EOS R5, EF 100mm f/2.8L Macro IS USM Red, Blue, White Rows of Dots in Product Photography

[Jay_Pea]

Hello community, 

I'm an amateur product photographer for work, learning as I go. I use the Ortery 3D PhotoBench 280 and their software to capture the photos, particularly using their Focus Stacking feature. 

Please see specs below:

Camera: Canon EOS R5 (Purchased in 2022)
Camera Lens: EF 100mm f/2.8L Macro IS USM (Replaced 10/25/25)
F-Stop: f/11
Exposure Time: 1/2 sec
ISO: Ranges from 160-200
White Balance: Auto

I've run into the following with these red/blue/white rows dots that show up on some of my product pics. Please see examples below (please disregard quality - this is just to showcase the dotted rows):

I've recently got a new lens so I know for certain its not a lens issue I've wondered if maybe they show more when I shoot black products but they also show on lighter colored products so, I am at a loss.

Any insight would be appreciated.

Thank you for your time. 

[wq9nsc]

Jay,

What type of product are you photographing?  Is that photo you submitted a composite of several separate photos?  Do the lines show up in different places on different images?  If they are showing up in the same part of the frame on every image, that would indicate the sensor "saw" a laser or other intense energy source and has been damaged.

Rodger

[Peter]

Hot pixels that have been stacked? You can run "Clean now" to remove hot pixels but it may not remove all of them. 

Another solution is to turn on Long Exposure Noise Reduction.

[Jay_Pea]

I'm photographing automotive parts that range in size, material, and color. And yes, the picture I posted is a mini collage of various products. I need to zoom in around 150-300% to find the dots, which is really annoying during the editing process, slowing my work flow.

It's also difficult to determine if they do indeed show in the same areas, since they range in size and location per product. 

[wq9nsc]

Try taking a few photos of a wall painted in a solid color and that will easily let you see if they show up in the same place in every frame.

Rodger

[Jay_Pea]

Hey Peter,

Yeah, I've tried the "clean now" but they still show up and Long Exposure Noise Reduction is set to off. 

[Jay_Pea]

Forgot to mention - it's difficult to determine if they show up in the same area as I adjust the camera around a lot (up, down/left/.right). The camera is on a repeatable kit, like THIS

[ebiggs1]

"Try taking a few photos of a wall painted in a solid color ..."

A better way is to turn off long exposure noise reduction. Set your camera to manual.
Take several photos with no light by putting the lens cap on the lens. Take several exposures 10 seconds at ISO 100. Take several exposures at high ISO but shorter SS times as quick as 1/1000.

Your can then use your camera's pixel mapping function to compensate for any detected hot or stuck pixels or turn long exposure noise reduction on.

I am not convinced that is what you are seeing the explanation is simply how to eliminate hot or stuck pixels. Keep in mind it may not be 100% successful either as some may still remain.

I need to zoom in around 150-300% to find the dots,..."

That's a lot of magnification. 100% is considered pixel level so are you saying you need this much magnification for publication or is that the level you do your editing?

[ebiggs1]

What are hot pixels? Most hot pixels are red, green, or blue. They are different than dead or stuck pixels as hot pixels do not always appear in the same place and are typically random. They will show up mostly in the darker areas of your photo.

Hot pixels are mostly caused by heat. This is often caused by long exposures or high ISO. If the bug you, you can edit them out in several ways in Photoshop. Try the Spot Healing brush, pretty easy.  Every camera has them. And, most of the time nobody can see them or notice them.

[johnrmoyer]

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@Jay_Pea wrote:

Hey Peter,

Yeah, I've tried the "clean now" but they still show up and Long Exposure Noise Reduction is set to off. 

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If using a tripod, maybe use Fv mode with the ISO set to 100, the aperture set get the depth of field you want and the shutter speed set to auto. This with long exposure noise reduction might do what you need as @Peter suggested. Long exposure noise reduction is like subtracting a dark frame.

In Canon DPP software one may use compositing to subtract a dark frame. https://cam.start.canon/en/S002/manual/html/UG-05_Synthetic_0020.html#Synthetic_0020_1 The dark frame is best created by putting on a lens cap and taking another photo of no light with the same settings as the real photos and the camera at about the same temperature. Canon DPP allows compositing raw images. Dark frame substraction will eliminate any hot pixels that the sensor develops.

ISO 100 will prevent the noise from not having enough photons for the average to be what is expected. https://people.csail.mit.edu/hasinoff/pubs/hasinoff-photon-2012-preprint.pdf 4 page PDF. With high ISO, the arrival of photons follows a Poisson distribution: https://en.wikipedia.org/wiki/Poisson_distribution https://en.wikipedia.org/wiki/Shot_noise 

 https://www.canon-europe.com/pro/stories/noise-reduction-low-light/