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02-29-2012, 09:40 PM   #1
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need help with focusing

I am trying to do some products shots and keep getting fuzzy edges. We want crisper edges and maybe a whiter background. I am using daylight bulbs and just a studio in a box setup. I am using a K-x and a Tamron 28-75. Any ideas on what I am doing wrong?

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02-29-2012, 10:06 PM   #2
Brooke Meyer
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Your aperture is f22 for no reason, you don't need a lot of DoF. Your Tamron 28-75/2.8, which I've had for years and is my most used, like most lenses, is sharpest at f8. If you are using flash and light bulbs on your box, let more ambient background light in with a slower shutter. Shutter speed doesn't matter for flash. I'm assuming your using a tripod. Also, the 2sec delay does Mirror Lockup to reduce vibrations.

Minimum focus on the Tamron lens is 12" so I'm not sure why you are at 75mm. I don't do product shots but here is a recent shot with that lens at f8 & 43 mm with diffused flash and a longer exposure to balance the ambient light. I had a black cloth behind the blossom. Red Camellia | Flickr - Photo Sharing!

Last edited by Brooke Meyer; 02-29-2012 at 10:12 PM.
02-29-2012, 10:10 PM   #3
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Each lens has an aperture setting where the lens can produce the highest sharpest resolution. Just because your shooting at f22 does not mean the whole frame will be sharp, degradation of IQ starts creeping up once the f climbs.

In program mode theres a way for the camera to show you what that optimal resolution is. It works primarily only with Pentax lenses, but a few have mentioned that some Tamaron lenses will report this back as well, someone else might chime in.


I would go into full manual mode. Go center weighted for both metering and auto focus. Press the green button, then adjust your aperture to around f8 and then adjust shutter speed to match. Shoot. Then change to f11, adjust your shutter to match, and try again.
02-29-2012, 10:23 PM   #4
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QuoteOriginally posted by Brooke Meyer Quote
Your aperture is f22 for no reason, you don't need a lot of DoF. Your Tamron 28-75/2.8, which I've had for years and is my most used, like most lenses, is sharpest at f8. If you are using flash and light bulbs on your box, let more ambient background light in with a slower shutter. Shutter speed doesn't matter for flash. I'm assuming your using a tripod. Also, the 2sec delay does Mirror Lockup to reduce vibrations.

Minimum focus on the Tamron lens is 12" so I'm not sure why you are at 75mm. I don't do product shots but here is a recent shot with that lens at f8 & 43 mm with diffused flash and a longer exposure to balance the ambient light. I had a black cloth behind the blossom. Red Camellia | Flickr - Photo Sharing!
That shot is gorgeous! Thanks so much for the tips, back to the drawing board.

02-29-2012, 10:24 PM   #5
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QuoteOriginally posted by Wired Quote
Each lens has an aperture setting where the lens can produce the highest sharpest resolution. Just because your shooting at f22 does not mean the whole frame will be sharp, degradation of IQ starts creeping up once the f climbs.

In program mode theres a way for the camera to show you what that optimal resolution is. It works primarily only with Pentax lenses, but a few have mentioned that some Tamaron lenses will report this back as well, someone else might chime in.


I would go into full manual mode. Go center weighted for both metering and auto focus. Press the green button, then adjust your aperture to around f8 and then adjust shutter speed to match. Shoot. Then change to f11, adjust your shutter to match, and try again.
Thanks Wired. I read that too, about program mode but I dont think I was doing it right. Thanks so much for the ideas.
02-29-2012, 10:36 PM   #6
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All these are great tips, the ones about increasing the ambient lighting and using a slower shutter speed on a tripod in particular. As well, you might want to use +0.7 or greater exposure compensation. Your camera wants to render the white background as neutral grey, so you'll need to over-expose in this manner in order to keep it whiter. Just like shooting outdoors against snow, if you've ever had such experience.
03-01-2012, 03:26 AM   #7
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QuoteOriginally posted by Wired Quote
In program mode theres a way for the camera to show you what that optimal resolution is. It works primarily only with Pentax lenses, but a few have mentioned that some Tamaron lenses will report this back as well, someone else might chime in..
You need to select MTF in Program Line via the Custom menu. On my K20D it's Custom menu option 1.
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