Re: choosing a digital camera for collecting landmark data

[morphmet_moderator]

----- Forwarded message from "Novack-Gottshall, Philip M." -----

Date: Tue, 23 Oct 2012 12:24:15 -0400
From: "Novack-Gottshall, Philip M."
Reply-To: "Novack-Gottshall, Philip M."
Subject: Re: choosing a digital camera for collecting landmark data
To: "sfin...@tcd.ie"

Dear Sive,

I work with fossil invertebrates, which tend to be a bit easier to photograph and digitize because they're typically somewhat flattened and two-dimensional. But hopefully this will be useful for your specimens.

In my experience, any decent camera does fine. I've listed the various equipment I've used on my website: http://www1.ben.edu/faculty/pnovack-gottshall/PaleoDIMPL.html

Overall, the most important factors are to (1) use a scale bar, (2) understand your camera settings (especially the aperture-priority setting), and (3) use a camera/copy stand to keep your camera steady.

Use of a scale bar is always critical; without it, you're very limited in the kinds of analyses you can do (although some shape-based morphometrics are OK). But given it is so easy to include one in every photograph, there's no reason not to. Just make sure that the scale bar is positioned close to you specimen (i.e., not along the border of your field of view, where you can get aberations) and in the same vertical plane as your specimen (to prevent parallax-focus issues). You also want to make sure the scale bar is in focus.

I often use a macro lens to get get large images of small specimens. In these lenses, the focal depth is dramatically reduced. (This is true for regular lenses, too.) The key in both is to use the aperture-priority setting (sometimes with different names in different camera models.) The aperture setting (sometimes called an f-stop of f-number) allows you to change the focal depth of your images. (Large f-numbers, such as f/16 use a very small aperture but allow a "deep" field of view; small f-numbers, such as f/2 have larger apertures and shallow fields of view.) This is important so that parts of your specimen close to you are as much in focus as parts away from you. The downside of a large f-number is that it takes more time for your camera to compensate for the reduced light passing through the aperture, which means the shot takes longer. If you are holding the camera by hand, it's essentially impossible to get a well focused image because of the camera shake. So a camera/photo stand is critical. (Another downside is that some lenses produce less focused images at extreme f-numbers, so you'll need to play with your camera and set-up to find the optimal settings to get sharp images with  "deep" fields of view.)

Finally, although a photostand is large and cumbersome (and not something you'd expect to travel with), it is very helpful for trying different settings, playing with different lighting scenarios (another important factor that can be critical in making a "flat" image of a non-flat specimen look non-flat), and especially for getting sharp focus (whether using large f-numbers of not.) (Lighting is also important when playing with f-numbers because a brightly lit specimen can be blanched by too-much lighting, even if relatively dim, if the aperture is open for a few seconds.) Most museums have photostands available if you ask. They're a critical tool if you are serious about photographing specimens.

(As an aside, most copystands use incandescent lighting, which can get incredibly hot when turned on for a batch of specimens! The only copystand I've seen that uses non-incandescents is a rather pricey model by Bencher that uses flourescent, but is well worth the price, in my opinion. Although it's not a traveling model by any stretch.)

Finally, depending on the f-numbers you use, you might consider using a remote switch (or a computer program that speaks to the camera), which can allow you to "click" the camera to take the picture from a distance, further reducing the camera shake on the camera which is the enemy of a sharp focus.

Best wishes,
Phil

On 10/23/2012 12:27 AM, morphmet_modera...@morphometrics.org wrote:

----- Forwarded message from Sive Finlay -----

Date: Sun, 21 Oct 2012 10:17:26 -0400
From: Sive Finlay
Reply-To: Sive Finlay
Subject: choosing a digital camera for collecting landmark data
To: morphmet@morphometrics.org

Dear all,

I'm starting a new PhD project studying convergent evolution in Malagasy tenrecs (Tenrecidae). I want to compare morphological similarities among the skulls and limbs of tenrecs and convergent species (moles, shrews, hedgehogs etc.)

I'd be very grateful for advice on which cameras and/or lighting set up would be suitable for photographing museum specimens for later analysis using landmark data.

I'll be travelling to different museums so ideally I would like equipment which is easily portable and can be re-assembled to create consistent photographing conditions.

Any tips or advice on which equipment might be suitable would be much appreciated.

Thanks

Sive Finlay

sfin...@tcd.ie

--
Sive Finlay
IRC EMBARK Initiative Postgraduate Scholar 

Macroecology and Macroevolution Research Group

Zoology building

School of Natural Sciences
Trinity College Dublin

sfin...@tcd.ie

http://www.tcd.ie/Zoology/research/ncooper/people.php

----- End forwarded message -----

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Phil Novack-Gottshall
 Assistant Professor
 Department of Biological Sciences
 Benedictine University
 5700 College Road
 Lisle, IL 60532

 pnovack-gottsh...@ben.edu
 Phone: 630-829-6514
 Fax: 630-829-6547
 Office: 332 Birck Hall
 Lab: 107 Birck Hall
 http://www1.ben.edu/faculty/pnovack-gottshall
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

----- End forwarded message -----