Focus Stack Question

mwilson263 · Oct 27, 2017

I’ve tried doing a focus stack a few times lately on macro images, but have hit a snag each time. Each image I took at a different focus point seemed to have a slightly different focal length and I haven’t been able to effectively align the images together. The first time I thought maybe I bumped my tripod or camera, but as it recurred I did a bit of research & learned something I didn't know before. If I understand, even on a fixed focal length lens (in my case 100mm macro) the focal length will change just a bit as you change focus. As I think it through it makes sense to me, but if I’m misunderstanding the explanation somebody please set me straight.

So now knowing why it’s happening, how do I get around it with focus stacks? I’m using Photoshop Elements which I understand isn’t as powerful in putting images together as Photoshop CC, so maybe it can’t be done in Elements. I’ve searched a bit on Google and looked at a few Youtube videos, but haven’t found anything to get me past the focal length issue. Anybody here work with focus stacking who can point me in the right direction?

Thanks,

Mike

480sparky · Oct 27, 2017

Try a different app. I've had no issues with CombineZN or Picolay.

snowbear · Oct 27, 2017

I've done focus stacking once and , I guess, Photoshop CC adjusted it all for me.
Maybe the best way then, is to leave the lens focus alone (my 105mm has a lock) and use a focus rail - then you just move the camera/lens closer or farther.

smoke665 · Oct 27, 2017

If I was really into it serous I would spend the money on a precision 4 way focus rail, but for all that I've done I 've found one of these to be adequate Pro 4-Way Macro Sliding Focus Focusing Rail Slider DSLR Camera Tripod Bracket | eBay i never had much success with adjusting focus on the lens between shots either.

480sparky · Oct 27, 2017

focus-stacking

mwilson263 · Oct 27, 2017

Thanks for the help. I'll look into these and keep plugging away.

Dave442 · Oct 27, 2017

I use Zerene Stacker. I don't have a rail so just do manual adjustment of the focus. The program makes the adjustments for the slight change in size as the focus is changed. Usually it does very well using the defaults, but there are a number of options to refine the stack.

Overread · Oct 28, 2017

Try Combine ZP its 100% free to use
CombineZP. Get the software safe and easy.

Otherwise there's Zerine Stacker and Helicon Focus - both paid software but also do focus stacking very well.

In general stacking is one of those very few editing areas where different software can give drastically differnet results. What might fail in one will work in another due to the subtle differences in how the code stacks up the photos.

Most should be fine with the tiny amounts of focal length adjustment as you change focus and I've never found a firm article that states that there's any significant gain using focal length changes (ergo changing the focus point) over changing the distances involved between the two subjects.