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| What you see (approx) f/4 |
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| What you get f/1.4 |
Digitalis Photography's Blog
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Digitalis are a small team of photographers who specialise in producing high quality bespoke images for our clients. Based in Cork and Tipperary, the team covers a wide geographic area. We specialise in Weddings, Portraits and Fine Art photography, but as you'll see from our gallery we do some commercial work as well. To relax, we enjoy wildlife & nature photography.
Our team members are members of the Society of Wedding and Portrait Photographers (SWPP).
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The problem with fast lenses
So you've gone and bought that lovely new f/1.4 or perhaps the f/1.2 (moneybags) and you're noticing that your images are not turning out quite as you expected, perhaps I can help explain why.
Most modern DSLR camera viewfinders are optimised for a lens with a maximum aperture somewhere between f/2.8 and f/4 (especially on the prosumer models). Typically with a kit lens of about f/3.5 your viewfinder is nice and bright, so you might notice if you put your fancy new f/1.4 prime on your camera that the viewfinder doesn't get any brighter. "I can live with that" I hear you say, my viewfinder is bright enough, I don't need it to be any brighter.
Unfortunately there is a trade off to having a lovely bright viewfinder at f/3.5, the maximum depth of field (DOF) that your lovely bright viewfinder can display is also somewhere about f/3.5, so when you put your nice new fast lens on there and open it up fully to get that lovely bokeh that you paid all that money for, you can't see any difference between f/4 and f/1.4 through the viewfinder? WTF ? Sorry about that, but that's simply how it is, it's a manufacturing decision and it's pretty difficult to make a viewfinder with a DOF representation of much more than f/2.8 so don't hold your breath for this problem to go away.
Here are some images of what you should expect: a view of what you actually see through the viewfinder and then what you actually get. The letter Y is the focus point in these images.
So what do I suggest you do ? Shoot lots and lots and do plenty of chimping until you get a good idea of what the wider apertures produce, the viewfinder isn't going to be any help so you may as well get used to guessing.
On camera's with liveview the story may be different, on Nikon, DOF preview doesn't help but it might on Canon - I haven't tested it as I'm a Nikonian, so if it works, let me know.
