Page 1 of 1

Getting started using FB Tube

Posted: 29.04.2019 23:19
by faw1421
I am using the following equipment and have several questions in need of answers to get me started. (I have read through all the material from the Helicon Soft website, but am still somewhat confused.)

Nikon D500 camera; Sigma 105mm F2.8 EX DG OS HSM macro lens; Samsung Galaxy S9 phone with the Helicon FB Tube configuration app installed; Helicon FB Tube.

1. When working with the Helicon FB Tube app I added my Sigma 105mm lens to it. The step values shown vary with the aperture setting as shown in the following examples: For F/8 the step value shows 8. For F/11 the step value shows 11. For F/16 the step value shows 16. In other words, the step values are equal to the F/ values. Are these correct? For comparison I looked at the step values shown for the Nikon 105mm lens. They are all ten times the F/ value. For example, for F/8 the step value is 80 and for F/11 the step value is 110. Are these correct? Do I have to go through the configuration process of determining the correct step values for my Sigma lens before I can use it?

2. When shooting a stack, how do I determine the number of frames to be taken? Do I first focus on the part of the subject closest to the lens and then shoot until I see the part of the subject in focus that is furthest from the lens, using live view and single shot operation of the camera? If so, how would I go about knowing how many frames to shoot while using high speed continuous shooting without using live view?

Maybe it's just my difficulty in understanding the existing instructional material, but I think the material needs some substantial improvement in order to satisfy the needs of the new user of FB Tube.

Thanks in advance for your help.

Re: Getting started using FB Tube

Posted: 01.05.2019 14:17
by Catherine
1. The size of the optimal focus step between consecutive shots is lens and aperture specific, there’s no figure that will fit all of the lenses, since they have different internal mechanics. Focus steps of the tube is the value proportional to rotation of the focus ring of the lens, not to the linear movement of focus in mm, it’s in arbitrary units. When you change the aperture, the width of the DoF area changes. The size of the step is being recalculated in the app automatically when you select a different aperture.
Step sizes for some lenses and different apertures are preset in the utility. As for the other ones, the step size should be determined experimentally, through successive refinement of the step size. For instance, this way:

Here you can find a video tutorial on adding a lens:

And here you can find text instructions with screen shots:

2. The tube does not control the camera, therefore it cannot calculate and communicate the number of shots to the camera. Indeed, when working with Helicon FB Tube you set the step size from the Configuration utility, then focus on the initial shooting point and control the number of required shots by holding down and releasing the shutter button, or from a remote control, or watching the focus move in the focus distance window on the lens. At the end of the series you will see the focus being shifted and you can make additional shots if needed. In general, we’d recommend to make more shots and to delete excessive ones on the focus stacking stage.

We will check how to improve the materials on the website to make it all clearer.
Helicon Soft

Re: Getting started using FB Tube

Posted: 01.05.2019 18:27
by faw1421
Your reply does nothing more than repeat the material previously published. It does NOT answer my questions.

If you read my first question, I asked about the accuracy of the step values shown on the configuration app. These values were apparently generated by Helicon in its software or copied from its database: one for a lens that I added and one for a lens that was already in your list. One would certainly expect that you would know if those are correct, or whether one or both would have to be established experimentally.

If you read my second question, I asked how I would begin the focusing process and how I would know when I had taken enough frames. You say I "can make additional shots if needed." That hardly answers the question. It seems obvious to me that the number of frames necessary would be dependent upon the depth dimension of the subject being photographed, as well as the F/ stop set for the lens and the depth of field desired in the final image. While I certainly understand that a precise number of necessary frames cannot be determined ahead of time, how does one decide approximately when to stop shooting? Is it by looking at the position of the focusing ring to see how far it has advanced, or by looking at enlarged images on the camera's LCD screen, or by shooting one shot at a time and enlarging the image in live view? These approaches would not be practical when hand holding the camera. So then do I shoot 10 or 30 or 50 or more shots to begin with?

Your response clearly demonstrates why I suggested the need for better instructional material. Please answer my original questions.

Re: Getting started using FB Tube

Posted: 02.05.2019 16:50
by Catherine
We’ve determined the optimal size of the step for several lenses that we’ve tested. These values have been found experimentally, with a conservative overlap. Some of our customers adjust the recommended step for preset lenses according to results of their own tests. The same works for user lenses. I’m not sure if we can comment on the accuracy of the step values for the lens you’ve added, but if you’ve found it to be optimal based on focus stacking results, that’s fine.
As for the number of frames, it is the same as when shooting a stack turning the ring manually, you can’t say exactly how many shots you will need. Again, it’s a questions of practice. After shooting several stacks at a certain step, you will understand the approximate numbers. Another option which may work for some cases is to have a look at the focus distance window on the lens before starting shooting, to see where the approximate start and end points of the desired range on the scale are and to stop once you see on the scale that you’ve reached the end point. Some of our customers do shoot with the tube in single shot mode, it’s also possible and it makes it clearer where the current focus point is. If you shoot with Mirror Lock-up off, you will also be able to see the focus advance through the viewfinder. There are several ways to make it, the choice depends on your workflow and shooting conditions.