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Budget planetary camera?

BlueMoon23

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BlueMoon23

BlueMoon23

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Hi everyone,

I have a Skywatcher Evostar 120 (EQ5 mount) and a solar filter and am interested in imaging the Sun. I need help deciding on what camera to buy as this is a new field for me. I don't want to spend more than £150 but do not want to buy a cheap one only to find it does not do the job.

Any advice would be much appreciated.

BlueMoon23

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JamesF

JamesF

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Well, the issue you're going to run into fairly quickly is that the focal length of the Evostar 120 gives an image at the focal plane just over 9mm across.  That means you have a few options.  First is to get a camera with a sensor that big.  Second is making mosaics.  Assuming of course you're after a full disc image.  I'm not sure you'll find an astro camera with a sensor that big in your price range and quite possibly you'll not get anything large enough to leave you needing less than perhaps a dozen panels for a mosaic.

A DSLR such as, say, the Canon 1100D would get the entire disc on the sensor in a single frame and certainly works for DSO astrophotography though it's not really going to match up to a dedicated CCD so if you already had one it might well be a good option to try.  You'd just need suitable T-ring connectors to mate up with whatever the telescope focuser offers and if you want, some software to control the camera from a PC (which can be had for free or relatively little cash depending on your needs).

Would I buy a DSLR for this purpose if I didn't already have one though?  Hmmm.  Not sure.  Perhaps others may have some better ideas.  The QHY5L-II colour is regularly offered (new) on ebay for £140-ish, for example.  It would still need mosaics, but I have no experience using it for solar imaging so I can't really comment on its suitability.

James

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Laurie61

Laurie61

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Hi, thinking along the same lines as James you could also try Afocal imaging if you have a compact camera. The usb ZWO cameras were proving popular and there is one in your price range http://www.365astronomy.com/ZWO-ASI034MC-Colour-1-4-CMOS-USB2.0-Camera.html.

You can get inexpensive .5 focal reducers that may help getting more of the Sun on a smaller chip.  

http://www.telescopehouse.com/acatalog/Revelation-0.5x-Focal-Reducer-1.25-.html

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BlueMoon23

BlueMoon23

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Thanks for all your replies so far :)

Firstly:

It depends if you want to do full disk solar imaging or sunspots...

I'm more interested in detail (sunspots) so I don't need the camera to image the whole of the Sun. I have a variety of eyepieces so finding the Sun is not a problem and I can then centre the sunspots for imaging.

Hi, thinking along the same lines as James you could also try Afocal imaging if you have a compact camera. The usb ZWO cameras were proving popular and there is one in your price range http://www.365astronomy.com/ZWO-ASI034MC-Colour-1-4-CMOS-USB2.0-Camera.html.

You can get inexpensive .5 focal reducers that may help getting more of the Sun on a smaller chip.  

http://www.telescopehouse.com/acatalog/Revelation-0.5x-Focal-Reducer-1.25-.html

So is the ZWO able to take a movie that I could then use with something like RegiStax?

Well, the issue you're going to run into fairly quickly is that the focal length of the Evostar 120 gives an image at the focal plane just over 9mm across.  That means you have a few options.  First is to get a camera with a sensor that big.  Second is making mosaics.  Assuming of course you're after a full disc image.  I'm not sure you'll find an astro camera with a sensor that big in your price range and quite possibly you'll not get anything large enough to leave you needing less than perhaps a dozen panels for a mosaic.

How exactly is this done (making mosaics) and would the ZWO camera Laurie suggested be suitable for this?

Thanks again,

BlueMoon

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JamesF

JamesF

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With mosaics you go through the same process as for single frame images, but create lots of overlapping images of a larger object, then use some software to stitch them all together into a larger image based on their overlapping areas.  I use Photoshop for that but there is other software that does the same thing.  It's like making a panorama of lots of different overlapping photographs.  Depending on the camera you may only need to do this if you want a full disc image.

If you're specifically interested in imaging sunspots then I might also be tempted to look out for something like an ASI120MM or QHY5L-II mono on the used market.  They have a slightly larger sensor, good sensitivity and used would probably be in the right kind of price bracket.  As they're mono cameras they also have better resolution than colour models.  You might also use these cameras in the future as a guide camera should you need one.

James

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BlueMoon23

BlueMoon23

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Sorry if this sounds like a stupid question: would a ASI120MM, QHY5L-II mono or Celestron NexImage need a focal reducer?

There's currently a Celestron NexImage 5MP on astrobuyandsell for £139 - what I found after a quick look round. Is this a good option?

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JamesF

JamesF

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Sorry if this sounds like a stupid question: would a ASI120MM, QHY5L-II mono or Celestron NexImage need a focal reducer?

There's currently a Celestron NexImage 5MP on astrobuyandsell for £139 - what I found after a quick look round. Is this a good option?

Whether or not you'd need a focal reducer depends on how large the target is.  In the general case for sunspots I'd not expect that you'd generally need one with those cameras.  If the target spot was a bit large you'd probably only need a two-pane mosaic which is fairly manageable.  It's when you get in to tens of panes that it all gets a bit hairy.

Don't really know much about the Neximage 5MP.  My recollection is that the frame rate is quite slow.  It may be that for this sort of imaging the "Burst" model would be a better choice, but I'm not speaking from experience here.

James

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Laurie61

Laurie61

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Thanks for all your replies so far :)

So is the ZWO able to take a movie that I could then use with something like RegiStax?

Thanks again,

BlueMoon

Yes, the ZWO and similar cameras can take a movie which is then processed in Registax or other image grading and stacking software.  http://firecapture.wonderplanets.de/ 

http://www.autostakkert.com/

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