 Ben F |
Long exposures - BULB.. Hi all... My question relates to the use of the bulb settings on manual focus rangefinder camera. Now if you take a look at this - http://www.anthonyroach.com/photography/catalog/product_16137_Image_612005_cat_248.html Surely any meter (in camera or otherwise) would suggest that this photo was going to be over-exosed. So why isnt it???... With most in camera meters, you can select your aperture and shutter speed and it will tell you what the result is going to be, ie overexposed, underexposed or right on the money... HOWEVER, when it comes to the bulb setting, your on your own (obviously because the camera doesnt know how long your gonna keep the shutter open).. So.. any advice on this stuff would help.. as I wanna be able to take pics like these with smaller margin for error (if its possible).. THANKS!!!!!!
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Swapnali Mathkar |
Hi Ben, For such exposures it is not required to use bulb always. It is your choice and ofcourse depends on meter reading. Now when you meter such seen, take the reading of mid or darker colors only. Don't include the brither clouds or sun in the view finder. Note down whatever reading your aregetting. Then in manual mode you can set these readings and take photos. For such scense you must bracket your photographs. For F stops mostly in such a wide angle scene I would keep the smaller F. like F/16 etc. Here in this photo the shutter is opened for 2 mins and f was 22. I think there might be some other filter like gradiant filter attached to lense. So that the brighter clouds did not overexposed. And the scene also might be little dark that what we see in the photo. sorry, I don't know how to estimate the bulb settings for sunsets etc. I used bulb setting only for fireworks shooting where you can guess easily. And for sunset photos I use the above technique.
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Ben F |
Thanks for your response but I think you missed the point a little - these effects are what I want to create... using the long shutter speeds (ie bulb). To me they look awesome and id love to be able to get good shots like these.
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Michael H. Cothran |
I think you're missing a couple of important points here. First, Bulb should only be used when the shutter speed is slower than your camera's slowest available shutter speed. Secondly, you don't need to "guess" at the exposure. You can meter at a larger aperture, if possible, then translate the shutter speed to whatever other aperture you choose. For instance, if you meter your scene to 1 second @ f4 (getting pretty dim), and you want to shoot @ f 11 for some reason, simply translate your 1 second shutter speed to 2s @ f5.6, 4s @ f8, and finally, 8s @ f11. Then set your camera to bulb, the aperture to f11, and count off 8 seconds. Reciprocity Failure - here's where you run into problems, and probably what you experienced, thinking that the exposure should have been brighter. Reciprocity failure is a phenomenon that occurs with film when it is exposed for longer time periods, usually over a couple of seconds. The film no longer responds to light at the same rate of speed that it does with faster shutter speeds. And while there have been charts made to determine additional amounts of time needed to compensate, they are all still only starting points. Different films respond differently, so there's just nothing cut & dry about reciprocity failure compensation.
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Christopher A. Vedros |
"Surely any meter (in camera or otherwise) would suggest that this photo was going to be over-exosed. So why isnt it???..." That's not necessarily true. When taking low-light landscape pictures like the one in your link, you usually want to use your smallest aperture to get the greatest depth of field. In your example, the photographer used f22. At that f-stop, the exposure time would be out of the range of shutter speeds for most cameras. I'll use my camera as an example. My longest shutter speed (other than bulb) is 30 seconds. If I metered a dark landscape like that at f22, my camera would show a blinking 30" in the viewfinder, meaning that the required shutter speed was longer than 30 seconds. What I would need to do is to take a "base meter reading" at a lower f-stop to get a "starting exposure". I'll try f8. My meter tells me that I should use a shutter speed of 15 seconds. So my starting exposure is f8 @ 15 seconds. I still want to use f22 for the picture, so for each stop that I increase, I also double the exposure time. f8 @ 15sec, f11 @ 30sec, f16 @ 1min, f22 @ 2min. So I can set my camera at f22 and use the bulb setting for 2 minutes. Of course there are still situations when you would want to adjust for more or less exposure than what the meter reads, but this gives you the basic math of shifting exposures from a base meter reading. For each f-stop that you go up (decreasing your aperture) you double the exposure time. For each f-stop that you go down (opening your aperture) you cut the exposure time in half. Bryan Peterson's book "Understanding Exposure" explains how to use this method across many different photo situations. I think it's a very helpful book. Chris
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Christopher A. Vedros |
Michael types so much faster than I do! ;-)
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Jon Close |
Ditto Swapnali's comments re f/22 and probable use of graduated neutral density filter so that the foreground and sky have balanced exposure. Additionally, it was shot of very slow Fuji Velvia - ISO 50 and often rated even slower (40 or 32). Regarding how a photographer might meter for that - meter the portion of the scene (with whatever filter you're using) that you want to be mid-toned (18% gray). If you meter in aperture priority at f/22 and the exposure is longer than the maximum timed shutter speed for your camera, then do it at a wider aperture, say f/8 or f/4. Suppose the meter tells you 2 seconds @ f/4, but you want to shoot it at f/22. The difference between f/4 and f/22 is 5 stops, so you'd adjust the shutter speed 5 stops the other way from 2 seconds to 1 minute. This is the reciprocity rule. Now most films do not follow the reciprocity rule at longer shutter speeds, and would require additonal exposure compensation. This is called reciprocity error. The data sheet for Velvia recommends +1 (or more) exposure compensation for exposures longer than 30 seconds. So instead of a 1 minute exposure @ f/22 as metered, you'd need 2 minutes @ f/22. Additionally you'd want to bracket the exposure since reciprocity error isn't necessarily uniform. So shoot one at 1 minute, one a 2 minutes, one at 4 minutes.
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Jon Close |
Sorry for the redundant answer. I'm too slow as well. ;-)
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Jon Close |
P.S. I didn't put the right link in. The Velvia data sheet here. Fuji and Kodak publish similar data for their other films at their websites.
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Ben F |
Jon your reply is most useful, and thanks everyone for ur help.. Your comment about velvia "The data sheet for Velvia recommends +1 (or more) exposure compensation for exposures longer than 30 seconds. So instead of a 1 minute exposure @ f/22 as metered, you'd need 2 minutes @ f/22" I didnt know that, and its very helpful, but im curious to know, would an "Exposure Compensation" feature on my camera do the same thing, ie effectively making it 2 minutes in 1 minute???? or is this a separate thing altogether? So if it equalled 1 minute (like in your example), however reciprocity would make me +1, could I +1 on my exposure compensation or would I have to add the stop in time - ie 2 mins instead of 1?
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Jon Close |
Exposure compensation settings on the camera are only functional in autoexposure modes like P or Av. It would have no effect if you are in M mode or BULB.
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