Nikon D500, D850, Sigma 150-600C and a LOT of bad images!

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dperez Regular Member • Posts: 306
Nikon D500, D850, Sigma 150-600C and a LOT of bad images!

After the disastrous Sandhill Crane debacle, I’m continuing to try to figure out if I have a lens problem, a body problem, a technique problem, OR I’m just expecting more of my lenses than they’re capable of.

I’m trying to figure out how to get the sharpest images in MY “real world”.

I’m using a Sigma 150-600C on a Nikon D500 and a D850.

The lens spends the VAST majority of its time at maximum focal length. And at apertures around f/8 or less, f/11 once in a while, even in sunny conditions to keep shutter speeds reasonable and ISO to a value that keeps noise a non-factor - around 400 for the D500 and maybe 500 for the 850. Usually hand-held or on a monopod.

When I do SINGLE shots on a tripod, especially using AFS single, I GENERALLY get reasonably sharp images. But that’s NOT what this lens does, so after a LOT of garbage images I started paying attention to my results to see if there’s some pattern or method or setting… I’ve tested in AFC Single, Group, D25 on the D500, and D9 on the 850. Makes very little difference as near as I can tell. I’ve shot on a tripod with the O/S ON and OFF, and at reasonable shutter speeds it APPEARS to make virtually no difference. I’ve shot with the lens Custom settings ON to provide the fastest AF and most aggressive stabilization, and I’ve shot with the Customization OFF.  AGAIN it APPEARS to make VERY LITTLE DIFFERENCE…

So, what should I reasonably expect from either of these combinations (lens on D500 or D850)?

At WHAT maximum distance SHOULD I be able to reasonably expect (say 50% or better) sharp images? Is there SOME distance (see the images of the sign at the Coast Guard building to see what I’m talking about)… I’ve got birds at 8 meters, 15, 20, 33, 40+ and further and they’re ALMOST ALL NOT SHARP…

Both bodies are set up in Release + Focus mode (so if I understand it correctly, the camera should shoot the first image, then NOT capture another one until it’s IN FOCUS), blocked shot delay usually at 2, but I’ve tried it everywhere from 1 to 5 and it doesn’t APPEAR to make any difference. The D500 is shooting 10 fps, the D850, 9.

Here’s a sample from the D850, shooting the 150-600, ISO 250, aperture mode, f/8, 1/800 – 1/1000. I’m sitting on a bench, with a monopod, the geese are swimming slowly 26.61 meters (according to the exif data) in front of me, the camera is on AFC single. So, about as easy a set of images as I’m every likely to get.

ZERO post-processing has been done on any image. They’ve been snipped, assembled in PS, and resized to reduce bandwidth needed (I’m traveling and on a metered connection).

Here’s a full image so you can see how large things are.  The geese are swimming slowly, but the images are all very similar and the distance in the exif data is 26.61meters. It didn’t change through the 9-shot series.

Here’s a set of images from Viewnx-i showing where the focus point (center point) was for each image.

And last, the same 9 images without the focus point… TO ME, one is pretty sharp, one is adequately sharp the rest are in various degrees NOT sharp…..A check on depth of field says at 26 meters, even at 600mm I've got almost a METER of DOF.  Which means if it's missing focus it has to missing by a TON.

I did a similar thing with the D500, shooting the 150-600, ISO 400, aperture mode, f/10, 1/640 – 1/800. This time the camera is on the sturdy tripod, the geese are walking past me and the exif data SAYS the distance is 26.61 meters on some and 33.5 meters on others (I'm not getting SOMETHING about distance 'cause that MAKES NO SENSE).

The camera is on AFC single. So, again, about as easy a set of images as I’m every likely to get. The geese are walking a little faster than they were swimming, and the head is bobbing more, so I had a couple that weren’t FULLY on the head…

Again, ZERO post-processing has been done on any image. They’ve been snipped, assembled in PS, and resized to reduce bandwidth needed.

Here’s the set of images from Viewnx-i showing where the focus point (center point) was for each image.

And last, the same 8 images without the focus point… TO ME, one is fairly sharp, a couple are marginal, and the rest are in various degrees NOT sharp…..Same question as before - at 26 meters the D500 should have about .8 meters of DOF and at 33 about 1.2 meters.  If it's missing focus I has to be missing it by a TON.

Looking at the above, I decided there’s a problem with the lens. I have other images of birds from 8 meters to 35 or 40, and the same thing is happening… BUT, before you agree there’s a lens problem, 15 SECONDS before I shot the geese I shot a sailboat in the harbor.  Same equipment, same settings, 600 mm, distance farther than what the exif data says is “infinity” – it APPEARS that EVERYTHING past some distance is 125.89 meters. No matter HOW FAR past.

I shot NINE OF THESE, and every single one is SHARP…… I put the single focus point on “Hjordis” and EVERY image I shot is good.

ANOTHER sailboat… I shot SEVEN images of this sailboat, with the focus point on the white sail, and AGAIN, EVERY ONE is sharp. No problem at all. This time it’s at 440 mm instead of 600. Near as I can tell, that’s the only meaningful difference…

A second later, swing the tripod slightly on to the big sign at the Coast Guard station and shoot 3 shots… Starts soft, and totally composts in the three shots.

Swing back to the sailboat and shoot another half dozen shots with the focus point on the sail AND AGAIN THEY’RE ALL SHARP.

Swing back to the sign, let it stabilize, and shoot ONE MORE that’s totally out of focus.

I can put more images in here, but they look like the ones above...

I have NO idea what’s going on….. The birds are moving, but slowly. So are the sailboats, both moving and moving up and down with the waves. The SIGN on the Coast Guard Station is BIG and it’s sitting still. And it’s got at LEAST as much contrast as everything else I’m shooting. I can add more pictures to show what I mean, but at this point I’M TOTALLY BAFFLED…….

Two bodies can’t both be bad – and BTW, they BOTH work fine with EVERY OTHER LENS I HAVE…

The lens MAY be bad, but it CAN’T be bad SOME OF THE TIME… Fine and sharp on “larger” things like a sail or a car and very not sharp on a big sign or a bird 8 or 20 or 30 meters away…

SO, I figured I’d ask here and hope someone in here has some idea what’s going on…

Nikon D500 Nikon D850
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