Posts Tagged ‘ommatidia’

Macromia illinoiensis exuvia (face-head) redux

May 22, 2020

A Swift River Cruiser dragonfly (Macromia illinoiensis) exuvia was collected, with permission from park staff, on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA.

The preceding image shows the remnant ommatidia clearly.

From this viewpoint, it’s harder to see the prominent horn on the face that is a key field mark for larvae/exuviae in the Family Macromiidae (Cruisers). The base of the triangular horn is located above the labium (face mask), between the long, thin antennae; the apex of the triangle is pointed toward the viewer.

It’s easier to see the horn in the featured photo in my last blog post.

Tech Tips

The subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.

20 photos of the specimen were taken using 2.5x magnification at an aperture of f/4; in-camera focus peaking was used to highlight select areas in each photo. RAW FILE CONVERTER EX 3.0 was used to convert Fujifilm RAF files to TIFF files. Adobe Photoshop CC 2017 was used to create a focus-stacked composite image that was edited using Apple Aperture.

Copyright © 2020 Walter Sanford. All rights reserved.

Quick and dirty macro photos (Part 1)

October 27, 2017

Several Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted on 25 October 2017 during a photowalk along the boardwalk in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA. All of these individuals are male.

The photographs in this gallery were taken using my Panasonic Lumix DMC-FZ150 superzoom digital camera set for ~12x zoom, Raynox DCR-250 close-up filter, and Canon 580EX Speedlite external flash (manual mode). I estimate the “working distance” between the camera and subject was approximately three-to-six inches (~3-6″). Now that’s what I call cooperative models!

ISO 100 | 56mm (~300mm, 35mm equivalent) | f/4.1 | 1/800s | -1 ev

The following photo is my favorite in the set.

ISO 100 | 56mm (~300mm, 35mm equivalent) | f/4.1 | 1/800s | -1 ev

Each compound eye has approximately 30,000 ommatidia!

ISO 100 | 56mm (~300mm, 35mm equivalent) | f/4.1 | 1/800s | -1 ev

The Raynox DCR-250 close-up filter is a relatively inexpensive solution that enables my Panasonic superzoom digital camera to be used for macro photography. Set-up is quick and easy — the filter simply screws onto the front of the camera lens using a 52-43mm step-down ring.

As you can see, depth-of-field is very shallow, caused in part by shooting in Shutter Priority mode rather than Aperture Priority. A cooperative subject, good light, and a lot of patience are essential for success.

Related Resource: Quick and dirty macro photos (Part 2), a blog post by Walter Sanford featuring photos of a mating pair of Autumn Meadowhawk dragonflies (in wheel).

Copyright © 2017 Walter Sanford. All rights reserved.


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