Wednesday, August 15, 2012

Wednesday Q & A: What Is Sharp? Photographically.

Got an email the other day from a fellow I know from the local summer college baseball league.  He's at all the games and is the unofficial team shooter.  In the email he had several shots posted online by a Boston area photographer.  He just wanted to ask a question about them, so there's no piracy of intellectual property.  His point was that the shots were nice and sharp and he wanted to know why his shots didn't come out like that.  The shots involved were of a vintage baseball game.  I just shot a vintage game back in June, so I had a couple shots I could use to explain what he was seeing in his comparison of the Boston photogs shots versus his.  The shot on the left in today's image is similar to the one from Boston.  The other is the original of the shot.  The Boston guy left all the MetaData on his shot, so it was easy to see what he was doing when he clicked the shutter.  High shutter speed, slightly elevated ISO, lens cranked out to 200 mm, F4, and the subject was 21' away.  I was able to take a SWAG (Scientific Wild A$$ Guess) at what was going on.  To find out the secrets I uncovered (sounds like a mystery novel), hit the Read More.

First thing is that at 21' and a full frame (he was shooting a D700) sensor with the lens racked out to 200mm the Boston shot is probably very close to fully cropped in the camera.  So he wasn't throwing away any pixels.  He tossed a couple pixels that didn't matter by cropping to, what appears to be, a 16 x 9 format.  I'd guess he removed some distraction above the batter.  The image would still have been the total width of the sensor.  Point number one: he was in close.
Second is that he was shooting with a very high shutter speed (1/8000 sec.).  At that speed there would be absolutely no blur do to either a twitch by the batter or by really mashing the shutter button.  Point number two: he set up his camera to insure a sharp image.
Third would be that his set of images gives the impression that he knows what he's doing in the digital darkroom.  We'll just guess that the image was sharpened by some method in whatever post processing he did.  The images all had a vintage look to them to set the mood of the vintage ball game.  Point number three:  he knew what he was doing after the shoot.
So, the Boston shooter did everything right to get a good, sharp image.
Back to today's image.  I was standing next to the fellow who asked me the question at   other baseball games.  Therefore I knew the conditions he was shooting in.  I know the lens he uses.  It's a 70 x 200 on an FX sensor camera.  I was using a 70 x 300 on a very similar camera.  The shot on the right of today's image is about the most he could get from behind the fence about 100' away from the batter.  We were standing at the first base  bag and at about a 45 degree angle from the baseline.
Then we try to "get the same shot" as the Boston shooter got we'd have to do some serious cropping.  Getting in to the crop that the Boston guy had means cropping away about 80% of the information the sensor picked up.  What looks sharp in the full shot looks kind of soft after cropping.
So, what advice did I give to the local guy?  I told him to grab the batter, take him somewhere where he would have a good, non-distracting  background and fill the frame with the shot he had in his head.  The person viewing the image can't possibly tell if the batter is at home plate or behind the popcorn stand.  It's the result that matters.  Cropping just doesn't make it to try getting a tack sharp image.    
Now, if he wanted to run out and buy a nice new Nikon D800 he could probably (definitely) get away with "some" cropping.