@robandmarianne wrote:
this is pretty technical for me. .. . so, when you say eclipses can be as much as 10 stops darker, I should move my ISO up at least 10 different positions?
You can do a combination of things...
If you start at ISO 100, f/11, and 1/100th second exposure... then you can get stops by:
1) Drop the f-stop to f/8 (that's 1 stop)
2) Drop the f-stop to f/5.6 (that's 2 stops) ... many zooms can't go lower than f/5.6 when zoomed in. But if you have a high end zoom, you might be able to go to f/4, or f/2.8 (for a 3rd and 4th stop).
3) Start increasing ISO to ISO 200 (that's 3 stops)
4) Go to ISO 400 (4 stops)
5) Go to ISO 800 (5 stops)
If your camera can handle ISO 1600, or 3200, or even 6400 and still have low noise then you coudl get to 6, 7, and 8 stops that way)
6) Start dropping shutter speeds (you DO have a tripod, right? You'll need it. Also if you have a remote shutter release, you'll want to use that to trigger the camera. If not, use the 2-second delay timer or even the 10-second delay timer that way after you press the shutter button (will will induce some vibration on the camera) it has a chance to calm down before the shutter opens.) Drop the shutter speed to 1/50th (that's 6 stops)
7) Keep dropping the shutter by halving it each time (e.g. 1/25th = 7 stops; 1/12th is 8 stops, 1/6th is 9 stops, and 1/3rd sec is 10 stops.)
But it might need to go EVEN DARKER (so you might have to go start doing 1 second, 2 second, 4 second, 8 second expoures or even 15 second expoures.
Check your HISTOGRAM (do some reading to understand how that works.)
When you take an exposure, you can check your historgram and you'll see a rectangle with a graph that looks like a mountain-range in it. You want to make sure that the bulk of data in that graph stays away from the extreme left edge or extreme right edge and that your "mountains" are somewhere in the middle (without bunching up on either end). If they do bunch up on either end then it means you've clipped data (you are under-exposed if your "mountains" are chopped off on the left side or bunched up against the left side. You are over-exposed if it's bunched up or chopped off on the right side.)
Do not trust how it "looks" on the LCD screen when you review the image. That can be misleading.
You may need to adjust these exposures (in fact, you'll almost certainly want to do that). If you shoot in RAW (Canon ".CR2" files) then you'll have a much easier time adjusting the images (using something like Adobe Lightroom or even Canon Digital Photo Professional which came with your camera and even if you can't find it you can always re-download it from Canon.)
Tim Campbell
5D III, 5D IV, 60Da
