two questions after my trip today

[echoyjeff222]

Just got back after a long day's trip shooting! I think overall things went well, but there are two technical things that I couldn't figure out:

1) When it got dark, I could no longer use my viewfinder reliably to compose the image. Even with the LIVE view, things were not showing up brightly at ALL. I was using aperture priority mode. Thus, I was not able to see the dark areas in the photo until AFTER I shot. The actual photo turned out fine, and I could see what was in the previously dark area. How come the live view didn't (or couldn't) show the dark areas in the preview? It was frustrating trying to compose images.

2) I was doing some +/- 1 stop continuous shots, but at some point (~15 second time exposure), the continuous mode just stopped working. Is this because +1 would be past the maximum shutter length, or is there another reason?

Thanks!!

 

[The_Traveler]

Without knowing your camera well, my suggestion is that, since Live View shows the scene at the decided-upon f stop, there just may not be enough light on the sensor to see into the shadows even if the camera boosts the live view (see below)

When you say 'continuous', I imagine you mean auto bracketing.
I imagine the manual would also say what the longest possible time that a camera controlled shutter speed would allow.
A simple internet search for 'T5i' and 'shutter speed' yields this:
"The T5i has a shutter speed range from 1/4000 of a second all the way down to 30 seconds."

 

[echoyjeff222]

So it seems like the solution is to compose at the widest aperture possible, then go back to f/11 or wherever I was at?

 

[The_Traveler]

yes, but f11 is not often the best f stop.
It is liable to be well away from the sweet spot of the lens (particularly on entry level lenses) and it extends the exposure time immensely thus increasing chance of motion blur.

Also the needed exposure at f11 may be beyond the capacity of the camera to expose automatically.

If you are doing it to extend your depth of field, it would be worthwhile to spend some time at dofmaster.com both to calculate the depth of field you need at http://dofmaster.com/dofjs.html or just to look at the charts of hyperfocal distances Hyperfocal Distance Chart - DOFMaster

 

[TCampbell]

What sort of shots? Are these portraits? I ask because the focus-assist beam on an external speedite (e.g. such as a 430EX II) will project a pattern that the camera can use to lock focus even in completely darkness. But that assumes you have a subject you want to focus on which is somewhat close (e.g. 10-20' or so). You wouldn't want to use that for landscape shots.

Whether you use the view-finder or liveview to to compose a shot, the camera always does this with the f-stop "wide open". When you take the exposure, the aperture blades stop down to the selected setting, take the shot, then retract to wide-open again. It does this even in live-view mode... which is why the camera calls the image in live-view an "exposure simulation" (it's not really using the f-stop you selected... it's just adjusting the brightness of the image on the viewfinder to simulate approximately what you'd get if it really stopped the aperture blades down.)

 

[KmH]

As point of focus (PoF) distance increases, the need for a small lens aperture to get a deep DoF decreases.

With an 18 mm lens @ f/4 on a crop sensor camera and a PoF distance of 1000 feet, the near limit of the DoF is 13.8 feet in front of the camera and the far limit is at infinity. If the PoF is even further away - say 2500 feet the near limit of the DoF is then 13.9 feet and the far limit doesn't change and stays at infinity.

If the focal length is even shorter the near limit of the DoF just gets closer to the camera while the far limit stays at infinity.

 

[echoyjeff222]

What sort of shots? Are these portraits? I ask because the focus-assist beam on an external speedite (e.g. such as a 430EX II) will project a pattern that the camera can use to lock focus even in completely darkness. But that assumes you have a subject you want to focus on which is somewhat close (e.g. 10-20' or so). You wouldn't want to use that for landscape shots.

Whether you use the view-finder or liveview to to compose a shot, the camera always does this with the f-stop "wide open". When you take the exposure, the aperture blades stop down to the selected setting, take the shot, then retract to wide-open again. It does this even in live-view mode... which is why the camera calls the image in live-view an "exposure simulation" (it's not really using the f-stop you selected... it's just adjusting the brightness of the image on the viewfinder to simulate approximately what you'd get if it really stopped the aperture blades down.)

Ok now I'm confused ... because I asked someone who was using a simple point and shoot to look through their live view and it was much brighter than mine. I couldn't really even see anything in mine. How is it possible that their point and shoot has a better live view than mine? My maximum aperture is like f4 or something, so I don't get how I wasn't able to get more light.

I was doing night landscapes.

 

[weepete]

Maybe the p&s had different settings to the ones you were using making the exposure simulation different. I know that on my p&s the max aperture is f2.8.