Diary

Bill Lunney's photography diary.  Blog to everyone else.  :)

 

Glasgow and Lanarkshire based photography and video

Effects of f-Stop on getting sharp images

During some some property (real estate) shots today I came across something I didn't know.  With the objective of getting images as sharp as possible I had did all the usual prep.  Tripod, remote release etc.  In this case I was using a quality prime lens so the 'sweet spot' associated with zooms wasn't a factor.

Took two images per scene - f11 & f32, manual focus.  The f32 images were, without exception, softer than f11.  I had expected them to be sharper providing there was absolutely no movement during exposure.  Know f32 is a bit extreme but was useful in establishing a reference point.  Both images below are straight out of the camera (Nikon raw).

At first I thought the longer exposure time coupled with a very slight wind may have been a factor.  Still possible but I feel unlikely given I took around six scenes with a three bracket exposure on each.  Every image showed the same 'softness'.

After a little research I found the issue, which I should have known anyway.  I spend a lot of time shooting at small f-stops (2.8 ish) so this doesn't come up.  In a nutshell, smaller aperture (larger f-stop number) equals more distortion of light.  Very small apertures cause increasing light diffraction.  In layman terms, forcing the light through a tiny hole causes light rays to interfere with each other.  At this high an f-stop other factors start to play a part - aperture blade profile, camera shake etc.

As with most things there's a wealth of information on this specific topic, Cambridge in Colour and Brad Sharp's article were two resources I used.

The zoomed images below shows two different scenes, first image f11 second f32.  Images below are 100% JPG exports from Lightroom.  Aware this introduces error but am too lazy to export as TIFF then to PNG.  PNG support in Lightroom is long overdue!

Takeaway here is there's a cut of point on all lenses where higher f-stop does not equal a sharper image.  Some simple tests shooting a series of shots on a tripod aimed at a fine detail subject will show where that is.  As a rule of thumb f11 seems to be sensible. 


billlunneyphotography.com now live

Been on my todo list for a long time now.  Had very specific requirements for how I wanted this to look and function.  Most goals have been achieved.

  • Big, bold images
  • Clean, fuss free design
  • Ruthless image selection
  • Small number of categories

It's actually a really sobering experience and I'm very glad I've done it.  Gathering what is your best work and putting it out there for all to see really gives perspective.  Warts and all.  There's nowhere to hide.  You're saying to the world 'this is the best I've got'.  Personally, I'm 'ok' with this.  I feel everything is of a good standard.  Some of it very good.  However, when I compare it with the absolute best out there it falls short.  This is a great thing.  Why?  Well, I can see where improvement is needed.  Plenty of areas where my game needs raising.

Purpose of the site is two fold:

  1. Personal satisfaction.  Take an idea and see it through.
  2. Commercial interest.  Serves as a good reference for client work.  Have several side projects simmering which can leverage this.

Enjoy your visit.  Suggestive comments very welcome.

 

B.

 

 

Moving objects - Ireland trip. Cars, dogs and a place called Muff.

Spent the weekend in Ireland with a pal.  Flash git owns two of the best drivers cars you'll find.  A Porsche 911 (996) and a BMW M3.  This wasn't a professional gig but got a few decent shots to share.  A favourite was the wedding car.  Believe it or not this was literally passing by at 20mph, I just grabbed the camera, tracked the car and got a real good shot of who is presumably the bride.  She saw me with the camera, held her glass up, the focus gods were kind to us and bang.  A little post work later and there's a decent shot.  Sun rays were gently breaking through the clouds and with a little cropping to give that cinema look we're done.

I take too many pictures of cars so will keep the collection short.  The best shot here is a combination of decent base level technique and luck.  So here's a breakdown of how it was achieved.

  1. Readiness - Keep your camera ready.  If you're out taking snaps then lens cap off, and get the camera ready to pick up and shoot.
  2. Settings - That means autofocus, aperture priority, and sensible ISO.  A good tip is set make use of auto ISO which ensures a shutter speed of no less than around 1/100th of a second.  Let the camera manage ISO.  Better to get a slightly noisy shot (grain) but sharp than anything else.  Shutter release should always be high speed.
  3. Tracking - Move your camera with the subject.  In this case I moved the camera with the car.  Keeping the car in the centre of the shot.
  4. Spray and pray - Say this all the time, but take plenty of shots.  As the car was moving I held down the shutter release which meant the camera could take pictures as fast as it can.  It's a dirty secret of photography that behind many good images are lots of crap ones.  Things like blinking of eyes, focus point movement, environmental issues all play less of an issue if you have more choice.
  5. Post work - Decide on the mood you're going for and post process accordingly.  Putting lip stick on a pig is never going to give satisfying results.  Reach a compromise between what you want and what the image lends itself to.  In this case it was the usual white balance, bump up saturation, contrast and I think a little selective sharpening.  I sharpened up the car alone just to make it pop.  Also, the cropping makes this shot.  Did a widescreen movie type crop to give it a cinema feel.  That suited the vintage car subject perfectly.