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CanonTx88
15th of December 2008 (Mon), 14:29
I'm new to landscape photography but I have been reading much about it in Popular Photography Magazine and I believe that I have a pretty solid understanding of what I have read minus a few - potentially - technical questions about landscape photography. So landscape photographers, here's to you:

*Also -- In writing this I have asked some detailed and diverse questions so I have numbered them. It would be beneficial to me and other readers if in your answer(s) you corresponded with the question number(s) (i.e. 4-A, 6-B, etc) -- thanks!*

1. I own a Canon 5D Mark II. I am planning to purchase a Canon 17-40mm f/4L lens as I believe to favor the results of this lens over the former Canon 16-35mm f/2.8L. Your thoughts?

2. Please argue for or against my understanding of the calculation of f-stops in relation to changing shutter speeds:

My understanding is such:
When you double the shutter speed either up or down, it will constitute 1 stop. Maintaining a constant f-number and ISO, lets assume I photograph my first exposure at 1/15. If I increase my shutter speed to 1/30, my image becomes darker by one stop [15 x 2 = 30]. If I again increase my shutter from 1/15 to 1/60, my original image then becomes darker by 2 stops [30 x 2 = 60]. If I again increase my shutter from 1/15 to 1/125, my image becomes darker by 3 stops [60 x 2 = 120, registered as 1/125 in the camera].

A. Is this an accurate understanding of the calculation of f-stops by the increase or decrease of the shutter? B. What other information might I be misunderstanding or missing?

3. An example:
Manual mode with a constant aperture of f/13 - horizontal image.

Using Spot Metering, I determined the foreground was 1/50th of a second for a proper exposure. I then determined the sky to be 1/250th of a second for a proper exposure by use of spot metering, still at f/13.

In preparation for the image I returned the shutter speed back to 1/50th*, maintaining f/13. Then, calculating the shutter speed differences as to my understanding of the correlation of shutter speed increments to constitute f-stops, as explained above, I determined that in this situation a 2 stop ND filter would be required.

My math for the determination is here:
1/50th x 2 = 100 (shutter speed would register at 125 in the camera) = 1st f-stop
1/125 x 2 = 250 = 2nd f-stop.

A. Did I determine the proper ND filter to use given this example? If not, where did I make a mistake?

*According to an article I've found online: After you’ve determined which filter you need to use, change your shutter speed back to the original setting used to determine the foreground exposure. This is very important to remember. It often happens that you’ll figure out which filter is needed, put it on the lens and fire away and then wonder later what went wrong when you see your image 2 or 3 stops under exposed.

B. Is this information correct?

4. Using my example above, I assume (using -/+ 1 EV) AEB would read 1/25th for overexposure, 1/50th for proper exposure, and 1/125 for underexposure.

A. Is this correct?

B. If so, this confuses me, because the sky (in the given example) registers an exposure of 1/250th of a second. If I combined the 3 above exposures (assuming my understanding of AEB is right), then wouldn't the sky still be over-exposed, even with the determined 2 stop ND filter on my lens, or would it not be? (Someone who could fluently explain the use of AEB after the polarizer and determined ND filter have been applied would be of big help to me).

5. If you plan to use a polarizer in your landscape photograph, which I see being used in many of the images, do you take your different meter readings of the scape with the polarizer on or off the lens?

6. Earlier I mentioned Spot Metering as a method by which to take the exposure of both the foreground and sky, as to determine the proper ND filter to use.

Popular Photography Magazine, quote: "Spot meter the sky and foreground to determine the difference in stops, indicating how strong a filter to use". Additionally, "The foreground should be 1 stop darker".

A. Do you agree with this?

B. If the last quote is true "the foreground should be 1 stop darker", then given my above example, what component changes? Does the ND filter need to be a 3 stop filter instead of 2, or does the foreground shutter speed need to be increased, or... should I just give up at life?

7. The first step to landscape photography is determining which f-stop to use and then changing your shutter speed accordingly. True or false?

Thank you everyone for you help.

blackcap
16th of December 2008 (Tue), 03:54
2A. Yes I believe your understanding of shutter speeds and stops is correct.

3A. Firstly, you are referring to GND (graduated neutral density) filters, not ND filters. But yes, your calculation seems correct to me.

3B. Yes that would make sense because the GND filter will darken the sky so that it's (in theory) the same level of light as the foreground.

4A. Yes that's correct.

4B. If your GND filter completely balances out the light in the scene, then there's no need to combine multiple exposures. However sometimes your filter may not be strong enough, or there may be parts of the scene that are just too dark or bright to be properly exposed in one shot, in which case by auto bracketing you can blend in those parts from the other exposures.

7. Not necessarily. You may want a long exposure to capture silky water and therefore have a shutter speed in mind, and set the aperture accordingly. But mostly yes, I would shoot with a constant aperture (f/11 works well for me) with varying shutter speeds.

My advice to you is to get out there and start shooting rather than worrying about all these technical details. Your understanding is good enough to get started, and then fine tune later when you have specific problems to address.

I find I get pretty good results by guessing the strength of filter I need, and since I only have a 2-stop and a 4-stop my choices are limited. By bracketing exposures, I can correct things by blending them if I need to. Also, I shoot in Av mode and let the camera decide the shutter speed. It's much easier in changing light (e.g. sunrise, sunset) and also you can't auto bracket in Manual mode.

Feel free to look through my photos if you like (http://www.flickr.com/photos/chris_gin/) and ask any questions.

CanonTx88
16th of December 2008 (Tue), 19:48
Additionally, I have found this information somewhat difficult to understand, pulled from a source article on the internet:

"Exposures can be tricky and they often will be long enough that you will have to turn your shutter speed setting to Bulb. I set my camera's shutter in manual mode for a 30-second exposure at f/5.6. I shoot one frame and evaluate that exposure on my histogram. If the exposure looks good at f/5.6 for 30 seconds, I will then recalculate the right exposure based on an aperture of f/16 to be around four minutes. I subtract or add time based on the exposure from this formula. With the length of such exposures, noise can be a difficult issue in underexposed areas, so I always make sure that at least one of my bracketed images is not underexposed."

Here I may emphasize your attention on the underlined sentence in the above quote. How in the world does someone know that at f/5.6 @ 30 seconds your exposure time will be 4 minutes at f/16? Why not, say, 4 minutes 20 seconds? The speaker goes on to call this a 'formula'. And no, quadratic equations don't help you here as the numeric values are not the same (f-numbers and time).

Who's unhinged enough to solve this non compos mentis 'formula'?

CanonTx88
16th of December 2008 (Tue), 20:53
w00t! I found what I was searching for! I was trying to do some crazy things with algorythem formulas and such to find the answer I was looking for (see my previous post above), however, I found what I was looking for!

Ohhh how I loooove wikipedia!!! Like I said, new guy to landscape photography = me.

What I was actually searching for is called an 'EV Indication Chart' used to correlate camera settings with exposure value, found here: http://en.wikipedia.org/wiki/Exposure_value