Not focusing between A & B.

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Jon-R
Posts: 3
Joined: 12.08.2017 09:34

Not focusing between A & B.

Unread postby Jon-R » 12.08.2017 09:50

Hi All,

I have searched for a solution to this issue before posting but could not find anything, hopefully someone can help?

Here's what I am doing...

- In Remote I set up the nearest and farthest focal point and save them to A and B respectively.
- I click the buttons to re-focus the camera to each point to make sure I have the right range.
- One I am happy I click the Start Shooting button and the process starts.
- The required number of shots are taken and the software shows the progress, including the focus range counter changing from nearest to farthest.
- Processes finishes and I am prompted to open Focus. Which I do and the Focus process also finishes successfully.

However, when I review the captured photos and final stacked image, I see that the camera has not been focussed between the set nearest and farthest points, only the first ~25% of the range has been captured. E.g. If I set a range from 0 to 200 the images seem to only focus from 0 to 50, although Remote indicates it has focused to 200!

Any ideas?

PS: Setup is a Nikon D7100 with a Tamron 90mm 1:1 Macro lens.

Jon-R
Posts: 3
Joined: 12.08.2017 09:34

Re: Not focusing between A & B. (solved)

Unread postby Jon-R » 13.08.2017 10:35

Quick update....

I played with this for many hours yesterday and eventually found it was just the Tamron lens that caused the issue, 3 other lenses I tried worked fine.

After much head scratching I decided to see if this advice on correction factors helped: http://www.heliconsoft.com/forum/viewtopic.php?t=8591

I didn't really expect this to work as I (wrongly) thought CF only controlled the number of steps required to get a good set of focused images across my chosen focal range, and only cause either banding or too many pics if set wrong. I didn't expect it to actually affect the front to back focus range!

However, after running a few test CF settings I found that at CF4 the Tamron would focus front to back without any problems, and I am getting a good DOF across the entire range, with fewer shots. Initial results from Remote & Focus are excellent, great software,

So, problem solved for me but I hope this post helps others who are experiencing similar issues with focusing. Remote and Focus are such easy packages to work with, CF is the only "fiddly" setting but once you understand this you are on a winner.

mrose
Posts: 31
Joined: 02.04.2014 16:50

Re: Not focusing between A & B.

Unread postby mrose » 13.08.2017 22:07

I often use the Tamron 90mm (USD Di version) and have found that the default CF is perfectly ok! I have Nikon FX cameras though but I don't know if that makes a difference.

Jon-R
Posts: 3
Joined: 12.08.2017 09:34

Re: Not focusing between A & B.

Unread postby Jon-R » 14.08.2017 09:35

I did initially think it was down to DX/FX sensors, which gives the Tamron an effective focal length of ~135mm on the D7100, but am not 100% convinced. Especially as the instructions for Helicon clearly say you should always use the lens' actual focal length when calculating DOF, CF and steps.

The more I read about the functionality of Correction Factor, the more I think it isn't the cause of my original problem. So, although I now seem to have things working, I don't really understand how/why and that frustrates me!

I will carry on playing with this to see if I can suss out what the real root cause of my issue is/was.

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Stas Yatsenko
Posts: 3958
Joined: 06.05.2009 14:05
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Re: Not focusing between A & B.

Unread postby Stas Yatsenko » 14.08.2017 13:54

Apparently, the issue is sensitive to the specific step size. So you've increased the correction factor from 1 to 4, which means 4x longer focus distance between shots. That's odd, because with Nikon lenses issues usually arise with long steps, not short ones. Bottom line - I don't know what's going on there.


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