Shooting into spotlights

My good friend @petitmew asked me on twitter today how to cope with a tricky situation for getting exposure right. She's shooting a scene with lots of spotlights in it and they're throwing off the camera's ability to correctly meter the scene and choose an appropriate aperture and shutter speed.

Spotlights can confuse the camera's metering system

To understand what's going wrong we need to know how the camera meters the scene. By default the camera looks at our picture and tries to figure out where the subject is based on an internal database of picture types. Then it looks at how bright everything is, giving extra importance to the subject and chooses the aperture and shutter speed that will make the average brightness "mid grey". So there will be some stuff darker and some brighter but the average will be mid grey. 

However, your camera has more than one way of metering the scene. The default mode is intelligent and that database of picture types gets probably 99% of pictures right. But sometimes the camera can be fooled and that's what's going wrong with those spotlights. So it's time to choose a different metering mode. Most cameras have a "spot" or "partial" metering mode. Instead of looking at the whole picture, "spot" metering will just look at the very middle of the picture and try to make that part mid grey. "Partial" metering is the same but the spot in the middle of the picture is a little bigger. Sometimes there will be a circle in the middle of your viewfinder showing the partial metering area.

Spot metering is useful because it lets you control exactly what parts of the scene the camera will use to make its decision about aperture and shutter speed. You'll typically want to pick a face if you're shooting people or something that should be about mid-grey in the scene. For extra credit you might want to add +2/3 of a stop exposure compensation if you're metering off a face. Once you're metering off your subject instead of the whole scene you will, of course, find that the spotlights are blown out and that's as it should be. You want your subject to be well exposed and the camera can only handle a small range of brightnesses above and below that midpoint. 

The down side of using spot or partial metering is that you have to be very careful and steady handed while shooting to make sure the spot is in the right place. And if you forget you're in spot metering mode you'll get some very strange pictures until you figure out what's wrong. So if the light in your scene isn't changing I'd suggest using spot metering to get a good exposure then make a note of the aperture and shutter speed that the camera chose. Switch to manual mode, dial in those numbers and shoot away without worrying about metering any more. 

Have fun and let me know if it works for you!

Tutorial 24, Chapter 2 - Smoke pictures

Part 2 of our tutorial on shooting smoke pictures shows you how to edit the pictures once you've taken them. I'm using Lightroom 4 for this tutorial but the same techniques could be applied in just about any photo editing package. I'll show you how to improve contrast and tonality, how to get a clean background and then invert the image and add vibrant colours. After that it's all down to your own creativity to see the possibilities within the picture and bring them out.

Tutorial 24, Chapter 2 - Smoke pictures

Exporting multiple different sizes from Lightroom

[Update 17/2/2012: Modified the script slightly to fix a path capitalisation bug]

[Update 22/3/2013: Re-recorded the video to explain the process better]

I've been shooting a lot of model sessions lately and one of the things I always need to do after these sessions is put the processed pictures into my dropbox where the model can see them. These pictures are for a variety of different uses including Facebook, 500px, Google+, various modelling sites and, of course, print publication. 

These sites often have different size limits and requirements so I usually need to export versions with and without watermarks and at various different pixel dimensions. So it's always been a pain in Lightroom that I can only export images at one size. Here's what I export by default: 

• full-size clean
• full-size watermarked
• 2000px watermarked
• 1000px watermarked

That's 4 separate exports and of course I have a preset for each. It's not a *lot* of work but all those clicks bug me so I set about finding a way to export multiple different sized versions in one step. I tried a number of different approaches but the one I settled on was to write an application. Steady-on, it's not as scary as it sounds. My plan was to set up an export preset to save a full sized watermarked version then my application, called automatically from Lightroom, would take that full sized version as input and create 2 more smaller versions and save them in the same folder. The problem now, was writing the application. 

I'm on a Mac so I started looking at Automator and when that proved too limited I looked at Applescript and when that proved too hard to debug I did what any reasonable, right thinking person would do and started whining on Twitter. I have a background in programming so surely I could accomplish this apparently simple task but no, I'd wasted a whole day on this so finally I asked for help. And to my great joy a couple of people did try. I posted my broken Applescript on pastebin in a huff and the next morning John Day (@johneday on twitter) had completely rewritten and simplified it for me. Thank you so much John - you're a superstar. Here's the script he wrote for me:

on open of myFiles
	set newSizes to {1000, 2000}
	
	repeat with aFile in myFiles
		set filePath to aFile's POSIX path
		set bPath to (do shell script "dirname " & quoted form of filePath)
		tell application "System Events" to set fileName to aFile's name
		repeat with newSize in newSizes
			do shell script "sips " & quoted form of aFile's POSIX path & " -Z " & newSize & " --out " & quoted form of (bPath & "/" & rename(fileName, newSize) as text)
		end repeat
	end repeat
end open

on rename(fName, fSize)
	do shell script "sed 's/fullsize/" & fSize & "/' <<< " & quoted form of fName
end rename

If you'd like to use this yourself run "Applescript editor" on your mac, create a new script and paste the above code into the code window. Then from the file menu choose save and be sure to save this as an Application, not a script. There's a drop-down box in the save window that lets you choose to save as Application. Save it in a folder somewhere and that's it, you're done. You just wrote an application. Congratulations - you're a programmer now. :)

Finally create your Lightroom export preset to save a full sized version, watermarked or not as you prefer. Then look at the bottom of the export dialog. You can choose post-processing actions. One of those is "Open in other application..". Pick that and then just below you can choose which application to use. Simple. Set your new application as the post-processing action and you're done. If you want other sizes instead of my 1000px and 2000px versions you can just modify the numbers in the line near the top of the script where it says, "set newSizes to {1000, 2000}". Add as many sizes in there as you like, comma separated.

So this solution is not mine at all. This is all down to John Day. If you find this useful please follow John on twitter (@johneday) and check out his website at https://www.johneday.com/. 

This is obviously a mac only solution but writing something similar should be quite easy on Windows. SIP, the Scilab Image Processing toolkit, is pre-installed on the Mac but it's free and available for windows too. So is ImageMagick, which does similar stuff. All that's needed is a little code to wrap that up written in C#, Python or even a DOS batch file. Let me know if you do something like that and I'll be delighted to add links to it from here.

PW187 - Exporting multiple different sizes from Lightroom