1189 replies to this topic

[Jon Rista]

I ordered one up from ZWO.  I'll install it on my NEWT, which I have setup right now without the reducer.  (8" f4) That gives me an image scale of .62"/px.  I've had clouds for two straight months, so not sure when it will clear.... but this will be a nice compliment to my 1600MMC. 

Looking forward to your first light! This is the setup that greatly interests me. I had been very seriously interested in a TEC140, one of the new fluorite ones, but with the small pixels I think a newt is just a better option. Bigger aperture, much faster. I don't think I could image at f/7.

 

So this is the ONTC 8" from TS, right?

[Jon Rista]

I don't and will NEVER belong to Facebook. I hate social networking.

 

Peter

Right there with you, my friend! (Well, sadly, I do have a Facebook account...I mistakenly got into "social networking" at the very beginning, before it became what it is today...I was a very early adopter of facebook, but haven't used it in years and don't intend to again.)

 

I do wish absolute Q.E. graphs were more common, though. It is tough to find them. Before the cameras become more official, I had a real tough time finding the first absolute Q.E. graph that Bill posted. I eventually found it on a machine vision camera page that used the same sensor. I was a bit surprised at the 84% peak efficiency, that is extremely good. I am also a little bummed that the Ha efficiency is only 50%, but I guess it is still better than the ASI1600. Sony's ICX ccds still have better red sensitivity than the CMOS sensors so far. I am kind of curious why that is...silicon tends to be naturally more sensitive to reds, somehow Sony seems to have made highly blue sensitive sensors for a while now, though...

Edited by Jon Rista, 20 January 2018 - 12:18 PM.

[ChrisWhite]

I ordered one up from ZWO. I'll install it on my NEWT, which I have setup right now without the reducer. (8" f4) That gives me an image scale of .62"/px. I've had clouds for two straight months, so not sure when it will clear.... but this will be a nice compliment to my 1600MMC.

Looking forward to your first light! This is the setup that greatly interests me. I had been very seriously interested in a TEC140, one of the new fluorite ones, but with the small pixels I think a newt is just a better option. Bigger aperture, much faster. I don't think I could image at f/7.

So this is the ONTC 8" from TS, right?

Correct. I upgraded the tube and put a 2.5" threaded focuser on. I'm going to image at f4 for a while. The 183 with small pixels and higher read noise may make me more interested in using the reducer.

[rockstarbill]

At some point I might have to get one of those. What all did you need to buy for it?

[james7ca]

Speaking of Dawes' Limit and sampling, I've done a fair amount of work capturing close double stars with my IMX178 cameras (same 2.4um pixels as the IMX183) and below is a thread where I captured a double star that had a separation of around 0.9 arc seconds using a Tele Vue NP127is (5" refractor). The image scale was 0.14 arc seconds per pixel (with a 5X Powermate) and you can definitely see the differences between the blue and red subs in terms of resolution (the blue being significantly better -- look at some of the images at the end of the thread).

 

  https://www.cloudyni...s/#entry8041810

 

I've also done a lot of lunar work with the IMX178 and it kind of excels at that function since you reach critical sampling at around f/12, which is close to what you get at the prime focus of the typical SCT (and even more so if you image in the red or near IR to help with seeing). Interestingly, with a 2X barlow it also matches a lot of APOs that offer native f/6 ratios.

 

Lastly, pixel size has an interesting relationship with field coverage when working at critical sampling (or any given image scale). In this case it's not simply the size of the chip that matters, you also need to scale by the size of the pixels, since with smaller pixels you can use a shorter focal length to reach the critical sampling and that results in a wider field of capture. So, compare the 3.8um pixels on the ASI1600 with the 2.4um pixels on the IMX178/IMX183 and the latter gets a 3.8/2.4 = 1.6X boost in terms of field coverage. Now, factor in the actual chip size and you get the following:

 

ASI1600 chip size: 17.7mm x 13.4mm, but the equivalent size at critical sampling in comparison to the IMX183: 17.7mm / 1.6, 13.4mm / 1.6 or 11.2mm x 8.5mm

IMX183 chip size: 13.2mm x 8.8mm

 

So, the IMX183 can offer a wider field at critical sampling or at any given image scale than the ASI1600. However, this is only valid if you work at exactly the same image scale for both cameras, something that is not that easy to do unless you use a variable magnification barlow (or similar technique).

 

I actually gave some simulated imaging examples of this using a variety of different cameras in the following two posts (#23 and #24):

 

 https://www.cloudyni...a/#entry7590925

[Goofi]

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

[Ken Sturrock]

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

 

Buy one.

[rockstarbill]

 

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

 

Buy one.

 

 

Excellent summary! 

[Goofi]

Well, I asked for that!  

 

My debate is between a QHY183C and ASI294C ... both are $1000 dollar color OSC cameras, but they have some differences.  What I'm hoping to avoid is wading through almost 400 posts to understand the pros and cons of the camera.

 

Oh, and right now if I pull the trigger it will be for the ASI294 (for a variety of reasons that matter to me and my setup).

[rockstarbill]

FWIW, I went with the 294 for a OSC. That full-well, low read noise, and high QE was a good selling point. Like the 183, it is also AR coated, per the ZWO Facebook page.  

[Goofi]

All those reasons are on my list for the 294, plus similar pixel size to my Sony 694 so image scale is similar means I can use it to shoot RGB stars.  But mainly, gotta love that field of view!!  

 

The thing the 183 has going for it is those tiny pixels work great with my AT65EDQ.

[rockstarbill]

Yeah the FOV was a good selling point! It is also highly revered for EAA, and since I do have some interest in that (mostly for the lady and a six year old boy) the 294 won out. 

 

As far as the 2.4 micron pixels go, that is why I got the mono version of the 183. Works well with my refractors, and I can bin it 2x2 to use on my 8" Edge. The 294MC + 183MM combo was a victory in my book. 

 

Both cameras still cost less than the QSI690 I sold. So I am still in the positive. 

[PhysicsStudent]

Ordered My 183 yesterday. Can't wait until Thursday when it gets here!

[ChrisWhite]

At some point I might have to get one of those. What all did you need to buy for it?

 

Was this question directed at me regarding the Newt?  If so, let me know and I can PM you so I don't stray from the thread topic.  (Unless Jon wants it here....)

[ChrisWhite]

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

 

I just got into this thread a week ago.  I started reading and after a few days caught up.  It's not so bad and there is a lot of info in here, so it's worth a read. 

[Jon Rista]

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

Sure.

 

SAME IMAGE SCALE:

 

IMX183 has higher Q.E. (84% vs. 60%, so 40% more sensitive)

IMX183 has a larger FoV

IMX183 has lower read noise @ min gain (2.8 vs. 3.5, so 46% more sensitive)

 

ASI1600 has larger FWC (20,000e- vs. 15,000e-)

ASI1600 has lower read noise @ unity (1.55e- vs. 2.0e-, so 40% more sensitive)

ASI1600 has lower read noise @ max gain (1.13e- vs. 1.5e-, so 43% more sensitive)

 

At the same image scale, the two cameras will perform about the same, as read noise vs. QE tends to balance things out. The IMX183 has the FoV advantage, though, due to being 2:3 format rather than 4:3 format.

 

SAME FOCAL LENGTH:

 

IMX183 has higher Q.E. (84% vs. 60%, so 40% more sensitive)

IMX183 has ~40% higher resolution (2.4um vs 3.8um)

 

ASI1600 has bigger pixels (so more sensitive)

ASI1600 has a larger FoV

ASI1600 has lower read noise on normalized area basis at all gain settings (so more sensitive, balancing out IMX183 Q.E.)

 

At the same focal length, the ASI1600 is the more sensitive of the two, having much lower read noise and larger pixels (overpowering the Q.E. advantage of the IMX183). This gives it an edge for wider field narrow band imaging. However, the IMX183 has a distinct resolution advantage, allowing better sampling at any focal length. This can potentially give it the ability to sample as well as much larger scopes with much larger cameras that cost many times more, thus potentially saving you a significant amount of money for high resolution imaging. IMO, the IMX183 is best paired with an f/4 system around 1000mm for optimal image scale to maximize the resolution benefits on small objects. 

Edited by Jon Rista, 21 January 2018 - 01:29 PM.

[dvalid]

Would be interesting to compare the IMX183 sensor with CCDs. Looks like even binned, it could hardly (if at all) outperform my QSI660, which characteristics btw, are inferior to that, stated on QSI's site. Not to mention mediocre performance at Ha. High resolution is clear benefit though..

 

QSI660wsg:

 

Edited by dvalid, 21 January 2018 - 08:48 AM.

[terry59]

I don't and will NEVER belong to Facebook. I hate social networking.

 

Peter

Ummmmm....isn't that what THIS is?

Edited by terry59, 21 January 2018 - 08:42 AM.

[Jon Rista]

Would be interesting to compare the IMX183 sensor with CCDs. Looks like even binned, it could hardly (if at all) outperform my QSI660, which characteristics btw, are inferior to that, stated on QSI's site. Not to mention mediocre performance at Ha. High resolution is clear benefit though..

 

QSI660wsg:

 

QSI660_Report1.jpg

Interesting... Based on your measurements there, the IMX183 would actually have more dynamic range when binned 2x2.

 

You are showing 11.43 stops of dymamic range with a 4.4e- read noise and 11.7ke- FWC.

 

The IMX183 when binned would technically have a capacity of 15,000e- x 4, or 60,000e-, over total binned read noise of around 5.6e-, which would lead to dynamic range of 13.43 stops.

 

The read noise hurts the IMX for narrow band work, but I think the increased dynamic range would be a bonus for galaxy work. Even if you did not bin, which would be the case if you want the resolution, you still have 15,000e- FWC over 2.8e- read noise, which is 12.43 stops. It will clip to 12 stops due to he bitt depth, but it is still over half a stop more. I think that is a bonus for galaxies, especially if you are chasing any IFN. 

[calypsob]

 

I don't and will NEVER belong to Facebook. I hate social networking.

 

Peter

Ummmmm....isn't that what THIS is?

 

If you look at what Ghostery is blocking right now in my browser heading, you would be correct, not much different than being on facebook social media, FB connect, Google platform, and Gravatar are 3 socail media trackers being blocked right now on this page.   

Edited by calypsob, 21 January 2018 - 02:30 PM.

[dvalid]

 

Would be interesting to compare the IMX183 sensor with CCDs. Looks like even binned, it could hardly (if at all) outperform my QSI660, which characteristics btw, are inferior to that, stated on QSI's site. Not to mention mediocre performance at Ha. High resolution is clear benefit though..

 

QSI660wsg:

 

QSI660_Report1.jpg

 

The IMX183 when binned would technically have a capacity of 15,000e- x 4, or 60,000e-, over total binned read noise of around 5.6e-, which would lead to dynamic range of 13.43 stops.

 

 

Oops, did the same mistake again, have multiplied the RN by four

[Goofi]

 

Can I ask a favor from the group?  Is it possible to summarize this thread for those who don't want to wade through 15+ pages?  

Sure.

 

SAME IMAGE SCALE:

 

IMX183 has higher Q.E. (84% vs. 60%, so 40% more sensitive)

IMX183 has a larger FoV

IMX183 has lower read noise @ min gain (2.8 vs. 3.5, so 46% more sensitive)

 

ASI1600 has larger FWC (20,000e- vs. 15,000e-)

ASI1600 has lower read noise @ unity (1.55e- vs. 2.0e-, so 40% more sensitive)

ASI1600 has lower read noise @ max gain (1.13e- vs. 1.5e-, so 43% more sensitive)

 

At the same image scale, the two cameras will perform about the same, as read noise vs. QE tends to balance things out. The IMX183 has the FoV advantage, though, due to being 2:3 format rather than 4:3 format.

 

SAME FOCAL LENGTH:

 

IMX183 has higher Q.E. (84% vs. 60%, so 40% more sensitive)

IMX183 has ~40% higher resolution (2.4um vs 3.8um)

 

ASI1600 has bigger pixels (so more sensitive)

ASI1600 has a larger FoV

ASI1600 has lower read noise on normalized area basis at all gain settings (so more sensitive, balancing out IMX183 Q.E.)

 

At the same focal length, the ASI1600 is the more sensitive of the two, having much lower read noise and larger pixels (overpowering the Q.E. advantage of the IMX183). This gives it an edge for wider field narrow band imaging. However, the IMX183 has a distinct resolution advantage, allowing better sampling at any focal length. This can potentially give it the ability to sample as well as much larger scopes with much larger cameras that cost many times more, thus potentially saving you a significant amount of money for high resolution imaging. IMO, the IMX183 is best paired with an f/4 system around 1000mm for optimal image scale to maximize the resolution benefits on small objects. 

 

 

 

Perfect, thanks Jon!  

[dkeller_nc]

 

I don't and will NEVER belong to Facebook. I hate social networking.

 

Peter

Right there with you, my friend! (Well, sadly, I do have a Facebook account...I mistakenly got into "social networking" at the very beginning, before it became what it is today...I was a very early adopter of facebook, but haven't used it in years and don't intend to again.)

 

By the way, guys, the proper way to refer to it is "FacePlant", which is a perfect description of the evil nature of it.

[dkeller_nc]

 

I don't and will NEVER belong to Facebook. I hate social networking.

 

Peter

Ummmmm....isn't that what THIS is?

 

Nope.  The difference is that this board is moderated.  It should be really obvious that the completely unacceptable behavior that goes on at what's labeled "social networking sites" is barely moderated, if at all.

[DaveB]

... IMO, the IMX183 is best paired with an f/4 system around 1000mm for optimal image scale to maximize the resolution benefits on small objects. 

With a reducer, my RC would come in roughly at 1333mm @ f/5.3. That sounds like it would be a reasonable match, correct? The FOV would actually be *slightly* larger (mostly wider) than my 8300 on my RC without the reducer. 

 

Having said that, the 1600 is nearly the same size as the 8300, so maybe that would be a better option at this focal length.