DX Mode Versus Teleconverter?

[Anjin San]

Good day. My question is, what are the differences between using a 1.5 teleconverter vs. dx mode?
A 500mm lens = 750mm in both incidences. Is there a good reason as to why people buy one, rather than use the DX camera mode?
I would do the experiment to find out the result(s) but I do not own a teleconverter.

Had this question myself…so I did some testing out back on the lanai using the 500PF, the Z 70-200 and 100-400 with and without the 1.4 and 2.0 TC, and using both DX and FX mode on all combos. Put the Z9 on my tripod and since I had very cooperative subjects (my wife's Teddy Bear named Gunther and a Boehm bird ceramic sculpture) on a table in the late afternoon light at about 20 feet or so range so I had frame filling shots.

Looked at all of those in LR with 1:1 previews and cropped everything to the same effective image size…bear and bird filling the frame…and my conclusion (looking at these on my Apple Studio Display monitor…was that there's not really much difference at all even pixel peeping at 100% and 200%. Very minor differences but to my eye they really aren't better/worse…just slightly different and all were pretty darned good. The 2.0TCs were slightly less good at pixel peeping magnifications.

OTOH, once I zoomed out to the normal…for me at least since output is almost exclusively screen for the blog…Fit option in LR and then going to full frame mode in LR and the differences for anything but the 2.0TC shots just isn't there…and even the 2.0TC shots aren't really worse…they're just not quite as good…but all of the shots are still very good.

My conclusion was that it doesn't make much difference…and if I"m so far away from the subject that I need 800mm because (an actual happening for me)…the park rangers at Yellowstone wouldn't let anybody. go closer than the road to the grizzly eating the bison killed in a battle over the lady bison so we were forced to shoot at probably 300 yards anyway. At that distance all you're going to get is environmental shots anyway and heat distortion and all the other factors that come up when shooting at extreme distances kill the IQ anyway (plus I was shooting on a D7500 at the time so older tech in sensor).

Once I did that…my order for the 800PF got cancelled because of use percentage and size/weight. Cost too but the bang for the buck just wasn't going to be there for me as an amateur…at least until I win the Powerball and no longer care how much anything costs. The 100-400 and 1.4TC are my go to birding lenses these days although as I said in another thread keeping the 500PF to use in DX mode on the Z7II is still under consideration…going to think about it over this birding season and probably do some more comparisons with the 500PF in DX mode vs the 100-400 and TC in both FX and DX mode at longer range subjects…but again all of the other long range subject problems start to come into play there. The pros and cons in the videos in the thread come into play in a decision as well.

I only have the Z TCs which are better optically than the F mount ones along with the Z lenses generally being better optically…and it is true that shifting to DX mode can make the AF subject detection a little better although this is still somewhat anecdotal since it's the same AF sensors being used.

 

[Anjin San]

I was recently faced with a situation where I needed a longer lens than I had… z7, 100-400, 2x converter… still not enough, so flipped to DX got out to effectively 1200mm. And got the shot. Then cropped a little more to an 18mpx image

That's what I did with my grizzly eating the dead bison killed in a mating fight at Yellowstone images…we shot from probably 200-300 yards at least and the rangers would not let anybody leave the road. Even on a DX body with a 150-600…the bear was about the size of two or three focusing red boxes in the D7500 viewfinder…so any sort of closeup went right out the window. I cropped in one as much as I dared but it started getting pretty fuzzy due to crop and heat distortion (Yellowstone in the summer) but I put it in the blog anyway because it was a relatively unique opportunity. The better shots from the encounter were more environmental as the grizzly and a wolf pack squared off over lunch…but the image was still mostly not the wolves and bear…but ya gotta do what you gotta do.

 

[NorthernFocus]

…and it is true that shifting to DX mode can make the AF subject detection a little better although this is still somewhat anecdotal since it's the same AF sensors being used.

The supposition is that in the Z9 the AF works on the data stream to the VF which is separate from the data stream to the imaging sensor. Subject detection works better the larger the subject is in the VF simply due to relative size. Switching to DX mode simply makes the subject larger therefore easier for the camera to recognize.

It's easy enough to test albeit subjectively. Just set up a stuffed animal or a doll with lifelike eyes. Keep backing off until the camera struggles to lock onto the eye in FX mode. Switch to DX mode and see what happens.

 

[bleirer]

The supposition is that in the Z9 the AF works on the data stream to the VF which is separate from the data stream to the imaging sensor. Subject detection works better the larger the subject is in the VF simply due to relative size. Switching to DX mode simply makes the subject larger therefore easier for the camera to recognize.

It's easy enough to test albeit subjectively. Just set up a stuffed animal or a doll with lifelike eyes. Keep backing off until the camera struggles to lock onto the eye in FX mode. Switch to DX mode and see what happens.

I tried a similar experiment with my R5 a couple weeks ago. I was surprised that it also improved the eye autofocus capability by switching to DX. I assumed it was just a Z9 thing. I used a human subject in full frame and kept backing up until I lost the eye AF, then switched to crop mode and found I could continue to back up about 70% more and still have eye AF. I get why it works with the Z9 with the dual stream, but I'm not sure what the mechanism is with the R5.

 

[NorthernFocus]

... I get why it works with the Z9 with the dual stream, but I'm not sure what the mechanism is with the R5.

I suspect the key isn't necessarily the dual data stream but how/where in the circuitry the data from the cropped image gets dropped out. Sounds like the R5 must only analyze the cropped image like what appears to occur in the Z9.

 

[bleirer]

I suspect the key isn't necessarily the dual data stream but how/where in the circuitry the data from the cropped image gets dropped out. Sounds like the R5 must only analyze the cropped image like what appears to occur in the Z9.

Steve mentioned in another thread that the A1 does not seem to improve AF with crop mode.

 

[NorthernFocus]

Steve mentioned in another thread that the A1 does not seem to improve AF with crop mode.

Suggests that maybe Sony doesn't drop the unused data prior to feeding it to the AF algorithm.

 

[NikonForever]

Interesting comments from everyone - I have a D7200 and on it I keep a Nikon AF-S 300 F4 and also a mk2 Nikon 1.4 X TC, I use it for mostly aircraft and some BIF but still find I sometimes need to Crop.
I crop by eye making sure I am not hurting the IQ too badly and always try to keep at least 2000pixels on the long side.

This is one of mine the plane was about Five Miles over and flying at 35,000 feet its been cropped to 1950pixels but looks not too bad.

You can only see EXIF info for this image if you are logged in.

 

[arbitrage]

Steve mentioned in another thread that the A1 does not seem to improve AF with crop mode.

Worse than that...I've seen numerous times where the A1 actually gets worse in crop mode. Switch back to FF and eye af activates. I can't explain that one but I see it time and time again.

R5 was very obvious that crop mode helped BEAF activate. More obvious than the Z9 from what I remember.

 

[Anjin San]

The supposition is that in the Z9 the AF works on the data stream to the VF which is separate from the data stream to the imaging sensor. Subject detection works better the larger the subject is in the VF simply due to relative size. Switching to DX mode simply makes the subject larger therefore easier for the camera to recognize.

It's easy enough to test albeit subjectively. Just set up a stuffed animal or a doll with lifelike eyes. Keep backing off until the camera struggles to lock onto the eye in FX mode. Switch to DX mode and see what happens.

I should have also added that my testing that showed little difference was done in good light at low ISO…the higher ISO caused noise for low light old accentuate the cropping increases noise issue that Steve’s video talks about. In good light, switching to DX if it makes AF stickier is a good thing…but in lower light I would tend to stay against it and use the TC instead. Next time I’m out in low light I will try both modes and compare them myself…but that will be with real subjects and not the controlled situation I tested before. DX does help eye focus lock on better…I’ve seen that myself and read in multiple places that your reasoning is the cause…but typically even if I am forced to crop in post I normally don’t crop as far as DX would and try to get a final comp between portrait and environmental…in fact that’s my preferred mode rather than just a portrait although for cooperative subjects I’ll try to include both in the blog posting.

 

[Steve]

Worse than that...I've seen numerous times where the A1 actually gets worse in crop mode. Switch back to FF and eye af activates. I can't explain that one but I see it time and time again.

R5 was very obvious that crop mode helped BEAF activate. More obvious than the Z9 from what I remember.

That's interesting and good to know. I don't use the a1 in crop mode very often so I haven't spotted that.

 

[NikonForever]

That's interesting and good to know. I don't use the a1 in crop mode very often so I haven't spotted that.

Steve have you ever shot the Nikkor AFS 300 F4 (Not PF) with the mk2 1.4 X tc What would be your recommendation for min shutter speed for BIF?

 

[Steve]

Steve have you ever shot the Nikkor AFS 300 F4 (Not PF) with the mk2 1.4 X tc What would be your recommendation for min shutter speed for BIF?

I did YEARS ago. As I recall, it was a good combo.

However, BIF shutter speeds are not necessarily tied to the lens but rather to your ability to keep the bird in place in the viewfinder. My go-to is 1/3200th, but there are times I need faster speeds (like for small birds like meadowlarks or swallows) and there are times I can go much slower, like for herons, egrets, etc.

 

[NikonForever]

I did YEARS ago. As I recall, it was a good combo.

However, BIF shutter speeds are not necessarily tied to the lens but rather to your ability to keep the bird in place in the viewfinder. My go-to is 1/3200th, but there are times I need faster speeds (like for small birds like meadowlarks or swallows) and there are times I can go much slower, like for herons, egrets, etc.

Thank you kindly, I guess its a similar situation with aircraft I have been using 1/2000 minimum hand held with no VR.

 

[Steve]

Thank you kindly, I guess its a similar situation with aircraft I have been using 1/2000 minimum hand held with no VR.

Shouldn't need VR at those speeds. However, if you have propellers, 1/2000th might be freezing them (I don't shoot aircraft, so I don't know for sure). Sometimes, it's better to use slower speeds and careful panning, even if the hit rate isn't as high.

 

[splatbass]

Shouldn't need VR at those speeds. However, if you have propellers, 1/2000th might be freezing them (I don't shoot aircraft, so I don't know for sure). Sometimes, it's better to use slower speeds and careful panning, even if the hit rate isn't as high.

I've shot prop planes at an airshow, and I needed a pretty slow shutter speed to get movement on the props. I don't recall exactly but it was probably around 1/100 or 1/160.

 

[NikonForever]

I've shot prop planes at an airshow, and I needed a pretty slow shutter speed to get movement on the props. I don't recall exactly but it was probably around 1/100 or 1/160.

I used to have the old screw drive Nikon 300 f4 and was able to hand hold it at 1/500sec to get a partial blur on props but found it harder below that speed while standing and panning.

 

[Bob Hullinger]

Good day. My question is, what are the differences between using a 1.5 teleconverter vs. dx mode?
A 500mm lens = 750mm in both incidences. Is there a good reason as to why people buy one, rather than use the DX camera mode?
I would do the experiment to find out the result(s) but I do not own a teleconverter.

Let me step back to the beginning of this thread and add this.

Maybe the point is that we all don't shoot exactly the same. Without qualifying the subject, locations we are shooting and, most importantly, what the ultimate use will be of the images, how can any answer be more correct than another. For instance, does it matter that one technique results in a theoretical pixel loss and the other is technical perfection if the image is only going to be posted in an internet forum or on Instagram in postcard format and will never be printed over 8 1/2 by 11?

I think what personally frustrates me the most in these type of internet discussions is that there are many, many opinions and sometimes serious nasty debate, but far less truly instructional responses. Please let me be clear that this isn't a serious nagging point about this thread or any thread here, but instead about the entire world of internet photography sites and in no way intended to insult or demean anyone on BCG.

A lot of people post opinions and common knowledge points of views that one can find all over the internet but I wish more included remarks like " This is what I think and believe. Let me show you some images to demonstrate what I just said". Or include "I'm attaching an excellent Steve Perry, Hudson Henry or Fstoppers or Matt Granger or Gregory Basco video to illustrate my comments so you can decide for yourself."

Steve's articles have already been shared in other posts.

Hudson Henry does an excellent overview of the alternative options for the 400 4.5S.

Like these for example:

DX or FX for Sports and Wildlife Photography

photographylife.com

For anyone who doesn't care to wade through the details contained in any of the resources above I am quoting the last paragraph of the Photography Life article which says what most people who use sites like BCG already know:

"At the end of the day, however, keep something else in mind – any camera, whether DX or FX is capable of producing excellent results. It is not the gear, it is the guy behind the camera " The smiley is the original authors remark.

Happy shooting everybody.