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ASI1600mm cool


Andyb90

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Honestly you should use the optimal settings from the start. I made the mistakes too many nights wasted to using incorrect gain settings. Every setup is different but for me if you're using 60 second subs then unity gain with ha is too low. This was taken at gain 399 in 60 second subs at f4.9. 

2017-10-04_10-26-24.thumb.jpg.2c34852225aa42841fc1cf124c2374fc.jpg

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Ok looks like a clear night tonight but a full moon so im going to try some narrowband again in fact try for the heart again I think. Very roughly am I right in thinking a high gain for short subs and low gain for longer subs. I will prob do it in unity gain TBH  but (this will probably sound stupid) my bias/darks and flats would they have to be done in unity gain also? if so i can make them up in each of the three settings and put them in their own folder 

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Yes. All calibration frames at same gain and offset. What capture program do you use?  

I just saw you use sgpro. An easy way to gauge which setting to use would be to try a certain length of sub say 60 seconds. Try unity gain on frame and focus. Then hover your mouse over the centre of the stars. You will see numbers change as you move the mouse they're just under the image. 65000 means they're saturated. Personally i ignore the brightest ones and look instead at the medium brightness ones. I would then adjust the gain as high as possible without saturating these stars while also keeping an eye on the histogram to avoid clipping the whites. 

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I do try and do that but I have a question as it does annoy me, when I connect all my gear in particular SGPRO i have a choice of what settings to use with the ASI1600  (unity gain hdr etc) if I go with unity gain for exampl and connect there is no way of changing the gain or offset later on unless I disconnect SGPRO and start again which is annoying as it would be good to take samples in different settings and compare them there and then instead of disconnecting, or am I missing something there?

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Just now, brrttpaul said:

I do try and do that but I have a question as it does annoy me, when I connect all my gear in particular SGPRO i have a choice of what settings to use with the ASI1600  (unity gain hdr etc) if I go with unity gain for exampl and connect there is no way of changing the gain or offset later on unless I disconnect SGPRO and start again which is annoying as it would be good to take samples in different settings and compare them there and then instead of disconnecting, or am I missing something there?

You can change by clicking on the wrench icon next to the camera connect button on the sequence tab. You can only change while there's no image being gathered.

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2 minutes ago, brrttpaul said:

Ahh the penny drops, so there i was clicking disconnect then going to the wrench icon I didnt realise I could just change it, thankyou very much that has been a great help

No bother. I'll look forward to a fine image from you after tonight.

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slight change in plan lol, just set everything up and always wanted to try the pacman nebula as I have never tried it before. After a bit of playing about I went with unity gain and I took a single sub of 3 mins long and there it was when I gave it a medium stretch, so I then used the mouse to check the stars and a few were over 65000 so I thought ok lets try 2 min subs, again I took a single sub and the nebula is still visible so I am at the moment taking 60 of each in Ha Oii and Si, Im thinking more subs less exposure time. Also I am rotating through events rather than finish one lot first so if it does fail at least I will still have something

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Can somone confirm for me that if I buy an ASI1600MM as per ....

https://www.firstlightoptics.com/zwo-cameras/zwo-asi1600mm-cool-usb-3-mono-camera.html

a) I take off the 11mm black ring, screw the camera hard against the ZWO filter wheel (20mm), then apply the 18.5mm supplied tube to the other side of the filter wheel then I will be 10mm short of the 55mm correct backfocus distance from my 80ED FF/FR, therefore I need to buy an additional 10mm T2 extenstion tube?

b.) leave the black ring on the camera screw it to the FW using a baader T2 inverter and then be overall at 56mm back focus - this doesn't seem right from a vignetting or back focus point of view?

c) even take the black ring off the camera screw the camera straight to the FW, put the 11mm on the other side with a T2 inverter with the 18.5 and still be at 56mm?

 

I'm having adapter confusion today, I'm fairly sure option a, 10mm is the right plan - but why doesn't the camera just come with the right connections for a 20mm ZWO FW and 55mm back focus?? :)

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Hi john

This is how i have mine setup,

From the camera i have a 3 mm gasket/oring made from vitron rubber to get the cmos sensor aligned correctly then the filter wheel then the 18 mm supplied extenstion ring  and an 5mm revelation extenstion ring also note you already have 6.5mm from the sensor to  the fron of the camera see phot below for my set up all this screwed directly to telescope draw tube.

IMG_1380[1].JPG

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3 hours ago, John78 said:

Can somone confirm for me that if I buy an ASI1600MM as per ....

https://www.firstlightoptics.com/zwo-cameras/zwo-asi1600mm-cool-usb-3-mono-camera.html

a) I take off the 11mm black ring, screw the camera hard against the ZWO filter wheel (20mm), then apply the 18.5mm supplied tube to the other side of the filter wheel then I will be 10mm short of the 55mm correct backfocus distance from my 80ED FF/FR, therefore I need to buy an additional 10mm T2 extenstion tube?

b.) leave the black ring on the camera screw it to the FW using a baader T2 inverter and then be overall at 56mm back focus - this doesn't seem right from a vignetting or back focus point of view?

c) even take the black ring off the camera screw the camera straight to the FW, put the 11mm on the other side with a T2 inverter with the 18.5 and still be at 56mm?

 

I'm having adapter confusion today, I'm fairly sure option a, 10mm is the right plan - but why doesn't the camera just come with the right connections for a 20mm ZWO FW and 55mm back focus?? :)

a) this is the option to use.

you need to screw the camera directly to get the sensor as near to the filters as possible

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13 minutes ago, Gina said:

I use option c).  That needs no extra bits and is the ZWO recommended way.

I do wonder if its really 1mm over the backfocus distance they must know as manufacturers that 55mm is the money distance - maybe ill try it and see - the 10mm extension tube is only £5 from a well known auction site so I'll order one just in case.

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1 minute ago, John78 said:

I do wonder if its really 1mm over the backfocus distance they must know as manufacturers that 55mm is the money distance - maybe ill try it and see - the 10mm extension tube is only £5 from a well known auction site so I'll order one just in case.

But you’re going to be using filters which will add 1/3rd filter thickness to the back focus, which for me is 1mm getting to 56mm.

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7 minutes ago, Filroden said:

But you’re going to be using filters which will add 1/3rd filter thickness to the back focus, which for me is 1mm getting to 56mm.

Ahh I see - so now I see the difference between the ZWO RGB and the ZWO RGB optimised for ASI1600MM is different thickness.

I have a set of LRGB at 1.1mm and a Halpha at 2mm so I need 55mm + either 0.36 or 0.66 so is it best to shoot under or over??  Under right?

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Just now, John78 said:

Ahh I see - so now I see the difference between the ZWO RGB and the ZWO RGB optimised for ASI1600MM is different thickness.

I have a set of LRGB at 1.1mm and a Halpha at 2mm so I need 55mm + either 0.36 or 0.66 so is it best to shoot under or over??  Under right?

I’d probably go closer to 0.36 as your stars will be bigger in LRGB (assuming you blend in your Ha). You can always add a spacer to go longer. Much harder to go shorter :)

But easiest to go with the simplest combo and hit 55mm and test the image. No matter how precise each component is measured, you’ll probably naturally end up longer as you won’t want to over tighten each piece (been there, still can’t unscrew them!)

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1 minute ago, Filroden said:

I’d probably go closer to 0.36 as your stars will be bigger in LRGB (assuming you blend in your Ha). You can always add a spacer to go longer. Much harder to go shorter :)

But easiest to go with the simplest combo and hit 55mm and test the image. No matter how precise each component is measured, you’ll probably naturally end up longer as you won’t want to over tighten each piece (been there, still can’t unscrew them!)

Yeah to be honest I doubt I'll ever get to the point where 0.3mm piece of shim in my image train is making distinct improvements in my final image!!  So I'll go 55mm, then I can easily laser cut shim stocks to go longer.

 

I quite fancy a thin shim between the camera and fw just to stop them scratching each other up and stopping them getting stuck.

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3 hours ago, John78 said:

Ahh I see - so now I see the difference between the ZWO RGB and the ZWO RGB optimised for ASI1600MM is different thickness.

Actually, the ASI1600 optimisation is exposure related and not mechanical/optical, afaIk.

The transmission curves of the filters are such that you collect equal amounts of electrons (or adu's) in equal times. The red part of the qe curve is lower than the green part, so the green filter is narrower to compensate for this. The red filter is designed to block the spectral line of sodium (light pollution) and be transparent all the way to the edge of the ir window.

From zwo web site:

The new  ZWO LRGB Filters  are designed to approximately equalize the flux of ASI1600 mono sensor

RGBL-ASI1600.jpg.b194d8ebc9775cdc6e635a8afb16509c.jpg

Unlike most other rgb filters, the blue filter doesn't cover the Oiii spectral line. Here's zwo standard rgb filter set. Notice the larger overlap between green and blue, and the narrower red curve. If you use this filter set, you need about 50% longer red exposures to get the same adu count with a white light source.

LRGB-201503081.png.21eb4268b1294dea85f58a308ce51969.png

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29 minutes ago, wimvb said:

Actually, the ASI1600 optimisation is exposure related and not mechanical/optical, afaIk.

The transmission curves of the filters are such that you collect equal amounts of electrons (or adu's) in equal times. The red part of the qe curve is lower than the green part, so the green filter is narrower to compensate for this. The red filter is designed to block the spectral line of sodium (light pollution) and be transparent all the way to the edge of the ir window.

From zwo web site:

The new  ZWO LRGB Filters  are designed to approximately equalize the flux of ASI1600 mono sensor

RGBL-ASI1600.jpg.b194d8ebc9775cdc6e635a8afb16509c.jpg

Unlike most other rgb filters, the blue filter doesn't cover the Oiii spectral line. Here's zwo standard rgb filter set. Notice the larger overlap between green and blue, and the narrower red curve. If you use this filter set, you need about 50% longer red exposures to get the same adu count with a white light source.

LRGB-201503081.png.21eb4268b1294dea85f58a308ce51969.png

This is correct, and to expand on this, anyone thinking of getting Astrodon e series filters for the this camera should think about getting the i series instead as they more closely match the optimised set.

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