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TSRobot

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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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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

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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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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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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. 

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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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  • 4 months later...

Many apologies for resurrecting this thread. Chemo's done now for this round. 

Since i managed to source a reasonably priced GPcam1 color and a discounted WO ZS70ED. How would the AZGTI be to give me a stab at VA and some pretty pictures? Still only back yard in Coventry though. LP is quite high, but later i could travel to darkness.

Thanks

Tim

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  • 1 month later...

Hi. Finally had a long night using my GPcam 1 Color. I can't get live stack to work in Sharpcap. The message in red says they're aren't enough to alignment stars. I focussed on a bright star. And I'm using the 0.5 focal reducer, ZS70 f6 and azgti. Have tried all exposures from 40ms to 33 seconds and tried the gain up and down. Gave up after 2 hours ?

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3 minutes ago, TSRobot said:

Hi. Finally had a long night using my GPcam 1 Color. I can't get live stack to work in Sharpcap. The message in red says they're aren't enough to alignment stars. I focussed on a bright star. And I'm using the 0.5 focal reducer, ZS70 f6 and azgti. Have tried all exposures from 40ms to 33 seconds and tried the gain up and down. Gave up after 2 hours ?

Did you try reducing the star threshold for stars ( think min is 10) , plus increasing the noise reduction value in small amounts especially when using longer exposures as it takes time to work thru IMO. I use Sharpcap Pro so I am presuming you get the same features in "normal" sharpcap.  Keep persevering it will come ! 

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Is the "star threshold" the maximum number of stars used to make the alignment? This setting has a value of 10 or 15? I've found the noise reduction tool now under the alignment tab. At least this isn't boring. Only 12 hrs till it goes dark :happy11:

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I've used a GPCAM v1 colour for video astronomy in the past. Keep the gain at maximum when trying to stack with live stacking. I found exposures of 10-60 seconds good for deep space objects depending on their brightness. You have to make sure your focusing is accurate or you will have trouble with live stacking, its easy for you to be slightly out. When focusing on a bright star make sure your gain/exposure is low so the star is fairly faint. That way it isn't saturated and you can achieve a finer focus. You can enlarge the on screen image in Sharpcap. When focusing I enlarge it by 300-400%, if there is a small hole in the center of the star you're still out of focus.

With the live stack alignment settings it will take some experimentation to find what works best with your system. I generally go with something like this:

Noise Reduction: 2-3

Minimum Star Width: 3

Maximum Star Width: 32

Black Level Threshold: 50

Digital Gain: 2x - 4x

This is what works for me, but my set up is different. Hopefully it will get you started though. Clear Skies!

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Forget about clicking the Live Stack option until you have a live image on the screen which looks bright enough to see many stars as well as some details in the actual object. Don't worry about grainy noise in the image as thats what stacking fixes. Only when the live image is showing many stars and some bits of the object do you start stacking. Stacking will get rid of the noise. 

Isn't there a sticky on how to use SharpCap on SGL? Or am I thinking of Lodestar Live how to?

As other posters say ...bump the gain up to 300 to 360 and then adjust the exposure time to start to get stars n stuff. But you should also adjust the image gamma and contrast n stuff so its a learning curve/balancing act. We've all had to learn and overcome the learning curve. Then when you do click Live Stack you then have to adjust the histogram curve (in the stacking windows TAB's). Worth doing in the end though ;)   

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On 17/04/2018 at 16:02, TSRobot said:

Many apologies for resurrecting this thread. Chemo's done now for this round. 

Since i managed to source a reasonably priced GPcam1 color and a discounted WO ZS70ED. How would the AZGTI be to give me a stab at VA and some pretty pictures? Still only back yard in Coventry though. LP is quite high, but later i could travel to darkness.

Thanks

Tim

I've just bought the AZ GTI for EAA with my C5 and revolution imager R2. Only had one night out but I would say it was good enough for my needs. 95% of the time when I goto a new object it was in the field of view (the only DSS object I could not find on the night was M101 and everything else appeared straight away after doing a north level align to 2 stars), and tracking was stable enough to integrate frames for several minutes without any issues. I did put it on a AZEQ5 tripod for added stability. Based on a first light I would say good, but I would like to try it again a few more times before I say definately reccomend it to others.

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To add my 2 cent's worth - I have tried my C8 + ASI120MC on some deep-space objects. I found it works well on planetary nebulae where it is decidedly worth the effort of setting up -  without stacking and an exposure of a few seconds, small pn's of high surface brightness show up brighter than the eyepiece view and in strong colour.

The field of view is small and unlike with eyepieces there is no easy way of increasing the FOV.

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Hi once again. I finally got stacking to work last night a bit till the clouds came in at mid night. Thanks for the settings info. Gain at max and exposure at about 8 seconds with Vega in the middle of the view. Focussed on the moon to begin with. Lots of blue, red and green pixels showing. Still lots to learn, but thanks very much. Finished off visually on Jupiter then off to bed. Not a bad night though ?

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