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Old 22-08-2019, 01:30 PM
meellor (Jack)
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ASI183MM Pro vs ASI1600MM Pro

Hi guys,

At some point in the (hopefully) not too distant future I'll be making the jump from my stock Sony A6300 to a monochrome CMOS camera. I feel like I've narrowed my choices down to the two cameras in the title, but I'm having a bit of trouble figuring out which would be best for my current set up.
I use a Sharpstar CF-80 (500mm at f6.25) guided on a HEQ5 Pro.
I'm beginning to understand the basics around under/over-sampling and from what I can gather the 183MM seems more versatile for my set up, sampling well with average to good seeing, but also having the ability to bin 2x2 when seeing is below average. Is this correct?
My reservations are that I'm yet to find a forum post on any site where everyone isn't praising the 1600MM over anything else around this price range?

I don't have plans to add any more scopes to my gear, at least not for a couple of years yet. So as far as FOV concerns, I'm actually happier with the narrower FOV on the 183 than the 1600.
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Old 22-08-2019, 02:27 PM
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Terry B
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Originally Posted by meellor View Post
Hi guys,

At some point in the (hopefully) not too distant future I'll be making the jump from my stock Sony A6300 to a monochrome CMOS camera. I feel like I've narrowed my choices down to the two cameras in the title, but I'm having a bit of trouble figuring out which would be best for my current set up.
I use a Sharpstar CF-80 (500mm at f6.25) guided on a HEQ5 Pro.
I'm beginning to understand the basics around under/over-sampling and from what I can gather the 183MM seems more versatile for my set up, sampling well with average to good seeing, but also having the ability to bin 2x2 when seeing is below average. Is this correct?
My reservations are that I'm yet to find a forum post on any site where everyone isn't praising the 1600MM over anything else around this price range?

I don't have plans to add any more scopes to my gear, at least not for a couple of years yet. So as far as FOV concerns, I'm actually happier with the narrower FOV on the 183 than the 1600.
I have an ASI183MM pro that I chose mainly because of its very high quantum efficiency. Admittedly I am using it for spectroscopy and not pretty pictures but it is a very capable camera. See here http://www.astrosurf.com/buil/asi183mm/
It is in french but you can google translate it with good results.
Here is a test of the 1600 http://www.astrosurf.com/buil/atik_vs_zwo/


Cheers
Terry
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Old 22-08-2019, 09:54 PM
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It will depend on how well your mount guides. The pixels of the 1600 have 2.5x the area of those on the 183, so with the latter you’ll be wanting to expose longer to get comparable SNR. At f/6, you’d probably be aiming for around 5 minutes.

They are both versatile cameras with their pros and cons. The 1600 is the larger sensor, so consider the types of targets you’re interested in and simulate how they fit in your FOV with planetarium software.
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Old 22-08-2019, 10:04 PM
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They're two very different cameras.
The ASI1600 has a larger sensor, larger pixels and lower read noise but having a little bit lower QE.

What this means is that you'll have to take significantly longer exposures with the ASI183 as you will the ASI1600. As you're only using an 80mm telescope you probably don't want to be trying to resolve down to its Dawes limit (it's ability to resolve) so I think you'd be better off with the ASI1600 personally.

The microlens issue that people (myself included) have experienced tends to happen more so with larger faster optics than an 80mm F/6. It'll be there on brighter stars but it won't be as intrusive as a bigger and optically faster telescope.
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Old 23-08-2019, 08:27 AM
meellor (Jack)
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Originally Posted by Camelopardalis View Post
It will depend on how well your mount guides. The pixels of the 1600 have 2.5x the area of those on the 183, so with the latter you’ll be wanting to expose longer to get comparable SNR. At f/6, you’d probably be aiming for around 5 minutes.

They are both versatile cameras with their pros and cons. The 1600 is the larger sensor, so consider the types of targets you’re interested in and simulate how they fit in your FOV with planetarium software.
Longer subs wouldn't phase me, I've been taking at least 5 min subs as of late since upgrading to a guided set up. Also, later down the track if I were to upgrade my gear with a new scope I'd like to imagine I'd be looking into getting something like a RASA.

I prefer the idea of a narrower FOV, also I'm a bit of a sucker for higher resolution images allowing me to zoom in and really explore the detail.
Are there any inherent issues with the 183 that you've heard of?
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Old 23-08-2019, 08:34 AM
meellor (Jack)
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They're two very different cameras.
The ASI1600 has a larger sensor, larger pixels and lower read noise but having a little bit lower QE.

What this means is that you'll have to take significantly longer exposures with the ASI183 as you will the ASI1600. As you're only using an 80mm telescope you probably don't want to be trying to resolve down to its Dawes limit (it's ability to resolve) so I think you'd be better off with the ASI1600 personally.

The microlens issue that people (myself included) have experienced tends to happen more so with larger faster optics than an 80mm F/6. It'll be there on brighter stars but it won't be as intrusive as a bigger and optically faster telescope.
Looking at quite a few images of the microlens issues people have and it's been the biggest turn off for me with the 1600 (unfortunately seen a lot of examples of it even with f6/f7 refractors). Have you had much success processing/calibrating it out?

As per the need for longer exposures I don't really mind. I'll be coming from a stock Sony crop sensor, battling low sensitivity to Ha as well as star eater issues, so I'm sure I'll be blown away with results using the same 5 min subs I've been taking.

I guess I'm just a bit lost with all the information on under/over-sampling. If it were unavoidable and I had to be in one ball park, I'd prefer to be over-sampled to my understanding? Or will this still provide bad results

Last edited by meellor; 23-08-2019 at 08:45 AM. Reason: typo
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Old 23-08-2019, 09:57 AM
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The_bluester (Paul)
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Over sampling will not really net you any gain in detail unless Conditions no are perhaps exceptional and allow you to get right down to the theoretical limit of your scope. I have found that my marginally undersampled combo of an ASI294 on a 72mm refractor produces noticeably squared off stars, but with enough well dithered subs to control the noise that results, drizzle processing recaptures a lot of the otherwise lost detail and leaves me with a camera that is pretty well sampled on my SCT.

I would love to see a mono version of the 294 as it actually has about 1um sub pixels rather than the 4.63um RGGB “pixel” that is captured. Basically the un debayered output is 2x2 binned pixels of each colour which combine into a single RGGB pixel that size wise is effectively 4x4 binned on the native size of the pixels.
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Old 23-08-2019, 06:03 PM
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Originally Posted by meellor View Post
Longer subs wouldn't phase me, I've been taking at least 5 min subs as of late since upgrading to a guided set up. Also, later down the track if I were to upgrade my gear with a new scope I'd like to imagine I'd be looking into getting something like a RASA.

I prefer the idea of a narrower FOV, also I'm a bit of a sucker for higher resolution images allowing me to zoom in and really explore the detail.
Are there any inherent issues with the 183 that you've heard of?
My experience with the ASI178 (which is a smaller version of the 183 with the same 2.4 micron BSI pixels) and my Esprit 100 (=550mm) has shown me that I only get better resolution from the smaller pixels on nights of substantially above average seeing. The rest of the time, the 1600 collects signal faster, is easier to calibrate and can always be cropped.

A mate of mine has a 183 mono and I’ve seen some promising results from it, but the amp glow is a little shocking (especially at high gain and/or longer exposures) and requires more care to calibrate out.
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Old 24-08-2019, 03:42 PM
meellor (Jack)
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Originally Posted by The_bluester View Post
Over sampling will not really net you any gain in detail unless Conditions no are perhaps exceptional and allow you to get right down to the theoretical limit of your scope. I have found that my marginally undersampled combo of an ASI294 on a 72mm refractor produces noticeably squared off stars, but with enough well dithered subs to control the noise that results, drizzle processing recaptures a lot of the otherwise lost detail and leaves me with a camera that is pretty well sampled on my SCT.

I would love to see a mono version of the 294 as it actually has about 1um sub pixels rather than the 4.63um RGGB “pixel” that is captured. Basically the un debayered output is 2x2 binned pixels of each colour which combine into a single RGGB pixel that size wise is effectively 4x4 binned on the native size of the pixels.
So essentially if I end up over-sampling with the 183, all I'm really doing is getting the same(ish) amount of detail I'd get from the 1600, but it's just taking me a hell of a lot longer to get there due to the smaller pixel size?
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Old 24-08-2019, 03:47 PM
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Originally Posted by Camelopardalis View Post
My experience with the ASI178 (which is a smaller version of the 183 with the same 2.4 micron BSI pixels) and my Esprit 100 (=550mm) has shown me that I only get better resolution from the smaller pixels on nights of substantially above average seeing. The rest of the time, the 1600 collects signal faster, is easier to calibrate and can always be cropped.

A mate of mine has a 183 mono and I’ve seen some promising results from it, but the amp glow is a little shocking (especially at high gain and/or longer exposures) and requires more care to calibrate out.
This was really helpful actually, thank you. I'm realising now that the benefit of higher resolution is really only gained on a "once in a blue moon" kind of night. Also that down the track when I get a larger/longer FL scope the 1600 will be a better fit.

I'm curious if you've ran into the microlens issue, that Atmos mentioned earlier, with your Esprit 100?
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Old 24-08-2019, 10:08 PM
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So essentially if I end up over-sampling with the 183, all I'm really doing is getting the same(ish) amount of detail I'd get from the 1600, but it's just taking me a hell of a lot longer to get there due to the smaller pixel size?
Pretty much

Quote:
Originally Posted by meellor View Post
This was really helpful actually, thank you. I'm realising now that the benefit of higher resolution is really only gained on a "once in a blue moon" kind of night. Also that down the track when I get a larger/longer FL scope the 1600 will be a better fit.

I'm curious if you've ran into the microlens issue, that Atmos mentioned earlier, with your Esprit 100?
Yeah the seeing along the east coast of Australia isn’t usually anything special. Also consider what you may be intending to achieve with a longer FL scope is comparable to shrinking the pixels. The SNR will improve with larger aperture/faster f-ratio, but the resolution you’ll be able to achieve is limited by the seeing. (Assuming decent figuring of optics...)

The seeing is the real wildcard here. Do you get the smaller pixels in the hope that you get good seeing more regularly and potentially better resolution? Or do you sacrifice a little resolution for speed on every occasion? More likely, you’d not notice the difference with 80mm aperture, but it’s not impossible.

I have seen the microlens issue with my 1600 / Esprit 100. Only once was it really noticeable, and that was while imaging the Horsehead nebula. Alnitak is a nuisance, and the microlens pattern is pretty obvious in that shot. I’ll see if I can dig it up to demonstrate. But it’s the only image I recall it being an annoyance, YMMV...
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Old 25-08-2019, 12:21 PM
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The ZWO-1600 microlens issue is an easy fix, if one is brave enough to remove the glass cover slip from the sensor and replace it with an Anti-Reflective glass cover slip.
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Old 25-08-2019, 06:05 PM
meellor (Jack)
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Originally Posted by Camelopardalis View Post
Pretty much



Yeah the seeing along the east coast of Australia isn’t usually anything special. Also consider what you may be intending to achieve with a longer FL scope is comparable to shrinking the pixels. The SNR will improve with larger aperture/faster f-ratio, but the resolution you’ll be able to achieve is limited by the seeing. (Assuming decent figuring of optics...)

The seeing is the real wildcard here. Do you get the smaller pixels in the hope that you get good seeing more regularly and potentially better resolution? Or do you sacrifice a little resolution for speed on every occasion? More likely, you’d not notice the difference with 80mm aperture, but it’s not impossible.

I have seen the microlens issue with my 1600 / Esprit 100. Only once was it really noticeable, and that was while imaging the Horsehead nebula. Alnitak is a nuisance, and the microlens pattern is pretty obvious in that shot. I’ll see if I can dig it up to demonstrate. But it’s the only image I recall it being an annoyance, YMMV...

I'll say I'm definitely set on a 1600MM/163M now after your help. Realised after doing more searches the microlens issue was really only popping up on the same targets for people (horsehead, etc). It's a sacrifice I'd be willing to make for the sake of hugely increased sensitivity and ease of use.

Thanks again for the advice!
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Old 25-08-2019, 06:05 PM
meellor (Jack)
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The ZWO-1600 microlens issue is an easy fix, if one is brave enough to remove the glass cover slip from the sensor and replace it with an Anti-Reflective glass cover slip.
I would say with absolute confidence I am not brave in this scenario haha.
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Old 25-08-2019, 06:23 PM
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I'll say I'm definitely set on a 1600MM/163M now after your help. Realised after doing more searches the microlens issue was really only popping up on the same targets for people (horsehead, etc). It's a sacrifice I'd be willing to make for the sake of hugely increased sensitivity and ease of use.

Thanks again for the advice!
No worries!

Look, in most cases it's not an issue, but it does rear its ugly head if there's a bright star in FOV, so it's good to be aware of it before you spend your hard earned $$$. For an example, see attached. This is a crop at 1:1 of 322x322 out of 4656x3520. The full image includes the Horsehead and Flame nebulae, as seen with my Esprit 100.

Regarding sensitivity...that's a harder term to define. The Panasonic sensor in the 1600/163 has lower quantum efficiency (QE) than the 183, but that alone cannot defeat the larger pixels of the 1600. The same is (of course) true of sensors with still larger pixels, but there's a trade-off between resolution and signal collection in an image - and there's no "perfect" balance point.
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Old 25-08-2019, 09:19 PM
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Originally Posted by Camelopardalis View Post
No worries!

Look, in most cases it's not an issue, but it does rear its ugly head if there's a bright star in FOV, so it's good to be aware of it before you spend your hard earned $$$. For an example, see attached. This is a crop at 1:1 of 322x322 out of 4656x3520. The full image includes the Horsehead and Flame nebulae, as seen with my Esprit 100.

Regarding sensitivity...that's a harder term to define. The Panasonic sensor in the 1600/163 has lower quantum efficiency (QE) than the 183, but that alone cannot defeat the larger pixels of the 1600. The same is (of course) true of sensors with still larger pixels, but there's a trade-off between resolution and signal collection in an image - and there's no "perfect" balance point.
Is there a relatively straight forward way of processing the issue out? Or is it a bit tricky?
Still though, your supplied image I can live with. At the end of the day, I'm using a stock Sony A6300 which I just cannot wait to replace with any kind of dedicated astro camera. To be fair, it has given me images of bright regions such as Carina and Rho Ophiuchi that I've been stoked with. I'm just facing the fact it really doesn't live up to my expectations now that I have guiding and am attempting faint/semi-faint targets such as NGC6188 and M17.
Part of me is tempted to go the cheap cop out and get an OSC version of the 163, but I know I'll be left disappointed again and end up upgrading to mono not long after.
I'm also just sold on being able to narrowband image during full moon instead of sitting and staring at a tantalising clear, yet washed out sky.

As for your reply regarding sensitivity, I think the ease of use and versatility of the 1600/163 sensor sounds like less frustration/disappointment in the future, which, again, I'm more than happy losing a bit of resolution to just have a better time.
Now I just need to find a kit that my budget can match

Last edited by meellor; 25-08-2019 at 09:21 PM. Reason: typo
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Old 26-08-2019, 07:50 PM
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I’ve never really tried to process it out...put it in the too hard basket. But as far as I can remember this was the only shot where it was really obvious.

Just my opinion, but I think the 1600 is a great camera overall, especially as you appreciate you want something more than a OSC. If you find yourself feeling like you’re missing out on resolution, they never stay for sale on the used market for long.
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