60D - Why does exposure bracketing not always work

Hi group,

I have a problem with my Canon 60D. I have set under the "C" setting, a user defined option with ISO forced at 100, 2 second timer, forced Av and +/-1.3 bracketing.

Now, when I use the "C" setting, sometimes the bracketing works and sometimes it does not.

It ALWAYS takes 3 shots, and all the other settings work. But, when I look at the 3 photos in PS, the aperture/timing is always the same for all 3 shots. However, in the meta data for the shots, it does show either "--", "-1.33" or "+1.33" in the exposure setting. All 3 photos look that same.

Sometimes, it does work - and I get the above, but the 3 photos have different exposure durations (so one is darker, one is lighter than the middle) as I would expect.

Do I need to reset something after every set of 3 (such as change setting to Av then back to C, or switch camera on/off)?

Confused.

You aren't at any shutter speed limit, are you? If you use, say, a f/1.4 lens, then you may run into issues if you set it to f/1.4. On a sunny day, at ISO 100, you'll need about a 1/16000 s exposure, and your camera can't do that.
If you've reached such a limit, then the camera isn't techncally able to vary the exposure.

No - these were long night time shots at f16.

When it worked, the exposure was at 15secounds, 25s and 35s

When it didnt work, all were at 30s.

Are you using MLU? You can't bracket, with mirror lockup enabled.

jaffab wrote in post #15166751
When it didnt work, all were at 30s.

OK, so you ran into the same problem, just at the other end of the shutter speed scale?

Nope (at least not thought the menu option) - but........ I was using live view to get focus spot on. I know that this locks the mirror for the live view feature - would I need to turn off live view prior to kicking off the shot?

apersson850 wrote in post #15166771
OK, so you ran into the same problem, just at the other end of the shutter speed scale?

No, that cant be right. 30s is the longest exposure available?

Anders has your answer. The LONGEST shutter speed you have avilable is 30 seconds. If you had a base setting of 20s and +- 1stop you would need exposures of 10, 20, and 40s. Your camera though would limit out at 30s. In my example you would see some variation, but not the full amount between std and +. If yourshortest exposure would work out at 30s you would see no change in exposure, in this situation you may find all of the images look under exposed.

Alan

Why are you working in "C"? Get it to work in whatever mode you want to use, first. I suggest Av, so you get the same DOF in each shot. Lock ISO; do not use AUTO. Set DRIVE mode to High-Speed. Set bracketing and EC to whatever you need. That will get you a three-shot, bracketed burst every time.

One problem could arise if you are shooting raw. I suspect this is your problem. Some programs import the raw image and the jpgs as one image. What you may be seeing is the raw image only. Look for something in your preferences to "View jpgs next to raw as separate photos." I use LR4 and that same thing drove me nuts until I figured this out. If you are shooting jpg this is not your problem.

I hope this helps.

BigAl007 wrote in post #15166801
Anders has your answer. The LONGEST shutter speed you have avilable is 30 seconds. If you had a base setting of 20s and +- 1stop you would need exposures of 10, 20, and 40s. Your camera though would limit out at 30s. In my example you would see some variation, but not the full amount between std and +. If yourshortest exposure would work out at 30s you would see no change in exposure, in this situation you may find all of the images look under exposed.

Alan

Great - at least I know. Thanks all. Must remember to check that with doing bracketing and dial down the apature where I get close to the 30s limit. Not sure why Canon would limit when I can get longer exposures with bulb mode (its just not automatic).

jaffab wrote in post #15166797
No, that cant be right. 30s is the longest exposure available?

Exactly! If the scene required 30s, 60s and 90s, the camera can't do that!

Install Magic lantern and the camera will automatically switch to bulb mode if it needs to use longer than 30sec.
If nothing else ML is a boon for bracketing shots. It will also automatically work out how many shots are needed (if you want it to) and IIR you can shoot up to 9 frames

TSchrief wrote in post #15166815
Exactly! If the scene required 30s, 60s and 90s, the camera can't do that!

To be pedantic I think you would actually want 30, 60, and 120 seconds for full stops (it nearly caught me out on my example too). Otherwise your example is -1, +1/2 stops. But what ever the requirement, for the OP you would have to resort to using bulb mode. Anyway 30s is a very long shutter speed, back in the days of mechanical shutters, speeds longer than 1s were rare. Even when electronically controlled shutters were introduced, along with modern control / display systems (the move from a shutter dial to buttons and LCD's) that allowed longer speeds to be set, film started to suffer from reciprocity failure at exposure times much over 10s and badly by the time you got to 30s. This made it of little point to incorporate longer shutter speeds, as the film was not consistent in exposure or for that matter colour enough to make it worth while.

Also after 30s the slight error you may have in timing the exposure is not significant. At an exposure of 30s a variation of 1/3 of a stop takes you up to 40s so even if you make a 3s error in counting the exposure at 30s you only have a 1/10 stop error which is not really noticable. They have to stop somwhere after all.

Alan

BigAl007 wrote in post #15166869
To be pedantic I think you would actually want 30, 60, and 120 seconds for full stops (it nearly caught me out on my example too). Otherwise your example is -1, +1/2 stops. But what ever the requirement, for the OP you would have to resort to using bulb mode. Anyway 30s is a very long shutter speed, back in the days of mechanical shutters, speeds longer than 1s were rare. Even when electronically controlled shutters were introduced, along with modern control / display systems (the move from a shutter dial to buttons and LCD's) that allowed longer speeds to be set, film started to suffer from reciprocity failure at exposure times much over 10s and badly by the time you got to 30s. This made it of little point to incorporate longer shutter speeds, as the film was not consistent in exposure or for that matter colour enough to make it worth while.

Also after 30s the slight error you may have in timing the exposure is not significant. At an exposure of 30s a variation of 1/3 of a stop takes you up to 40s so even if you make a 3s error in counting the exposure at 30s you only have a 1/10 stop error which is not really noticable. They have to stop somwhere after all.

Alan

Thanks. I did notice that while composing my reply. You caught me! I was just too lazy to figure it out at 5:30 in the morning. I figured, "Just an example." I should have known someone would reply to my laziness. Of course, you are correct, sir.

TSchrief wrote in post #15166811
Why are you working in "C"? Get it to work in whatever mode you want to use, first. I suggest Av, so you get the same DOF in each shot. Lock ISO; do not use AUTO. Set DRIVE mode to High-Speed. Set bracketing and EC to whatever you need. That will get you a three-shot, bracketed burst every time.

One problem could arise if you are shooting raw. I suspect this is your problem. Some programs import the raw image and the jpgs as one image. What you may be seeing is the raw image only. Look for something in your preferences to "View jpgs next to raw as separate photos." I use LR4 and that same thing drove me nuts until I figured this out. If you are shooting jpg this is not your problem.

I hope this helps.

Using a customized C slot that the OP stored settings under (which could have been Av) is not the issue here, and is a valid use for the custom slots.