Posted by: David Vernon | July 2, 2009

This is not mediocre!

Lake Josephine Taxi

I’ve been reading Lev Grossman’s blog about all things nerdy over at Time Magazine. Here’s how he started his entry a few days ago:

“See, I’m running with this new top 5 format. It’s for days when I’m having trouble finding a blogworthy item, so instead you get five items that aren’t blogworthy. Let’s go!”

Now personally I think every thing we put forth is, ummm, well, okay – maybe he has a point. Let’s go!

  1. You spend a lot of money on a lens, you have a realistic expectation that it’s gonna focus spot on. Indeed you do. And yet it’s possible you’ll have a small – even tiny – problem with front-focus or back-focus. And what are those two things? It’s relatively simple actually. Front-focus just refers to your focus point being slightly in front (closer to camera) of your intended focus point and back-focus – well yeah – slightly behind your intended focus point. You focus on an object that’s exactly five feet away. With front-focus issues your camera/lens will focus, for example, at 4′-11 3/4″. With back-focus – say 5′-0 1/4″. That might not always matter when you’re shooting at f/8 or higher, but if you’re shooting at f/1.4 then it can be a  royal pain in the patooty. There’s good news on a couple fronts here. First off, you can buy a system to test how accurate your focus is and whether you are front- or back-focusing. Secondly, with most new digital SLRs, you can actually compensate for that slight misadjustment in camera. And not only that, but your camera will know which lens is attached and adjust accordingly when you put that lens on. So if you think you’ve got a small focus problem – then check out this article over at Canon’s Digital Photo Pro eNews on Precision Focus. I then strongly encourage my friends at the Peoria Camera Club to break out the checkbook and buy a LensAlign system which they can rent to members for a very reasonable fee.
  2. Ever been flummoxed (yes flummoxed) by all the gobbledy-gook associated with lens terminology? Aberration, Aspherical Elements, Dispersion, Stabilization, blah, blah, blah. Does it mean anything to you? Well it does if you want really sharp images. Since I was spending more then a few minutes reading a Canon publication the other day – I though I would also pass on this nice primer on Lens Tech. It’s written very down to earth and it tells you a lot about the things in a lens that can steal sharpness like a dingo steals a baby. Enjoy that mental picture.
  3. And when you’re done reading the Lens Tech article you will have a slightly better understanding of the two kinds of aberration: spherical and chromatic. I’ve got a whole article planned on those two lovlies but one thing you may have encountered is PURPLE FRINGING – a sure sign of chromatic aberration. Check out this short Wikipedia article on purple fringing to see if you’ve ever encountered it and then stay tuned. We’ll talk about all the fringes – like red/cyan and blue/yellow fringing – when it happens and how to fix it – in a separate post. And I had a classic case of fringe to deal with in this shot above because of how I put this image together. Problem resolved but watch shooting really wide open, watch your overexposed highlights, and if you don’t shoot with a haze or strong UV filter – well now may be the time.
  4. Speaking of embarassing photographic moments, I had a 40-minute long exposure mistake on my recent trip. We’ll save the evidence and laughs for a whole separate post (again!) on long exposures that’s coming up but consider this: what if – instead of taking one 40-minute exposure you could take 40-one minute exposures and get the same results? If you already know of which I speak then you might really be interested in Image Stacker. If you are momentarily befuddled – come back shortly and we’ll give you the 411 on long exposures – and what not to do with your hat (oooooh foreshadowing).
  5. And as one last preview for an upcoming article on slide shows and multimedia presentations of your photography – I point you towards this Strictly Business Blog article on Prepping Images for Multimedia and Video. And if you don’t know the Strictly Business blog from the ASMP – it’s a great source of ideas and resources for folks in the photo biz (and just mouse over the ASMP link to see what it stands for).

Alright – there’s the top five for today. All mediocre great stuff to say the least.

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