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Camera best suited to Video Astronomy (not for imaging/A.P)

dob EAA
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#1 FourOwls

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Posted 18 February 2019 - 05:19 PM

Hi all!

 

I wanted to ask kindly for advice on a camera for video astronomy (not planning to do imaging or astrophotography). I have a F4.7 GOTO Dobsonian which for shorter exposure video is fine (others I know use them for this). As I don't need long exposure etc I am asking for cameras that do this short exposure 'live/real time' observing well. I am in a light polluted area, in suburbia not the city but still plenty of L.P and wondering about something for DSO, which I assume would easily be able to do planets too. I have about $1000 max just on the camera and have some recommendations such as the GStar Ex.3, ZWO ASI174 (mono) ZWO224....

 

Thanks in advance!!! undecided.gif



#2 OleCuss

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Posted 18 February 2019 - 07:34 PM

Judging from your previous posts, you appear to have a heavily light-polluted sky.

 

You are also getting a telescope which will be heavily impacted by peripheral coma/curvature.  I believe it will also have a focal length of 1200mm.

 

I believe you also indicated you might be OK with monochrome.

 

One thing which we are missing is how you wish to view.

 

If you plan to use a large screen with high definition and then view from up close you will likely be preferring a camera with a lot of pixels.  Since you have no ambitions to do Conventional AP I'd be recommending an ASI294 or the equivalent from QHY.

 

These particular IMX294 cameras will have great compatibility with SharpCap and will give you a relatively generous FOV (bigger than that of other IMX294 cameras).  If your ambient temperatures are not too high then you can confidently get an un-cooled camera and expect to get results about as good as if you had a cooler.  If you get a coma corrector then you can get that generous FOV with very little to no aberration.  If you choose not to get the coma corrector and are bothered by the peripheral aberrations you can define a smaller portion of the camera's sensor as your ROI and simple not acquire the aberrated portion of the collected light.

 

Note that with the IMX294 cameras you will be mildly under-sampled under the kinds of skies most of us expect.  However, given that your mount is not all that good that bit of under-sampling is likely to be swamped by tracking errors and just won't matter.

 

A big bonus is that the IMX294 cameras have a very, very good SNR1 along with very good dynamic range.

 

Another option which I do not like for you quite as much because we don't really know how its SNR1 compares to that of the IMX294 cameras would be one of the IMX183 cameras.  This sensor is smaller but has a great QE and low noise so it just might have a better SNR1 than does the IMX294 or the IMX385, but Sony hasn't tested and published so we don't know.  If one goes with the monochrome version I'm really betting that the SNR1 is better and that can matter in bad light pollution but I'll touch on that more in the next paragraph. . .  The smaller IMX183's smaller sensor means that your FOV will be smaller and also means you are less likely to see the aberrations because of the smaller FOV.  Under typical skies it will also be over-sampled with your system which will mean a little more read noise in your images, but only a little more because it is not a noisy system.  Dynamic range is not as good as with the IMX294.

 

But, under very heavy light pollution the cure can sometimes require going to narrowband imaging.  This means you are not bothered by almost any ambient light (including the Lunar searchlight).  In the past this was not a great option for those of us doing OAP but we now have narrowband filters which allow just the most important wavelengths of light to be gathered.  This means you can use a camera with a great SNR along with something like OPT Corp's Triad Ultra and do multi-wavelength narrowband imaging in some of the worst of light pollution.  For this purpose it seems to me that the ASI183 would be a very good choice - but note that the upgraded Triad is very expensive!

 

Overall I really think that if you got the IMX294 camera from either QHY or from ZWO you are likely to be happiest.  Get a decent coma corrector and if it is not good enough then consider seeing if a Paracorr would work and save up for that.

 

If you want a little more security in your camera purchase, get a cooled version.  OAP and CAP are not really distinct disciplines and it is not at all uncommon to find someone who started out intending to do only OAP and then finding that they wanted to do some images with longer sub-exposures where the cooling can be very helpful.

 

One other thing?  Budget for some magnets.  The camera adds weight to one end and you can use the magnet(s) to balance your OTA.  Orion sells some magnets designed for use with Dobsonians but people use everything from welding magnets to whatever.  Personally, I've a bunch of smaller magnets which are coated with silicon or rubber so they cannot scratch the paint on the OTA.  The Orion Dobsonian magnets have felt or something to keep from scratching.


Edited by OleCuss, 18 February 2019 - 07:36 PM.


#3 WarrenK

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Posted 19 February 2019 - 03:37 PM

OleCuss, I’ve read some positive comments on CN about using Micro FourThirds cameras for video EAA astronomy, such as a Panasonic GH4, connected to an iPad for display. Would be interested in your views on this as an alternative for the OP. 

 

Thanks. 

Warren



#4 OleCuss

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Posted 19 February 2019 - 05:20 PM

OleCuss, I’ve read some positive comments on CN about using Micro FourThirds cameras for video EAA astronomy, such as a Panasonic GH4, connected to an iPad for display. Would be interested in your views on this as an alternative for the OP. 

 

Thanks. 

Warren

I just don't know enough about the typical Micro 4/3rds cameras built for the typical consumer.  They are, indeed, more likely to be able to achieve prime focus with OTAs not intended for use for AP than would be the case with a DSLR but otherwise I just don't know enough of their capabilities.

 

However, I'd note that we have very capable astronomical cameras using the IMX294 and MN34230 sensors - both of which I believe are classified as 4/3rds sensors.


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