How to capture a photo of a person with sharp background of building lights at night

[csphua]

Hello to all,


I understand that in order to get sharp background objects one has to use f/11 - f/22 to get greater DOF. However, at night, with my kit lens, these settings seem too dark to get the shot. I had used fill in flash but the background still blur. I have with me Canon 50D with 18-200mm f3.5-5.6 IS kit lens.

Recently I went to Shanghai, China, trying to take sharp picture of my wife and a popular communication tower and historical buildings there at night, but I am not so happy with the pictures I'd got.

[David Selby]

without a tripod it will likely be difficult unless you use a high ISO





please refer to the following:





http://www.learnslr.com/slr-beginner-guide/how-to-take-night-portraits


http://www.learnslr.com/slr-beginner-guide/depth-of-field-explained

[George Slusher]

Another trick is to the shortest focal length you can. For example, using 20mm at f/11 and 8 ft focus distance gives a DOF from 3.5 ft to infinity. To get the same framing of the main subject with 100mm, you'd have to go back to 40 ft. (You'd lose much of the background.) At that distance, with f/11, you'd get a DOF of 32 ft to 54 ft. That will also have the effect of giving you the best maximum aperture (f/3.5 vs f/5.6).


Another solution, if you want to take photos at night, is to get a faster lens. You might consider a fast, inexpensive prime lens, like the 50mm f/1.8 or 35mm f/2 (equivalent to 80mm and 56mm for a full-frame camera). The 50mm lens would be at least two stops faster--probably more--than your kit lens, the 35mm almost the same. That would give you a shutter speed 1/4 as long (e.g., 1/60 vs 1/15) or even faster. These lenses don't have IS, but would work well on a tripod or monopod.

[peety3]

"Yeahbut". The faster lens is useless if you're just going to dial in f/11 or f/22.


Grab "Understanding Exposure" by Bryan Peterson. It's a great read. One of the concepts in there is the "exposure triangle". I usually explain it like this (apologies for the ASCII Art):





f/1 Aperture f/91


---------------------------


thin DOF long DOF





30"+ Shutter 1/8000


-----------------------------


blur crisp





25600 ISO 100


-----------------------------


noisy clean





Start with whatever settings you have on your camera right now (unless you're in manual mode, in which case you'll have to zero-in an exposure or just go to P for a minute for me!). Half-press the shutter and memorize the exposure values your camera has selected. Imagine them on the three horizontal lines above (you don't have to be exact or even close). If you want to optimize one of the values, say you want more "crisp" and less "blur", you'll want to move shutter to the right. To achieve a proper exposure, you'll need to move aperture or ISO (or a combination thereof) to the left.


If you feel that the meter is coming up with a too-dark image, you'll have to dial in some exposure compensation. By default, doing so will move whichever variables aren't hard-set towards the left (+EC) or right (-EC). Which values are hard-set? ISO, unless it's Auto, Aperture if in Av mode, Shutter if in Tv mode.

[George Slusher]

Well put, peety3! The only thing that I could add is that very small apertures (smaller than f/11 or so on most DSLRs) can reduce image quality because of diffraction.


My suggestion for the faster lens was for night shots, in general.

[Keith B]

Also try the lens at it's widest angle, get to a distance where your background is cropped the way you want it. Then have the subject walk into the frame. Have her/him move forward or back until you have them where you like in the frame.


The wide angle will help keep the background tight.

[Samwise]

I would go for a fast prime (like the 50mm f/1.8 that others mentioned), set up on a tripod, take a picture of the main subject in the foreground, then have them step out of the frame, refocus on the background, and then blend the exposures later in photoshop. Focus bracketing is one of the glories of digital. This takes a bit of post processing work, but is a great solution.


While wide angle and or narrow apertures will help increase depth of feild, it's not generally a good solution for night scenes because of motion blur and or high ISO levels.


hope that helps

[Bob]

<span style="font-size: 6pt; color: black; font-family: 'Verdana','sans-serif';"]


<span style="font-size: 14pt; color: black; font-family: 'Arial','sans-serif';"]Take two shots. <o></o>


<span style="font-size: 14pt; color: black; font-family: 'Arial','sans-serif';"]One of the background and one of your wife with a flash. Then cut out the background on your wife's photo (use knock-out, etc.) Because you used the flash most of the background in your wife's photo will be black.


<span style="font-size: 14pt; color: black; font-family: 'Arial','sans-serif';"]Using layers in Photoshop, place the layer of your wife in front of the background shot.<o></o>


<span style="font-size: 14pt; color: black; font-family: 'Arial','sans-serif';"]Now everything will be in focus and exposed properly.<o></o>


<span style="font-size: 14pt; color: black; font-family: 'Arial','sans-serif';"]Bob<o></o>

[Keith B]

I would go for a fast prime (like the 50mm f/1.8 that others mentioned), set up on a tripod, take a picture of the main subject in the foreground, then have them step out of the frame, refocus on the background, and then blend the exposures later in photoshop. Focus bracketing is one of the glories of digital. This takes a bit of post processing work, but is a great solution.


While wide angle and or narrow apertures will help increase depth of feild, it's not generally a good solution for night scenes because of motion blur and or high ISO levels.


hope that helps

My point was with wider angel lens he could open up the aperture and still have a relatively sharp background. My thoughts were of keeping it "organic." Composites usually end up looking like...well, composites.


Best solution I read, would be tripod and second curtain if that is an option on the flash being used. I'm not sure what the built in 50D's flash can do.