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  1. #21
    Senior Member
    Woodyg3's Avatar

    Re: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500

    I was wrong.

    So I took both the 100-400 and 150-600 outside and tried focusing at the extreme edges on the D500 in single point mode at max focal length. You are right, it will not focus. Why? Because these focus points are not able to get enough light at f/6.3, I assume. It is very usual to have the center focus points better able to focus in lower light than the ones on the edge, so this isn't too surprising. With my Nikkor f/4 and a 1.4X TC, effectively f/5.6, these focus points work fine. That tells me that the focus sensors on the edges have a "break point" beyond f/5.6. That seems to be indicated by the chart you posted in the first post. Lenses that Nikon makes and that are normally used on the D500 are only slower than f/5.6 if used with a teleconverter, so this limitation seems pretty reasonable within the Nikon product range.

    I suspect that ANY lens put on the D500 with a minimum f-stop smaller than f/5.6 will have this problem. I don't think the manufacturer or any kind of firmware has anything to do with it.

    The fact that I have used both lenses a good deal and never noticed this issue tells me that it is not a limitation in my photography. Obviously, it might well be a problem for others.

    To sum it up, I suspect ANY lens that is slower than f/5.6 is going to encounter single point focusing problems on the extreme sedges with the D500.


    › See More: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500
    Thanks/Like hark, snerkler, Kevin H Thanks/liked this post
    Best Answers snerkler voted best answer for this post
     
    Woody Green

    Clear Eyes, Full Hearts, Can't Lose

    D500, D7200, D7100, D70



  2. #22
    Junior Member

    Re: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500

    Quote Originally Posted by Woodyg3 View Post
    I was wrong.

    So I took both the 100-400 and 150-600 outside and tried focusing at the extreme edges on the D500 in single point mode at max focal length. You are right, it will not focus. Why? Because these focus points are not able to get enough light at f/6.3, I assume. It is very usual to have the center focus points better able to focus in lower light than the ones on the edge, so this isn't too surprising. With my Nikkor f/4 and a 1.4X TC, effectively f/5.6, these focus points work fine. That tells me that the focus sensors on the edges have a "break point" beyond f/5.6. That seems to be indicated by the chart you posted in the first post. Lenses that Nikon makes and that are normally used on the D500 are only slower than f/5.6 if used with a teleconverter, so this limitation seems pretty reasonable within the Nikon product range.

    I suspect that ANY lens put on the D500 with a minimum f-stop smaller than f/5.6 will have this problem. I don't think the manufacturer or any kind of firmware has anything to do with it.

    The fact that I have used both lenses a good deal and never noticed this issue tells me that it is not a limitation in my photography. Obviously, it might well be a problem for others.

    To sum it up, I suspect ANY lens that is slower than f/5.6 is going to encounter single point focusing problems on the extreme sedges with the D500.
    Thanks for this I really appreciate it. I figured that it was light loss at the long end of the 150-600mm but was hoping that that it wouldn't be the same for the 100-400mm. The reason that I didn't think it would automatically be the case is that my 150-600mm stops down to f6.3 around 420-450mm from memory, yet the AF points don't stop working until around 520mm (obviously there will be a subtle light loss zooming from 420mm to 520mm).

    It does beg the question why this new AF system isn't as tolerable as the older ones. My guess is that it's either this way by design to 'entice' you to buy Nikon glass, or as mentioned before it's the limitations of the wider AF spread.

    As for usage, you are dead right. Most people I've spoken to only tend to use centre point/the central cluster and so will never notice an issue. Unfortunately for me, I do tend to use the outer edges for composition purposes. I now need to decide whether I can work around these limitations, or have to contemplate the much more expensive and heavier 80-400mm. I'm thinking I could possibly learn to live with the limitations of the 100-400mm

    Anyway, thanks again. As I said, I appreciate you taking the time to try this and post your findings.
    Thanks/Like Woodyg3 Thanks/liked this post
     

  3. #23
    Senior Member
    mikew's Avatar

    Re: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500

    Thanks/Like hark Thanks/liked this post
     
    Mike

    https://www.flickr.com/photos/7239177@N07/

    Nikon D500, Sigma 100-400, Sigma 105 macro, Nikon 18-200

    Nikon 1 V2,FT-1,10-30mm 30-110mm Viltrox extension tubes










  4. #24
    Junior Member

    Re: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500

    Quote Originally Posted by mikew View Post
    Thanks Mike, appreciate it. I have actually seen that but I believe itís in relation to the 180-400mm and not necessarily the issue with f6.3 lenses. However, fingers crossed it will indirectly help. Iíve been in talk with both Tamron and Sigma. Tamron have been no help whatsoever but Sigma have been back and forth to Sigma Japan and say that their lenses should work with all focus points at all focal lengths but said if I have any more experience with their lenses to give some feedback and theyíll go back to Japan HQ with feedback. Just so happens Iíve hired the Sigma 100-400mm for next weekend so Iíll do some extensive testing
    Thanks/Like mikew, RocketCowboy Thanks/liked this post
     

  5. #25
    Junior Member

    Re: Question regarding the Sigma and Tamron 100-400mm lenses on the D850 and D500

    So the Sigma 100-400mm arrived today and it shows exactly the same traits as the other f6.3 lenses, past 320mm or so you only get the reduced number of AF points that work. Iíve notified Sigma and it will be interesting to hear their response as Sigma Japan assures them that the lens would work fully.

    As Iíve said before, Iím sure neither are faulty, just the way they behave unfortunately.





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