Posted by dan elster on November 22, 2006 at 10:54 AM
Is it possible my Canon 1-400mm IS lense is not as sharp as it used to be? My technique hasn't changed a bit in the last several months, but I swear my percentage of "keepers" isn't what it once was. Can autofocus lose accuracy over time? Or the IS? This lense had it's autofocus repaired by Canon in May, but seemed to work well when I first got it back.
My only other explanation is that my definition of "sharp" keeps getting pickier.
Posted by Ed Dubois on November 22, 2006 at 11:29 AM
Hi Dan,
the short answer is that the autofocus with a particular camera and lens combo can shift. For the first couple of years I had my 500 f4 IS I was super impressed with how sharp the images seemed to be. Gradually though I began to doubt my technique as I couldn't seem to get a really tack sharp shot to save my life. I completely reevaluated my shooting and still wasn't satisfied. So I took the whole rig home, set up a ruler on a table with a pin set up at the 6" mark. Then I focussed as carefully as I could manually with measurements and also with autofocus. The result was that I'd developed some front focus. The pin would be in focus but even at f16 a quarter inch behind was soft. (A long way in front of the pin was sharp though ) Anyway, I sent the camera and lens to Canon and they adjusted the focus and all's been well since. Maybe that's the next thing to try.
The other thing you mentioned is that you're getting pickier. I think we all are. That said I use the 1-400 a lot in my photography of flight shots and also of kiteboarders and have found the results to be superbly sharp. I recently made a vertical 20"x30" print from a crop out of a horizontal shot I took handheld with that lens and the detail and sharpness was remarkable.
Posted by Alex Lofquist on November 23, 2006 at 12:59 PM
Before optical coating was in vogue, old vintage lenses could acquire a coating with time that would improve the speed and contrast. I don't know the cause of this, but suspect that it may have been from tobacco smoke in the air.
Posted by Scott Elliot on November 23, 2006 at 11:55 PM
My old Konica SLR lenses got so old they can't even be seated on any currently made camera.
Lenses are a complex mechanical contrivance. AF motors can wear out, contacts can corrode, wiring insulation can break down, lens-to-body mounts will wear, lubricants will deteriorate, and aperture diaphragm blades will wear. Also, vibration and shock can displace glass elements, and depending upon conditions, coatings can deteriorate. Yep, lenses do get old, apart from obsolesence.
What can we do about it? I suppose the easiest course is to keep our eyes open and look for hints of image degredation, and then attempt to isolate the probable cause. Todays lenses with IS, AF and complex zoom mechanisms have much greater potential for problems than lenses of yore, so our job of identifying the cause of problems is more complex. Having an understanding of the various systems involved would certainly help, I think.
I hope you can idenify and correct the issue, Dan. It is possible that your definition of 'sharp' is evolving.
Discussion
4 repliesMy only other explanation is that my definition of "sharp" keeps getting pickier.
the short answer is that the autofocus with a particular camera and lens combo can shift. For the first couple of years I had my 500 f4 IS I was super impressed with how sharp the images seemed to be. Gradually though I began to doubt my technique as I couldn't seem to get a really tack sharp shot to save my life. I completely reevaluated my shooting and still wasn't satisfied. So I took the whole rig home, set up a ruler on a table with a pin set up at the 6" mark. Then I focussed as carefully as I could manually with measurements and also with autofocus. The result was that I'd developed some front focus. The pin would be in focus but even at f16 a quarter inch behind was soft. (A long way in front of the pin was sharp though
The other thing you mentioned is that you're getting pickier. I think we all are. That said I use the 1-400 a lot in my photography of flight shots and also of kiteboarders and have found the results to be superbly sharp. I recently made a vertical 20"x30" print from a crop out of a horizontal shot I took handheld with that lens and the detail and sharpness was remarkable.
What can we do about it? I suppose the easiest course is to keep our eyes open and look for hints of image degredation, and then attempt to isolate the probable cause. Todays lenses with IS, AF and complex zoom mechanisms have much greater potential for problems than lenses of yore, so our job of identifying the cause of problems is more complex. Having an understanding of the various systems involved would certainly help, I think.
I hope you can idenify and correct the issue, Dan. It is possible that your definition of 'sharp' is evolving.
-PB