Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera is Z7II and low light Af is turned on and also lens focus was limited to 6m-infinity. I used dynamic area AF to focus.

AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.

Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions. any other configurations that can help in this situation? I almost couldn't take a single picture with right focus when it was around dusk.

AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions.any other configurations that can help in this situation?I almost couldn't take a single picture with right focus when it was around dusk.Turning offd9if it isn't already may help.https://www.dpreview.com/forums/post/62530300

Wahrsager wrote:AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions.any other configurations that can help in this situation?I almost couldn't take a single picture with right focus when it was around dusk.Turning offd9if it isn't already may help.https://www.dpreview.com/forums/post/62530300This is a good point. I can change it and see if it helps. thanks a lot.

AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions.any other configurations that can help in this situation?I almost couldn't take a single picture with right focus when it was around dusk.Turning offd9if it isn't already may help.https://www.dpreview.com/forums/post/62530300This is a good point. I can change it and see if it helps. thanks a lot.Also, (I find) it very easy to quickly switch to AF-S underway (Fn2 + a single click of the main command dial) to utilize low-light AF should target be stationary.

Wahrsager wrote:AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions.any other configurations that can help in this situation?I almost couldn't take a single picture with right focus when it was around dusk.Turning offd9if it isn't already may help.https://www.dpreview.com/forums/post/62530300This is a good point. I can change it and see if it helps. thanks a lot.Also, (I find) it very easy to quickly switch to AF-S underway (Fn2 + a single click of the main command dial) to utilize low-light AF should target be stationary.That also makes sense. My fn2 is already assigned but I can use the function button on lens for that and test it. thanks.

AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera is Z7II and low light Af is turned on and also lens focus was limited to 6m-infinity. I used dynamic area AF to focus.What ISO settings were you using AND what was the resulting exposure?  We know that mirrorless camera work better when the exposure is slightly positive (as opposed to under exposed).

ajm057 wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera is Z7II and low light Af is turned on and also lens focus was limited to 6m-infinity. I used dynamic area AF to focus.What ISO settings were you using AND what was the resulting exposure? We know that mirrorless camera work better when the exposure is slightly positive (as opposed to under exposed).I was playing with ISO and light but from my pictures, some of them were around 6400 to 8000 ISO. EVF was okish to my eye but of course a bit dark because it was near dusk. I can test again with more bright EVF and see if there is any improvement.

AlireaPhotography wrote:Wahrsager wrote:AlireaPhotography wrote:Hi, I am using new Nikkor 400 f4.5 and I love this lens from image quality perspective and handling and portability. However, I faced some issue yesterday which makes me worry about using AF with longer telephoto lenses... Around dusk, I was trying to take pictures of deers and clearly it was in low light so camera would struggle to focus. But as soon as the lens lost focus, it would take a long time until it could find the subject again. What I mean is that I noticed the lens is just moving all elements from far to the front and this process was really, really slow... it could take up to 3 seconds maybe... at some point I had to overwrite the focus by manually focusing and ignore autofocus. I am wondering if I am missing some configurations or if this is camera issue than lens issue? My camera isZ7II and low light Af is turned onand also lens focus was limited to 6m-infinity. I useddynamic area AF to focus.FYI,dynamic area is when in AF-Candlow-light AF only works in AF-S.Thanks. I didn't know that... but that makes it useless then because I rarely use AF-S in this sot of conditions. any other configurations that can help in this situation? I almost couldn't take a single picture with right focus when it was around dusk.When you get in extreme low light situations, you need to choose a different type of image or make other compromises. Switching to AF-S makes sense. You're not going to have shutter speeds fast enough for fast motion anyway. Low Light AF is a good option for times when you need a different strategy.Manual focus is a reasonable skill to learn. If you hold the AF-On button while turning the AF ring you can invoke Focus Peaking.Be sure your lens is using the AF limiter switch to reduce hunting.ISO 6400-8000 is not really low light for the camera.  Make sure you are choosing a good AF target with contrast.  Pre-focus if necessary on near the correct distance.

That also makes sense. My fn2 is already assigned but I can use the function button on lens for that and test it. thanks.I finally settled on using the Movie Record button for this due to its location and the times when I am not using a lens with a lens function (or multiple ones).   I had the Movie button on Preview, as I thought I read thats needed in some instances.  I may make a separate Bank for that scenario where I am using AF-S mostly.

Low Light takes anywhere from a brief blip to a few seconds in very dark conditions. Too long for AF-C moving subjects.It flashes up a "Low light" message at the top of the display, and I see the scene brighten as it gathers more light, then reverts to a normal display once focus is set.It can even focus in scenes where it's too dark for me to see details on the subject.Low light=On doesn't slow down AF in normal lighting conditions, so I leave it on all the time.

Thank you all for your comments. I will try a combination of your suggestions here soon and see if I can get more keepers. thanks.