Creating Exposure Depth from Focus Stack

[siderealxxx]

Hi, I'm medium level proficient in Photoshop so bear with me.

I have a focus stack of an object made up of 15 images which works nicely. But I would like to add exposure by depth if possible. By that I mean I would like the images further back in the object to be darker in exposure and gradually getting lighter at the focus points. Sort of artificially creating an exposure bracket from a focus stack if that makes sense.

I have no idea how to achieve this if anyone can advise - thanks in advance!

 

[IamSam]

Hello and welcome to PSG. This process may depend on what technique you used to create the focus stack. Please explain in detail your workflow for the focus stack.

If you used the auto-blend feature in Ps to create the focus stack, then you may need adjust the final image by using an adjustment layer (Curves) and it's layer mask to darken the BG.

Otherwise, you can adjust the lighting/exposure during the photography phase or you can adjust the layers with a Curves adjustment for each of the stack layers before auto-blend.

 

[siderealxxx]

Thanks for the welcome and info.

The object in question is approx 8cm diameter with a depth of around 3cm, which was photographed with focal length of 60mm, f/2.8, exposure 1/400th. 15 shots were taken in RAW. Stacking wasn't done in camera but will be applied in Photoshop.

Essentially I want to apply object select and past onto a flat background colour, then take advantage of the fact that I have 'slices' representing focus points so that the contrast/exposure is increased from the back of the object (darker) to the top of the object (lighter) incrementally.

From what you're saying, it sounds like I can just adjust each layer to suit before auto-blending the stack? I wonder if this will impact on the auto-blend algorithm in any capacity. Sounds simple, maybe I'm over-thinking it?!

Thanks

 

[IamSam]

I wonder if this will impact on the auto-blend algorithm in any capacity.

It shouldn't, but I have never tried this technique. I would make copies or copy the PSD file/Project, and then merge the adjustment layer into each of their perspective layers before using auto-blend.

 

[siderealxxx]

Thanks, yes I've got it now. Wasn't as complicated as I thought. Cheers!

 

[siderealxxx]

As far as I can tell, there's no need to merge the adjustment layer before auto-blend. Maybe there's a good reason to merge first though...?!

 

[IamSam]

Maybe there's a good reason to merge first though...?!

No.................it was a precautionary measure as to not confuse the algorithm. As I stated, I have not tried the technique.