I bought the QHY5
for autoguiding my astrophotos, but since it is also
capable of capturing images of brighter astronomical objects,
I gave it a try as a camera for lunar imaging. A few weeks
ago our association (VAA)
bought a Imaging Source DMK21
camera especially for lunar and planetary imaging.
As I currently have both cameras at my home, I thought
it might be interesting to do a comparison between the
The Astro-Professional 80ED on my Super-Polaris mount.
I used a Vixen 2x Barlow lens and two extension tubes
to increase the focal length of the telescope.
||1/10000 to 30 s
||1/1000s to 5s (using QGVideo)
|Region of Interest
||M48 (T2), 1¼"
||50,6 x 50,6 x 50mm
||64mm Ø 26.5-32mm length
My experiences with the QHY5 are a little bit mixed,
it works great as a guidecam, and even though I am using
a 60mm achromatic refractor as a guidescope, I never had
to search for a guidestar, but was always able to find
one with 1 or 2 seconds of exposure.
For lunar imaging, I ran into the issue that on exposures
shorter than 85ms the lower part of the image appears
brighter than the rest on some of the images. Because
it is more difficult to sort out individual frames from
an avi file, than just brows through a folder with thumbnails
to delete / deselect the brightened images, I always capture
individual bmp images instead of recording an avi. (see:
A few percent of the images taken with the QHY5 show
such a defect in the form of a bright part of the
image. This happens only with exposure times below
A single bmp from the qhy5 is more than 3MB big, so you
eat up a lot of harddisk space in an imaging session.
Since Registax crashed when I tried to process 500 images
in one batch, I limit the files per image to 300. With
the DMK21 1000 frames result in an avi file that is about
300MB. But of course the field of view of the DMK is pretty
limited (see images at the bottom). If you want to cover
a bigger area, you have to create a mosaic.
I have seen both Registax and Avistack crash when processing
images from the QHY5.
I use QGVideo which came with the camera (I bought a
used one), since the HDCAP software apparently uses a
driver which is not compatible with the autoguiding programs
(I use PHDGuide). I spent an evening trying out the different
software drivers and had to manually edit the registry
to get rid of them...
The images below have all been taken with an Astro-Professional
80mm ED Doublet refractor.
A Vixen 2x Barlow lens and two extension tubes were used
to increase the focal length to get a useful image scale.
This is 200% enlarged crop, move the mouse over the image
to compare the cameras.
The image from the DMK camera was rotated and enlarged
to show the same area as the crop from the QHY5 camera.
Move the mouse cursor over the image to compare
The image taken with the QHY5 shows some patterned noise,
which is absent from the DMK21 image.
One Big advantage of the QHY5 is the bigger chip area,
compare the two shots below to get a feeling of how much
bigger it is: