Focus and the inevitable rise and fall

[PanoMapper]

This is a new venture for me and something I am not that confident with yet.

However, I have been asked to make some object movies for an insurance company. The remit is that they are detailed enough for them to be used as good photographic documentation in case of theft.

This means that I shall have to use focus stacking on the images, with which I have been experimenting over the last few days. Much to my frustration . . .

I would love some input into this:

The final image, which can be seen at http://tactus360.com/panos/razor/test5.html, is alright as a test run and, apart from a few problems with my studio lamps, relatively acceptable when it comes to having clearly documented images. However, there is something that is bugging me considerably, and this is the rise and fall of the object as it is rotated.

The camera and turntable are well placed and the object is placed at the turntable's absolute centre, so this I don't think this is the problem. The razor is perhaps a rather strange test subject, but it is an odd shape and a good subject to use for focus stacking.

What I think is, is that as I took each slice, I was having to sometimes alter the starting point for the focus. Elsewhere, possibly another reason for the problem, I altered the number of stacked images, since several slices were redundant.

In people's experience, I wonder if this is the cause of the problem, or is it something more to do with the technique/software I am using?

The software is Control My Nikon for the slicing and Helicon Focus for the montage. I would use the Helicon control, which might make a considerable difference, except that on the laptop I am using for controlling the image, it runs quite poorly and, it seems, is not set up for capturing more than a stack at a time. This is, of course, quite useless if you are wanting to make a series of 36 separate images.

I hope someone will be able to give me the benefit of their advice.

Jon

[Hopki]

Hi Jon,
I have not heard of this being used for 360 objects, perhaps because of this very reason.
Interesting stuff, I think the only way to stop this would be to have the same amount of slices per image.
Regards,
Hopki

[PanoMapper]

Yes. I think so. The problem is quite large for me, since I want as good as I can provide (don't we all). However, the controller programs - Helicon Remote and ControlMyNikon - are less useful than useful. I have been testing both for a couple f weeks. The former seems very buggy. The second seems to work on the smallest focus to set the finalised image size. However, it also seems to return the focus after a stack to something a little closer than before. I can compensate for that by using markers, which is fine, since these are for reference purposes only. However, there is still (I hope) a bit of an artist still left in me, despite -30-degree temperatures (to quote Grandpa Simpson, "It's cold and there are wolves...).

Jon

[BrownewellPhoto]

I got involved shooting treehoppers for the USDA a while back which lead to some interesting problems.

First, I noticed that if you don't have a high quality table you will see irregularities in your table height and absolute center. Cheap (stressing the word cheap) bearing based tables are terrible when it comes to these problems. The bearings are slightly different sizes, have flat spots, tall spots, etc, and all those factors lead to wobble in the table as well as lateral drift. On my 18 inch table, I use a 15 inch bearing plate so that the differences in bearing size lead to less angular (rise and fall) movement. If I'm shooting something really small, like small insects, I use a milling station which has almost no table movement what-so-ever.

You second problem is in your focus stacking. Will you be shooting very small or incredibly detailed items? If not, why not shoot at a smaller aperture. I was shooting 3-5mm insects at f/32-45 with acceptable results. On something as large as a razor you should be able to get good results shooting at f/11 or f16. Moving to a smaller aperture will also speed up the computer processing time by leaps and bounds.

If you do plan on stacking, I'd switch to an automated rail. They can reset themselves back to the same location that you started shooting. Just use the same amount of images for every stack and then compile the stacked images in O2VR. I've done 3 frames of a 36-image stack using a Nikon Pb-6 bellows and it works well enough but man was it ever time consuming.

And just to throw this out there, the insurance documenting that I have done was happy enough with a still photo or two, not a full web presentation.

[PanoMapper]

Thanks for the reply, Pat.

The table is actually a Nodal Ninja, placed on top of a Seitz Roundshot, so from that point of view, I think things are all OK. Well, I would damned well hope so.

The problem, I have found is with the stacking. I have been using Helius and ControlMyNikon stacking remote (the Helius one is buggy and, although they have released a newer version in the last couple of days, I have yet to try it out). ControlMyNikon is also buggy and inconsistent with the return image, resulting in the lens returning to a slightly different position each time. This of course affects the overall dimensions of the final image.

The full-sized presentation is moot at the moment, since I am trying my best to find a way forward with something that I thought would be similar to taking a normal 360x180 . . . How wrong that was! It comes with its own sets of problems, and each presents another dimension to the learning curve: lighting, degrees of rotation, stacking, aperture and the like.

So still in the early days, and possibly something I would not have attempted but for the need to eat!

Thanks again,

Jon