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TSRobot

Which cam

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furrysocks2    718
5 hours ago, TSRobot said:

...even smaller pixies...

Don't know if you've ran through the numbers or not for pixel scale and field of view - if you have, hopefully mine agree. Unless I've made a mistake, I think they look like this:

blob.png.ef2d826aac7497aafa413297cae07b95.png

While the 80mm with the shortest focal length gives you the widest field of view, it also has the smallest aperture and largest focal ratio.

The 290 and 224 differ in aspect ratio, so while the 290 gives a wider horizontal field of view (+16%), it also gives a reduced vertical field of view (-13%).

Other than those physical parameters, I have no idea how the two would compare.

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Robrj    98

I've read from more technical users that the order of sensitivity of the 290 and the 224 are as follows:

1. IMX290 Mono 

2. IMX224

3. IMX290 Color

So if you don't care about color and are more interested in picking up faint detail, get the IMX290 mono.  If you want a one shot color (OSC), get the IMX224.

I like the ZWO ASI224MC.  I picked one up recently as it was on sale for $250 which works out to about £186.  There is very little amp glow (purple fringing on the right edge) and what is there can be reduced with darks.  I have no experience with the Altair but from what I've read, it works fine natively with Sharpcap.

As for pixel size, it won't make a tremendous difference unless plan on doing planetary.  In a perfect world with no atmospheric interference, if you could get equal sensitivity for both cameras, an object like NGC 40, with your 80mm and the IMX224, you'll get an object that is about 24x24 pixels in size.  With the 80mm and the IMX290, you'll get an object about 30x30 pixels in size.  In this case, the IMX290M would be the best case (higher sensitivity and smaller pixels).  The IMX290C has less sensitivity than the IMX224.  You're probably seeing limited though.  You'll likely see fainter objects with the 290 mono as it doesn't have a bayer matrix but you may not see any difference in fine detail between the two chips when you zoom in due to seeing. 

I've attached a 24, 30, and 41 pixel image of NGC40 (about 38 arc seconds in width).  So assuming you could get the exact same sensitivity, you can see there's only a slight difference in the detail you would see.  With the 130, you'd see a 41 pixel image with the 290 and and the 30 pixel image with the IMX224.  Again, that's assuming your seeing would allow that level of detail.

24pixel.png

30pixels.png

41 pixels.png

Edited by Robrj
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TSRobot    43

OMG. The help received is unbelievably on the ball and helpful. The work you put into your answers is amazing me each time. Thank you. Though with all this help to hand i think to myself the best thing is to get a cheap, but well supported colour cam for some pretty pictures then when/if i crave more detail a mono cam. Does this make sense? Can't be wrong surely....:happy11:

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furrysocks2    718

Personally, I went mono.

Colour cameras have 1/4 red pixels, 1/4 blue pixels and 1/2 green pixels and the camera or software calculates the in-between values, kind of smears the colour values around to give you full colour everywhere. So consider capture of white light... first you lose light to each and every pixel through the bayer matrix on the sensor, then interpolation will make up information. Worse, if you used a Ha filter for example, you're only illuminating 1/4 of the pixels to start with. If you've only got a 2.0MP or 1.3MP sensor to begin with, I think every little helps. Mono will be more sensitive and possibly give you more fine detail.

Just thinking out loud. That's why I went mono, but promptly gave up. Should probably have spent more.

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furrysocks2    718

With the caveat that in an achromatic refractor, you're capturing all wavelengths and they may spread out a bit - light will land where it lands and you can't distinguish.

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London_David    23

Just to complicate things slightly.

ZWO has realeased the asi385 very recently. You can buy it direct from their website. This has very similar specs to the 224 but marginally better and about $150 more expensive. The main advantages are a slightly larger sensor and slightly lower read noise. I haven’t seen anything about the 385 and don’t own one — but there is a thread on cn about it. Thought I’d point it out in case you suddenly realise you’ve not seen all the options.

However, from what you’ve been saying I suspect the asi224 colour is your best camera pick. I love my 290 but unless you’re really into mono before you buy I suspect you’ll want colour. The 290 mono is better and more flexible and will give you more detail but... there is something quite fun about just seeing a colour image appear, especially if this is your first camera. Between the 385 and the 224 I’d say it just depends on your budget — they’ll both be good. 

Edited by London_David

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furrysocks2    718
5 minutes ago, London_David said:

ZWO has realeased the asi385 very recently.

Same 16:9 aspect ratio as the 290, and 3.75um pixels as the 224. 30% increase in FOV compared with the 290, and +50% (h), +12.5% (v) compared with the 224.

blob.png.216bcaf0bd26783b463db59ede86847a.png

 

Good luck, TSRobot... look forward to hearing of first light.

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TSRobot    43

No shopping at the moment. Bit cold out to start something new. Just found out i need a course of chemo too. Plans onhold for now. Thanks once again for all the help :icon_biggrin: 

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furrysocks2    718
4 hours ago, TSRobot said:

No shopping at the moment. Bit cold out to start something new. Just found out i need a course of chemo too. Plans onhold for now. Thanks once again for all the help :icon_biggrin: 

Sorry to hear that. Best wishes.

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shirva    257

Good luck with your treatment

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