Thursday 25 July 2013

Estimating Exposure – A Little Light Relief…


Of the plethora of photographic subjects confusing both to the novice and experienced film photographer, few can be a greater source of torment than that of “exposure”.  “What aperture are you getting?”  “What shutter speed are you using?” “Will the Auto’ setting cope with this scene?” “What Zone should I put the shadow / light / mid-tone into?” All are commonly heard conversations between photographers of any standard.

In a bid to assist those of us who may have limited knowledge in the subject, I list a few of my own experiences in finding methods that have worked for me with, for the most part, some degree of success.


1. Manual estimation 
For outdoor photography, I use the “Heavy Overcast 4” rule. This is a seemingly simple method.  Take the ISO setting you’re using e.g. – ISO 250 – and set this as your shutter speed i.e. 1/250th. Then set your aperture to f4.   The result will be perfectly exposed pictures.
I should point out that this is a derivation of the universally-recognised and implemented “Sunny 16 Rule”. All I’ve done is to  calibrate it for the Scottish climate, where humidity often reaches 100% (or “rain” as other parts of the UK call it).
As a reminder, the “Sunny 16” rule states that, if it’s sunny, take the ISO setting you’re using e.g. – ISO 250 – and set this as your shutter speed i.e. 1/250th. Then set your aperture at f16.   The result will be perfectly exposed pictures.
In Scotland, adoption of the “Heavy Overcast 4” produces almost identical results, i.e. perfectly exposed pictures, but with less depth of field than those taken in a sunny country.


2. Phone Bill
No, not that dreaded envelope asking for money, or your latest contract update tariff details.  I refer to Bill, my BFF, photographic advisor and general all-around good guy. Bill has been taking photographs longer than I have. To be a little more pedantic, I have taken photographs longer than he has, but this was mainly due to those panoramic shots I had enlarged to about 36”, he’s never done anything bigger than 20” x 16”.  But he has taken photographs for a longer period than me (let’s not get into night-time photography and lengthy exposures, I’m confused enough by the first part of this paragraph).
Bill has an uncanny ability to accurately measure light values without the aid of any mechanical device.  If I’m in any doubt with regard to manual estimation of exposure (see 1 above) I know I can ask Bill for advice and he’ll fine-tune it to within a 1/3rd of a stop – very useful if I’m using slide film.  
Bill’s expertise became even more available with the advent of the mobile phone. Now I don’t even need to take him with me on photographic outings to get the benefit of his remarkable lux-calculating gift.
Bill’s capacity extends beyond visible light, too. I’ve called him from some remote locations in the USA when it’s been night time in the UK where he was and day time where I was and he’s given me some incredibly accurate advice re’ exposure and  light zones, even though he couldn’t see the conditions.  He also gave me some advice related to phone calls and world time zones (which I think was uncalled for – I don’t know how anyone could that angry so quickly, especially in the middle of the night).

I'm pretty sure he wouldn't object to me handing out his phone number to interested parties, so PM me if you're having difficulty and I'll get his number to you.  Expect a response as soon as he's completed his Anger Management course.


3. Organic method
Thread a natural quartzite crystal* onto some linen string. Holding the string lightly between thumb and forefinger of one hand, suspend the quartz pendulum-like over the palm of the free hand. Then state clearly your estimated exposure loud enough to register with the crystal’s harmonic vibrations e.g. “1/125th @ f8 @ ISO 200”.  The pendulum will swing in a clockwise circle if the exposure is correct, anticlockwise if it’s not.  Obviously, if it’s wrong change one or more of the variables and state the new exposure. Repeat the changes in variables etc until the correct exposure is indicated by the pendulum.
Pros :
  • Easy storage
  • Lightweight (depending on the size of the crystal)
  • No battery dependency issues. 
Cons :
  • Accuracy within 2/3rd of a stop means it may not do for slide film**
  • Needs concentration
  • String can sometimes get tangled
  • Upcoming Pagan Festivals can sometimes adversely affect accuracy 
  • Any area where Ley lines converge can cause underexposure (I normally allow +2 stops for this).
*Use quartzite for black and white negative film only.
**For colour work – especially slides – I use onyx and cobblers’ twine (waxed) for more accuracy.  For night photography, try moonstone (yes, I know that sounds ridiculous, but it’s given me consistently good results) and string made from the fibres of young nettle stems.


4. Homeopathic method
Drink up to a half pint of evening primrose anti-stress cure diluted in ion-free water at 1 part evening primrose to 1,000 parts ion-free water.  Your pupils may dilate a little initially – particularly if it’s dark – as they become more sensitive to changes in light levels. Allow at least 45 minutes to elapse before estimating exposure settings.  When the 45 minutes is up, go with your gut instinct for shutter speed and aperture (NB : set the shutter speed first, then aperture, for obvious reasons).
NB : You may suffer prolonged nausea and one or two severe rashes on various (unpredictable) parts of your body as a result of mild poisoning or allergic reaction from the primrose.  However, consider this a small premium to pay for such well-exposed negatives. 


5. Use a hand-held* light meter
Using a hand-held light meter opens up a whole new range of problems.  Do I point it at the subject? At the camera? At the light source? Do I calculate a point where all three intersect and point it at that? Do I measure reflected light bouncing off the subject? Do I measure incident light falling on the subject? Do I take a spot reading? If Yes, which spot?  A light spot? A dark spot? Both and divide by two?
In my opinion the whole thing  just isn’t worth the weight of one of these things in the bag. 
Personally, as far as light meters go, I have vast experience gained over a long number of years in estimating the light without one, and even greater experience in finding plausible excuses (many of them used more than once) re’ why I got it wrong, so I don’t usually bother with one of these contraptions.
*Other parts of the body may be used for gripping the device as a no-cost option.


6. Auto setting
Auto-exposure is good for 98% of the photographs I take.  Unfortunately, the ones I want to keep usually fall into the other 2%, where it makes a complete mess of the whole thing.
I had high hopes that this inability to predict what’s going to be good / not good would be somewhat diminished by the advent of digital photography and the availability of the preview / review screen.  Although I can now see what went wrong much quicker than I used to, I haven’t yet seen a corresponding increase in the quality of my output – a fact which I lay squarely at the feet of the digital camera manufacturers in a large box already near-full to capacity and clearly labelled “Broken Promises”.
The ultimate auto setting identifies scenes / people worth photographing and categorises them as suitable for magazine / journal / National Geographic / newspaper / stock photography / prize-wining competition / domestic use only etc etc. This would be really useful and I’m pretty sure would sell like hot cakes (although the “Hot Cakes Shop” in our local High Street went out of business recently, so perhaps that’s not the best analogy).  Of course, this degree of advancement of auto-exposure has yet to be achieved. Until such time, take my advice and leave auto-exposure well alone.


7. Bracketing
By far the best solution and available to all photographers at zero cost since the digital revolution.  Set your auto-bracketing camera to take 6 or 7 shots with 1 stop intervals either side of whatever it thinks is “normal”.  Your journey may be delayed slightly as your picture-taking will take 7 times longer – but it’s your hobby anyway, so no loss there.  Additionally, you’ll be able to tell all your friends – photographic or not – that you visited (place the name of country / city / event etc visited here) and took 700 shots where they would have taken 100 (or any other number multiplied by the 7 shots you’re now taking).  This automatically promotes you to their superior in the photographic world and, potentially, opens up the professional scene and a new source of income.
The downside, if it can be called that, is that you have to view all the shots and discard the under / over exposed ones.  However, I’m sure there’s a setting in Photoshop that can do that automatically while you get a coffee or something.
Pros :
  • Photographer thinking eliminated
  • May even be able to produce one of those HDR (Horrendously Digitised Rubbish) images from a merge of seven below-par images.
Cons :
  • Digital photography promises in general.
  
8. Lucky Dials
You’ll need a piece of stout card about 6” x 3” (150mm x 75mm), a pair of compasses for drawing circles, a pen, two strips of card about 3” long x ½” wide (75mm x 12mm) and a pair of scissors.
Draw two circles about 2½” (62mm) diameter on the card. Using the pen, mark a series of your preferred shutter speeds around the circumference of one circle (they don’t need to be in any order and you can repeat a speed if it’s a particular favourite).  Mark a series of your ideal apertures around the circumference of the other circle – again if there’s one or two you really like, repeat them a couple of times.
Using the scissors (NB : you may want to get a non-photographic person to help you) cut the card strips into arrow shapes.  Make a small hole about half-way along the arrow.
Now attach each arrow to the circles so that it can spin freely (one of those old-fashioned paper clip thingies is good, but, come on, you can improvise for this bit, you can’t expect me to do everything for you).
Load the camera with film, hold the card with the circles horizontal and spin each arrow. When the arrows stop, note the speed and aperture they indicate and set these on the camera (no need to bother with ISO for this method – that stuff’s over-rated anyway).
You can use these settings for the whole day or you can re-spin the arrows at any time during a photo session – entirely up to you.
Pros :
  • If you’re the lucky type, this is the method for you.
  • Eliminates worries regarding ISO settings
  • Works equally well for flash, ambient, incident and reflective light without changing position
  • No battery dependency issues.
Cons :
  • If you’re not the lucky type, this method may be prone to error.
  • Small amount of exertion in spinning the dials.
  • Waiting for the arrows to stop spinning means it may not be suitable for action photography.
  • If your handwriting is messy, there may be a bit of difficulty in reading the results on the dials.
  • In wet weather ink can run and the card can get a bit soggy. NOTE : There is a commercially-available carbon fibre set available (with titanium arrows) with inset-silver ring engraved with speeds and apertures which is lightweight and waterproof. Call me if you’re interested.
Results I’ve had from this method vary, but then again, what part of “Lucky Dials” didn’t you understand?



These are just a few of the methods I’ve used which I trust you’ll find helpful. As your experience grows, no doubt you’ll develop equally good techniques for getting that ideal exposure.

I wish you good shooting…

Eddie

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