Chris Dodkin
West Coast Correspondent
It was a rainy day here yesterday, so I took the opportunity to spend an hour or so, calibrating my lenses to my camera.
This is a relatively recent feature on DSLRs, available on the Canon 1DIII, 1DIV, 1DsMkIII, 5DII, 50D, 7D, Nikon D3, D3x, D300, D700, Sony A900, Pentax K20 - may be others as well...
The idea here is to micro-adjust the focus of each lens on your particular camera, to ensure it is as sharp as it can be when using the camera AF system.
What you need:
The set-up:
I used the hallway at home, with the laptop displaying the moire pattern image placed at one end, and the camera on tripod placed down the hall at the correct distance for each lens.
The moire image was downloaded from this website - http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html
I put the laptop on top of a couple of ottomans, to get it at a decent height - set the screen brightness to max - centered the moire image on the screen at 100% size.
I placed the tape measure on the floor, so I could quickly see the distance from the laptop screen.
I set my tripod at a height so that the lenses were at the same height as the center of the laptop screen.
The Technique:
More than one way to do this, I used this method...
Place camera and lens at a minimum distance of 50 x focal length from laptop screen
Line up camera so target image is in in the middle of the screen
Switch AF to use single center AF point only
REPEAT until adjusted focus provides max moire resolution when AF is used
By putting the lens to infinity focus at the start of each test loop, you get a higher accuracy on the whole calibration.
Takes a while to get used to how it works - but the moire pattern is a very clever way of checking for max sharpness in focussing.
When you have you calibration dialed-in do a few extra checks around the testing loop to be sure.
Note: with a zoom lens, always use the longest focal length to calibrate.
You'll need to move the camera/lens for each lens you test - depending on focal length.
You'll need a lot of space to test anything over 200mm!!!!!
I had to adjust every one of my lenses to some degree - some only 1 step, the worst 5 steps out of a possible 20.
Those adjustments are stored in camera for each specific lens - so you do it once, and you're good to go.
Worth doing - just be sure you set everything up carefully, and give yourself time to do it properly.
Now, I need to figure out where I can test my 300mm and 600mm lenses
This is a relatively recent feature on DSLRs, available on the Canon 1DIII, 1DIV, 1DsMkIII, 5DII, 50D, 7D, Nikon D3, D3x, D300, D700, Sony A900, Pentax K20 - may be others as well...
The idea here is to micro-adjust the focus of each lens on your particular camera, to ensure it is as sharp as it can be when using the camera AF system.
What you need:
- A moire pattern image as a target
- A laptop or LCD screen to display it on (printouts don't work)
- A tape measure to ensure you are at the correct distance from the target
- A tripod for your camera
- Your lenses
- A chair to sit on whilst you go through the calibration process!
The set-up:
I used the hallway at home, with the laptop displaying the moire pattern image placed at one end, and the camera on tripod placed down the hall at the correct distance for each lens.
The moire image was downloaded from this website - http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html
I put the laptop on top of a couple of ottomans, to get it at a decent height - set the screen brightness to max - centered the moire image on the screen at 100% size.
I placed the tape measure on the floor, so I could quickly see the distance from the laptop screen.
I set my tripod at a height so that the lenses were at the same height as the center of the laptop screen.
The Technique:
More than one way to do this, I used this method...
Place camera and lens at a minimum distance of 50 x focal length from laptop screen
Line up camera so target image is in in the middle of the screen
Switch AF to use single center AF point only
- Manually set focus to infinity
- Press shutter half way to allow AF to focus on laptop screen
- Engage Live View mode
- Use zoom feature to view moire pattern at x10
- Manually adjust focus ring slightly to see if any adjustment provides more moire detail
- If it does - then micro-adjustment is needed - front or back focus adjust
- Set micro adjust on camera
- Set lens back to infinity focus manually
- Switch off Live View
REPEAT until adjusted focus provides max moire resolution when AF is used
By putting the lens to infinity focus at the start of each test loop, you get a higher accuracy on the whole calibration.
Takes a while to get used to how it works - but the moire pattern is a very clever way of checking for max sharpness in focussing.
When you have you calibration dialed-in do a few extra checks around the testing loop to be sure.
Note: with a zoom lens, always use the longest focal length to calibrate.
You'll need to move the camera/lens for each lens you test - depending on focal length.
You'll need a lot of space to test anything over 200mm!!!!!
I had to adjust every one of my lenses to some degree - some only 1 step, the worst 5 steps out of a possible 20.
Those adjustments are stored in camera for each specific lens - so you do it once, and you're good to go.
Worth doing - just be sure you set everything up carefully, and give yourself time to do it properly.
Now, I need to figure out where I can test my 300mm and 600mm lenses
