Showing posts with label technique. Show all posts
Showing posts with label technique. Show all posts

Monday, January 28, 2013

Lighting Technique: Taking Photos of Dark Objects


With most subjects, the form and its texture is revealed by shadows.  With black or very dark subjects, the shadows blend into the subject, therefore the shadows don't show its form as easily.  Instead, we see the form through the specular highlights and reflections.

I took some photos of a pair of black leather shoes.  In this post, I discuss how I lit the shot.




Friday, September 14, 2012

Then and Now


From time to time I look at photos I've taken in the past to analyze how I can continue to improve.  Here are some comparisons between some photos I've taken before and some that I took recently.
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Comparison 1: Post-processing
April 2011
September 2012
The shots here were taken in similar ambient conditions (sun above and behind the subjects, subjects facing open light).  In the top one I added flash bounced off a reflector.  The bottom one was all ambient.  These days I use my flash less and rely more on post-processing.
In terms of composition, both were taken with a wide angle lens (around 24mm equivalent) but the top one was taken much closer to the subject for a more casual, intimate feel, while the lower one is more formal and the foliage takes on a more prominent role as a natural frame.
For me the biggest difference is how the two shots were processed.  Both have deep blacks and bright highlights but the top one looks more contrasty, while the bottom one has much less contrast in the midtones.  The bottom one is also less saturated, and looks more natural to me.
BTW, the top was with a D300 and Tamron 17-50 VC while the bottom was with an LX5.  Until we got the LX5, I was bringing the D300 everywhere.  Now I make a conscious decision to bring a DSLR or the LX5 depending on the opportunities I'm likely to encounter, and the kinds of shots I want (taking into account the depth of field I would want, and whether I could use the 10-17 fisheye, 11-16 ultrawide, or Sigma 50-150 for telephoto).
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Comparison 2: Backlit shots
October 2009
August 2012
In this pair of shots, the ambient conditions again appear similar by the look of the shadows (cloudless sky, sun at around the same angle).  The most significant differences in these two shots are the intent and the camera.  In the top one, I did not care about preserving highlights and as you can see the sky was blasted to white.  Now, I actively seek to preserve highlights as much as possible, which leads to the second difference -- the camera.  The shot on top was taken with a Nikon D80, while the bottom one was taken with a Fuji S5 which has exceptional highlight range.  With the Fuji S5 and my active intent to preserve highlights (by choosing an exposure that avoids blownout highlights), I was able to preserve all highlights in this contrasty scene.
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Comparison 3: Direct Sunlight
October 2009
August 2012
Both of these shots were taken in direct sunlight (although in the top one, the sun is at a lower angle) but the way the sun was used is very different.  In the top shot, the sun was acting as key light.  In the bottom shot, the sun was acting as an accent light.

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Comparison 4:  Parades

August 2009
August 2009
December 2009

October 2011
August 2012

The three shots on top are representative of the kinds of photos I used to take when we watch parades.  At that time, I had been using the Tamron 28-75 on a Nikon D80, giving an equivalent focal length of 42mm at its widest, which is to say not wide at all.  I've since switched to the Tamron 17-50 VC and positioned myself further away from my kids so I can capture more of the event.  Recently I also acquired the Tokina 11-16 ultrawide and Tokina 10-17 fisheye which allow me to capture more of the scene and enable me to get shots of the parade even when my position is not ideal.
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Comparison 5: Night Portraits
September 2008

October 2011

December 2011

 
These were all shot in Disneyland, on Main Street.  In the top shot, I was able to get a sharp shot in low light by using flash, while also preserving some of the ambience by allowing a sufficient amount of ambient light from the background.  The problem (besides the dude on the right) is that the flash looks very unnatural.  Now, I use two solutions for this kind of situation. 
The first alternative is to use bounce flash.  Yes it can be done, even outdoors.  In the middle shot, I just bounced the flash off the shop windows.  To make this work, you need three tools: First, a fast (i.e. wide aperture) lens -- f/2.8 or wider.  Here I used the Tamron 17-50 VC.  Second, you also need a camera with decent noise at ISO 1600 or preferably ISO 3200 or above (here I was using the D300 at 1600 ISO, which is so-so).  Third, you need a powerful flash.  I was using the SB-800, zoomed to 105mm.  It was on TTL so I don't know how much power it used but I am almost sure it was close to full power.
The second alternative is to use a handheld umbrella.  In the bottom shot, I was using the Lumix LX5 with the Lastolite Brolly Grip.
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Tuesday, August 7, 2012

The Big Picture

We recently had a birthday party for our son. It was at a playhouse with large bounce houses and a play structure, with tall black ceilings (maybe about 30 feet high or so) and multicolored walls.
Inline image 1

What lighting technique would you use in these circumstances? Hit the jump to see what approach I used.

Thursday, May 6, 2010

Improving Flash Efficiency with an ND filter (Intermediate)

A neutral density (ND) filter reduces the exposure value of the image, as if you used a lower ISO.  ND filters are commonly used in: 1) taking long exposures in bright conditions (e.g. waterfall shots with flowing water); 2) getting a wide aperture (for shallow depth of field) in bright conditions.

Another way ND filters can be used is to improve flash efficiency compared to high speed sync. 

Quick Review of Sync Speed:
Sync speed is the fastest shutter speed that will still allow the entire image frame to be exposed to the flash.  At a shutter speed higher than the sync speed, the rear curtain of the shutter begins to close even before the front curtain has traveled fully, so at any particular point in time while the front and rear curtain are traveling, only a portion of the image is exposed (let's call this the "window").  As a result, if flash is fired at that time, the flash beam would reach only the window portion of the image.  The part that is not reached is usually seen as a dark bar along the edge of the image.  For this reason, many cameras prevent you from selecting a higher shutter speed than sync speed if the camera knows that flash is being used (however, the camera can be tricked into firing anyway with the use of a radio trigger).

High Speed Sync:
High speed sync works around the natural sync speed limitation by causing the flash to fire repeatedly while the window is traveling, thus in effect allowing the entire image to be exposed to the flash.  The downside of high speed sync is a drastic reduction in power.  Instead of one big output, the flash releases multiple smaller outputs.  The higher the shutter speed, the more drastic the reduction in power.

ND Filter vs. High Speed Sync:
Using an ND filter is a reasonable alternative to high speed sync and allows the flash to function more efficiently.  To prove the greater efficiency of an ND filter, I did the following test: I compared flash ranges between high speed sync versus the equivalent range with an ND filter.  I did this comparison with an ND2, ND4, and ND8 filter.

Test 1: 1/250 with ND2 filter vs. high speed sync at 1/500.
  • 1/500 shutter speed @ f/2.8, ISO 200. Indicated range (displayed on the flash): 5.0 meters.
  • 1/250 shutter speed @ f/2.8, ISO 200 with ND2 filter (1 stop reduction). Indicated range: 15 meters.  Adjusting for a 1 stop reduction*: equivalent to 10.7 meters.

Test 2: 1/250 with ND4 filter vs. high speed sync at 1/1000.
  • 1/1000 shutter speed @ f/2.8, ISO 200. Indicated range: 3.6 meters.
  • 1/250 shutter speed @ f/2.8, ISO 200 with ND4 filter (2 stop reduction). Indicated range: 15 meters.  Adjusting for a 2 stop reduction*: equivalent to 7.5 meters.

Test 3: 1/250 with ND4 filter vs. high speed sync at 1/2000.
  • 1/2000 shutter speed @ f/4, ISO 200. Indicated range: 2.5 meters.
  • 1/250 shutter speed @ f/4, ISO 200 with ND8 filter (3 stop reduction). Indicated range: 15 meters.  Adjusting for a 3 stop reduction*: equivalent to 5.4 meters.

*Note: the range adjustment for a 1, 2, or 3 stop reduction is based on a division by a factor of 1.4 per f-stop.  See here or http://www.photozone.de/the-guide-number-gn . Thus a 1-stop reduction would divide the range by 1.4. A 2-stop reduction would divide the range by 2.  A 3-stop reduction would divide the range by 2.8.

The range with an ND filter is consistently at least double that of the range with HSS, implying at least a 2-stop advantage (i.e., 4x more available power) with the ND filter.

Conclusion: all other factors being equal, using an ND filter at the camera's sync speed will allow the flash to reach a longer range (i.e., have a higher effective output) compared to using a faster shutter speed (with equivalent exposure) with high speed sync.  Specifically, the range with an ND filter is at least double the range with HSS.  However, in cases where freezing action is the goal, HSS may be necessary unless flash duration is being used to freeze action.

I don't have access to other equipment such as other flashes, other bodies, or other brands, but given that HSS works similarly across manufacturers, I suspect the predicted increase in range will be similar for other equipment.

UPDATE: Neil van Niekerk did an HSS tutorial.  He found a 2-stop loss from HSS (same as predicted by the experiment above).