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7 messages in edu.ku.nhm.mailman.taxacomdigital images| From | Sent On | Attachments |
|---|---|---|
| Timothy Rowe | Aug 22, 1995 12:52 pm | |
| Alan Harvey | Aug 23, 1995 9:25 am | |
| Peter Rauch | Aug 23, 1995 9:26 am | |
| Jim Manhart | Aug 23, 1995 9:26 am | |
| Joseph Laferriere | Aug 23, 1995 10:09 am | |
| Joseph Laferriere | Aug 23, 1995 1:27 pm | |
| Alan Harvey | Aug 23, 1995 2:56 pm |
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| Subject: | digital images | Actions... |
|---|---|---|
| From: | Jim Manhart (MANH...@BIO.TAMU.EDU) | |
| Date: | Aug 23, 1995 9:26:23 am | |
| List: | edu.ku.nhm.mailman.taxacom | |
Date: Wed, 23 Aug 1995 09:25:48 -0400 Reply-to: Alan Harvey <aharvey at AMNH.ORG> From: Alan Harvey <aharvey at AMNH.ORG> Subject: Re: digital images To: Multiple recipients of list TAXACOM <TAXACOM at CMSA.BERKELEY.EDU>
Timothy Rowe wrote:
Actually, depth of field is not a property of the recording medium (i.e., film vs. video); it depends on the lens that is in between the object and the medium. Aperture controls are not restricted to camera lenses; I have two video camera lenses with aperture controls, and I suspect this is standard. It is true that most microscopes, or at least dissecting scopes, do not have built-in aperture controls, but you can get video-microscope adapters (which you need anyways to attach the video camera to the scope) with this function, and they can dramatically increase the depth of field of a digital image (to make sure, I just tested this by capturing two images to a Macintosh using a Hitachi KP-M1U CCD camera attached to a Wild M-5 dissecting scope; on my Mac screen, the closed aperture image has a much greater depth of field than the open aperture image, as expected).
This is correct, we have been able to increase our depth of field on video images by increasing the light when using a automatic exposure camcorder fitted with a macro lens. The camera closes down the lens in response to the light and provides greater depth of field. This is obviously very important for macro subjects.
We do not get nearly the same resolution with a Hi-8mm video camera that can be obtained with 35mm film. However, I would expect that if you had a video system capable of 700 lines of resolution, it would be as high or higher than the resolution of any computer monitor. If you need higher resolution than that, you will have to stick with silver.
Jim Manhart, Dept. of Biology, Texas A&M University Manhart at bio.tamu.edu