Nikon 85 mm 1.4 G

Ok well funny the discussion about 2/3rds, so today the post office helped me make it to 2/3rds. Whew!

On the D7000....





On the D800....







The sharpness and contrast is amazing even when looking at the images on the LCD screen, but I've only done test shooting so far this evening.

I did some testing of the autofocus as soon as I put the lens on the two cameras. And noticed a problem. On the D7000 the focus is always fine, even wide open. It finds a face perfectly and gets the eyes usually in very good focus. On the D800, however, any aperture above 2.8 has a focus problem whereby the focus is just in front of the subject, just by a small amount but sometimes then because of the shallow depth of field the subject just isn't in focus. I tried AF-C, AF-S, and many variations of different focus modes and could not seem to get around the problem. At f/2.8 or higher, the focus is perfectly ok, absolutely no problems. I found online discussion of this issue with the 85 1.4 in terms of the wider apertures in combination with the large sensor of the D800. But it is not really what I would have expected in terms of performance from this combination. AF fine tune? I read that it didn't help. One guy had sent his D800 to Nikon three times and it still wasn't solved. This is not the left focus issue, either. So I'm a bit bummed out about this because what is the point of getting a fast short tele lens and can't even use it wide open?

I tried also DX mode on the D800 and there's no difference. I can get a perfect image at f/2.8 and then go to f/2.5 and boom, out of focus. There's such a sharp difference between f/2.8 and f/2.5 or less. And it isn't even like on occasion it is out of focus. It is ALWAYs out of focus for apertures less than f/2.8.

On the postive side, I'm impressed with the build of the lens. There is even a weather seal around the back of the lens where it makes contact to the camera body (!).

Anyone else with this issue on their 85 1.4? I even read online that there had been reports of the same thing happening with the 50 1.4 but my 50 1.4 has been perfect with this camera.

Tried AF Fine tune from -20 to +20 with no difference.

That's weird...wonder what it would do on a D700 or D600...

From what I read about the D700 it would be perfectly fine. However after some more digging it seems to be cropping up with the D600 as well. Large sensor + high resolution = backfocus issue at larger apertures than f/2.8. And I've found by reading that the f/2.8 cutoff is fairly consistent. It isn't just my D800, this is very common evidently. Also the 85 mm f/1.8 seems to fair a lot better than the 1.4.

85 is real nice on DX...

That is a one sexy lens. Congrats!

Try doing some micro adjustment to get the focus spot on with your D800.

Funny that you should mentioned this, but I was in a Scott Kelby workshop yesterday and he mentioned this lens specifically as one that people talk about having "focus issues". What he said is that the narrow DoF on lenses like this (and other 1.4 but no so much with 1.8 lenses) means that they demand to be treated differently. Many photographers, himself included, are in the habit of establishing focus in the center of the frame and then reframing the shot while holding the shutter button down halfway (I do it too). Because the dof is so narrow, even minor reframing will cause focus shift. With these lenses he was saying it's mandatory to frame first and move your focus point over top of subject and then focus and shoot.

I wonder if something as slight as the curvature of the lens can effect the focal point since the margin of error is razor thin.

Rick M said:

I wonder if something as slight as the curvature of the lens can effect the focal point since the margin of error is razor thin.

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I've read that it does exactly that. And, there is also a slight focus change when the lens closes down to take the picture. I've gone into the habit of using the depth of field preview button when I use my manual focus lenses (55 1.2 and 85 1.4) just to make sure.

So then why does it work on the D7000...none of that mumbo jumbo focus shift there???

Having not performed the test, I can't explain what I didn't test. I only thought it was interesting that I'd just heard yesterday that maintaining focus on the 85mm 1.4 was a familiar problem.

That said, if the problem is apparent through apertures f2.5 then you're now dealing with a deeper dof and it isn't just a reframing issue.

On every prime I would perform a fine tuning focus adjustment on the camera at maximum aperture (f1.4). Once that's done I would assume that it should maintain focus at smaller apertures, regardless of camera. Reading that it didn't help and experiencing it are two different things. I do recall reading something about the 1.4 behaving badly after fine tuning, but I couldn't possibly remember where.

OP on this thread says the D7000 focuses it fine every time wide open on the D7000...good enough for me I believe him...so what gives????

Maybe the DX vs FX aspect of it?

Eye-level said:

That's weird...wonder what it would do on a D700 or D600...

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I can't speak for this particular lens but I will show you what a manual focus 85mm f/1.4 AIS Nikkor does on a D700. It is so sharp you have to wear leather gloves to keep from cutting yourself! I am pretty sure Nikon did not change the optical formula of this superlative lens when they went from AIS to AF

Eye-level said:

OP on this thread says the D7000 focuses it fine every time wide open on the D7000...good enough for me I believe him...so what gives????

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Hey, I'm not picking a fight, just offering advice. And without photos and examples I have nothing to go on but his word, which I don't doubt - I only wanted to clarify that my words come from an utter lack of personal experience and first hand evidence, so take them at face value. He says he played with AF Fine Tune but didn't necessarily calibrate it properly. My suggestion was to do that on the D800 first and eliminate it as a symptom, not just assume it would do nothing because you read that it wouldn't.

yes, The 85 1.4 AIS is one of those DREAM lens, on my D800, it consumes the entire ability of the D800.

What I mean by that, is that when focused properly, the picture is 100% as sharp as the camera is capable of producing down to the finest pixel points.

even opened up, the lens is sharp. so,, for folks thinking of an awesome used lens,

85 1.4 AIS manual focus,, but it won't be that cheap.

So I wonder if it is the DX/FX thing or perhaps the megapixels of the D800??? What is the difference between 1.4 and 1.8? Is that half a stop (no 2/3)? Crazy that the D7000 will handle it but the D800 needs special handling...

Eye-level said:

Maybe the DX vs FX aspect of it?

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Jeff - Yes. In order to get a similar framing compared from a FX camera, using his D7000 with the Nikon 85mm f1.4 lens will require him to move back a lot more which increases the distance to the subject, therefore, increasing the DOF which results to the subject being more focused and less error.

Eye-level said:

So I wonder if it is the DX/FX thing or perhaps the megapixels of the D800??? What is the difference between 1.4 and 1.8? Is that half a stop (no 2/3)? Crazy that the D7000 will handle it but the D800 needs special handling...

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It's an issue of resolution. If you took a D800 image and down sampled it to 16 mp I'm thinking you wouldn't see this effect just like you do not see it in the D7000.

So consider that from what I read it isn't a problem with the D700 because the pixel count is a lot lower. So the problem, at least from my cursory reading, lies with the size and the pixel density of the D800 sensor (and apparently of the D600 sensor as well from preliminary reports). Also consider that the same problem exists when I put the D800 in DX mode, although that is just a crop so I guess it wouldn't make a difference since the sensor still sees the same thing. It may have to do with how the light falls on the sensor and for an FX sensor of higher pixel density, there may be fewer differences in focal change at the pixel level than for a D700 which has much larger pixels. I'd have to look into that further.

I can try a more systematic and careful focus correction, putting the camera on a tripod and using a static subject. But I've read that people have tried a lot of correction and it still shows up. But I agree.....why would f/2.5 be a problem even? I would expect perhaps f/1.4, f/1.8. And then why doesn't it show up with the 85 mm f/1.8? Anyone with a D800 and that lens?

Dave_W said:

It's an issue of resolution. If you took a D800 image and down sampled it to 16 mp I'm thinking you wouldn't see this effect just like you do not see it in the D7000.

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From what I can tell, it isn't a resolution issue. The images are clearly out of focus. Imagine shooting someone from 5 feet away and the focus falls about 0.5 inch ahead of their face. And it is that precisely consistent. If the head is turned to the side and the camera see the eyes, then the hair on the side of the head is in focus but the eye on that side will not be in focus. It is that fine a difference.