Experiments I Do Recommend

Although in a previous post I railed against a life in photography spent experimenting with films, developers, new cameras etc., there are in fact some experiments that I do think worth doing - they are fairly simple, can produce a result in an afternoon, and make your life easier in the future.

Depth Of Field

Modern cameras often don't have depth of field scales and frankly the ones that do aren't much good anyway - adequate for 5X7 prints but nothing larger. You need to do a test for your equipment and your size prints. I wouldn't be difficult to shoot a fence or long brick wall or even a road. Remember though to make your decisions based on the print, not on what you see on screen at 100% - do that and I guarantee you will be very frustrated (it will show you that you have no depth of field at any f stop). What I think you probably want to find out is the hyperfocal distance for the f-stops you commonly use when you need depth of field - say f8 - 16. Hyperfocal distance is the distance at which you focus the lens so that everything is in focus from half that distance to infinity. I'd assume that infinity is 100 feet for a normal focal length lens and longer and shorter proportionate to the change in focal length (eg. if normal is 50 mm. lens, then a 25 mm. lens is going to use 50 feet as infinity but a 200 mm. lens is going to use 400 feet as infinity).


Diffraction Limits

Don't guess what f stop is the smallest you can use - actually find out and having found out never ever use a smaller one. What happens is that you get to the point that the out of focus areas don't get any sharper and the in focus area starts to get fuzzier - what is your limit - again check prints, not the screen!

Hand Holding

Do you know for sure what your limits are for hand holding - both vertically and horizontally (they are often sig. different)? Can you do anything to change it - an extra strap or grip, a battery pack? Do the test with a normal focal length lens, a really long lens that is heavy to hold and a really wide lens (if you have one). For other focal lengths just adjust shutter speed by the change in focal length (eg. 100 mm. instead of 50 mm. is going to need twice as fast a shutter speed).

E.I.

Do you know just how much difference to a print it makes if you increase the exposure index in your digital camera - what is the maximum you can get away with for your standard print size?

Tripod Stability

Check to see if it really makes a difference to use mirror lock (if you have it) and how long after letting the camera go (with a bit of a tap for luck) before it settles down.

D.P.I.

A recent article on The Online Photographer suggested that the number of pixels didn't matter and used as an example a downrezed image of a child - there are two flaws in such a test - downrezing is not the same thing as shooting with a camera with fewer pixels and a nice round soft edged child is about as undemanding of resolution as you can get. Test with a landscape. Crop it to a modest size so you can run your test with 8.5X11 prints. Print an image so you get the centre of a quite large print in the 8X5X11, simply using the print driver to enlarge the image to the right size (the actual size will depend on your camera but for example you might take a 6MP dslr and print the central portion of what should be an 10X15 enlargement. Now go back to photoshop and uprez so the image can be printed at 300 dpi for the 10X15 and print again. This time you won't have to use the print driver to upsize the image. TO do the upsizing you can use dedicated software but I'd suggest simply using Photoshop's image/image size/resample smoother, then do a final sharpening on the upsized image. You want to know if upsizing really makes any noticeable difference in the print.