Friday, July 13, 2007
The first step is to create a completely white picture and a completely black picture. The next step is just to view & fill your screen with white.jpg & black.jpg respectively. Using white.jpg look for anything that's dark (a dead pixel). Using black.jpg look for anything not black, usually blue, green or red (hot pixels).
Check the max resolution of your monitor and create an image in Photoshop that large or slightly larger. 1600x1200 should be fine for most people. Next take the paint bucket and paint the image white. Save your image as white.jpg. Next select black as your paint color and using the bucket make the entire image black. Save this as black.jpg.
Hmm, just realized I'm not sure how to do the next step for a Mac system. Well you need to completely fill the screen with your image. Maybe some nice Mac person can post how to do that.
For Windows users, open your white.jpg in the Windows Picture & Fax viewer (right click and hit preview or open with...). Hit F11 to start the slideshow and hit pause in the upper right corner. Move your mouse off screen and in a few seconds the control panel will disappear leaving you with (hopefully) an entirely white screen. Spend some time staring at the screen (I usually check it as quadrants for ease). Spotting individual pixels is not easy so don't rush. Next switch to black.jpg and look again. This time look for pixels that aren't black.
And that's pretty much it. A couple of minutes and you learn quite a bit about the condition of your LCD monitor. If you find 8 dead pixels you LCD is considered defective per most manufacturer's policies. However I always try to get a product with zero.
Thursday, July 05, 2007
I'm not defending the manufacturers. Quite the contrary; I want to empower you to inspect your products for typical errors.
Regardless of manufacturer, when I buy a lens I run a couple of quick tests to determine its working the way it should. I'm sure there's better and more elaborate ways to test lenses, but this works for me. If you have suggestions, I would like to hear them.
First I shoot a focus test. If you have never done one of these, everything you need to learn is here: http://www.focustestchart.com/chart.html It only takes a couple of minutes (after the first time).
Next I do a sharpness test. I lay a newspaper down or hang one up (usually the stock listing in the business section) and shoot it at various apertures in good light. I view the results on my PC and compare the various corners to each other. Is the left bottom as sharp as the right bottom, et cetera. I do the same with the sides and even check the center to make sure nothing seems odd. If there is a bad corner or an unbalanced lens you'll notice it quickly. And again it doesn't require much time or energy to do this test.
You should also do a quick physical inspection of the lens, making sure the glass is clear, the movement of components is proper and even jiggle the lens to make sure nothing rattles or is loose.
I usually do these tests right away while I'm still within the return period from my retailer. If I spot something that looks suspicious I return the lens and request a new one.
I recently purchased a new Sigma 24mm 1.8 and noticed it front focused. I sent it back to B&H received a second unit that tested perfectly. Sure I was bummed I had to do this but the alternative is not buying anything new or wishing on blind faith that the lens is perfect.
Wednesday, July 04, 2007
The Future Mrs. & I's engagement shots can be seen here:
Credit: Tom Yi