I finally bought the Sigma 50-500 for my Nikon D50, and it works great. However, sometimes it really takes a considerable amount of time autofocusing without a tripod. Do I need to adjust ISO, shutter speed, F-Stop, or anything to improve this?
Also, when you attach it to the body, it will only work with the ring on the red "22" setting. Is that normal?
That ring is for manualing setting the aperture in the lens. The D50, D70, D2X and D200 all have shutters in the body, so when you change the aperture from the highest number on a CPU lens you will get an -E- on your display. Just as a side note, this doesnt happen with manual focus non-CPU lenses.
As for the focusing, do you hear the motor turning when you try to focus? Thats the lens hunting, some lenses dont auto focus as well as other. Im not sure why, maybe it has something to do with their ablility to take in light or the CPU chip (if there is one) in the lens. A good way to get around this is to focus on something with good contrast (a black frames edge and a white wall) that is on the same focal plan as your subject then reframe.
Hope I got most of this right, but it has helped me out
You need to turn the aperature ring to the highest setting and there is a little locking tab to lock it there. You will not need to ever adjust it because the adjustment is on your camera and it electronically adjusts the lens as long as it's locked at it's highest setting.
I used one on my D70 for a while. It will hunt in low light because it's an f/4 lens when it's wide open (like it is when focusing). It's a great lens and takes great pics. When the light gets low just switch to MF.
I just received a 50-500 earlier this week. The autofocus seems fine if the focus is close to start with. I found that you can give it a little help by manually focussing now and then, when for instance you are going from a long distance to a short distance. I've read that this lens is ok to do this with even without switching the af switch to manual on the body.
Posted by Kent Staubus on July 7, 2006 at 11:47 PM
The aperature ring must be set to f22 for the lens to work. This will be true for all your lenses that have a ring--they must be set at the "f" with the highest number.
Changing ISO, f-stop, etc. will have no effect on focus speed. Part of this has to do with the fact it's not a $5,000 lens. The other part may have at least a little to do with the focus setting on your D50. Check your owner's manual and see if you can change the AF area from "large" to "small." What that will do is narrow down the exact spot you want to focus on. Also, be advised that long lenses tend to pick up "stuff" at different distances (e.g. branches etc.) and this confuses them some. After awhile you learn to be more precise in picking the spot to focus on. To test if you lens is basically OK, find a brick building with high contrast bricks/mortar (e.g. dark red bricks and white mortar in between.) Find a wall in full sunlight and face the building from a 90 degree angle, and see if the lens will focus OK. It should because it has lines to focus on, and the subject is basically two dimensional. You can also try to see if it will focus on a highway or railroad bridge that is silhouetted against the sky. That too has strong lines it can "see" with a lot of contrast.
The Bigma has a maximum aperture of 6.3 at the long end, which is very, very small. Nikon designs their cameras to work with 5.6 and larger apertures (larger aperture = more light = more data to focus on), so 6.3 is already pushing the limits a bit. I have a 500 f/7.2 lens and AF doesn't work well at all in low light, but fine with a lot of light, so this is perfectly normal (I think at a maximum aperture of f/8 or smaller the camera would shut down AF completely).
The "Bigma" is not a speed demon for focusing as others have noted. You may want to experiment with the camera's autofocus settings (focus point, type of focus) too to see what works best for your style. I prefer using the center focus point only most of the time, but that is just me.
Discussion
6 repliesAlso, when you attach it to the body, it will only work with the ring on the red "22" setting. Is that normal?
That ring is for manualing setting the aperture in the lens. The D50, D70, D2X and D200 all have shutters in the body, so when you change the aperture from the highest number on a CPU lens you will get an -E- on your display. Just as a side note, this doesnt happen with manual focus non-CPU lenses.
As for the focusing, do you hear the motor turning when you try to focus? Thats the lens hunting, some lenses dont auto focus as well as other. Im not sure why, maybe it has something to do with their ablility to take in light or the CPU chip (if there is one) in the lens. A good way to get around this is to focus on something with good contrast (a black frames edge and a white wall) that is on the same focal plan as your subject then reframe.
Hope I got most of this right, but it has helped me out
I used one on my D70 for a while. It will hunt in low light because it's an f/4 lens when it's wide open (like it is when focusing). It's a great lens and takes great pics. When the light gets low just switch to MF.
Changing ISO, f-stop, etc. will have no effect on focus speed. Part of this has to do with the fact it's not a $5,000 lens. The other part may have at least a little to do with the focus setting on your D50. Check your owner's manual and see if you can change the AF area from "large" to "small." What that will do is narrow down the exact spot you want to focus on. Also, be advised that long lenses tend to pick up "stuff" at different distances (e.g. branches etc.) and this confuses them some. After awhile you learn to be more precise in picking the spot to focus on. To test if you lens is basically OK, find a brick building with high contrast bricks/mortar (e.g. dark red bricks and white mortar in between.) Find a wall in full sunlight and face the building from a 90 degree angle, and see if the lens will focus OK. It should because it has lines to focus on, and the subject is basically two dimensional. You can also try to see if it will focus on a highway or railroad bridge that is silhouetted against the sky. That too has strong lines it can "see" with a lot of contrast.
Kent in SD
Basil
The "Bigma" is not a speed demon for focusing as others have noted. You may want to experiment with the camera's autofocus settings (focus point, type of focus) too to see what works best for your style. I prefer using the center focus point only most of the time, but that is just me.