400 F/2.8 and 600 F/4 AF Accuracy with TCs poll

[Amasaback]

My biggest issue with the Nikon 600f4 with TC engaged is the reach can get into situations where heat waves affect focus and of course image quality. Last week in the Lamar Valley it would not subject detect coyote, wolves or foxes or a bald eagle where there were heat waves. Inother conditions it was great.

 

[Amasaback]

Would add that I also stacked it with a 1.4 TC so effectively 1176MM and of course made all of comments above even more of a factor but was very impressed when I was able to get the right conditions.

 

[zemlin]

My main gig with big glass is motorsports - IndyCAR racing. I usually use a slower shutter to get a bit of motion blur, but do shoot some safe shots a 1/1600 where it's easier to evaluate the hardware. There's still motion blur at this speed, but it's a pretty safe, easy shot.

I'm shooting Z9s with the 400 TC lens. I have the 2X TC, which is great, but if I want to go to 800 my setup is the 1.4 external with the 1.4 internal for 784mm. This gives me the flexibility flip the internal TC out and shoot 560. With the 2X Plus the internal 1.4X (1120mm), things do get a little sketchy. It's hard to quantify as there are a lot of heat-haze, exhaust fumes, and even the air coming off wings can upset an image when shooting that long.

If I look at sequences of on-track images at 784mm, for all intents and purposes almost every frame is spot on. There are misses, but they are outliers.

I voted JUST AS ACCURATE since I feel trying to use the 2X+internal 1.4x is asking a lot.

 

[Ken Miracle]

I only have the Z600 f/4 TC and only use it with the built in 1.4TC. I have only had the lens since 10-31-2024 so I have not used it as extensively as many.

My use is for bird ID photography, hand held on Z9 and Z6III in wind, cloudy snowy, sunny and recently inversion fog and cold along the Boise River.

I voted just as accurate with TC for stills and action.

On the Z9 with bird ID in some situations the AF is more accurate with the TC than without when the bird head/eye is filling less of the frame. With the Z9 and Z600 f/6.3 or my f mount 600 f/4E (on used a few times on Z9 before I sold it) I helped the focus out by toggling quickly to DX mode and now it is engaging the TC.

In backlighted situations or low light AF is often helped by increasing exposure value EV with the control ring when using Manual with auto iso, and I need to get a more accurate exposure of the bird anyway.

I use center weighted metering more than most since my concern is first for the bird and less so for the rest of the frame. I will also go to spot metering as needed and have fn3 on Z9's set up to quickly change metering.

As I would expect I need to brighten the exposure more and more often with the TC engaged with f/5.6 instead of F.4.

 

[maikm]

It's all relative. Only thing I have enough experience with is my own Z9 and 400/2.8 TC combo. The built-in TC or external TC14 don't make any difference for me, while with a TC20 everything is a bit slower but still accurate, at least I didn't notice anything to the contrary so far. With both internal TC and TC20 stacked it gets worse, but of course that's at f/8 and all, and I don't often shoot action at 1120mm. So, to squish all that in one "with TC" answer is quite hard.

 

[Steve]

It's all relative. Only thing I have enough experience with is my own Z9 and 400/2.8 TC combo. The built-in TC or external TC14 don't make any difference for me, while with a TC20 everything is a bit slower but still accurate, at least I didn't notice anything to the contrary so far. With both internal TC and TC20 stacked it gets worse, but of course that's at f/8 and all, and I don't often shoot action at 1120mm. So, to squish all that in one "with TC" answer is quite hard.

It really is tough and I probably should have skipped the poll and just asked individual experiences with different combos. There are just so many variables involved - it seems some are seeing AF inconsistency, some aren't and I think it's very dependent on conditions.

 

[zemlin]

It really is tough and I probably should have skipped the poll and just asked individual experiences with different combos. There are just so many variables involved - it seems some are seeing AF inconsistency, some aren't and I think it's very dependent on conditions.

and technique becomes more critical the longer you go as well. My first shots with stacked TCs on the 400 were horrible until I realized I needed to try harder. It is hard to evaluate.

 

[Steve]

and technique becomes more critical the longer you go as well. My first shots with stacked TCs on the 400 were horrible until I realized I needed to try harder. It is hard to evaluate.

For sure. Plus, there's individual standards that come into play which makes it even tougher. What one person might deems perfectly acceptable is utterly unusable to another.

At this point, I think it's more or less safe to say something along the lines of this: For static shots, most people are pretty happy with either lens with a TC attached, however, for action it's more of a mixed bag, with some users seeing AF inconsistency and others not.

 

[maikm]

Another factor is that adding TCs is often an attempt to overcome longer distances to the subject, at which point heat diffraction becomes more of a factor, too. That makes it even harder to make an accurate statement about AF performance with TCs, as the contrasting edges which the autofocus needs to latch on to become more blurry with more air between subject and lens, too.

So, the answer would really need to take that into account and compare performance at similar focus distances with and without TCs, rather than same subject size in frame at different distances. Hard to answer.

 

[Ken Miracle]

and technique becomes more critical the longer you go as well. My first shots with stacked TCs on the 400 were horrible until I realized I needed to try harder. It is hard to evaluate.

Great point.

When I was using the Z800 f/6.3 I was at almost the same focal length as the Z600 f/4 TC with the TC engaged. So I was always using my subconscious longest focal length technique and faster shutter speeds whenever possible.

With the Z 600 f/4 TC it is easy to be using a faster shutter speed at 600mm f/4 with the extra light and then not increase it or even lower it after that easy flick of the switch to engage the TC and have less light at 840mm f/5.6.

 

[Steve]

Another factor is that adding TCs is often an attempt to overcome longer distances to the subject, at which point heat diffraction becomes more of a factor, too. That makes it even harder to make an accurate statement about AF performance with TCs, as the contrasting edges which the autofocus needs to latch on to become more blurry with more air between subject and lens, too.

So, the answer would really need to take that into account and compare performance at similar focus distances with and without TCs, rather than same subject size in frame at different distances. Hard to answer.

It really is - and it's tough to test because there are just so many variables. So, I have to ask around a bit and see what others have experienced.

 

[Dinusaur]

I hope you can help me. I'm doing a video on 400 2.8 vs 600 F/4 and want to collect a wider breath of data for it regarding AF accuracy with TCs . NOTE - I'm not talking about sharpness, but rather AF accuracy. For the most part, TCs cause a minor loss in sharpness are still plenty sharp on either the 400 2.8 or 600 F/4 - however - where I notice a problem is with AF accuracy. In other words, when you take a series of images, do you find the number of sharply focused ones are the same with the TC or do you find that you get fewer perfectly focused shots with the TC than without it. And again, this is for the 400 2.8 and 600 F/4.

You can pick multiple choices in the poll above - and your comments are welcome as well. I can't put enough detail into the poll, so I'd like to hear about the differences you find between 1.4 and 2X TCs in regard to AF accuracy compared using the lens without a TC (with either lens).

So, here's my anecdote to get things started:

FWIW, I always have noted a drop in AF accuracy with my big primes when using a TC compared to when not using one. For instance, with my 400 2.8 lenses, I find that they are great without the TC (no surprise), good with the 1.4TC, and OK for stills but not action with the 2X (especially the Sony 400 2.8 - it's terrible for action with the 2X attached).

With my 600 F/4 it's the same thing. It';s great ton it's own, good with the 1.4X and "stills only" with the 2X.

Interestingly, I also find that the 600 F/4 is more accurate than the 400 2.8 + 1.4TC, even though the F/stops are the same and the focal lengths similar.

Since I acquired a Z9 in 2022, I started collecting data for focus accuracy in order to find the best possible combination of settings. Initially I was shooting with F-mount 500m f/4 FL lens and an FTZ adapter. Then I started using 400 2.8TC from early part of 2023. The subject I chose was an Osprey diving in a local storm water pond for fish during summer months. The pond is about 200 meters at the longest end and 128 meters at its widest. It has quite a busy background at the perimeter in the form of cattails, big trees and even people's houses. There's a wooden platform on the south end of the pond, where one can stand while birds circle above the pond and dive wherever it sees a fish, often times towards the edges of the pond. Sometimes you get lucky when the bird dives somewhere in the middle.

Initially I had challenges in keeping the diving bird in focus; however, since FW 4.0 and with 400 2.8TC things improved drastically. During 3 to 4 months in summer it is not unusual to get hundreds of photos and thus statistically excellent data sets for analytics. One day I'll put it all together. In the meantime, for Steve's sake, I've put together a short summary (see attached file) for Z9 focus accuracy using 400 2.8TC and both 1.4x and 2.0x teleconverters. This is only based on a small sample data set in the month of August this year. One thing to note is that I've used ExifTool to find an approximate subject distance. The tool reads the distance in terms of steps: 147.52m, 73.76m, 49.17m etc., I didn't find anything in-between. The distance it reads is not precise, but it is a good indicator of relative closeness of the bird. Take a look at the dataset, the comments associated with each and let me know if you have any question or comments.

 

[fulltimewanderer]

I’m shooting with the 600F4 G lens. I’ve used this lens on my D500, D4, D850 and now on a Z9. I’ve been completely satisfied with the results on all bodies when shooting with the bare lens. I’ve shot the above bodies ( minus the Z9) with the 1.4, 1.7, and the 2.0 and for the most part I’m not satisfied with the results. I’m probably the odd one out here, I feel that my best results when using a TC is with the 1.7. All cameras have been calibrated with the 600 and all TC’s. I have yet to try any TC on the 600 while shooting with the Z9, maybe in time I will but for the most part I avoid using a TC.

 

[jpgrove]

It was my understanding that the built in TC was matched to each lens to ensure the optical characteristics were well controlled? I haven't noticed any really difference in AF performance when using he built in TC but that doesn't mean their isn't, because everyones use case would be different?

 

[arbitrage]

Another factor is that adding TCs is often an attempt to overcome longer distances to the subject, at which point heat diffraction becomes more of a factor, too. That makes it even harder to make an accurate statement about AF performance with TCs, as the contrasting edges which the autofocus needs to latch on to become more blurry with more air between subject and lens, too.

So, the answer would really need to take that into account and compare performance at similar focus distances with and without TCs, rather than same subject size in frame at different distances. Hard to answer.

This is spot on. People stick TCs on to try to reach out to far and this really affects final results. On the flip side, action can come in too close for the TC sometimes where it is too hard to keep the bird in frame and/or DOF gets too small and hit rate takes a dive.

For the most part, I've decided to shoot at 600mm max and only shoot when I'm happy with how much of the frame the bird is filling. I find at 600mm and less, if the bird satisfies my % of frame, I will get images that satisfy me. Beyond 600mm I can certainly use it if shooting perched birds to get them to really fill the frame but the issue comes that when I'm shooting perched birds I'm just doing it to kill time till some more interesting BIF happens and I don't like being stuck at 840mm. Now I realize the Nikon 600TC would solve that issue. One day I hope to own that lens but I need Nikon to make a camera that is worthy of it and they aren't there yet (for me, YMMV).

 

[Ken Miracle]

This is spot on. People stick TCs on to try to reach out to far and this really affects final results. On the flip side, action can come in too close for the TC sometimes where it is too hard to keep the bird in frame and/or DOF gets too small and hit rate takes a dive.

For the most part, I've decided to shoot at 600mm max and only shoot when I'm happy with how much of the frame the bird is filling. I find at 600mm and less, if the bird satisfies my % of frame, I will get images that satisfy me. Beyond 600mm I can certainly use it if shooting perched birds to get them to really fill the frame but the issue comes that when I'm shooting perched birds I'm just doing it to kill time till some more interesting BIF happens and I don't like being stuck at 840mm. Now I realize the Nikon 600TC would solve that issue. One day I hope to own that lens but I need Nikon to make a camera that is worthy of it and they aren't there yet (for me, YMMV).

Your right the Z600 f/4 TC takes care of the need to fill the frame when I want to for my bird ID and since that is my primary photographic pursuit the bird sitting in the bushes is just a important as a BIF. I have posted the lens used on the Z9 and Z6III in this forum.

 

[Steve]

Since I acquired a Z9 in 2022, I started collecting data for focus accuracy in order to find the best possible combination of settings. Initially I was shooting with F-mount 500m f/4 FL lens and an FTZ adapter. Then I started using 400 2.8TC from early part of 2023. The subject I chose was an Osprey diving in a local storm water pond for fish during summer months. The pond is about 200 meters at the longest end and 128 meters at its widest. It has quite a busy background at the perimeter in the form of cattails, big trees and even people's houses. There's a wooden platform on the south end of the pond, where one can stand while birds circle above the pond and dive wherever it sees a fish, often times towards the edges of the pond. Sometimes you get lucky when the bird dives somewhere in the middle.

Initially I had challenges in keeping the diving bird in focus; however, since FW 4.0 and with 400 2.8TC things improved drastically. During 3 to 4 months in summer it is not unusual to get hundreds of photos and thus statistically excellent data sets for analytics. One day I'll put it all together. In the meantime, for Steve's sake, I've put together a short summary (see attached file) for Z9 focus accuracy using 400 2.8TC and both 1.4x and 2.0x teleconverters. This is only based on a small sample data set in the month of August this year. One thing to note is that I've used ExifTool to find an approximate subject distance. The tool reads the distance in terms of steps: 147.52m, 73.76m, 49.17m etc., I didn't find anything in-between. The distance it reads is not precise, but it is a good indicator of relative closeness of the bird. Take a look at the dataset, the comments associated with each and let me know if you have any question or comments.

Thanks for this, although the distance skews it a little I think. The problem is, even at 49 meters, you have 1.4 meters worth of DoF, so it can cover up a lot of near-misses. It's interesting that the ones at 147m were somewhat worse, although at that range I think atmospherics are certainly a factor.

Although, this may account for some of the varied experiences in this thread. When I'm shooting a lens with a TC, I'm shooting at a range where I won't need much or any cropping in the final shot. My approach with TCs has always been to use them to sort of finish filling the frame the way I want. So, my DoF is almost always at or less than 1/2 meter - often even less than .25 meter. So, AF errors are more easily spotted since DoF can't cover them.

 

[Steve]

It was my understanding that the built in TC was matched to each lens to ensure the optical characteristics were well controlled? I haven't noticed any really difference in AF performance when using he built in TC but that doesn't mean their isn't, because everyones use case would be different?

It is, but it's not a "get of of jail free card" either. You still have all of the 1.4TC characteristics to deal with even with a matched TC.

As a side note, I used to have a 180-400 TC (F-Mount) and in testing I discovered that the external 1.4TC actually produced a sharper result than the built-in one. While I don't think that's the case with the 400 and 600 TC lenses, it goes to show that a built-in TC isn't "invisible" from an optical and performance standpoint.

 

[BLev65]

I'm not sure I have anything new to add, but here are a few of my thoughts. In general, I do not find that the internal 1.4x converter on my 400 f2.8TC impacts image quality or AF speed when I am shooting subjects that are relatively close. By relatively close, I mean within 30 feet or so. While there might be a slight AF speed difference on paper, it is not anything I've observed in practice and thought... "I would have got the shot if I didn't engage the TC." The 400 f2.8TC and Z9 pair so well together, that any marginal deficiency in performance seems trivial to me.
On the other hand, if I stack 1.4x converters (internal + external) or I use a 2x (which I don't any longer), I do see a drop in both AF performance and ultimate image quality.
I tend to be a little more forgiving of my gear and less critical than others, so take my words for what they are. At this point, I am a firm believer that all of this moderate to high end gear is so good that we should stop spending so much of our time looking for the flaws and spend more time on focusing on the making of images. With that said, the curious scientist in me still wants to know what you find...

cheers,
bruce

 

[Marcelo_R]

I find the Z600 TC with the TC engaged as accurate as the Z800 PF, not better, not worse. Speaks loads about the Z800 and how good it is.

Would I expect more from an internal TC? Maybe yes (same with the 180-400 TC) but we can't see thru that we are adding (as good as these might be) a TC regardless of how good the optics are.

 

[Ken Miracle]

I find the Z600 TC with the TC engaged as accurate as the Z800 PF, not better, not worse. Speaks loads about the Z800 and how good it is.

Would I expect more from an internal TC? Maybe yes (same with the 180-400 TC) but we can't see thru that we are adding (as good as these might be) a TC regardless of how good the optics are.

I agree the 600 f/4 TC with TC engaged = 840 performs pretty much the same as my Z800 f/6.3 did. The only reason I splurged on the Z600 f/4 TC was the versatility for my birding and low light capability, fast focus, great bokeh @ 600 at f/4 and yet with the flip of the switch a lens that performs like my Z800 f/6.3 did with a bit of an edge in bokeh in some situations primarily around water at certain angles an light.

 

[PAUL50]

I shoot with two Nikon Z9s and the Nikkor Z 400 f/2.8 TC and the Nikkor Z 600 f/4 TC. I recently returned from 16 months of nearly daily shooting in Yellowstone and the Tetons and used both lenses extensively with and without the TCs engaged and almost exclusively on a tripod. Generally, I shoot wide open, which minimizes my depth of field, and manually with auto ISO with one finger continually on the auto focus button, and at 20 frames per second I've had plenty of opportunity to witness whether auto focus speed was a factor in capturing sharp shots. If auto focus speed was effecting the sharpness of my shots with the TC engaged, I'd readily be able to see significantly varied results in the bursts I generally take attempting to capture the motion of the animals. (Techniques, I should add, I've learned from @Steve ). I have not seen that. I voted that for both lenses, for still and action shots of animals, that the use of the internal TCs did NOT impact auto focus speed with the caveat that I was mentally comparing shots under similar conditions. I do not use external TCs, nor do I stack them, and I've never used a 2.0 TC. Because of the distances folks have to shoot out west, I've had many days where heat diffraction, snow, rain, and fog made capturing tack sharp shots nearly, if not totally, impossible, but that was not a function of auto focus speed as measured by the use of the TCs or not, but simply a result of difficult conditions. Problems I ran into were not related to auto focus speeds but rather the auto focus capturing the grass in front of an animal or a background behind an animal, but that's a different subject.

 

[Marcelo_R]

I agree the 600 f/4 TC with TC engaged = 840 performs pretty much the same as my Z800 f/6.3 did. The only reason I splurged on the Z600 f/4 TC was the versatility for my birding and low light capability, fast focus, great bokeh @ 600 at f/4 and yet with the flip of the switch a lens that performs like my Z800 f/6.3 did with a bit of an edge in bokeh in some situations primarily around water at certain angles an light.

That's exactly the same reason I bought the Z600 TC.
I took the Z800 last March to Pangolin, and I missed some shots due to the fixed FL... so I'm taking the Z600 instead next time (in 3 weeks, I'll be returning). Krgds, Marcelo

 

[Marcelo_R]

I voted that for both lenses, for still and action shots of animals, that the use of the internal TCs did NOT impact auto focus speed with the caveat that I was mentally comparing shots under similar conditions.

Same as I feel, subjectively of course, by engaging the TC on/off.
Haven't measured (wouldn't know how to do it) it though, nor I think it can be done without some specific man-created scenarios to get such a repeatability that could be considered a fact either way (I can imagine that with a machine that shoots objects at the same chosen speed all the time at the same angle and in the same light/wind conditions...)
Krgds, Marcelo

 

[jad]

I hope you can help me. I'm doing a video on 400 2.8 vs 600 F/4 and want to collect a wider breath of data for it regarding AF accuracy with TCs . NOTE - I'm not talking about sharpness, but rather AF accuracy. For the most part, TCs cause a minor loss in sharpness are still plenty sharp on either the 400 2.8 or 600 F/4 - however - where I notice a problem is with AF accuracy. In other words, when you take a series of images, do you find the number of sharply focused ones are the same with the TC or do you find that you get fewer perfectly focused shots with the TC than without it. And again, this is for the 400 2.8 and 600 F/4.

You can pick multiple choices in the poll above - and your comments are welcome as well. I can't put enough detail into the poll, so I'd like to hear about the differences you find between 1.4 and 2X TCs in regard to AF accuracy compared using the lens without a TC (with either lens).

So, here's my anecdote to get things started:

FWIW, I always have noted a drop in AF accuracy with my big primes when using a TC compared to when not using one. For instance, with my 400 2.8 lenses, I find that they are great without the TC (no surprise), good with the 1.4TC, and OK for stills but not action with the 2X (especially the Sony 400 2.8 - it's terrible for action with the 2X attached).

With my 600 F/4 it's the same thing. It';s great ton it's own, good with the 1.4X and "stills only" with the 2X.

Interestingly, I also find that the 600 F/4 is more accurate than the 400 2.8 + 1.4TC, even though the F/stops are the same and the focal lengths similar.

With the built in TC on my 400 or an additional 1.4 tc I see no difference at all. But, adding a 1.4 or a 2x TC does make focus slower to acquire, but when it does I think it is just as good - if the light is good. Low light is more of a problem in all cases with or without an added tc.