shouldn't really have a downside, it just gives you more control. It being turned off means that instead of having the camera override your decision and pick a different speed, you'll get too dark or maybe too bright an image but it will be what you dictated. And if you head into custom functions, you'll see that safety shift affects Tv and Av modes only, not M.

canon400d

Robinivich wrote:

It shouldn't really have a downside, it just gives you more control. It being turned off means that instead of having the camera override your decision and pick a different speed, you'll get too dark or maybe too bright an image but it will be what you dictated. And if you head into custom functions, you'll see that safety shift affects Tv and Av modes only, not M.

Thanks for that Robin, I will give it a try and see how it goes.
Regards
Bob

canon400d

canon400d wrote:

Thanks for that Robin, I will give it a try and see how it goes.
Regards
Bob

Well I disabled it and OMG I was getting dark shot after dark shot and I could no way handle that,, so I have enabled it, and I really appreciate the help. I have now learned about the Safety Shift. I will certainly consider increasing the sensitivity on such shots.
Regards
Bob.

Scott_Quier

canon400d wrote:

Well I disabled it and OMG I was getting dark shot after dark shot and I could no way handle that,, so I have enabled it, and I really appreciate the help. I have now learned about the Safety Shift. I will certainly consider increasing the sensitivity on such shots.
Regards
Bob.

:soapbox
IMHO (or not so H), disable the Safety Shift, shoot manual for such shots ('cause you have the time to play with it and get it right - not a lot of pressure to get it right the first time/every time when you are shooting a waterfall - it's not going anywhere), but pay attention to what your camera is telling you about the scene. Watch the camera light meter. Look at the histogram. Make adjustments to shutter speed, aperture, and/or ISO as necessary to achieve the look you are going for. This is the way to be creative.

When you have the understanding that comes with practice and some trial and error, then is the time to use the automated features - when you know exactly what they are doing and why. Understand the tools. <*/ soapbox *>