updated tutorial on "dragging the shutter" « Neil vN

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updated tutorial on "dragging the shutter"

September 16, 2009

One of the most popular pages on this site is the one dealing with that often confusing phrase – dragging the shutter. The original page was written a few years back and needed some drastic updating. Not only did I want to improve the text, but the original article also featured some less than spectacular photographs (to be kind about it).

The main text on that page has now been complete rewritten, and I’d like to direct everyone to it and catch up with a more fresh explanation of dragging the shutter.

Based around a new sequence of images, it should be more clear now how a change in shutter speed affects the ambient light only, and not the flash exposure.

For example with this comparison, the settings for aperture and ISO remained the same (f5.6 @ 400ISO), leaving the manual flash exposure the same .. but I changed the shutter speed from 1/250th to 1/60th .. and thereby bringing a huge change in how the background appears.

Since shutter speed (largely) has no effect on flash exposure, it becomes our immediate choice in controlling our ambient exposure when using manual flash. With TTL flash though, it’s a different story … and the details are explained on the new page.

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13 Comments »

“so that the ambient light registers, but doesn’t dominate. Since your subject would then still be under-exposed, you would then use your flash to expose correctly for your subject.”

Is this essentially a educated guess (-1.5 to -2 stops) based on experience, or would you recommend a flash meter?

Comment by Pete — September 16, 2009 @ 1:53 pm
Pete .. the educated guess often gets you there faster. However, I would never dissuade anyone from getting a flashmeter. : )

Neil vN

Comment by Neil — September 16, 2009 @ 2:06 pm
Great update to an excellent article.

Comment by Stephanie — September 16, 2009 @ 2:24 pm
Every time I view your website & blogs I learn something new. I can’t wait until October when I will be attending your workshop in Atlanta.

Comment by Sandy — September 17, 2009 @ 6:00 pm
Hi Neil,
It is good that you added the two situations from your August 26, 2009 blog to this, as it provides even more clarity on the subject. You will have plenty of material for a second edition of your book. :-)

By the way, since you updated the “3- Dragging the Shutter” article, I noticed that you had previous update remarks dated Feb. 29, 2008. I presume none of those linked blog articles needs updating, correct?

Comment by Stephen — September 18, 2009 @ 4:36 pm
Stephen, the technique remains the same, even if I did improve my explanation and the images.

Neil vN

Comment by Neil — September 19, 2009 @ 12:38 am
Great explanation, Neil
I have 2 questions:

When you meter the subject, do you use center (spot) metering (meter the model) or evaluative metering (meter the whole scene). and what kind of setting do you get with it?

Secondly, how much F stop do you adjust ( -2 stop??) for your final shot to get the image on the right?, Do you have a guide as how you adjust the setting ( from the camera metering setting) in this outdoor kind of scenerio , and what about indoor scenerio
Thanks
Roy

Comment by Roy — September 19, 2009 @ 5:51 pm
Roy, when you shoot in manual exposure mode on your camera, and you use techniques other than using the camera’s meter to get a general meter reading of the scene, then essentially it wouldn’t matter which metering pattern you used.

For example, if you used the histogram to calculate your exposure settings, then you are guided by the falling edge of the histogram … and this is not affected by your metering mode, but would be affected WHAT you are metering off.

re your second question – I do give the camera settings there, and the aperture remained constant in this case.

Neil vN

Comment by Neil — September 19, 2009 @ 8:45 pm
Hi Neil,
I always learn something new from your website.
I have Sony DSLR with a function Slow Sync (I don’t know about Canon and Nikon) – which looks like your technique. What do you think about this?
Probably I should try both.

Best regards,

Niki

Comment by Niki — September 20, 2009 @ 3:33 pm
Niki … Slow Sync does the same thing, but automatically. Usually though, the technique of dragging the shutter is done in manual exposure mode where you have control over the exact shutter speed being used.

Neil vN

Comment by Neil — September 20, 2009 @ 3:38 pm
Thank you Neil for that prompt answer!

Comment by Niki — September 20, 2009 @ 3:45 pm
Hi Neil,
I work very hard to put your concepts into practice and maybe someday you will make it back to Chicago. For TTL lighting, I have used your comments and ideas and then reformulated them into a way that I can think/use them quickly. So I want you to tell me why my formulation is not quite right or really wrong!! If I am lucky, maybe it is not too bad!)

When I use TTL, I think about the total light coming to the camera with contributions from ambient and strobe. If I want ambient to be equal to the strobe contribution, I set my exposure to be about 1/2-1 stop below the ambient reading and then the TTL on the strobe to about -1EV. If I want the strobe to be more dominant, then I set my exposure 2-3 stops below the ambient reading and set my strobe for 0EV. In doing so, I think I am just changing the ratio or balance of light contributed by ambient vs strobe.

Comment by Steven Seelig — September 21, 2009 @ 6:01 pm
Steven, your formulation there would be a solid starting point .. and from there you adjust to taste. The key would be to regard that as a starting point, and not get locked into the idea that it *has* to work for every situation.

Neil vN

Comment by Neil — October 3, 2009 @ 9:05 am