Friday, 13 January 2017

Colour - A Bird In The Hand

I was recently asked if it there might be software available that would restore perfect white balance to jpegs of birds captured in the hand.  I am not aware of any software guaranteed to do this accurately every time without the aid of a white balance card when the images are first captured.  If there were, cameras would surely already be using this in place of current auto white balance algorithms, which, let's face it, can be rather hit-and-miss.  This got me thinking about typical in-the-hand photos and wondering, why ringers (banders) and photographers don't take a moment to properly cater for exposure and white balance when capturing these images.  After all, a lot of work has gone in to catching the bird.  Surely having a mini in-field studio setup nearby is not a major impediment, assuming of course the bird is not stressed and there is a moment or two to take some record shots.  In the time it takes the ringer to process the bird a photographer could quickly rig up a decent neutral mid-grey backdrop in an area with suitable lighting. But this is rarely the case.

Yellow-browed Warbler Phylloscopus inornatus - a real treat to observe and photograph in the hand. Unfortunately, images like this are often less than perfect owing to a contrasting backdrop and unavoidable lighting conditions.

I gave this problem some thought and concluded that there must be a tool and a simple process ideally suited for ringers/photographers in the field which would help improve the quality of images captured and help get the most of these images in terms of exposure and white balance control.  After a bit of internet searching I came across a product by Manfrotto called Lastolite Ezybalance.  I decided to purchase one to test out it's handling and, in particular, to compare it's neural white balance with the professional, and far more expensive, Colorchecker Passport.

The Lastolite comes in three sizes ranging from 30cm up to 75cm.  The 30cm one costs about €25 and should be more than adequate for photographing passerines at least.  The unique selling point for our purposes is that the product folds down to one third of it's working size to allow easy transport.  Unboxed, the ezybalance comes in a nylon pouch to keep it from unfolding, plus a useful user guide (HERE).  As soon as the ezybalance is removed from its pouch it automatically expands to full size.  It seems really durable, with a nice matt finish to minimise reflection.

One side of a the ezybalance is an 18% reflectance or mid-grey card with a white and black surround.  This is intended for exposure capture but may also be used for white balance correction.  The other side is a paler approx. 60% reflectance, neutral grey card more specifically intended for white balance correction than exposure metering.

Compared simply with the white-balance card from my X-rite Colorchecker passport I detected a very slight difference so I suspect the ezybalance which I purchased is not 100% neutral.  In fact I am pretty sure I can see a slightly warm yellow cast in it with the naked eye.  But for €20 its pretty good.  The 18% reflectance card is not too bad either and, given its usefulness for exposure metering I recommend using this side of the card for both exposure and white-balance purposes.  Okay so strictly speaking this method may not give 100% perfect white balance, but coming from a low base where few people introduce any white balance tool to their photographs, this is a good starting point.

Recommendations for using this card in the field would be to clip the card onto a pole mounted using a couple of clamps or clothes pegs, oriented vertically.  The card needs to be located in the shade if conditions are sunny.  It can be located out in the open if conditions are overcast.  In order to avoid lens and perspective distortion, and to minimise stress on the bird I recommend using a long lens 200mm plus and hanging back a bit from the subject.  Ideally place the camera on a tripod with everything already framed.  Before the bird is introduced, having already decided on an appropriate shutter speed and aperture check the exposure based on the 18% grey card, filling the frame with the card as recommended.  Based on the available light you might want to play around a bit more with ISO, aperture and/or shutter speed.  Just to be on the safe side I would recommend some exposure bracketing and of course shooting in RAW.  Now with the studio all set up it's just a matter of waiting for the model to arrive.  As the camera and settings are already set, it may take as little as a minute or two to obtain a perfect photographic record of the subject which can be reasonably corrected to a high standard for exposure and white balance.

On the left we have the original image warts and all.  On the right, a mock up of how the same image might have looked with a neutral backdrop such as the ezybalance card, positioned in a more controlled location in terms of diffuse lighting.  I hope this short note prompts some ringers and photographers to consider improvements in the capture of in the hand images come this year's ringing season.