alan_wilder1

Yes, I arbitrarily applied +5 to all 4 distance groups. Sharpness is excellent at near and far despite my determination of the +5 setting at one distance (6ft). I only used 2 to 3 ft as an example of a test distance to make it easier to see ruler markings when angled at 45 degrees to determine focus in front or behind the point of focus. Any distance you choose should work. I would suggest trying my method first rather than apply different adjustments for the 4 groups as I think it may be overly complicated.

<p>I recently picked up the Sigma 35/1.4 Art with no regrets so far. AF is fast, precise and accurate once the AF fine tuning is completed with the Sigma USB Dock. It works better than Nikon's AF fine tuning on a 3rd party lens and also doesn't use up one of the twelve memory slots for Nikon's AF fine tuning feature on my D750 body. The main reason it's worth it is because optically it handily exceeds anything Nikon offers in a 35mm prime lens.</p>

<p>All shots were taken on phase detect.</p>

<p>Easiest thing to do is:<br /> 1. Set the camera's AF fine tuning and Sigma USB Dock distance scale setting to to "0"<br /> 2. Using a tripod aim the camera's viewfinder center AF focus sensor on the middle of a ruler at a 45 degree angle to the camera, focus and shoot at f/1.4 on a desired marking like exactly 6". Use a shooting distance of about 2-3 feet.<br /> 3. Look at the shot at 100% to see if the in sharpest focus where the sensor was aimed. This can be done on the camera's LCD at 100% crop.<br /> 4. If actual focus is closer than where aimed, add plus to the four groups on the focus scale adjustment with the Dock and reshoot. This will shift focus towards infinity. If actual focused further from the intended point of focus, add minus to the four groups to shift focus closer. The amount selected will be by trial and error but I woud start with +/-5 points on the Dock to see what happens since the maximum is +/-20 points.</p>

<p>Corner sharpness and contrast was surprisingly very high, even wide open, although obviously not as high as central images. Mid frame was in between corner and center test images. The main advantage of keeping it over renting is for future software updates or fine tuning AF on another body, after all who keeps the same digital body much more than about 5 or 6 years?</p>

<p>As you can see, sharpness is quite high as claimed by Sigma. Detail was too small to see in the viewfinder but only revealed at 100%. Here is the image uncropped to get an idea how small the moon was in the frame.</p><div></div>

<p>At f/4</p><div></div>

<p>At f/2.8</p><div></div>

<p>At f/2</p><div></div>

<p>Let's try this again. Full moon at f/1.4. It was well inside the AF square and atmospheric condition was slightly hazy. All crops are at 100%.</p><div></div>

<p>Example of sharpness of the lens at f/2.8 with a very tightly cropped image of the full moon.</p>

<p>Unfortunately Sigma doesn't provide much guidance in their instruction sheet but I learned by trial and error to apply Sigma's distance scale adjustment program for AF fine tuning, not for more accurate distance scale display. Avoid changing Nikon's AF fine tuning and just leave it set for "0". I initially made the mistake of fine tuning the lens' AF with Nikon's fine tuning control and then used the Dock's distance scale adjustment to more accurately display focus scale distance. This wound up throwing off the Nikon's AF fine tuning for the lens and led to significant AF mis-focus at wider openings. Just like Nikon's fine tuning, "+" for Sigma shifts the lens focus towards infinity and "-" shifts the lens focus towards 0.3 meters. I also kept the same incremental distance scale change in all four groups in the program. Everything I've stated is predicated on the camera's AF to be correctly calibrated from the start.</p>

<p>Having just purchased the Sigma DG HSM 35/1.4 Art prime for my D750, I found performance to be without question the sharpest wide angle or standard prime that I've ever tested for Nikon (including Leica M). Sharpness well exceeds the capability of the sensor at f/2.8 and smaller. Even at f/1.4, central resolving power is 64 lp/mm and MTF contrast is 70% at 40 lp/mm (using Norman Koren's MTF targets). I suspect it will likely exceed the capability of the D810 sensor. The only thing as good may be the 14-24/2.8 in a wide angle. My only point of this post is simply to point out that the USM dock is a useful accessory in setting up AF fine tuning by re-programming the lens rather than using up one of the 12 slots Nikon as allocated in the body for AF fine-tuning. Simply use "0" for the camera's AF fine tuning setting and customize the lens's focus scale setting with the USB dock for sharpest focus. In my case, I only had to set it up for +5 points out of +/-20 points.</p>

<p>I use to own the 500/4 P and notched it's mount to allow use of their superb AF-S extenders. The lens was a great performer and would likely handily outperform the new 200-500 zoom especially with a 1.4 extender. The biggest problem is if that if your subject isn't static (like landscapes or a bird perched on a branch), you won't get many keepers given the low ISO and the need to track action or freeze event slightly moving subjects. The 200-500 makes the most sense as it will keep the lens focused on moving subjects but unfortunately won't help in freezing motion on moving subjects unless you significantly boost shooting ISO.</p>

<p>I noticed the same fringing issue but it's small enough that a little LR5 de-fringe correction knocks it out as seen after the correction is applied on the TC-17E II combo.</p><div></div>

<p>Shun, we are in agreement that an f/2.8 lens would be optimal with the TC-17E to maintain fast AF function anywhere in the frame there are AF focus points, something practically required for BIF. My only point in the posts was to demonstrate IQ between the TC-17E II and TC-20E III were fairly close since the OP wanted to know why Nikon hasn't updated the TC-17E. Fortunately, at least the center AF point accurately focuses on lenses combos with effective aperture of f/8 or faster for more stationary subjects.</p>

<p>Lastly a crop of 58% of the TC-20E III. All shot were unprocessed in LR5 and shot wide open.</p><div></div>

<p>Now the TC-20E III full frame.</p><div></div>

<p>Now a 69% crop of the TC-17E</p><div></div>

<p>I recently compared performance of the TC-17E II and T-20E III on my 300/4E PF shot wide open and saw virtually no difference. Optimally, the TC-17E should be paired with an f/2.8 lens to take full advantage of AF but works in a pinch on f/4 lenses in good light or center point AF focus. First the TC-17E III:</p><div></div>

<p>Hi Rosario,<br> I'm confused by "let's put it like that: if I try to find where the focus is, I'm never sure."<br> Are you focusing at f/3.5 and using the "standard view" at maximum magnification (10x?) with the MF Assist mode? Exact focus within the magnified rectangular box is very easy to assess but it should be placed exactly within the spot you want perfect focus, for example the eye of a bird. Anything outside the magnified rectangle that doesn't share the same focusing plane will be soft since you are effectively dealing with a 600/3.5 with razor thin DOF. Again make certain the aperture ring is set for f/3.5 wide open, not for example stopped down to f/22 as this will make it much harder to nail exact focus.</p>

<p>I checked out your dropbox images and I'm not sure what you consider as "soft". Your shooting speeds and ISO seem fine. I use my 600/4 AFS with my Fuji XE-2 and IQ is fine to my eye. Are you using the camera's focusing aid for exact focus? I use the standard view 10X magnification aid as it's more accurate than their digital split-image or focus peaking aids. The 400/3.5 is far sharper than any lens Fuji will introduce in a zoom form but obviously it is going to be preferable in size and AF capability.</p>

<p>Great bokeh on the sample shot of the Noct wide open! This is what the 58/1.4 Noct is also designed to do as well.</p>

<p>I would fine tune at the long end 200mm or possibly 135mm. If testing is done at slow speeds like 2-4 seconds with ISO 100 and room lighting is controlled by a simple switch in an otherwise completely dark room, one thing that makes a <strong>huge</strong> difference in sharpness is to completely bypass any shutter/camera vibration by turning off the lights, open the shutter for about several seconds and control the exposure by turning on/off the light for the exposure. This way lens performance is the <strong>only</strong> factor in measuring sharpness.</p>

<p>The main benefit of the 58/1.2 Noct is superior coma correction wide open, great for astrophotography and low light shooting. Like other high speed lenses in it's class, it has high curvature of field. Hard to justify the price unless you are a collector. From a shooting standpoint, the Sigma 50/1.4 ART lens runs rings around everything else considering price/performance ratio if a 50mm lens range is your preference.</p>