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Most suitable camera for Celestron 127SLT Mak?

Beginner Celestron CMOS Maksutov Cassegrain
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#1 fender90

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Posted 22 October 2021 - 08:57 PM

Hi everyone!

 

So I recently bought a Celestron Nexstar 127SLT Mak telescope to do my first steps in astrophotography. 

It is a 1500mm f11.8 scope. Unfortunately I rushed with my decision on which camera to buy, and I went with a Svbony sv205 without doing a proper research and math.

The camera has several problems. Besides having a terrible green circle in the middle and purple vignetting (changing hue saturation or white balance doesn't help) it also disconnects randomly.

 

Now I plan to upgrade to a proper camera and came to these 2 options

ZWO ASI224MC or ZWO ASI462MC

 

If I am correct generally it is considered that for an average to good seeing you should push focal ratio of 5 times camera’s pixel size.

 

ZWO ASI224MC has a pixel size of 3.75µm so 5x3.75= f18.75

ZWO ASI462MC has a pixel size of 2.9µm so 5x2.9= f14.5

 

Using Barlow lenses will give me these results.

1.5x Barlow: 1.5 x 11.8 = F/17.7

2x Barlow: 2 x 11.8 = F/23.6

 

So which camera would be more suitable for my scope for planetary imaging in terms of details and image clarity?

 

Also I know that 11.8 is quite slow for DSO, but will using a 0.5 reducer to get f5.9 be enough to get started?

(I will not use the ASI224 or 462 for DSO smile.gif )

 

I would really appreciate your advice.

Thanks.


Edited by fender90, 22 October 2021 - 09:04 PM.


#2 YossiZ

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Posted 23 October 2021 - 07:00 AM

Hello,

 

I have a similar scope (SW 150mm Mak) and use it with ASI178MC for both planetary imaging (no barlow) and DSO EAA (SCT f/6.3 reducer) with satisfying results.

 

20211023_145557.png

 

20211023_145844.png

 

Light Stack 23frames ASILive 45sec Bin1 30.1C gain270 2021 09 01 233547
Album: EAA 2021
26 images
0 comments

 


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#3 sevenofnine

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Posted 23 October 2021 - 12:31 PM

Welcome to C/N! welcome.gif I am not an imager but I've started reading this book that was recommended by another member. It seems quite thorough and will likely lead to less mistakes. The Deep-Sky Imaging Primer (2nd ed) by Charles Bracken. I'd be thrilled to get YossiZ's results wouldn't you? jump.gif


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#4 fender90

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Posted 24 October 2021 - 06:02 AM

Hi sevenofnine, YossiZ.

Thank you for your replies.

I did a bit more research and also checked CCD Suitability tool from Astronomy Tools and decided to go with ASI224 for the time being.

 

224.png

 

224 offers the largest pixel size thus leading with the less oversampling than 462 with my 127SLT

 

When using 2x2 binning it is possible to get in the perfect spot in terms of sampling.

 

224binning.png

 

I have no Idea if using binning in combination with barlow is a good idea but the 224 still would allow me to use a 1.5x barlow without oversampling much

 

224bin1.5bar.png

 

 

Meanwhile 462s smaller pixel size means that I will be deep in the blue zone

 

462.png

 

 

I still have doubts if I am choosing wisely, so let's keep the thread alive so that other people with the same questions will be able to get some info.

I will also post my test results in this thread. if anyone owns a scope with similar specs and a 462, posting your results in the thread would be much appreciated.

 

Thanks!

 



#5 Tulloch

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Posted 24 October 2021 - 06:21 AM

The tools you used to determine optimum focal ratio are not applicable for planetary, you had it right the first time.

 

Use a barlow and aim for a focal ratio around 5x the pixel size of the camera.

 

Andrew



#6 fender90

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Posted 24 October 2021 - 03:47 PM

The tools you used to determine optimum focal ratio are not applicable for planetary, you had it right the first time.

 

Use a barlow and aim for a focal ratio around 5x the pixel size of the camera.

 

Andrew

Thank you Andrew.

Is my assumption correct that since the aperture of my scope is only 127mm it is more preferable to get a camera with larger pixels to gather more light for a brighter image? 

 

My scope has focal length of 1500mm/127 = f11.8

with 1.5 barlow I will get 2250mm / 127 = f17.7

with 2x barlow 3000/127 = f23.6

 

With ASI224MC the focal length will be f18.75

With ASI462 the focal length will be f14.5

 

Do I get it right that with 224 I can still use a 1.5 Barlow in case of excellent seeing condition but not with 462?



#7 Tulloch

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Posted 24 October 2021 - 08:30 PM

Is my assumption correct that since the aperture of my scope is only 127mm it is more preferable to get a camera with larger pixels to gather more light for a brighter image? 

No, the idea is that you should try to match the focal ratio with pixel size - aperture doesn't matter for light gathering purposes. A larger aperture will give you more detail on the planet however, so a larger aperture is always preferred.

 

 

My scope has focal length of 1500mm/127 = f11.8

with 1.5 barlow I will get 2250mm / 127 = f17.7

with 2x barlow 3000/127 = f23.6

 

With ASI224MC the focal length will be f18.75

With ASI462 the focal length will be f14.5

 

Do I get it right that with 224 I can still use a 1.5 Barlow in case of excellent seeing condition but not with 462?

Yes, that's correct. As to which camera to use, I'd probably recommend the 462 over the 224, it's more sensitive but the colour balance is more problematic. I use a 224MC and am very happy with it, it's only flaw is that the sensor size is very small, but so is the 462. 

 

If you have a bit more cash to spend, I'd probably recommend the 485MC (just released) or even the 385MC which is basically a 224MC on a bigger chip. 1.5x barlows are not easy to find, but you might be able to unscrew the front element off a 2x and screw it onto the camera nosepiece for a lower magnification.

 

Andrew



#8 laserjet

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Posted 29 October 2021 - 08:44 AM

Hello,

 

I have a similar scope (SW 150mm Mak) and use it with ASI178MC for both planetary imaging (no barlow) and DSO EAA (SCT f/6.3 reducer) with satisfying results.

 

attachicon.gif20211023_145557.png

 

attachicon.gif20211023_145844.png

 

Seems that I was Imaging Jupiter at the exact same moment !

 

Just for reference, I was using the 127SLT mak with asi120mc and 2x Barlow for this capture.

 

 

pJXtmhx.png


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