What is this ?

[GT AUDIO WORKS]

Hello All,

I have just recently gotten back into photography after a long hiatus...my last decent camera was film...so its been awhile.

Got myself a used Sony A7 and a few vintage Olympus Zuiko prime lenses so all the AF stuff is rendered inoperable which is OK by me.

All has been going well with daytime shooting, so I decided to give comet Neowise a shot.

I am having an aberration show up on all my shots with different lenses when I process the image.

I took this shot of some stars and I purposely boosted the brightness and color to accentuate the issue.

The other shot of the comet you can see the same issue 

I am pretty much flying by the seat of my pants with this digital stuff.

Any expertise would be appreciated.

Any ideas ?

 

Edited July 21, 2020 by GT AUDIO WORKS

[JamesF]

I would guess that the exposure time you're using isn't giving you enough dynamic range, so when the image is stretched you get the obvious colour banding.  I'd try being less aggressive with the processing, or longer exposure times.  Or both :)

James

[Stargazer33]

Do you mean the circular colour banding? It looks like low colour depth. As though it's displaying in 256 colours only. Other than that I can't see any anomalies. 

If it's not colour depth, then a previous owner may have tried to clean the sensor with a poor outcome! Have you tried taking a frame without a lens attached to see what you get?

[GT AUDIO WORKS]

6 minutes ago, JamesF said:

I would guess that the exposure time you're using isn't giving you enough dynamic range, so when the image is stretched you get the obvious colour banding.  I'd try being less aggressive with the processing, or longer exposure times.  Or both

James

Thanks James,

I shot the first one with a 28mm at about 5 seconds at f2.8 ISO 2500. 

This processing was deliberate to bring out the flaw....

But now that I look at the frame in the camera monitor the color banding is apparent unprocessed as well..guess I didnt notice it in the dark last night.

So my exposure is too short.

So how far can I stretch the shutter time before star trails appear..And how far can I go with boosting the ISO ?

Greg

[GT AUDIO WORKS]

16 minutes ago, Stargazer33 said:

Do you mean the circular colour banding? It looks like low colour depth. As though it's displaying in 256 colours only. Other than that I can't see any anomalies. 

If it's not colour depth, then a previous owner may have tried to clean the sensor with a poor outcome! Have you tried taking a frame without a lens attached to see what you get?

Thanks Bryan,

Displaying in 256 ? You lost me.

Yes I cleaned the sensor first thing..other than a few spots went away..no improvement.

Greg

[wxsatuser]

I believe this is a known issue with the Sony's.

Mark, sharkmelley if he is about could fill you in on this.

[Mick J]

May be helpful to know what model of A7 and if you are shooting in raw.

[Stargazer33]

Displaying in 256 colours goes back to the old days of computing when the screens displayed a maximum of 256 colours only. You couldn't get the subtle variations that you get now; therefore if your picture went from black to light blue, you would see each new colour in the gradient as a separate band, rather like your image. Hence my observation. 

Can you set the colour depth on your camera; or, are you importing your images into your processing software in a low colour depth? Even 8bit colour depth should give better gradients than your image above is displaying.