[greenbaron]

Hi all,

I've been a happy K-1 owner since June this year. I've done some low-light shoots and really like that full frame sensor! It's my first ff so probably no wonders it's a joy. But, with low light I would run into these wavy patterns if the dynamic range was exploited heavily in post. At first I wasn't sure what to make of it, but during a recent shoot the patterns got pretty hefty so I decided to read a few things on the potential moire thing and play with some settings in adobe lightroom cc.

I was surprised to at some point find it was the lightroom cc dfa 24-70 lens profile that introduced them.. Still have to find out if it's distortion correction in general that will get these patterns going; it doesn't seem to be related to fine detail in the photos. Photos where the focus wasn't spot on seem to suffer as well. I understand these examples have been pushed beyond what might be acceptable, but the occasion begged photos no matter what and they do show rather well my point. If I export them at 1440p (my screen resolution) it's seems to be more clearly visible. Has anyone else run into this by any chance?

No lens profile:


with lens profile


No lens profile:


with lens profile


No lens profile:


with lens profile

[Digitalis]

Moire is the least of your problems with these images, I wouldn't be all that bothered with distortion in them to bother with using the lens profiles.. I think this is a subsampling and noise management issue. If you are using bicubic sharper to downsample your images it will exacerbate any fine patters [such as noise] in the image. For images like this, downsize them using Bicubic smoother, with some mild-strong NR, and a vignette filter with an appropriate amount of green tint to counter the magenta cast would be more effective than relying on canned lens profiles.

When you push things to extremes: be prepared to lower your standards for quality.

[stevebrot]

Moire is the least of your problems with these images, I wouldn't be all that bothered with distortion in them to bother with using the lens profiles.. I think this is a subsampling and noise management issue. If you are using bicubic sharper to downsample your images it will exacerbate any fine patters [such as noise] in the image. For images like this, downsize them using Bicubic smoother, with some mild-strong NR, and a vignette filter with an appropriate amount of green tint to counter the magenta cast would be more effective than relying on canned lens profiles.

When you push things to extremes: be prepared to lower your standards for quality.

What he said ^ ^ ^

Thing fall apart faster at the extremes and additional artifact is a constant risk when doing PP on an image that is intrinsically fragile (low data). FWIW, I almost never use the LR lens profiles or Pentax in-camera corrections.* The distortion correction is done by selective local removal of real data and selective addition of extrapolated pixels, both of which create potential for artifact by the process' very nature.


Steve


* To be honest, I can't remember EVER doing so and seldom have an image where it might be advisable.

[MaineNative]

Are you doing your post processing at 16-bit color settings. In the past I sometimes forget to import at 16 bits and when I start doing level adjustments at 8 bits I get severe banding...

[greenbaron]

Thanks everyone, appreciate the insight. Not bothering with lens profiles in this case makes sense, it's one of those things that slipped into the workflow without giving it much thought. Running into these 'wavy' results is something new though, I've pushed the limits with other systems before including the k-5 but never seen this. I looked into the down/upsizing method for lightroom cc but couldn't really find what method is used or how it can be changed, same for import 8/16 bit setting. I'll certainly try the Bicubic smoother with photoshop with dedicated manual corrections, but the main issue seems to be resolved by not using the lens profile.