Thanks to reader David C for bringing this feature to my attention—compensation for focus shift is rare among cameras and a Very Good Thing, so long as the behavior is understood (it can work against you in some cases).
Apparently Nikon silently slipped in this upgrade a few years ago and made no mention of it. And yet it is a critical behavior that one must understand if focusing manually.
Nikon D810 Autofocus Compensation for Focus Shift
This test with the Nikon D810 suggests that it actively compensates for focus shift by modifying the point of focus to compensate, based on shooting aperture. That is, when conventional AF is used.
I’ll have to confirm this behavior with other lenses; at this point it’s unclear which cameras and lenses support focus shift compensation. Nikon is hiding their light under a bushel for some reason, which is very strange from a marketing standpoint.
Focus shift compensation is a super nice feature when applicable, but there are situations where it can degrade performance, nor not apply—any situation in which the AF system is used to prefocus at one aperture, but the image is exposed at another aperture. It could mean, for example, needing to focus at f/2.8 because of dim light but then shooting stopped down. Or pre-focusing at f/5.6 but then deciding to shoot at f/2.8. And so on. Presumably these are a small minority of cases. For myself, it means that shooting an aperture series is problematic because AF is prone to precision errors, focus shift compensation or not. And focusing in dim light is not feasible stopped down and DoF adds ambiguity as well.
Also, focus shift is not a simplistic behavior: it can be rearwar in the center and forward in the outer zones. Presumably the limited coverage of the focusing sensors in Nikon full-frame DSLRs cover too little of the frame for that to be an issue. Still, such differential behaviors mean that a full understanding of the behavior is essential for optimal results. For massive focus shift, see the Sigma 12-24mm f/4 Aperture Series @ 14mm: Two Aspen. I don’t know if such a lens takes advantage of focus shift compensation.
Finally, focusing in magnified Live View has long compensated for focus shift in this sense: the lens is stopped down to the shooting aperture by default. However, that often leads to serious errors in my own experience.
So I would say this: for conventional shooters (focus and shoot), focus shift compensation is a wonderful feature. For other usage scenarios, one still needs to understand what is happening. In particular, it’s problematic to shoot aperture series my usual way (by focusing wide open) and yet the AF system doesn’t always have enough precision for reliable results. This is the severe headache I ran into with the Fujifilm GFX. A lens without focus shift is always far, far preferable.
Markus H writes:
According to Marianne Oelund, focus shift correction has been added to bodies released in 2014 onwards. This includes for sure the D810, the D500 and the D5. Most likely also the D750 (released in 2014 but after the D810) and the D4s (released in 2014 but before the D810) as well as the 2015 D7200 and 2017 D7500.
If you don’t know Marianne Oelund, she is an engineer by trade and photographer by passion and when she says something, you’ll know it’s true because she has actually tested it herself.
Note that when a new lens gets released, bodies that can correct for focus shift need a firmware update to get the focus shift parameters for that lens to properly correct the focus shift.
DIGLLOYD: how non-Nikon AF lenses with severe focus shift behave is unclear to me.
I used the latest firmware on the D810 in my testing.
Firmware on the Nikon D810 + 70-200/2.8E reads:
C = 1.12
L = 2.015
David C writes:
I have just tested D500 for focus shift compensation with 70-200 2.8 FL. Bad news. It does not seem to compensate for focus shift.
DIGLLOYD: contradicts the claim above vs the D500. I can only speak directly to what I have personally tested and verified: the D810 compensates for focus shift. I should also do more extensive testing with the D810, but this will take time. Also, at dusk I found the AF system unable to cope with dim light, forcing use of f/2.8 in Live View, so there is no compensation viable under those conditions. I would not trust the AF system for critical work that I do in any case, moreover focus shift at distance looks to be not an issue with the 70-200/2.8E.
Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR
The about $2700 Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR looks to be a very fine lens but clearly it has an optical formula that is balanced in a way with some drawbacks, including focus shift.
This page shows focus shift of the Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR at 200mm at a reproduction ratio of roughly 1:7 (for 200mm). The ratio of 1:7 was chosen because this is a tight head shot distance, thus making that reproduction ratio highly relevant to real world shooting. Sharp eyes are critical in a portrait, hence focus shift is a key performance attribute.
Update: also shows 70mm and 130mm at about a 1:12 reproduction ratio.
Presented in Advanced DSLR in my review of the Nikon 70-200mm f/2.8E FL ED VR:
Includes crops presented several ways for ease of viewing, from f/2.8 through f/8.
There is a major contextual consideration as to whether the focus shift matters or not: evidence suggests that some cameras such as the Nikon D810 with the latest firmware in fact modify the autofocus system to compensate for focus shift (when conventional AF is used). I confirmed this myself today that there is a very significant behavioral change that depends on shooting aperture. More on this idea in the link above, and it is a behavior I intend to investigate and document. Thanks to reader David C for bringing this feature to my attention—it is rare among cameras and a Very Good Thing, so long as the behavior is understood (it can work against you in some cases). Apparently Nikon slipped in this upgrade a few years ago and made no mention of it. And yet it is a critical behavior that one must understand if focusing manually.
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The about $79.95 Vulta Volcano Multi-Spectrum LED Flashlight (White, Red, Blue) takes 4 AA batteries and runs quite a long time on a set of four. While I tend to use Lupine cycling lights with rechargeable LiIon cells, the Vulta Volcano can get going fresh again with a set of four AA batteries.
- 1 / 60 / 200 / 500 / 880 Lumen Outputs
- One Primary White CREE XM-L2 LED Emitter
- Six Red and Six Blue Secondary LEDs
- Emergency SOS and Signal Beacon Modes
- Red/Blue and Red/Blue/White Strobe Modes
- Dual Body Switches with Last-Mode Memory
- Type III Hard Anodized Aluminum Housing
- Submersible and Impact Resistant
- Reverse-Polarity Protection Circuitry
- Active and Passive Overheat Protection
The Vulta Volcano flashlight is smart in that it won’t fry the LEDs as some lights will, which greatly shortens LED lifespan: if used on its Turbo Mode (extremely bad-ass bright), it will drop down to High mode after a few minutes. Its twist-on diffuser cap is useful for a broad area of light without the harsh glare of straight-on illumination.
The Vulta Volcano is best for its flexibility. For example, its “firefly mode” is not enough to walk by, but can illuminate a map or back of a camera, etc. As well, the red LED mode saves night vision and could be used as a taillight for a bicycle assuming it could be aimed appropriately. As for blue mode, it’s something I would not generally use (blue is the worst color for night vision), and red/blue flashing mode presumably is for law enforcement, but might be useful to pretend to be, say if in a skanky area where one feels at risk.
The SOS and strobe modes might be a good idea for those in trouble, assuming one has the flashlight along: it’s fairly heavy at 277 grams (including 4 AA batteries and lanyard). And that is the reason I might not take it at times; it is fairly large and heavy. When I hike up in the mountains, I’d prefer something lighter, like the Fenix RC09 and/or Fenix RC11. However, those lights have no red LED mode and they require rechargeable batteries—and they have run themselves down due to poor design of the lockout switch.
All in all I like the Vulta Volcano and I tend to take it with me in trips in the car. The diffuser makes a nice light for night use and/or for inserting contact lenses into my eyes in the dark.
Vulta Volcano Multi-Spectrum LED Flashlight (White, Red, Blue)
USB-C Dock for MacBook
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Dan B writes:
From your blog postings and subscription articles it seems that in the recent past you gravitated towards the Really Right Stuff TVC-24L as your go-to tripod for out in the field.
However most recently it seems you are using the Really Right Stuff TVC-34L. Is that because the 34L is better for the heavy pano rig, or perhaps you might prefer the 34L over the 24L when not doing panos but when it is windy?
In your blog article of May 15 you have two tripods in the field - the 34L and the prototype shorty. So, how do you get both tripods into the field - one on each arm? If you were hiking a fair distance with your camera equipment and two tripods did you eat a can of spinach before starting out - Popeye the Hiker Man ? :-)
DIGLLOYD: generally, I eat a can of sardines before or during.
I always carry the tripod in my hand, rarely in my pack (unless it’s a class 4 climb). That’s because I need the space and pockets in the pack for food, water, clothing and camera and lenses, and sometimes other things, like fishing lures. Since it can snow even in August and camera packs have load capability for water or food or clothing, rarely do I have any free pack space, so this is why I hand carry my tripod.
Two tripods is a “car shoot” meaning that I am not far from the car. The “shorty” is small enough by itself that I could probably stow it in the pack or strap it on somehow. But together with its nifty tripod head, it becomes bulky enough to not really be compatible with also carrying a full-size tripod like the TVC-24L on long hikes. Which is a pity. I'll have more experience this summer to prove out what might work because the shorty is tremendously useful for low-to-the-ground work.
For long hikes, it is always the TVC-24L and only that tripod— two tripods and heads on daylong hikes is a chore and there is just no space to do so. The TVC-24L is just under the threshold of what I can comfortably carry with the Arca Swiss Cube mounted. Anything heavier fatigues my hand and arm.
For shorter hikes near the car, I prefer the TVC-34L or the super beefy TVC-44L, the later being just lovely in use if I don’t have to carry it far. So I love working with the TVC-44L, but it’s heavy and half a mile would be my outer limit for carrying it along. The TVC-34L I will carry if there is a compelling reason for its extra mass—rare, but super teles qualify as does using the PG-02 Pano-Gimbal head, which itself is quite beefy. It’s not a question of supporting weight (all sizes do that just fine), it’s more about mass and stability to avoid a top-heavy rig.
Wind affects them all about equally, wind means resonance in the legs and for long lenses it’s a teeter-totter for the lens tripod foot (virtually all of them suck that way), and larger doesn’t generally help for resonance, necessarily, though RRS tends to be slightly better (Gitzo had some reversals when I researched this in detail, e.g., larger was worse).
Really Right Stuff TVC-34L tripod with Arca Swiss Cube vs new shorty TFC-13S model with PG-01 Compact Pano-Gimbal Head,
Hasselblad X1D clamped in place with Really Right Stuff BX1D-L