Monthly Archives: August 2015

TWO LONG EXPOSURE TIPS

Just a couple of quick tips relating to long exposures….

When using an ND filter, paired with a low ISO value, it’s often difficult to get a meter reading.  A standard solution is to crank up the ISO, take a meter reading, and then count stops back to the desired ISO.  For example, suppose you want to shoot at ISO 100.  Change the ISO temporarily to 6400:  1 second @ ISO 6400 = 2 seconds @ ISO 3200 = 4 seconds @ ISO 1600 = 8 seconds @ ISO 800 = 16 seconds @ ISO 400 = 1/2 minute @ ISO 200 = 1 minute @ ISO 100.

A shortcut I’ve used for a long time is to think of this in a slightly different way.  The time in seconds at ISO 6400 is the same numerical value in minutes at ISO 100.  1 second @ ISO 6400 = 1 minute @ ISO 100.  10 seconds @ ISO 6400 = 10 minutes @ ISO 100.  1/4 second @ ISO 6400 = 1/4 minute @ ISO 100.

Most cameras offer 30 seconds as the longest timed shutter speed.  After that you have to use an intervalometer shutter release such as the Nikon MC-36.  These things have long cords, so how do you keep one from blowing around in any breeze while it’s dangling from your camera running a long timed exposure?  For that matter, what’s a good way to control that cord in a camera bag?  My solution is this:  http://www.thinktankphoto.com/products/redwhips.aspx, basically a thin bungee cord and a cord lock.  You can easily make these yourself, but I admit being partial to ThinkTank’s red ones (easier to find when dropped).  Here’s a composited illustration, showing the MC-36 ready to pack, and attached to a tripod leg.

Two uses for ThinkTank’s cable ties.

 

TECH TALK: LIGHTROOM/PHOTOSHOP

This post is going to be a bit techie.  OK, don’t say I didn’t warn you up front.

I was surfing the Web recently and ran across a blog post by a well know photographer who does not use Lightroom.  One major point made in the post was the question of why would anyone use Lightroom at all (aside from its cataloging feature) since Lightroom shows percentages for R, G, and B values,  Yes, mouse over an image in Lightroom’s Develop module and the readout is indeed in percentages.  Other RAW file converters show numerical values of 0 to 255 for each of the color channels.  Doesn’t this make using one of those converters better than working with Lightroom?

Most RAW conversion software makes you select a color space.  For example, let’s consider Adobe Camera Raw (ACR).  ACR is a separate program, accessible from Photoshop or from Bridge (which you now have to download from Adobe, rather than it being automatically included with Photoshop).  Bridge is a browser, the same as Window’s Explorer or Mac’s Finder, while Photoshop is a pixel editor.  ACR is a separate in-between software program.  When you open a RAW file in ACR, it needs a color space to use.   In simplistic terms, a color space is a group of colors out of all possible colors.  Remember when you were a kid and your parents bought you a box of crayons?  There were different boxes available, holding just 8 crayons up to 64 crayons.  Yep, more crayons, more possible colors.  No matter how you worked with the 8 crayons, you could never have the possible options and mixtures that the big 64 crayon box held.  It had a larger color space.  The basic digital color spaces are sRGB, Adobe RGB, and ProPhoto RGB.  Think of these as small, medium, and large.  Open an image in ACR, and immediately below the image window is a clickable link:

Note that the default is sRGB, the “small” color space.  Click on this link, and Workflow Options opens where you can select the color space and bit depth you want.

Whatever you select, make this your RGB working space over in Photoshop’s Color Settings (you might notice that the default in Photoshop is also sRGB).  Personally I use ProPhoto RGB in both ACR and Photoshop.

OK, so we finally get to where Lightroom differs from other converters.  You ever notice that Lightroom does not offer a choice of color spaces?  Internally it uses a variety of ProPhoto RGB.   But Lightroom differs from those other converters because it is a parametric editor.  OK, so what’s that?  In simple terms, it sums up processing instructions, which are not applied to an image until that image is either converted or exported through that instruction set into an actual editable file format.  Open an image from Lightroom into Photoshop, and it is no longer a RAW file.  A file in Photoshop can’t be saved out as a RAW file, but only in a standard graphics file format.

Well, at last we’re back to the question about those R,G, and B percentages.  Because Lightroom does not assign a color space, it cannot show numerical RGB values, since those numerical values depend on the color space in use.  Open a RAW image into some other converter besides Lightroom, mouse over the image, and read the RGB values for any one spot.  Now switch to a different color space.  The RGB readouts for that same spot will be different.  You have to specify a color space to talk about RGB numerical values.  Do I really care about this one way or the other?  No, not at all.  Photography is a visual art, not a bunch of numbers.  Use a quality calibrated monitor, look at the image, and adjust to taste.

In that same blog post I mentioned it was implied that not using Photoshop was a big mistake.  Well, I partially agree.  Photoshop does allow workflow options, such as layer masking and luminosity selections, that no RAW file converter currently allows.  But wait, this is not an either/or question.  It’s not a choice of Lightroom or Photoshop no more than it is of DPP or Photoshop, or of Nikon Capture or Photoshop.  Personally I find Lightroom’s user interface incredibly easy to use, plus I use the database feature to catalog all my image files.  But I also want Photoshop for fine-tuning images.  For me it’s a combination of Lightroom and Photoshop (and a calibrated monitor).