Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 122 (8774 total)
Current session began: 
Page Loaded: 07-24-2017 4:45 AM
359 online now:
CRR, Dr Jack, Heathen, PaulK, Pressie (5 members, 354 visitors)
Chatting now:  Chat room empty
Newest Member: Tom Larkin
Post Volume:
Total: 814,489 Year: 19,095/21,208 Month: 1,854/3,111 Week: 75/574 Day: 7/68 Hour: 1/3

Announcements: Reporting debate problems OR discussing moderation actions/inactions


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev123
4
Author Topic:   Decisions, decisions......
Tanypteryx
Member
Posts: 1514
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 4.9


Message 46 of 48 (808819)
05-13-2017 11:27 AM
Reply to: Message 45 by NosyNed
05-12-2017 10:09 PM


Re: Focus Stacking
I am under the impression that you use some sort of rail to little tiny bit by little tiny bit move the camera to change the plane of focus.

Yes, I use a device called a Stack Shot, made by an outfit called Cognisys. It has a stepper motor that can very precisely move the camera in steps down to 1 micron.

STACKSHOT - AUTOMATED MACRO RAIL FOR FOCUS STACKING

But it seems to me that would change the magnification of some part of the subject as you moved closer to it. If that is the case how can software assemble that into a correct image?

Yes that is true and in the early days when I started experimenting with this technique the software was quite limited. It took a lot of post processing to get a decent image. The limitations were pretty frustrating.

Another frustrated stacker, who is a math wizard and a programmer started creating a program to address all of the problems encountered in processing stacks. I was one of his beta testers and he created an absolutely amazing program that has been very successful. The program, Zerene Stacker, aligns and resizes all the images in the stack and then builds a composite.

Some subjects will always have problem areas that the program cannot decide how to process. Specimens where there is spatial separation between features, for example head features with antennae above and legs below. The features would be sharp in different sections of the stack and an affect called diffraction allows you to see features that are directly below those that are out of focus.

Zerene has a very useful retouching tool that lets you paint from any layer in the stack to fix stacking flaws. It also has a module that lets you control the Stack Shot including setting the step size.

At high magnification depth of field is extremely shallow, so some of my stacks take 500 or more separate images to show the features I want.

As with all photography lighting is the key. Very small subject introduce their own issues with lighting. Most of us use various diffusion and reflector materials to avoid blown highlights and shadows with no details. Some people use continuous light sources, but I prefer electronic flash.

Edited by Tanypteryx, : No reason given.

Edited by Tanypteryx, : No reason given.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


This message is a reply to:
 Message 45 by NosyNed, posted 05-12-2017 10:09 PM NosyNed has not yet responded

    
Tanypteryx
Member
Posts: 1514
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 4.9


Message 47 of 48 (809834)
05-21-2017 1:27 PM


This is the head and thorax of a male Chironomid midge, species ID unknown.

This stacked composite is my first tests of some new electronic flashes. I fried 2 of my old standby Nikon flahes so had to get some cheapie replacements.

The composite took 350 stacked images. Shot through my Mitutoyo 10x objective.

I wonder what sorts of molecules these antennae evolved to detect? The females do not have all the fine setae (hairs) on their antennae and normally in cases like this the females produce pheromones that the males can detect and track from long distances. The pheromones of some insect species are used in lures for sampling traps. A common one you may have seen is used in commercial Yellow Jacket traps.

This is probably the last stacked shot I will have time for before I leave on my road trip to Virginia. A new road trip


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


    
Tanypteryx
Member
Posts: 1514
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 4.9


(2)
Message 48 of 48 (815068)
07-15-2017 4:05 PM


This is a male Pachydiplax longipennis. I am trying to develop a technique to photograph dragonfly eyes that shows the optical effects of the individual ommatidia (facets). I can see this in normal photos but the high magnification extended depth of field shots show surface details but not the internal "glow" caused by the lens in each ommatidia.

Note that eyes are divided into 2 different sizes of ommatidia, larger on the upper eye and smaller looking down. It is thought that the smaller ones provide finer resolution eyesight. The upper ones provide keen enough eyesight to spot very small prey and I have seen dragonflies suddenly fly straight up to investigate other dragonflies that are so high that I could not see them unaided. Binoculars were necessary to see them at all.

Dragonflies not only have incredibly keen eyesight in almost every direction, but they can process the visual information at very high speed considering the acrobatic maneuvers during high velocity flight.

Enjoy.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy

The reason that we have the scientific method is because common sense isn't reliable. -- Taq


    
Prev123
4
Newer Topic | Older Topic
Jump to:


Copyright 2001-2015 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2017