500mm PF rings in bright sky--help!

[janzin]

I was shooting these crows mobbing a hawk, almost directly straight up. Upon looking at the frames I now see concentric dark rings in the sky! They are in all the photos from this series. I assume this is from the Phase Fresnel element---but I've never seen this before in any other birds in flight photos.

This is straight from the camera, just converted to jpg (disregard the fact that it's not perfectly focused...I have a whole series of these and some are quite good, but those rings!! Arrgh!)

Has anyone else experienced this?

Thoughts on how this happened and how to prevent in future? And any idea how to fix it in post-processing? (I tried using the PF Flare correction in Capture NX-D but that had no effect--I didn't expect it to because it doesn't seem to be exactly the same issue but figured it was worth a try.)

 

[janzin]

okay, this is getting weirder. I noticed that when I viewed these images in Nikon ViewNX I didn't see the rings. I only see them in Capture NX-D. When I convert the NEF in Nikon ViewNX directly to TIFF or JPG the rings are not there. How is it possible that NX-D is actually introducing these rings???

Same image below directly converted out of Nikon-View, not brought into NX-D.

 

[janzin]

Hmm strange because both my NX-D and View-NX are not the most up-to-date--I can't use the most updated ones as I'm still on Windows 7 (I know, I know...) But my version of NX-D (1.6.0) DOES have the PF flare control, it just doesn't seem to make any difference whether its on or off.

 

[JP Onstwedder]

I think ViewNX shows you the JPG generated in camera, and Capture NXD processes the actual raw image, so that might account for the difference. It looks a bit like an interference pattern. Did you use a polariser and shoot at a small aperture? Diffraction and a polariser In theory can create such patterns, although I’ve personally not seen it. You might also try a different raw developer. Accuraw uses a different algorithm, and might give different results.

 

[dabhand16]

Hmm strange because both my NX-D and View-NX are not the most up-to-date--I can't use the most updated ones as I'm still on Windows 7 (I know, I know...) But my version of NX-D (1.6.0) DOES have the PF flare control, it just doesn't seem to make any difference whether its on or off.

Have to say that I was dreading having to switch from win7 to 10, but found that it was easy to adapt and have had no issues. been on it about 6 months now and don't miss Win 7 at all. I installed it on an unimportant laptop first so I could see what it was all about and very rapidly switched all on my computers over. My main desktop was done by my computer man when he did some other upgrades which was part on my plan. If you can give it a try either on a laptop or from a friend/family member's laptop I'm sure that you will loose your apprehension. I did.

 

[Woodpecker]

I was shooting these crows mobbing a hawk, almost directly straight up. Upon looking at the frames I now see concentric dark rings in the sky! They are in all the photos from this series. I assume this is from the Phase Fresnel element---but I've never seen this before in any other birds in flight photos.

I encountered these rings once myself. in a similar situation: Bird on top of tree with blue sky behind it and bright sunshine and I saw it in the index pictures as well in th big viewer.

I cannot tell for sure whether certain corrections have NOT been implemented simultaneously in Capture NX-D and View-NXi, which could have caused seeing an effect in one program while not seeing it or seeing something different in the other, but if you use either program to look at RAWs they BOTH go through an initial interpretation of the RAW file if you view the picture first time.

What I realized was - and I just tried to double-check - that after doing a few steps of post processing to the picture, then changing to another picture to make the program save the changes made in the sidecar file and finally coming back to the old picture and resetting to the original state prior to post processing (Ctrl+U) I couldn't see the rings anymore. I just did that with the a processed RAW to check and I am not able to get the rings back.

From that I assume it has something to do with the way the software is processing the modifications that you make.
For normal processing steps like EC, contrast etc. it makes sense to have the undo function. For processing options that are purely dedending on the lens that has been used one could argue that an undo does not make sense. This could explain the strange behaviour. I can't remember where it was but I think I have read something about corrections for PF lenses should have been going in the camera software itself just like the correction of vignetting and distortion via the lens profile data you load into your camera as part of a firmware update. Currently it just made its way into the processing software by means of a tick box to activate it - although it should be automatically selectable based on the lens information included in the RAW file, but it may be erratically or deliberately excluded from the undo function.

If I have another picture with these rings I will try it with separate copies of the same RAW file and different programs. It would be particularly interesting because I am just changing over to Capture One that is meant to work with the original RAW algorithms from Nikon. Would be interesting to see whether the rings can be seen in this program as well.

 

[janzin]

Thanks Woodpecker you actually hit the nail on the head deep within your response! You mention vignetting--I asked this question over on DPReview and someone asked if the vignetting control was checked in NX-D, and yes it seems it was checked by default--unchecking it and the rings disappeared! So unbeknownst to me NX-D was applying a vignetting control which introduced these rings.

As you note, perhaps the control is being set in-camera and transferred to NX-D. I will have to see if this control remains unchecked next time I use the lens and import into NX-D.

Problem seems to be solved, with vignetting unchecked, no more rings! Whew!!

 

[janzin]

Well it seems NX-D is opening with Vignette Control automatically checked even if I uncheck it and exit. Seems to be no way to turn it off and leave it off. That's annoying but now at least I know how to fix the issue if it recurs.

 

[Woodpecker]

Well it seems NX-D is opening with Vignette Control automatically checked even if I uncheck it and exit. Seems to be no way to turn it off and leave it off. That's annoying but now at least I know how to fix the issue if it recurs.

Well, that's something I haven't checked but it may depend on the setting in your camera. There I have set vignetting control set to "normal", but you can turn it completely off as well. I would expect this information finding its way into the RAW data and thus you would always have the tick box set after opening NX-D, because the option will be set by any picture you look at.

 

[janzin]

Right, I see that its a camera menu setting! I had it on Normal as well, on both my D850 and D500. Not something I ever paid attention to. For now, I set it to Low...at least if I know what the issue is I can easily rectify it in NX-D if I see it happen again. I suppose its still quite rare and would depend on specific lighting conditions, as I said I hadn't seen it before!