best camera to use if you want to image subcellular organelles or study the detailed
morphology of chromosomes or bacteria.
Short eye-relief or narrow field eyepieces
It is not recommended to use the AF51 with eyepieces that have a narrower angle field of
view than the OptArc WF 10X/20 oculars. Attempting to use the AF51 with narrower field
of view eyepieces will result in a very small field of view image disc with wastage of much
of the sensor area thereby giving a relatively low resolution in the useable part of the
image. Chapter 5 gives details of the amount of sensor area used by the field of view for a
range of different eyepieces.
The eyepiece clamp that comes with the AF51 is designed to be used with eyepieces that
have long eye relief. Some older or cheaper modern eyepieces with a small diameter exit
lens and low eye relief will need a custom mount to be used with the AF51 (not supplied)
because the standard eyepiece clamp that comes with the AF51 will not allow a close
enough distance to be set between the camera and the eyepiece to see the full aperture.
This results in a very small field of view and excessive vignetting. See chapter 5 for more
details and measurements for various eyepieces.
Extreme low light level imaging
The AF51 is not recommended for extreme low light applications such as faint
bioluminescence, deep sky faint object astrophotography or low light level imaging of fast
moving objects.
This is because the AF51 uses its own lens with a small aperture and also because it
images down an eyepiece using afocal projection photography. This means there will be a
lot of lens elements between the light coming from the object and the CMOS sensor chip
and each of these absorb, reflect or otherwise restrict some of the available light. Also the
AF51 has a small CMOS sensor chip which limits its light gathering ability and does not
have active cooling so dark current noise will be more prominent.
Although the AF51 can be used for some low light level applications, it will be working at
maximum exposure times and gain and require multi-frame integration and multi-frame
averaging to get the best quality images at these low light levels. Therefore it will not be
able to image fast moving action without significant motion blur at low light levels. Colour
sensitivity will also be reduced at low light levels.
OptArc AF51 Camera Page 19 of 99 User Guide v1.02
