Not enough steps for good stack

General discussions, bugs, support, suggestions
Post Reply
Kirkus1+
Posts: 2
Joined: 06.08.2018 00:48

Not enough steps for good stack

Post by Kirkus1+ » 06.08.2018 01:41

Hello!

I'm currently evaluating both HR and HF. For some reason I can't get HR to create enough photos to get a good stack. I set the closest focus and the farthest focus and the automatic step/interval ratio seems way off. Often something like 3 steps with an interval of 30+. So when stacking there are more unfocused areas of the final image than there are focused. I've tried with 2 cameras: Canon 80D and a Canon T3i, and 3 different lenses on each camera: all Canon, 50mm prime, 55-250mm, and a 18-55mm kit lens. I've tried both Big steps and Small steps set in preferences. I've also uninstalled and reinstalled both HR and HF.

I'm also using a set of extension rings, made for Canon EOS cameras (all electronic contacts). The extension rings work fine when I use them for regular shooting (all camera functions work).

I'm on an iMac (Retina 4K, 21.5-in, 2017) running High Sierra (10.13.5).

I've also noticed that often times HR will ignore my farthest set point, often times going too far and shooting a final image that is way past the set farthest focus point.

I've tried manually setting the steps/interval ratio but I've had no luck with that either (probably because I don't understand the math involved).

Any help would be very much appreciated.

Thank you!

User avatar
Stas Yatsenko
Posts: 3690
Joined: 06.05.2009 14:05
Contact:

Re: Not enough steps for good stack

Post by Stas Yatsenko » 06.08.2018 15:37

1. The automatic values are only a remote guess by default. The DOF calculator requires calibration to be precise. The link to the calibration procedure is in the DOF calculator dialog itself: https://www.heliconsoft.com/HeliconRemoteHelp/english/HeliconRemote.html#HR_CORECTION_FACTOR

Alternatively, if you see that the interval between shots is too large, you can un-tick "Auto" and make the interval 2x smaller. If it's still too large, keep cutting it in half until the result is satisfactory. Also note that the program doesn't know whether or not you have a tube installed, but the tube obviously requires correcting the interval as it affects DOF, so you will need to use different correction factors for the same lens and body with and without a tube.

2. The program always keeps even intervals between shots, which means it may overshoot the last point. Example: number of shots - 5, interval - 6, and point B set at 19 points (from the beginning of the stack). The shots will be taken at positions 0, 6, 12, 18, 24 - in this example, point B is overshot by (24 - 19) = 5 points, but that's OK because the concept of focus stacking implies that your interval is less than DOF. Which means that in the example above, the final point 24 is still within DOF from your requested point B at 19, so in terms of focus stacking these two focal planes are equal (by definition, interval may not be larger than DOF).

Bottom line: the program worked correctly but has been set up incorrectly. Overshooting the point B was obvious because the interval was exaggerated (large than the actual DOF). Calibrate the DOF calculator and it will be fine.

Kirkus1+
Posts: 2
Joined: 06.08.2018 00:48

Re: Not enough steps for good stack

Post by Kirkus1+ » 06.08.2018 21:54

Thank you, Stas, for the quick reply. Of course that all makes perfect sense. I should've realized there would need to be some kind of calibration process. I appreciate you taking the time to explain it to me.

--Kirk

rickchester
Posts: 1
Joined: 22.08.2018 12:35

Re: Not enough steps for good stack

Post by rickchester » 22.08.2018 12:37

I'm also currently evaluating both HR and HF. For some reason, unfortunately, I can't get HR to create enough photos to get a good stack.

User avatar
Stas Yatsenko
Posts: 3690
Joined: 06.05.2009 14:05
Contact:

Re: Not enough steps for good stack

Post by Stas Yatsenko » 23.08.2018 12:04

My post above gives a solution: you need to follow the calibration procedure described here: https://www.heliconsoft.com/HeliconRemoteHelp/english/HeliconRemote.html#HR_CORECTION_FACTOR

Alternatively, simply un-tick "Auto" and double the number of shots. If you're not satisfied with the result, keep doubling it until you're happy.

Post Reply