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

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snerkler

New member
hark said:
That must be what I'm thinking of. What I don't understand is why Woody, who has used the Tamron mounted on a D500, hasn't experienced the problem. It does seem like a setting somewhere. Anyway...good luck. I hope you find a lens that will meet your expectations! ;)
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Maybe he hasn't tried single point AF. I know when I was asking other users about the Tamron 150-600mm several said they had not experienced the issue and that there's worked fine, allowing them to use d153 etc. However, when I asked them to use single point AF and move it to one of the extreme corners they then confirmed that they experienced the same issue as myself in that it would let you choose the focus point, but past around 500-520mm it just refused to focus, it would hunt and then give up. I've not spoken to one Tamron 150-600mm user (or sigma 150-600mm user) who's extreme corner AF points work in single point AF at 600mm so I would be interested to know if Woody's tried this tbh as it could then point to firmware if his is a newer lens.

It's definitely not a setting imo, I believe it's a case that they're f6.3 lenses and therefore the AF points that actually work become limited due to this. The only confusing thing for me is why it's only this new 153 point system that seems to limit the AF points that work at f6.3, you'd think a newer system would be better. What would also be better/less confusing (imo) is if they designed the cameras so that you just couldn't select the points that don't work past a given max aperture.
 
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Woodyg3

Woodyg3

Senior Member
Contributor
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.
 
S

snerkler

New member
Woodyg3 said:
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.
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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.
 
S

snerkler

New member
mikew said:
@snerkler

Have you seen this

https://nikonrumors.com/2018/06/13/...not-released-for-nikon-d5-d850-and-d500.aspx/
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Thanks Mike, appreciate it. I have actually seen that but I believe it’s in relation to the 180-400mm and not necessarily the issue with f6.3 lenses. However, fingers crossed it will indirectly help. I’ve 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 they’ll go back to Japan HQ with feedback. Just so happens I’ve hired the Sigma 100-400mm for next weekend so I’ll do some extensive testing ;)
 
S

snerkler

New member
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. I’ve notified Sigma and it will be interesting to hear their response as Sigma Japan assures them that the lens would work fully.

As I’ve said before, I’m sure neither are faulty, just the way they behave unfortunately.
 
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