Tag : qhy5

QHY5 vs DMK21 for Guiding

I have always used my QHY5 for guiding, most of the time attached to a Skywatcher 9×50 finderscope and it has worked quite well.

But while at Kelling Heath this year I purchased an Altair Astro 80mm guidescope. Did I need to? I don’t know, may be a 60mm would have been a good upgrade as opposed to going for the larger 80mm. But anyway, I have now started to realise that the original QHY5 does suffer from some image degradation in the form of banding. (I do already use simple dark frames with the QHY5 camera).

Now instead of purchasing a QHY5 II Mono, I have been thinking about using my DMK21 AU618 camera instead.

I know the DMK21 sensor is half the size of the QHY5, so finding a guide star may be harder – but I bet the quality of the image will be a lot better. Plus it would mean I would not need to purchase a new camera but use the DMK21 that I already own.

So on the next clear night I shall try out the DMK21 for autoguiding and see what happens and report back.

UPDATE: 11th November 2014

Well last night I went out and tried the DMK21 for guiding. It worked OK, in Maxim DL the guiding calibrated OK. But the actual guiding itself was not that smooth, certainly not as smooth as when I use the QHY5.

I don’t think the small sensor and field of view is a major problem, as I found lots of stars in the field of view. But it could be because the DMK21 is only 640×480 – the sensor is so small you can’t bin the camera, so it lacks the sensitivity that you can get with the QHY5 camera when you bin the images as it’s 1280×1024 pixels.

April 2011 Sunspots

As we have been having some nice summery weather in April, it gives us a great chance to get out in the garden and do some solar imaging.

I have recently had a major equipment change, and sold my LX200 (sad to see you go) and I now have an NEQ6 Pro mount instead, with my trusty Skywatcher ED80 Pro onboard.

Luckily there seems to be a good selection of sunspots now appearing. I tried imaging with a newly purchased QHY5 camera which I intend to use as a guide camera, but I thought I would give it a go on the Sun. It’s ok but not a patch on the DMK21 camera. I was struggling to get 10fps out of the QHY5.

Solar Sunspot 24th April 2011This image was taken with the Mono DMK21 with a UV/IR filter and Baader Solar Continuum filter through the ED80 Pro and I used some cheap Baader Solar Filter paper which was taped to the inside of my scope plastic cover. Even though this solar paper has a scratch in it and a big fingerprint on it, it still manages to produce some great images, at about only 1 inch across. The exposure time is very low in order to get the detail. I then open it up in Photoshop and add some false colour.

My only problem at the moment is that the DMK21 has a lot of ‘dust bunnies’ in it, and I really need to take flats next time to get rid of them. As at the moment I have to get rid of them in Photoshop.