Figure 5.5 The range of field coverage by different eyepieces is very wide.
Left
: The low cost ‘WF’ x5
eyepiece from Ali Express only uses 0.58 MP of the full 5 MP frame.
Middle
: The OptArc x10/20 WF
eyepiece fills almost the full height of the frame and uses 2.48 MP of the available 5MP.
Right
: The
Celestron astronomical eyepiece has the widest field of view of all those tested – so wide that it overspills
the vertical aspects of the frame of the camera to use 3.88 MP of the available 5 MP at the expense of not
showing the full field of view. For some uses this will be preferable (e.g. if you want to crop the field of view
to a full rectangle). Of these three, only the OptArc eyepiece will be useable with the standard eyepiece
clamp that comes with the AF51 camera and the Celestron eyepiece will also need a custom adapter to fit it
to the microscope (most biological microscopes do not use a 1.25 inch barrel). Details of field of view usage
by the other eyepieces tested are given in table 5.1
Adjusting on an eyepiece to get a good image
Preliminary steps and aims
The first thing to do is ensure the microscope is on and, looking down the scope by eye
using the eyepiece you intend to use for photography, you see the whole field of view of
the scope is evenly illuminated and you can see a specimen in focus.
Next ensure the camera is on and you can see a live image preview (the MJPEG image
stream setting is useful for this purpose because it will usually give a high frame rate
regardless of the resolution). Ensure that auto focus is OFF and that the manual focus is
set to infinity (the default value of 68 should suffice for that).
Now slip the camera over the eyepiece so that the eyepiece is fitted into the clamp of the
AF51 (as described in chapter 3 in the section ‘Eyepieces clamp’).
At this point you will either see no image, a partial round field of view or the whole image
field of view. You will most likely need to perform some centration adjustments before
tightening the clamp screws in order to see an image (at all) and to get the best quality
image. These adjustments are necessary to align the optical axis of the scope with the
OptArc AF51 Camera Page 56 of 99 User Guide v1.02