QHY5L-II / new user / dust concern

QHY5L-II / new user / dust concern
« on: December 30, 2012, 04:58:18 pm »

I am making my first steps in astrophotography with a monochrome QHY5L-II purchased two weeks ago.
I am worried by several dust specks on images, of which I have not been able to get rid by air blowing nor by careful cleaning of the front camera window with distilled water. In fact these appear exactly the same after cleaning. One would think that the dust is behind the front window, on its back face or on the sensor itself, although everything looks pretty clean with a magnifier. Given that this is a brand new camera under warranty, I am not considering opening the chamber nor cleaning the inside myself. 

A few views are attached (Jupiter and Moon taken with C11 telescope showing one round black spot, and a view taken in grazing light without any optics which shows several specks, including the upper right one seen on the other pictures).

I know that this can be improved by making flats and processing the images, but was really not expecting to have to do that for straightforward planetary imaging.

Your advice and help will be much appreciated.

Best regards,


Re: QHY5L-II / new user / dust concern
« Reply #1 on: December 30, 2012, 05:41:30 pm »
Hi Philippe,
To judge by the sharp contours of the biggest two spots, I woud say it is durt on your sensor.
The only way to get rid of it is to open the chamber and try to remove it with air or a lenspen.
Using aceton may help when the dirt is really stuck on the sensor. Do not use alcohol or any other solvent,
because they leave a residu. Aceton evaporates totally.
Sooner or later you have to do this kind of thing anyway... we all do...

A lot of good stuff
and mostly bad weather

Re: QHY5L-II / new user / dust concern
« Reply #2 on: December 30, 2012, 07:14:31 pm »
Hi Waldemar,

Thanks a lot for your quick reply.
In the meantime I noticed that the ring holding the front window was loose and easy to remove, so went ahead and gave a few puffs of hand-blown air inside.
You are right, this nicely did the job. Images look very neat now. Eager to get the gear out and to have another go!