Without a doubt, the most important feature of the D750 is its autofocus system. As I have already mentioned before, the new Advanced Multi-CAM 3500 FX II module is quite different from its predecessor in a number of ways – the focus spread is a bit smaller and the AF system is rated to work at -3 EV, which means that it should be able to acquire focus even in very low light situations.
It is interesting that Nikon used the most advanced AF system on the D750 because one would expect a higher-end camera to sport it first (neither the D810 nor the D4S has this AF system). If you have ever used Nikon’s 51-point AF system, you know that it is a very solid and accurate AF system. All previous enhancements to this system, including the Group Area AF feature have been incorporated into the D750, so we can comfortably say that the D750 has Nikon’s best autofocus system to date. How does it perform and how accurate is it? Since AF performance varies by subject and photography, I decided to split the section into multiple sub-sections and discuss it in more detail.
Autofocus Performance: Daylight
In daylight situations, the AF performance of the Nikon D750 is stellar, as expected. I have used a number of different lenses such as: Nikkor 24mm f/1.4G, Nikkor 50mm f/1.8G, Nikkor 85mm f/1.4G, Nikkor 85mm f/1.8G, Nikkor 14-24mm f/2.8G, Nikkor 24-70mm f/2.8G, Nikkor 70-200mm f/2.8G VR II, Nikkor 300mm f/4D AF-S, Nikkor 200-400mm f/4G VR, Nikkor 400mm f/2.8E with and without teleconverters and all lenses performed admirably. From third-party lenses, I have used the Tamron 150-600mm and a number of Zeiss manual focus lenses. The focus was dead on and focus accuracy was excellent on all these lenses. Daylight conditions are not really a challenge for most modern autofocus systems though – even entry-level DSLRs do quite well when there is plenty of light. It is obviously a different story when photographing fast-moving subjects or photographing in low-light environments.
Autofocus Performance: Low-Light / Indoors
All AF systems start to suffer in low light situations, simply because very little light gets to the phase-detect sensor (as explained in my “how phase detection autofocus works” article). But the D750 has one key advantage compared to other Nikon DSLRs – its updated AF system can focus in lower light situations, down to -3 EV. Is it noticeable? Yes, it certainly is! I shot a wedding with the Nikkor 85mm f/1.8G and I was amazed by its AF accuracy when shooting in low light indoors – most of my shots were in focus. If you have ever used 85mm lenses, you know how difficult it is to nail indoor shots with those lenses. Due to their very shallow depth of field, shooting wide open is quite difficult, often yielding out-of-focus images. My Nikkor 85mm f/1.8G was so good indoors, that I never bothered changing my lens to the 70-200mm f/2.8G VR II, which has been more reliable for indoor shots but is a beast to carry around (especially with me having two cameras around my neck). You will find a number of tack-sharp images in this review that were photographed with this combination indoors.
Autofocus Performance: Wildlife and Sports
Although I am still working on testing the wildlife and sports performance of the Nikon D750 (mainly, I am interested in how the D750 does with the Nikkor 300mm f/4D AF-S with the 1.7x teleconverter combo, which has never worked well for me), our wildlife guru John Sherman has already published his thoughts in his Nikon D750 for wildlife and landscape photography article. In short, he is very impressed by the D750’s AF capabilities, particularly when using lens + teleconverter combinations. After he shot with the D750, he called me the next day and said “you just cost me $2300!”. Take a look at his shot of a mountain bluebird that he captured at 1350mm (Nikkor 800mm f/5.6E + 1.7x TC):
Now that is a very impressive shot, considering the focal length and the 1.7x TC. If you have not read his analysis of the D750, please check it out, as he has many more great image samples to showcase!
And if you own the Nikkor 300mm f/4D AF-S lens and have never been satisfied with its performance when using the 1.7x teleconverter, it is probably a good time to reassess this combo, since I found it to be quite good on the D750. Here is a sample image of a hawk in flight captured with this combo:
The camera was able to acquire focus perfectly, so there is plenty of sharpness in this shot.
Autofocus Performance: Landscapes
Landscape photographers rarely care about AF speed, since they mostly use Live View to obtain precise focus. For those situations, the D750 performs admirably, since Live View is implemented properly, without any interpolation issues. When zooming in, you will see plenty of sharpness (especially at the pixel level), which will help greatly in acquiring focus manually. When using the D750 with Zeiss manual focus lenses, I relied on contrast-detect in Live View quite a bit and I was able to nail focus every time.
Autofocus Performance: Portraits / Weddings
A number of images in this review were captured from a wedding that I photographed with two Nikon D750 cameras. During the wedding, I mostly had the new 20mm f/1.8G lens attached to one body and the 85mm f/1.8G lens attached to the second body. This allowed me to capture both wide and close-up shots and proved to be a superb combination for wedding photography. Only during the wedding ceremony, I switched my 85mm f/1.8G to the 70-200mm f/2.8G VR II, so that I could stay further away and capture it from a distance. Once the ceremony was over, I switched back to my 85mm f/1.8G, since it was a much lighter and faster lens to use indoors.
Overall, the D750 performed extremely well for shooting portraits and weddings. Autofocus was spot on and the number of keepers was much higher than what I had before with other Nikon DSLRs, especially when shooting indoors in low light.
If you shoot portraits or weddings, the D750 is probably the best Nikon DSLR to get at this point for the following reasons:
- It is very lightweight, which is a huge advantage when shooting those all-day weddings (even slightly lighter than the D610!)
- It is very comfortable to hand-hold
- Autofocus performance is amazing, whether using fast primes or zooms – this is especially true for indoor shots
- The 24 MP sensor produces superb images with little noise and the resolution is more than enough for most situations, even when tight cropping is needed
- Post-processing 24 MP images is pretty fast – images do not load as slow as 36 MP images from the D800/D810 cameras in Lightroom
- The tilting screen can be great for overhead shots, such as when shooting the dance floor
- Dual SD cards are better than one CF + SD, since you do not have to carry two different card types
- U1 and U2 user modes work far better than the Bank system on higher-end cameras – set one mode for non-flash and another for flash and you are good to go!
- Battery life is superb – the D750s I was shooting with lasted all day and I had plenty of charge left after the wedding
Shooting Speed (FPS) and Buffer
The Nikon D750 can shoot at 6.5 frames per second, which is not as fast as what the D4S can do, but still more than sufficient for most photography needs today. In comparison, the Nikon D700 with much smaller 12 MP images is limited to 5 frames per second (without a battery grip), the new Nikon D810 can only shoot up to 5 frames per second and the Canon 5D Mark III is limited to 6 frames per second. So 6.5 FPS on the D750 is actually quite reasonable for its price, as it strikes a good balance – not as fast as the D4S, but not a slow crawler either. The bigger concern is not so much the shooting speed, but how long the camera can last before filling up the buffer.
I have already covered this topic in detail in my Nikon D750 Buffer article, but if you have not seen it, here is a buffer capacity table that compares the D750 to other Nikon DSLRs, including the D700:
|DSLR||Image Type||FX Size||DX Size||FX Buffer||DX Buffer||Cont. Shoot|
|Nikon D610||NEF (RAW), Lossless compressed, 12-bit||23.4 MB||10.9 MB||21||55||3.5 sec|
|Nikon D700||NEF (RAW), Lossless compressed, 12-bit||13.3 MB||5.7 MB||23||65||4.6 sec|
|Nikon D750||NEF (RAW), Lossless compressed, 12-bit||21.0 MB||10.5 MB||25||100||3.8 sec|
|Nikon D810||NEF (RAW), Lossless compressed, 12-bit||31.9 MB||14.6 MB||47||100||9.4 sec|
|Nikon D610||NEF (RAW), Lossless compressed, 14-bit||29.2 MB||13.4 MB||14||34||2.3 sec|
|Nikon D700||NEF (RAW), Lossless compressed, 14-bit||16.3 MB||7.0 MB||20||46||4.0 sec|
|Nikon D750||NEF (RAW), Lossless compressed, 14-bit||26.9 MB||13.1 MB||15||48||2.3 sec|
|Nikon D810||NEF (RAW), Lossless compressed, 14-bit||40.7 MB||18.3 MB||28||97||5.6 sec|
|Nikon D610||NEF (RAW), Compressed, 12-bit||20.7 MB||9.7 MB||26||73||4.3 sec|
|Nikon D700||NEF (RAW), Compressed, 12-bit||11.0 MB||4.7 MB||26||95||5.2 sec|
|Nikon D750||NEF (RAW), Compressed, 12-bit||19.2 MB||9.8 MB||33||100||5.1 sec|
|Nikon D810||NEF (RAW), Compressed, 12-bit||29.2 MB||13.3 MB||58||100||11.6 sec|
|Nikon D610||NEF (RAW), Compressed, 14-bit||25.4 MB||11.7 MB||14||54||2.3 sec|
|Nikon D700||NEF (RAW), Compressed, 14-bit||13.8 MB||6.0 MB||23||63||4.6 sec|
|Nikon D750||NEF (RAW), Compressed, 14-bit||23.9 MB||11.9 MB||21||100||3.2 sec|
|Nikon D810||NEF (RAW), Compressed, 14-bit||36.3 MB||16.4 MB||35||100||7.0 sec|
|Nikon D610||JPEG Fine (Large)||12.4 MB||5.9 MB||51||100||8.5 sec|
|Nikon D700||JPEG Fine (Large)||5.7 MB||2.5 MB||100||100||20.0 sec|
|Nikon D750||JPEG Fine (Large)||12.6 MB||6.2 MB||87||100||13.4 sec|
|Nikon D810||JPEG Fine (Large)||18.1 MB||8.6 MB||100||100||20.0 sec|
From the above chart, you can see that the D750 has roughly the same buffer as the D610. This may not be important for portrait and wedding photographers, but it sure is important for sports and wildlife shooters. If you have been photographing sports/wildlife with the D700, you might be disappointed to find out that the D750 will only last about 2.3 seconds when shooting in 14-bit RAW, compared to 4 seconds on the D700. Granted the files are much larger and the speed of the D700 without a grip is only 5 FPS, but I still wish Nikon had increased the buffer memory to fit more images – it would have made the D750 an amazing sports and wildlife camera. At the same time, I have said it a number of times that Nikon does not want lower-end cameras to compete with its top-of-the-line cameras like D4S anymore, so it is understandable why Nikon is limiting the buffer size on the D750…
One important factor that greatly affects the continuous shooting speed is memory card speed. If you want to get the best out of the D750, get a fast SD card that can write at 95 MB/sec. I saw a huge difference in buffer performance between my older 45 MB/sec cards and the newer 95 MB/sec cards. The best candidates for the D750, in my opinion, are the SanDisk Extreme Pro Class 10 UHS-I cards. Sadly, the D750 only works with UHS-I cards, so you cannot use those ultra-fast 280 MB/sec UHS-II cards. The buffer could have been doubled or tripled, if the camera could write at that speed!
If you would like to see a complete buffer comparison of all current and some older Nikon DSLRs, take a look at my Nikon DSLR Buffer Comparison article.
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