Posted by Ryan Askren on February 27, 2010 at 4:03 PM
Hello all,
Once again I am relatively new to photography and want to pick the brains of thos greater than myself. I owned a Nikon 1.4X teleconverter which I tried using with my Nikon D300 and 200-400mm lens but always had problems with focus when using the teleconverter. I just brushed it off and tossed it in my closet where it has been sitting since the first attempt.
Now that I have a bit more understanding of cameras I realize this could likely be fixed easily with AF in-camera fine tuning. My question for all of you is; what is the best way to go about doing this? Any help is appreciated.
To find the AF adjustment for my lens, I simply put it on a tripod. Then I took pictures of a ruler at about a 45 degree angle to the lens (45 degrees away form perpendicular to the lens). I auto-focused on the 6 inch mark. I then viewed the result on my computer (which was hooked to the camera). I guessed and checked until I found the point at which the auto focus found the six inch mark perfectly.
Posted by David Bostedo on February 27, 2010 at 9:57 PM
One thing to note is that the AF adjustment is also focus distance dependent. So setting it by using a close target will not necessarily be correct for a target further away. So if you know the "usual" distance that you shoot objects at, getting close to that for the target would be better.
Posted by Buck Ward on February 27, 2010 at 10:36 PM
Not familiar with your lens or teleconverter, but the conventional wisdom is that tele-converters aren't as sharp with zoom lenses as they are with primes.
Try another teleconverter. Perhaps yours is bad. Go to your local camera store and put one on for a test. I've used the combination you mentioned without any in camera AF adjustments with great results. Keep us posted on your results.
Andrew
Posted by Gene Lugo on February 28, 2010 at 11:31 AM
Ryan, what problems are you having with AF on this camera/lens combination? My experience with the AF on the 300mm lens was a little frustrating at first, having come from a D200. The D200 achieved accurate focus very quickly, with hardly a miss. Depending on how you have your AF set on the D300, you may experience slow, inaccurate focus. There are up to 51 sensors that can come into play, and it takes time to info from all 51 to the processor, have the processor digest the information, then adjust the focus on the lens.
My strategy is to limit the number of sensors to 21. (A3) - Dynamic AF area; AF Point Selection to 51 (A8); AF-C Priority Selection to Release (A1); AF-S priority selection to Focus (A2); and finally AF Activation to off (A5).
With these settings, the typical way I use the camera's focusing system is to leave the front C-S-M switch to C or continuous focus nearly 100% of the time. If I want to simulate AF-S mode, I merely pick my focus target in the viewfinder, press the AF-ON button with my thumb to acquire focus, then release my thumb and recompose the image, if necessary. If I want to track a moving subject in Continuous Servo mode, then I hold my thumb on the AF-ON button to track.
By setting A5 to off, the focus on half press of the shutter release is disabled, with focusing only happening when the AF-ON button is pressed. I have found that, especially with moving subjects, focusing is more accurate and consistent. Letting the camera focus on the half-press on Continuous servo with moving subjects resulted in poor focusing performance and lots of deleted files. For macro work where you do not necessarily want to auto focus, you can easily manual focus and bypass the AF-ON button entirely.
With the camera set as above you never have to touch the C-S-M switch, with the added bonus of what may be slightly better focusing when you press the AF-ON button.
Results with the 200-400 should be pretty decent if you are using the Nikon 1.4x extender, with an just a barely perceptible loss of sharpness, especially if you have the lens sent to F5.6. That lens is as sharp as anything coming out of Nikon these days, and it is capable of spectacular performance, even with a 1/4x extender.
Posted by Richard Ditch on February 28, 2010 at 11:35 AM
... but always had problems with focus when using the teleconverter.
That's a rather general statement and needs more details before I'd assume it is an AF fine tuning issue.
Even the best teleconverter reduces image quality, so we ned to know what you are seeing that led to your conclusion.
What conditions does this happen? Always? Sometimes? Distant and close subjects?
Have you rules out long lens issues in general? Tripod? Enough shutter speed? DOF?
Speed of AF? The TC will slow down the AF function.
I understand there is a way to set your Nikon camera to better calibrate with the focusing point of specific lenses if they don't seem to be focusing at the right point. Once done, everytime afterward that you use that particular lens, you just have to activate that setting. Can someone shed light on this approach?
Thanks,
Rich
Posted by David Bostedo on February 28, 2010 at 1:30 PM
Richard - Your camera has to have an auto-focus fine tune option, which is available on a lot of the newer Nikons, Canons, Sony's, and Pentax's (that I know of - maybe others). It tunes the AF so that it front or back focuses a certain amount to adjust for inaccuracy in the default AF. Here's a Northlight Images instruction page that I know some photographers use with success. Make sure to look at the suggestions, though - particularly that the distance to the target should be 50 times the focal length. For long telephotos, that's a long way.
I've also read reports that some users have found that the adjustment needed isn't consistent across all focus distances. So the setting you need to focus at the MFD, for instance, could be quite different than focusing out near infinity. In that case, you might need servicing help.
Posted by Ryan Askren on February 28, 2010 at 1:54 PM
Hey all, I think David and Rich my question the best.
At first I thought the teleconverter was just reducing the image quality. I always have this problem whenever the teleconverter is attached even in great light. Always using a bean bag or monopod and with VR on. Only ever tried on distant subjects (larger birds such as ducks, geese, and raptors), usually stationary, to no avail. I have always been told this combo is super sharp and I love the 200-400mm alone.
I also always shoot at 9-pt for A3 and continuous for my wildlife photos. I have eliminated any other problems that I know of that it could be. Thank you for the help!
Discussion
9 repliesOnce again I am relatively new to photography and want to pick the brains of thos greater than myself. I owned a Nikon 1.4X teleconverter which I tried using with my Nikon D300 and 200-400mm lens but always had problems with focus when using the teleconverter. I just brushed it off and tossed it in my closet where it has been sitting since the first attempt.
Now that I have a bit more understanding of cameras I realize this could likely be fixed easily with AF in-camera fine tuning. My question for all of you is; what is the best way to go about doing this? Any help is appreciated.
Andrew
My strategy is to limit the number of sensors to 21. (A3) - Dynamic AF area; AF Point Selection to 51 (A8); AF-C Priority Selection to Release (A1); AF-S priority selection to Focus (A2); and finally AF Activation to off (A5).
With these settings, the typical way I use the camera's focusing system is to leave the front C-S-M switch to C or continuous focus nearly 100% of the time. If I want to simulate AF-S mode, I merely pick my focus target in the viewfinder, press the AF-ON button with my thumb to acquire focus, then release my thumb and recompose the image, if necessary. If I want to track a moving subject in Continuous Servo mode, then I hold my thumb on the AF-ON button to track.
By setting A5 to off, the focus on half press of the shutter release is disabled, with focusing only happening when the AF-ON button is pressed. I have found that, especially with moving subjects, focusing is more accurate and consistent. Letting the camera focus on the half-press on Continuous servo with moving subjects resulted in poor focusing performance and lots of deleted files. For macro work where you do not necessarily want to auto focus, you can easily manual focus and bypass the AF-ON button entirely.
With the camera set as above you never have to touch the C-S-M switch, with the added bonus of what may be slightly better focusing when you press the AF-ON button.
Results with the 200-400 should be pretty decent if you are using the Nikon 1.4x extender, with an just a barely perceptible loss of sharpness, especially if you have the lens sent to F5.6. That lens is as sharp as anything coming out of Nikon these days, and it is capable of spectacular performance, even with a 1/4x extender.
That's a rather general statement and needs more details before I'd assume it is an AF fine tuning issue.
Even the best teleconverter reduces image quality, so we ned to know what you are seeing that led to your conclusion.
What conditions does this happen? Always? Sometimes? Distant and close subjects?
Have you rules out long lens issues in general? Tripod? Enough shutter speed? DOF?
Speed of AF? The TC will slow down the AF function.
Thanks,
Rich
I've also read reports that some users have found that the adjustment needed isn't consistent across all focus distances. So the setting you need to focus at the MFD, for instance, could be quite different than focusing out near infinity. In that case, you might need servicing help.
At first I thought the teleconverter was just reducing the image quality. I always have this problem whenever the teleconverter is attached even in great light. Always using a bean bag or monopod and with VR on. Only ever tried on distant subjects (larger birds such as ducks, geese, and raptors), usually stationary, to no avail. I have always been told this combo is super sharp and I love the 200-400mm alone.
I also always shoot at 9-pt for A3 and continuous for my wildlife photos. I have eliminated any other problems that I know of that it could be. Thank you for the help!