– “First, they clearly beat cropping in terms of resolving fine details on distant subjects” . In optics there is something called “Empty magnification”. Imagine we have a photo, I go to the photocopy machine and put “200%”. Then I take the resulting copy and re-enlarge it at 200% again. According to that, I would have “gained” 4 times more resolution!!! And we all know that’s false. It’s the same when I put a “40x” eyepiece on a microscope and the objective is 10x. Mathematically I would get 400x, but the REAL resolution would be poor. The bottleneck is the objective (10x) resolution, the eyepiece only magnifies that initial resolving power. The big problem is that we confuse “number of pixels per point (or line)” with “resolving power”. The smallest level of detail that a lens can resolve is “resolving power” (in the optics realm). “Number of pixels” is size (in digital image realm) If you ask astronomy guys they will tell you the same thing: adding a “barlow” lens (the equivalent of TC for a telescope) it only magnifies the original resolution, it cannot create extra detail from thin air. And with the high iso/2x test, the issue there is that a photo with more noise will always have a greater “perceived sharpness”, it’s a well known issue in digital imaging. (btw,”Perceived sharpness” (what we see) is the result of resolving power (optics) and acutance (digital imaging) combined). That’s why a 2x TC, used with higger iso (and probably more noise) “seems” sharper in certain conditions. But again, it cannot create extra details, it only has what the master lens is capable of resolving (see Rayleight criterium)
What you say is correct, but you seem to omit that we use a sensor of finite resolution to record the image. If a lens is capable of resolving so much detail that the sensor cannot record it with complete fidelity, you do gain real detail by magnifying the image before recording it. That is why the MTF50 resolution values with the 2x TC are not half of what the bare 70-200/2.8 produces.
Jay Chow
February 9, 2025 6:35 am
I bought a Nikkor Z-mount 24-70mm f/2.8 lens and the 1.4x TC before realizing they were incompatible. My question is: If I were to get a teleconverter-compatible lens, should I get a zoom or prime lens? Also, for lenses with a built-in teleconverter, if I use that and a 1.4x TC adapter, what is the effective teleconverter magnification—1.4x or 2.0x? Thank you.
andy
January 19, 2025 7:00 am
Which TC is most useful for 190-600 mm Nikkor Z lens?
Definitely the 1.4x. The 2x would be way too dim with the 180-600mm (your maximum aperture would become f/11-13, which is not viable for most photography).
Rick
December 7, 2024 10:06 pm
Thanks, Spencer for the very thorough analysis. I was particularly pleased that you investigated the sample variation in the TCs. I often wonder how much sample variation there is in cameras and lenses, particularly after reading reviews. I also wonder if part of the premium that one pays for the manufacturers’ lenses (Nikon, Canon, Sony, etc.) versus third-party lenses is because you get more consistency in quality from sample to sample. It is nice to see that Nikon has paid attention to this particular parameter. Well done!
Thomas
June 28, 2024 4:41 am
Hi Spencer, knowing I’m a bit late :-) I still wanted to thank you for this reminder. It is always worth to take a closer look to topics that are adressed in a methodic manner after they have been often quickly brushed off the table by others. As I haven’t managed yet to get hands on one of the faster Z-mount primes and I am not using Z TC’s yet, because I am currently using the Z the 100-400 and the 180-600, which both take a dip in resolution at the long end and the TC would bring me to f8 or even f9.
But for the stationary work I still use my AF-S 500mm f4 G and here I found your results confirmed. The lens was known to provide excellent results with the TC-14E II, but it was known not to perform well with the TC-17E II on DSLR’s, mainly because of AF issues. But with the Z8 this combo seems to work really well, as the cameras’s AF system is more capable compared to my last DSLRs. Yes, I am still dreaming of a Z 400 f2.8TC with additional TC’s, but for the time being this 500mm dinosaur provides a pretty nice 850mm f6,7 and the TC-17E II is glad to see some daylight again after spending years in the draw.
Juan Capurro
June 1, 2023 7:48 am
Hello, thank you very much for the article. I would like to know if these converters work for a Z7II with a FTZII and fx lenses. Thank you
Read the article. I states the position clearly… 😊
Steve M
May 30, 2023 10:28 am
I have and use all 3 of the TCs for the F mount. The most used is the 1.7 as it gives a good reach addition with little loss in quality in my 300/2.8. If I could only have one TC in my bag it would be the 1.7. I’m surprised they haven’t released a newer version of it. At least I can still use my long F glass on the Z gear while waiting.
Lucent
May 28, 2023 9:06 am
Doing the math on MTF discernible lines, 200mm bare does 3600 lpi while the 2.0 TC knocks it down to ~2350 lpi, a loss of 35%. By the same measure, would cropping be considered a loss of 50%, the 200mm cropped to half its resolution would theoretically have 1800 lpi? Just looking for the number to compare 2350 lpi to.
That sounds correct if loss of pixels does not cause an MTF reduction. That 2350 implies that the TC is providing an increase of resolution. A TC magnifies the image center just like cropping does. Maybe I am missing something.
petersutcliffe
May 27, 2023 5:28 am
Thanks for all the effort Spencer, I have just bought the Z7ii and got 100-400 and the 1.4TC before reading your article. Your comments were very helpful especially the overall verdict. I have a mind set of f8 for moving nature photography, so the low light comments are a reminder to think and back off to f6.3 & 5.6 for try. Cheers, Peter
Try to avoid shooting with the Lens at 400mm, wind it in to 360mm and get a little closer when possible to a subject, there is to my assessment additional sharpness to be had using the Lens>TC combo on a Z9.
ericbowles
May 26, 2023 3:30 pm
Very nice review, Spencer. Your results with the 2.0 TC are quite good – and it will probably end up in my bag before long. I really like the 1.4 TC – small size, light weight, and excellent optically.
Glad you liked the review! Both TCs exist for a reason, not that everyone needs to get both of them. For maximum detail on distant subjects, it’s better to use the 2x TC rather than cropping from the 1.4x, which is better than cropping from a non-TC setup. So it’s a matter of how much reach you need.
– “First, they clearly beat cropping in terms of resolving fine details on distant subjects”
.
In optics there is something called “Empty magnification”. Imagine we have a photo, I go to the photocopy machine and put “200%”. Then I take the resulting copy and re-enlarge it at 200% again. According to that, I would have “gained” 4 times more resolution!!! And we all know that’s false. It’s the same when I put a “40x” eyepiece on a microscope and the objective is 10x. Mathematically I would get 400x, but the REAL resolution would be poor. The bottleneck is the objective (10x) resolution, the eyepiece only magnifies that initial resolving power.
The big problem is that we confuse “number of pixels per point (or line)” with “resolving power”. The smallest level of detail that a lens can resolve is “resolving power” (in the optics realm). “Number of pixels” is size (in digital image realm)
If you ask astronomy guys they will tell you the same thing: adding a “barlow” lens (the equivalent of TC for a telescope) it only magnifies the original resolution, it cannot create extra detail from thin air.
And with the high iso/2x test, the issue there is that a photo with more noise will always have a greater “perceived sharpness”, it’s a well known issue in digital imaging. (btw,”Perceived sharpness” (what we see) is the result of resolving power (optics) and acutance (digital imaging) combined). That’s why a 2x TC, used with higger iso (and probably more noise) “seems” sharper in certain conditions. But again, it cannot create extra details, it only has what the master lens is capable of resolving (see Rayleight criterium)
What you say is correct, but you seem to omit that we use a sensor of finite resolution to record the image. If a lens is capable of resolving so much detail that the sensor cannot record it with complete fidelity, you do gain real detail by magnifying the image before recording it. That is why the MTF50 resolution values with the 2x TC are not half of what the bare 70-200/2.8 produces.
I bought a Nikkor Z-mount 24-70mm f/2.8 lens and the 1.4x TC before realizing they were incompatible. My question is: If I were to get a teleconverter-compatible lens, should I get a zoom or prime lens? Also, for lenses with a built-in teleconverter, if I use that and a 1.4x TC adapter, what is the effective teleconverter magnification—1.4x or 2.0x? Thank you.
Which TC is most useful for 190-600 mm Nikkor Z lens?
Definitely the 1.4x. The 2x would be way too dim with the 180-600mm (your maximum aperture would become f/11-13, which is not viable for most photography).
Thanks, Spencer for the very thorough analysis. I was particularly pleased that you investigated the sample variation in the TCs. I often wonder how much sample variation there is in cameras and lenses, particularly after reading reviews. I also wonder if part of the premium that one pays for the manufacturers’ lenses (Nikon, Canon, Sony, etc.) versus third-party lenses is because you get more consistency in quality from sample to sample. It is nice to see that Nikon has paid attention to this particular parameter. Well done!
Hi Spencer, knowing I’m a bit late :-) I still wanted to thank you for this reminder. It is always worth to take a closer look to topics that are adressed in a methodic manner after they have been often quickly brushed off the table by others. As I haven’t managed yet to get hands on one of the faster Z-mount primes and I am not using Z TC’s yet, because I am currently using the Z the 100-400 and the 180-600, which both take a dip in resolution at the long end and the TC would bring me to f8 or even f9.
But for the stationary work I still use my AF-S 500mm f4 G and here I found your results confirmed. The lens was known to provide excellent results with the TC-14E II, but it was known not to perform well with the TC-17E II on DSLR’s, mainly because of AF issues. But with the Z8 this combo seems to work really well, as the cameras’s AF system is more capable compared to my last DSLRs. Yes, I am still dreaming of a Z 400 f2.8TC with additional TC’s, but for the time being this 500mm dinosaur provides a pretty nice 850mm f6,7 and the TC-17E II is glad to see some daylight again after spending years in the draw.
Hello, thank you very much for the article. I would like to know if these converters work for a Z7II with a FTZII and fx lenses. Thank you
Read the article. I states the position clearly… 😊
I have and use all 3 of the TCs for the F mount. The most used is the 1.7 as it gives a good reach addition with little loss in quality in my 300/2.8. If I could only have one TC in my bag it would be the 1.7. I’m surprised they haven’t released a newer version of it. At least I can still use my long F glass on the Z gear while waiting.
Doing the math on MTF discernible lines, 200mm bare does 3600 lpi while the 2.0 TC knocks it down to ~2350 lpi, a loss of 35%. By the same measure, would cropping be considered a loss of 50%, the 200mm cropped to half its resolution would theoretically have 1800 lpi? Just looking for the number to compare 2350 lpi to.
That sounds correct if loss of pixels does not cause an MTF reduction. That 2350 implies that the TC is providing an increase of resolution. A TC magnifies the image center just like cropping does. Maybe I am missing something.
Thanks for all the effort Spencer,
I have just bought the Z7ii and got 100-400 and the 1.4TC before reading your article. Your comments were very helpful especially the overall verdict. I have a mind set of f8 for moving nature photography, so the low light comments are a reminder to think and back off to f6.3 & 5.6 for try.
Cheers, Peter
You’re very welcome! The 100-400mm + 1.4x combo works really well in my experience, and f/8 isn’t a big limitation most of the time.
Try to avoid shooting with the Lens at 400mm, wind it in to 360mm and get a little closer when possible to a subject, there is to my assessment additional sharpness to be had using the Lens>TC combo on a Z9.
Very nice review, Spencer. Your results with the 2.0 TC are quite good – and it will probably end up in my bag before long. I really like the 1.4 TC – small size, light weight, and excellent optically.
Glad you liked the review! Both TCs exist for a reason, not that everyone needs to get both of them. For maximum detail on distant subjects, it’s better to use the 2x TC rather than cropping from the 1.4x, which is better than cropping from a non-TC setup. So it’s a matter of how much reach you need.