Selecting important focus point in stack

Post Reply
MrBumpTiger
Posts: 1
Joined: 03.04.2019 20:23

Selecting important focus point in stack

Post by MrBumpTiger » 03.04.2019 20:46

Hi there
I'm working on a focus stacked multi row panorama. It is quite a wide angle interior, but there are some things in the foreground that I want to bring into focus. However, there is one part of the image that has to be as sharp as possible (a bookshelf), and it's towards the back of the image.

I'm using a D850 to focus stack in camera, then stacking in Helicon, then creating the panorama in PTGui. All is working well except for one thing, and that is that the bookshelf itself is coming out soft sometimes. I think it is because the camera is focussing just a little before or a little behind the bookshelf when it shoots that part of the stack, and not nailing it exactly.

There are 2 solutions I am aware of, neither of which I like, so I am wondering if you guys have another way I haven't thought about:
1. Decrease the distance between shots in the stack, shoot more shots - I don't really want to do this as I am already working with hundreds of images, and the only thing I need to be tack sharp is the bookshelf
2. Shoot each stack manually (yawn)

Is there a way to shoot the bookshelf sharp, then shoot the scene from front to back, and somehow insert the sharp image into the middle of the stack in Helicon? As far as I am aware it doesn't like images not being shot in consecutive order if you want to use all methods.

Sorry if I'm missing something blindingly obvious, would love to hear your thoughts on the easiest way to approach this in terms of workflow.

Thanks!

User avatar
Stas Yatsenko
Posts: 3850
Joined: 06.05.2009 14:05
Contact:

Re: Selecting important focus point in stack

Post by Stas Yatsenko » 05.04.2019 11:31

It's not impossible, but problematic. You would need to ensure exactly the same point and field of view for your extra shots that the rest of the set of images has, which I can imagine being difficult, and if the point of view is off, you will get artifacts. Then you need to assign appropriate names to your extra images so that they fall into the right spots in the whole stack when sorted automatically, because yes, the whole set of images needs to be arranged by Z-depth monotonically.

Methods A and C are a little more robust in this scenario than B.

BobStone
Posts: 36
Joined: 03.06.2017 10:13

Re: Selecting important focus point in stack

Post by BobStone » 05.04.2019 12:25

I suspect your focus step width on the D850 is too wide. After a good deal of testing with this camera, a step width of 4 seems to work across a broad range of focal lengths, f/stops and subject distances. It may not be the most efficient in terms of number of frames, but should provide a result without any fuzzy out-of-focus bands.

Warner98
Posts: 2
Joined: 28.05.2019 06:51

Re: Selecting important focus point in stack

Post by Warner98 » 28.05.2019 08:08

Yes I focus deeply

Post Reply