long exposure problem with H6D-100

[NBuxton]

Hi,
I have been taking long exposures (30 secs) at 3200 ISO with the camera. Several images have purple and deep red horizontal stripes of varying thickness through the image. Noted more when adding a little positive exposure in Photoshop. Is this just sensor noise or some other problem.
Thanks to you all for considering this problem and help in anticipation.

[mistercohen]

Could you post a photo?

[NBuxton]

sorry for delay. Thanks for response. hen back with main computer I will post a jpg.

[NBuxton]

Hi, Here is a JPG (small) of the image with bands. Image initially underexposed and has been brightened in Lightroom. No other modifications - as the bands upset my sensibilities!! It is, almost certainly, operator error but just making sure I am not missing something. Long exposures at night are new to me.
Thanks for advice and understanding.

[NickT]

I wonder if the image was just too far underexposed at too high ISO?

[mistercohen]

Did you use a red lamp at night or your red car lights where on? On a different camera I had light travel through the view finder and cast strips off light on the photo. I would go and repeat the night picture at high ISO and cover the view finder with gaffer tape. If this happen again then you know it has to do with the sensor and I would contact hasselblad support.

[ChrisL]

I would go and repeat the night picture at high ISO and cover the view finder with gaffer tape. If this happen again then you know it has to do with the sensor and I would contact hasselblad support.

I would find it hard to see how light can enter and affect the sensor from the viewfinder in a camera where the mirror is raised throughout the exposure.

My impression is the image is very underexposed, you will also benefit from converting the RAW file in Phocus which reads the back calibration and applies corrections that are superior to Lightroom. I have seen superb images from the combination at long exposures, you would also benefit from reducing the iso and further increasing exposure, higher iso will exaggerate the noise in the image. Simply, the sensor has not seen enough light.


Not my images but representative of the long exposure quality possible: https://sdpphotographics.wordpress.com/2017/03/05/salt-lake-by-night-with-hasselblad-h6d-50c/

[bdp]

Sadly I think your sensor needs replacing. I had this on my H6D-50 when it was new - more noticeable at 800ISO and above, but visible without pushing the files at all. Hasselblad replaced the sensor and now it's great.

Ben

[NBuxton]

First, thank you all for taking the time to respond and advise.
As I suggested in an earlier post, I thought it was operator error - so I will take on board the suggestions and try those and see what transpires. I do not use a red light and the cars were safely parked under the house. No extraneous light as we live in a rural area.
If the problems persist with correct exposures - then I will take to our Hasselblad rep who is in an office 2500 kms from my home!
Will try Phocus - I still have the 3FR files - I guess I was being lazy as I was downloading my wife's images from her Leica and justice t put my card into the same reader! (again operator error!!!)

[mistercohen]

I would find it hard to see how light can enter and affect the sensor from the viewfinder in a camera where the mirror is raised throughout the exposure.

Please check this article it shows how. Again this happen to me on a Nikon Camera.

https://photographylife.com/how-to-fix-light-leaks-in-long-exposure-photography

Beside that, you are right the photo looks underexposed, but that does not explain the red stripes in my opinion.