sscnxy wrote:
Hi Sippyjug. Thanks for teaching us the technical points to do your type of impressive macro. I have 3 questions:
What type of measurement device or method do you use to measure the location of the closest focus point and then the location of the farthest focus point in order to calculate the distance between the 2 points?
How do you determine the DOF width once you have set up your lens at the end of your bellows or a focusing helicoid to achieve the target magnification?
Do you know of an inexpensive focus stacking program to stack 400 photos?
Once again, your input is much appreciated.
NY
Hi Sippyjug. Thanks for teaching us the technical... (
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SSCNXY, thanks for asking about what I do and how I do it for I truly enjoy sharing it.
I find the closest and the farthest points of the subject, like the tip of a close hair as the closest and the back ridge of the top of its head for example as the farthest points of where my images will start and stop. I use a mirrorless camera and I watch the "blinkies" as I advance the camera from the closest point while I move it toward the farthest (endpoint for the series of shots). The attached photo shows what the starting point looks like where only the tip of the hair on the closest spider's leg is in focus.
The depth of field (DOF) is best found by the technical info of the lens....if we are lucky enough to find it and when using extensions such as a helicoid, extension tube, or bellows that info is no longer valid. Now, reversing the lens adds even more "off the published chart".
So.....to measure the resultant DOF we need to know two things. The f/stop and the amount of magnification we have accomplished with our rig is easy to measure using a scale marked in millimeters and viewing how many we see through the lens and then by knowing the size of our sensor be it full or crop.
See my past post on how to measure the amount of magnification you are getting with your setup.
https://www.uglyhedgehog.com/t-679798-1.htmlThe formula DOF = (0.0022*N*N*(m+1)*(m+1))/(m*m) , where N is the F-number and m is magnification. For example: f/stop-number 5.6 and magnification 0.50 computes as:
DOF = (0.0022*5.6*5.6*(0.50+1)*(0.50+1))/(0.50*0.50) = 0.6209 millimeters
So...in that case, we know where the first shot is taken and how far the camera must move to get to the last shot so we divide that travel distance by the DOF, and THAT gives us the number of shots to be taken at every 0.6209 millimeters that the camera moves forward in this example.
IF...you were to buy a dedicated focus stacking software...I STRONGLY recommend Zerene Stacker for the reason that it is created by Rick Littlefield who lives in the U.S. and he lives and breathes macro photography and he makes himself available to answer any questions and solve any problems you may have in addition to him giving advice as a mentor. Helicon Focus is highly comparable however it is written off-shore and there is no person-to-person support or mentoring. It is very good and well-liked by many. I just like to have the "local feel" and to be able to speak to the fellow that created the program who knows it best.
By the way, I've done stacks that were well over 1,000 images and I racked up over 250,000 shots on my Nikon D810 before switching over to a little mirrorless Fujifilm with an electronic shutter so as not to wear it out.