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[OM] Re: (OM) Choice of digital camera

Subject: [OM] Re: (OM) Choice of digital camera
From: Moose <olymoose@xxxxxxxxxxxxxxx>
Date: Thu, 27 Jan 2005 23:05:50 -0800
Brian Swale wrote:

>I  plan to mount my new digital camera on my microscope a lot more often 
>than I do with my film camera.  Although I have had a few photographs 
>published over the years 99.99% of the time my work is used in slide 
>presentations.
>
>To date my 35mm slides have clearly out-performed almost every power point
>presentation they have been compared with.  Alas most scientific meetings
>will not accommodate my old technology.  Given that I can not afford a
>pro-DSLR, should I go for a 6 MP DSLR or opt for a 7 or 8 MP point-n-shoot?
>
I would almost certainly go with a DSLR and 6 mp will be much higher in 
resolution than the capability of the display system. My key reason is 
the intended microscope use. Unless I could confirm for sure that a 
digicam under consideration could accurately and consistently auto-focus 
through the microscope, there would be the possibility of not being able 
to accurately focus. The EVF and LCD finders on these cameras are not 
usable as critical focusing devices. The also lack the dynamic range of 
DSLR finders, which may or may not be an issue through a microscope.

There is, however, a potential problem with the DSLR and a microscope. 
Anyone used to a good SLR viewfinder on a 35mm film camera will likely 
be dismayed with the viewfinders on the small sensor DSLRs. Because the 
image the lens projects on the sensor is smaller than a 35 mm frame, the 
view through the finder is necessarily some combination of smaller and 
dimmer than on a full frame SLR, digital or film. Some makers have 
equivalents of the Varimagni finder to aid in focusing through 
magnification of the image. Also only 1 or 2 of the DSLRs offer focus 
confirmation with manual focus lenses, which is what a microscope would 
be in this usage. So they would go to the top of the list. I'm pretty 
sure Nik*n is one, and maybe Pent*x??

The autofocus issue is quite different with DSLR than digicam. A digicam 
must use its permanently attached lens to do the focusing on its sensor. 
So I presume one must manually focus the microscope at least close, then 
let the camera capture and focus that intermediate image. With a DSLR, 
one just attaches it directly to the microscope with the microscope 
objective as the only lens*. Thus DSLR that can confirm focus for any 
image on its sensor, regardless of source seems the likely best choice. 
Just adjust the microscope focus 'til you hear the beep and shoot.

There must be lots of folks doing this. What are they using successfully?

>Is there any gain from anti-shake technology if my subjects are trees?
>
Theoretically, but not really at the shutter speed and focal lengths 
specified. If 1/125 with 50mm lens works for your film camera, it will 
work just as well with a digital.

Moose

* Or does the eyepiece lens have to be left in too? I can't remember, 
but it doesn't matter for the point at hand.



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