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Fueling the ongoing discussion about mono and color. this is a comparison shot of NGC 7380 (zoomed in). This is not a discussion about Bortle 1 with endless clear skies, this is for heavy light pollution with clear skies every other leap year.  Both are stacked of ~30 subs, each 300s, 200gain and same optics except filters. Both images have about the same total exposure of ~2.7h. ASI 2600MM + Mono filters: Edge Ha, Edge Oiii, Edge Sii ASI533MC + Color filters: Antlia Dual, Edge Sii For the color configuration, the Oiii data could be improved with using an Sii/Oiii filter, but that doesnt seem to be the main issue here. Also, i put more time on the Sii since that is very weak; maybe that could further improve the color variant SNR. |
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Mono wins, no contest, but can't you apply noise-xterminator to both as well and share those results, since that would be what most photographers would do anyway…
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The quality of asi 533 is not same to asi 2600. The test is not good , is partial. The sensor IMX 571 is better respect to IMX533.
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I'm not sure that this is really a fair test to be honest. There are just too many variables and the methodology I think favors the mono sensor. It would be more interesting to me at least to see a test like this done with everything the same. Maybe a hour with just the Ha filter with both images presented in monochrome. You could then just measure the relative SNR and it would also show up any real resolution difference between the two.
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D. Jung: Nice comparison.... but you'll never convince the guys that use color that mono is better for narrowband  |
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I have no doubt that mono is better, I just think that this particular test isn't the one to show exactly how much better.
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Arun H:D. Jung: That is not the issue at all. What a straw man... I don' t know anyone who thinks Color is better than Mono. Do you think you are breaking ground here? There are plenty of reasons to use Color cameras, the filters are getting better, it is simpler and some just prefer Color camera images for the ease of taking and processing. There are currently Images of the day on this site imaged with 2600mc cameras and Dual Filters. I think the comparison shows that a subpar camera can compete with a better camera. It is not a blow out here, the 533 image is decent in the competition and good processing could make them look about equal. |
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Seems pretty standard. The fact is, mono IS better. not just for narrowband. its just BETTER. But - is it worth the effort? for a lot of people who get few nights, and even less time to process images, no.. its not worth it. You'll never convince someone that mono is SIGNIFICANTLY better until they do it for themselves, but you'll never EVER convince someone who does not want to deal with mono data that mono is WORTH it…. And yes - Narrowband is 100% where you will see the most significant difference. What I could do in 8h with my 1600MM vs 16h with my 294C was crazy, then comparing what 8h with the IMX571 mono against the 294C is ridiculous… but it is without a doubt, a lot more time on the computer to attain the result… I might spend half the time gathering the data, but I spend nearly double the time processing it. |
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Tony Gondola: I agree; I am sure the test could be better conducted. To be fair, I don't think the OP intended it to be quantitative, merely qualitative. |
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Marco Luigi Tassi: Is be interested to know in what way the 533 is worse than the 2600. As I’m trying to choose which one as a new camera. Their specifications regarding well depth, pixel size, QE, dark current, read noise are essentially identical. The only obvious difference I can see is the 2600 has a larger sensor, and a 16 bit ADC. Have you tested both and found the 533 to be worse? |
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Mono always wins
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The reasons I went OSC instead of mono were that my primary scope is f/12 hence the image is oversampled anyway, and the weather here has been appallingly poor for the past 5 years thanks to what appears to be a permanent climate change. We're lucky to get an hour or two of darkness before the clouds roll in. If I was under clearer skies and using f/5 all the time , then sure, a mono scope would be the way to go. |
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Marco Luigi Tassi: The IMX571 is considerably less noisy than the IMX533. |
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Marco Luigi Tassi: Yes, I think that's a very interesting question. Unfortunately I don't own the 533mm to make a more direct comparison between the mc and mm version. I guess what would be interesting to see: Narrowband sho comparison for 533mc vs 533mm 2600mc vs 2600mm 533mm vs 2600mm If someone has any of those combinations and might feel like chipping in? |
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Marco Luigi Tassi: *** Yes I owned asi533 mc and asi533 mm. together with asi2600 mc. the images of the 533 compared to the 2600 were noisier and less detailed. Many images taken with the 2600 could avoid dark frames in the 533 dark frames were necessary. It is not only the quality of the sensor that counts but also all the complementary electronics. The IMX571 sensor is always the same but in the Touptek the final images are sufficient, in the Zwo Asi they are good, in the Player One they are excellent. *** |
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Have you tested both and found the 533 to be worse? I cannot speak to qualitative experiences, but if you look at the read noise curves, the dark current curve, the noise characteristics, particularly at HCG are identical, as is the QE (this is comparing the MM to MM in both cases; the effect of adding the Bayer array, for good or bad is just something that comes along with using the MC, just like the filter characteristics with the MM). So the base sensor characteristics seem identical, especially given the pixel size is the same other than of course that the 2600MM is much larger in total size. Thus the sampling with the same scope can be a basis for a fair comparison of mono vs color. If someone is saying that the base sensor in the 533 is worse or better than the 2600MM, I certainly would like to see that supported by data. |
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I agree with @Arun H . There are a lot of hear-say facts going around, which don't seem to be adding up with the datasheets. I wouldn't be surprised if the datasheets are "tuned" or better, I would be surprised if they weren't... We have some ideas mentioned: - Imx571 is a better sensor (though only diff in datasheet is the ADC) - electronics are different and somehow change sensor performance (interesting, but don't see how raw data would be affected by that?) - we can't compare, it's like comparing apples and bananas - it's just better because (for no reason) |
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IN reading this thread, I think the main issue of imaging under light polluted skies has not been directly dealt with. I has the 2600MC and use Ha/Oiii and Oiii/Sii filters. I am happy with the results thus far. The main advantage is a practical one of allowing reasonable image capture times under often cloudy and light polluted skies in the city of Chicago. I will eventually buy a mono camera and associated filters, but it would be more useful if I can either remote image, or move to an area with Bortle 4 or better skies.
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I actually suspect at least some of the differences between the 2600 and 533 people are claiming come from the fact that, although the sampling with the same scope is identical, the viewing scale the final image is very different. On a standard size screen, more pixels of the 2600 would be mapped to a given screen pixel than for a 533, resulting in an effective viewing SNR improvement.
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Arun H: That's an important point that's often overlooked although it doesn't apply in this case. Still, it's always valuable to compare sensors and images by viewing them at 1:1. That is to say, one pixel in the image equals one pixel on the screen. That levels the playing field no matter what the sensor size is. |
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Tony Gondola: I completely agree. The OP presented his comparison at the same viewing scale which is the appropriate way to compare. I was merely referring to general qualitative statements saying the 533 sensor is worse than the 2600 which are not supported by the data sheets. |
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Data sheets count only so much (and then you'd see that the sensitivity curves for both are rather unequal, a rather far cry from saying peas in a pod). I have both and clearly the IMX533 sensor is noisier than the IMX571, at the same exposure length and HGC settings (again, they are different for each sensor).
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andrea tasselli: *** Type your reply here ** The QE curves, and gain/read noise curves, are almost identical according to ZWO’s spec sheets. Have you done a sensor analysis? Perhaps the HGC point on your 533 isn’t quite at 100.   |
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andrea tasselli: I've been looking at these and they differ quite a bit for the gain curve. Not sure it means anything, but at lower gain values (<200) we see a factor of 3 to 5 difference in e/ADU. If I understand this correctly, the asi2600 needs less electrons by that factor to create the same digital signal? Could explain the significantly different noise characteristics of both sensors and the much higher sensitivity of the imx581. |
