Jack68 Loc: Sydney Australia

Hi all,
I wonder if all you cleaver guys on this forum can solve a problem I am having with focus stacking?. One of the topics at the photographic club was on focus stacking. It was very interesting, and I wanted to give it a try. So I set up a bowl of fruit and made several shots as per instructions given by the presenter at the club. The stacking worked well, but the sharpness from front to back was soft and only the centre was sharp.
The method I used was Manuel mode focus and exposure. By focusing on the front of the bowl and then moving the lens forward slightly for a total of 8 shots.
What am I doing wrong?.
Go for it guys, Thanks.

WayneT Loc: Paris, TN

What are you using for stacking software?

JimH123 Loc: Morgan Hill, CA

What SW did you use to stack it? Helicon Focus works well and is the one I use. On something as large a bowl of fruit, perhaps 8 images is not enough? When you have everything right, it works very well.

Jack68 Loc: Sydney Australia

Hi WayneT,
I am using Photoshop, I don't thing it's a software problem, but the focusing method I am using.

tdekany Loc: Oregon

Post a sample please?

Jack68 Loc: Sydney Australia

Hi JimH123,
The problem I am having is not software, but the way I am achieving focusing, I have tried both a Micro and a zoom lens, the bowl is 11 inches round.

Jack68 Loc: Sydney Australia

Here is the stacked image,

JimH123 Loc: Morgan Hill, CA

Do it again and hit the download button so it can be looked at closer. I suspect that you need more images. Also, did you set the camera for manual focus? Auto focus is no good for this.

Is the camera on a tripod? It is not necessary, but some use a focus rail. You can either leave the camera stationary and focus the lens for each shot. Or move the camera closer and closer without changing the focus. In covering 11 inches, perhaps more than 8 images might be necessary since at the distance you are shooting the focus depth is quite shallow and if each movement is too large, there will be parts of the fruit bowl that never are in focus.

I did go read up on focus stacking in Photoshop, and it is far more work than Helicon Focus! By the way, the camera I like to do this with is Olympus. Can set the number of exposures I want up to 999 and to then manually focus on the leading edge and start it going. I will then take all the images, changing the focus for each shot until done.

vetus pictorem

Are you on a really rigid tripod and moving the focus ring close to the same amount every shot?
Are you starting in the back and focusing in steps towards the front? Some people think that works better. Did the zoom move slightly when you stepped the focus incriments?
The photo looks blurry in the back. But more like camera movement than focus to me.

Jack68 Loc: Sydney Australia

Hi all,
I have taken all your comments on board and I will follow some of your good advice, this is really a learning curve. I will post some results after I had another go at this. Thanks it's appreciated.

tdekany Loc: Oregon

I used both and doing it in PS is not harder at all. In fact, I got rid of Helicon. I used to get weird artifacts, the owner of the program was very helpful and would actually make changes but I never have any issues with PS. I use an EM1 Olympus

speters Loc: Grangeville/Idaho

Did you not check focus on each shot, using enlargement in live view?

cthahn

There is no way anyone can tell what you are doing wrong. You do not indicate what lens or software you are using. Read articles about focus stacking. You have to understand completely about the process. I use Photoshop and my first shot came out fine.

jerryc41 Loc: Catskill Mts of NY

Here are lots of links I've accumulated on focus stacking.

https://digital-photography-school.com/photograph-images-needed-focus-stacking/
http://www.earthboundlight.com/phototips/focus-stacking-software-photoshop-helicon-combinezp-zerene.html
http://www.lightstalking.com/focus-stacking-in-photoshop/
http://www.digitalcameraworld.com/2015/05/13/focus-stacking-how-to-extend-depth-of-field-in-photoshop/
http://zerenesystems.com/cms/stacker/docs/purchasing
http://www.heliconsoft.com/heliconsoft-products/helicon-focus/
http://www.picturecorrect.com/tips/simple-steps-for-focus-stacking-in-photoshop/
http://digital-photography-school.com/how-to-improve-your-long-exposure-with-photo-stacking/

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Hard to tell from this small image, but I'd guess that you didn't take enough shots and/or the interval is too great for the depth of field for the distance/focal length/aperture you've selected.

Here is how I would handle it. Assuming your lens is sharpest at F8, consult a DoF table or calculator to see what your actual DoF is. I use DoF Master but you can use any online calculator - they will generally give you the same results.

Let's say you place the camera so that it's sensor (not the front of the lens) is 24" from the leading edge of the bowl, you are using a 35mm lens at F8 on a cropped sensor camera, like a Nikon D7200 or something similar. With the settings above, your DoF for "acceptable" focus at 24" (leading edge of the board) is 3.62 in. But for sharper focus I would set the calculator to determine DoF for an aperture of F4. This will ensure that you have critical focus, not just "acceptable." Keep in mind that as you adjust your focus to the rear edge of the bowl your sensor plane to subject has increased and your DoF will increase. The key is to overlap your focus steps so that there are no gaps.

Focusing at 24" your field of focus is from 23.1" to 24.9"
At 25" it's 24.1" to 26"
At 26.5" it's 25.4" to 27.7"
At 28" it's 26.8" to 29.3"
At 30" it's 28.6" to 31.5"

And finally if you focus to 32.5", the field of focus will cover from 30.9" to 34.3"

In six focus "steps" you have created a stack that will be in critical focus from 23" to 34.3" which is more than enough to take in the entire scene. Using the values for F4 even though you are actually shooting at F8 will help ensure that there is sufficient overlap.

If you are shooting down on the subject, the distance from the front of the bowl to the rear will be shorter, but the top of the pile of fruit will be closer, so you'll need to take that into consideration. Using live view to focus can sometimes help.

Needless to say you should use manual focus and manual exposure, camera mounted on a sturdy tripod, and a fairly low ISO for maximum image quality. If you are in doubt about how many focus steps to take, then take more smaller steps. From an image quality point of view, there is no downside to taking too many steps, but gaps will be easy to spot.

Hope this helps.