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7/5/2023
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Working on a new rig using hyperstar on a C6 and a new camera. The fast optics promises to collect data much faster than regular optics using this technology. Can a multitude of "fast subs" together with post processing using pixnsight with BlurExterminator and NoiseExterminatornmake the benefit of a cool camera unnecessary? In other words, can I save hundreds of dollars and attain a final product similar to a cool camera capture?
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11.34
7/5/2023
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The answer to your question depends on your processing and data collection skills and how much is your time really worth. It also depends on what astrophotography means to you. Having better equipment can certainly make the process of resolving issues during pre- and post-processing easier. With higher quality equipment, you may spend less time using the retouching tools you have mentioned to fix issues in your data. (Actually this is true for any other software tool which is not over-promoted from various influencers  ).A cooled camera can be more expensive than its uncooled counterpart but it offers the ability to obtain data in a controlled manner, which in my humble opinion, it fully justifies the extra cost. |
1.51
7/5/2023
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You really aren't saving much buying an uncooled camera. As an example, an uncooled 533MC is $600 new. The cooled version goes for $675 in like-new condition on the used market. And when you inevitably want to go for a bigger sensor you'll take a heavy loss selling an uncooled camera, if you find a buyer at all.
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3.81
7/5/2023
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If you already have the uncooled camera and just want to avoid buying new, you could try something like this https://rouzastro.com/product/active-cooling-kit-for-zwo-asi-uncooled-cameras/ I've never tried it, but I know Rouz and he's obsessive about testing and QC for anything he puts out there I think there are some comparisons for what you are considering out there. (1x 20min vs 20 x 1min subs) If I remember correctly, the 20x1min method gets you about 70% of the way there. Definitely search around though as somebody out there has definitely put time into this |
13.13
7/6/2023
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Just look at today's (07/06/2023) IOTD. The camera is not cooled. If you like, you can also take a look at my gallery. It's full of images taken with uncooled camera, from more than 10 years ago.
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7/6/2023
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For mine, the biggest benefit of the cooled camera is being able to calibration frames rather than needing to take a new set at each session to deal with temperature fluctuation. I'm using the same setup as you have there but with a QHY183c which is a cooled camera at a reasonable price. If you had the choice between a 533mc uncooled, or a 183mc cooled at the same cost, I'd go for the latter on your setup.
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9.81
7/6/2023
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Nick Grundy: I've done a mod very similar to what he's selling. Yes it helps cool the camera, but I highly recommend against them based on my experience. Unless you cut the camera open, you're effectively only cooling the case. It will drop temps marginally, however it will also create massive amounts of dew on the outside of the camera, depending on your environment. That dew will also slowly creep up to your image corrector as the night goes on. It sounded great in theory but far more issues created than it fixed. Edit: sorry I just realized he's only using a heatsink, not a peltier system. The effect is extremely marginal without peltier. |
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7.44
7/6/2023
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Everything has pros and cons. jose ortega: The cooled camera allows you to a) minimize thermal signal and noise b) predictably calibrate away most of the remaining thermal signal. This is true regardless of your optics. Conversely, you can achieve very similar results with an uncooled camera, it just takes a lot more time and effort. Again, this is true regardless of your optics. In other words, if you put a cooled camera on your new rig, higher quality results will be easier to achieve, short exposures or not. Now, a Hyperstar makes the C6 behave as a telescope with a 150mm aperture and f/2 focal ratio, which means an effective f/2 focal length = 300mm. The rig is able to collect 8 times more light (in the same time) as a humble 60/360 apochromatic refractor. With 8 times shorter exposures, the thermal stuff become much less of an issue. But there is other stuff to consider. A C6 with a hyperstar means about $2.3K to get slightly wider field of view than a 60/360 apo which will weigh/cost about half as much (cooled camera included) and is guaranteed to deliver an immensely better image in terms of aberrations. Not because "apos are cool" or whatever. Simply because it is much easier to get a sharp, aberration-free image at f/6 than it is at f/2. Put simply, if I wanted a cost-efficient way of imaging at around 300mm focal length, getting a C6 with a Hyperstar and saving up from the camera would not be the first thing that springs to mind. YMMV of course, for example of you already have the scope from before. Cheers, D. |
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11.34
7/6/2023
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Someone has to consider the added complexity of a setup based on a Hyperstar design, especially if he is a novice astrophotographer. Things like cable management, obtaining good flats, tweaking with tilt and collimation and managing stray light and reflections brings me in mind the wisdom of the ancient astrophotographers praising the bliss and happiness of the refractor operator  !If your new setup is inspired from the youtuber I have in mind, keep in mind that he settled on the C6 + Hyperstar after many years of experience with a variety of equipment. |
8.85
7/6/2023
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jose ortega: The answer is, am afraid, no. Been there, done that. That doesn't mean that un-cooled camera cannot be used. They can and I do use them (e.g., DSLR) as long as there is some predictability in the amount of thermal noise and that you dither A LOT (which is expensive in its own way). BX won't help you there in any way, shape or form and NX not that much either. There is no substitute to actual good, low-noise data. |
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7/6/2023
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Another factor is where do you live. Where I live, the nights are never above 15*C for 9-10 months of the year but if you live in Arizona and have nights that peak over 30*C then you may need cooling. It is also camera dependent. I have a QHY294M and I would never want to have that sensor in an uncooled version. It NEEDS good dark frames due to amp glow, the 183 is similar in that respect. But my Sony A6000 can get away without darks and certainly less than perfect darks. The cooling allows me to have an nice easy darks and darkflats library.
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1.51
7/6/2023
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Wei-Hao Wang: Maybe OP can clarify but I interpret the question to be whether to go with a cooled or uncooled astro camera. DSLRs have big, high-quality sensors that are far better and more versatile than the $300-400 uncooled ZWO cameras that I assume the OP has in mind. |
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13.13
7/6/2023
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Wei-Hao Wang: Hi, Nowadays many astro cameras use the same Sony CMOS sensors that are also used in DSLR/mirrorless digital cameras. In terms of sensor characteristics, they are about equally good. In terms of thermal properties (and hence the question of cooling or not), arguably the astro cameras (typically with metal housing and cooling windows) should be better, even without active cooling. |
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7/7/2023
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The dark current noises is very low nowadays . So i think that we do not need anymore to cool our camera BUT we need to do a hot/cold pixel map . And there is a very strange thing with the new sensor : the grey pixel . Some pixels that are not hot nor cold but have a medium value of ADU with temperature . and there is a lot ! just check a dark of a new sensor camera , you will notice that the dark are not "clean" like with a lot of noise . This is the grey pixels . then the hot pixel map shall be ajusted for different temperature it seems ...Then just do darks like before.;).. But in a very short time from now , Dark will be useless i guess. For now Bias is more important than Dark . And if you do only one calibration : FLAT !
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13.46
7/7/2023
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Joe Linington: I would certainly agree that the 294 sensor would be unusable without cooling. With respect to whether a cooled camera makes sense or not in a different case in the absence of severe amp glow - it is a question of simple math. Take the dark current curves supplied by the manufacturer and compute the dark current noise at your ambient temperature and exposure length and compare it to shot noise and read noise. If it is small, dark current noise is not significant. There is still a benefit to subtracting out average dark current to calibrate out predictable and repeatable variations in baseline pixel values regardless the contribution of dark current noise. |
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7/7/2023
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Joe Linington: That said, I love my 294M, nothing else can provide it's detail or resolution for the cost. I like it so much I'm saving for a second one. Of course there are major trade off's. |
8.79
7/7/2023
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Can you create nice images with uncooled cameras? Sure. Does that make cooled cameras obsolete? Nope.
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8.85
7/7/2023
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Jonny Bravo: Couldn't agree more. |
25.47
7/7/2023
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Team Atlaskies: The amount of dark current per volume of semiconductor is pretty much the same today as it was with CCD cameras. The difference is that the volume of each pixel is now smaller due to smaller pixels and to some extent, back thinning, which result in lower total dark current. CMOS cameras such as those with the popular IMX455 sensor don’t have a low enough dark current contribution that it can be easily ignored. “Grey” pixels are normally called warm pixels and along with hot pixels, they are part of the dark current inherent in the sensor. In fact, all pixels have some low level of “grey” added due to dark current variations across the sensor. Calibrating an image does two key things. First, it subtracts the dark current from the data. In doing so, you increase the contribution of dark noise due to dark current. However, when you use a master dark created from a stack of darks to calibrate a stack of images, the increase in dark noise can be reduced to a VERY small value. (I computed this years ago and I can post the results if you want to see it). Dithering further reduces the contribution of dark noise across the image (spatially). Second, image calibration allows flats to be accurately divided out. Either darks or bias can be used to correct for offsets in the data, but if you want the cleanest possible result, subtracting out the measured dark signal is the best option. And, cooling is what allows this to be done to a high degree of precision. John |
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13.46
7/7/2023
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I guess the way I look at this.. the response of a given pixel in ADU to some input number of photons N at some fixed gain can be given as: Y= M * N +C (+Noise) The values of M and C can vary between pixels. The purpose of dark frame subtraction is to remove and equalize the contribution of C between pixels. Because C depends both on exposure time and temperature, a cooled camera allows this to be done much more repeatably and consistently than an uncooled camera. The purpose of flats is to equalize differences in M between pixels (plus effects from the optical train such as light fall off). |
0.90
7/18/2023
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The other night, I forgot to cool my 2600MC and it imaged at ~20C all night with 120s subs. It was a hot pixel party. I wouldn't recommend it.
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2.41
7/19/2023
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What you save on the camera will have to be spent on SSD and processing time.
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