221201 - ZWO ASI2600MC-Pro
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EQUIPMENT: camera=ZWO ASI2600MC-Pro CMOS |
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ZWO introduced the ASI2600MC-Pro CMOS camera in October 2021. Although it initially suffered from an oil-leak problem, ZWO was successful correcting the issue, and addressing customers' concerns. Since then, it (and its big full-frame brother, the ASI6200MC-Pro) has become a block buster camera among the AP community because of several new innovations; including its back-lit sensor technology, high sensitivity, low noise, and large sensor. CNP Astronomy acquired one in December of 2022 after ZWO had successfully addressed the oil-leak problem; and, it has been an extremely beneficial addition to the equipment arsenal. As a result, the quality of image captures instantly made a quantum-leap forward.
So, why acquire / use this camera over the modified Nikon DSLR used up to this point? ...it's a great question. Another more general re-statement of the same question can be seen regularly across the online forums... "Why use a dedicated astronomy camera? Doesn't a DSLR perform just as well?" These questions go directly to the heart of the typical next logical step one might consider on the trek forward to improving image quality. These cameras aren't $cheap; one must be diligent to learn and weigh all the Pros and Cons before making the choice to acquire one. The answers are derived from many aspects of the basic elemental function of digital camera operation, particularly when used for long-exposure nighttime astrophotography.
1) As mentioned elsewhere, DSLR cameras are designed for the short, sub-second exposures typically associated with daytime photography. When forced into the world of long-exposure AP, they can be made to perform as intended; but, they do so with some shortcomings. ...the first and foremost of which is electronic noise in the resulting images. Many, many image processing techniques have been developed in recent years to deal with this noise; and, many of them are very effective. But arguably, the most universal truth about AP image processing says, "less is better". There have been more than a few images destroyed by too heavy of an approach to removing noise caused by the camera. If one can significantly reduce the production of noise at its source, then much less attention has to be given to it later in post-processing. Dedicated astro-cams like the ASI2600MC-Pro are designed for long exposures. One aspect of this design is the inclusion of an on-board cooler built directly into the sensor assembly to keep the sensor cool during operation. (This is actually a new-tech redesign of the forerunner CCD cooling technology.) When a DSLR is used as intended for daytime short-exposure photography, there's not much need to cool the sensor. The short exposures simply don't produce much heat in the sensor. But when used in the long-exposure world of AP, DSLR sensors can get quite hot, and the ensuing noise levels increase significantly as a result. The source of the heat is the bias current used to energize the sensor, turning it 'on' to perform its function of capturing and converting light photons to electronic signal. The issue can be particularly pronounced in the summertime when outside ambient temperatures stay elevated at night making it difficult for a camera to dissipate its heat. Modern, cooled astro-cams are designed to mitigate this malady. The ASI2600MC-Pro, in particular, is renowned for its reduction in noise levels, particularly the noisy build-up often seen either around the edges, or in the form of 'banding' across the middle of DSLR images called "amp-glow".
2) The manufacturer of the sensor (Sony IMX571) has developed the capability for camera builders to plug-in to a new "Back-Lit" technology; and, ZWO has taken full advantage of it. This technology allows the captured data to be read from the sensor pixels in parallel and bundled into large "packages" before sending them off for external storage and processing. This is as opposed to the sequential reading of older-tech DSLR sensors. The result is much faster reading of the data, further reduction of heat, and significant reduction in "Read Noise" lowering the total overall noise generated by the camera.
3) The IMX571 renders color in 16 bit hexadecimal wording. This compares to 8 bit for older DSLR cameras (more than ~10 years old); and, 12-14 bit for newer DSLR's. This translates into more accurate color rendition and nearly complete elimination of color banding by the 2600MC-Pro. ...both of which can be problematic for a DSLR.
4) The full-well depth capacity of the pixels on the IMX571 is rated at 50 ke- ; being a measure of the amount of electronic signal the pixel wells can "hold" (in between read-outs) before they completely saturate and spill-over to adjacent pixels. This has a bearing on the amount of "bloat" frequently seen in the stars of AP images. Stronger control of this bloating (deeper pixel wells) results in "tighter" stars and finer overall detail.
5) The ASI2600MC-Pro boasts an 80% quantum efficiency. ...being a measure of how completely it converts photons of light to electronic signal. This is extremely high; much better than the best DSLR's that run in the range of 55-65% efficient. (...older models can run as low as 35%.) This higher efficiency translates into better dynamic range in the resulting images.
6) The astro-modification process performed on many DSLR cameras to remove the daytime photographic IR-cut filter definitely helps 'improve' a DSLR for use in AP. But the dedicated, cooled astro-cams come with this improvement already built-in by default. In particular, the ASI2600MC-Pro comes with a nighttime astronomical (...not daytime photographic) UV/IR-cut filer with anti-reflective properties permanently fixed in front of the sensor. ...it serves two purposes - 1) to provide UV/IR-cut capability (...further reduces star bloat), and 2) to provide protection from dust on, and physical damage to the sensor.
7) One small feature that is often overlooked is that the ASI2600MC-Pro has a dew heater mounted just outside of the UV/IR-cut filter to prevent dew accumulation on the outside of the filter glass. It's somewhat counter intuitive to think that there is a cooler built in to the sensor assembly, and a heater built into the front end of the camera; but, that's exactly what it has. They are physically separate from each other so one has no real impact on the other. But with that said, there is no need to put-on a dew heater strap in front of the camera, particularly in the wintertime, because of this feature.
8) Finally, and as already mentioned, the ASI2600MC-Pro is not a $cheap camera. But with that said, it DOES represent a SIGNIFICANT reduction in $cost from the CCD technology that was so popular thru the 2000's and 2010's. ...so much so, in fact, that CMOS has successfully relegated the CCD to only the research and scientific communities; removing it almost completely from the amateur consumer market. It is from this perspective that it can now be said, CMOS is easily within reach of the common man.
Some of the shortcomings of the ASI2600MC-Pro include the inability to store images on-board. A separate computer with data storage capability (a laptop PC, miniPC or astronomical computer like the ASI-Air or Primaluce Eagle) has to be connected to capture and store the images. Also, the ASI2600MC-Pro has a completely electronic shutter. No mechanical shutter is present (...there is no shutter 'button'). While helping to reduce the amount of "shake" caused by moving mechanical parts, this electronic version cannot be actuated without being connected to an external computer loaded with software appropriate for operating the camera. And finally, due mostly to the on-board cooler and dew heater, the ASI2600MC-Pro is somewhat of a power hog. It requires a dedicated 12vdc power supply capable of delivering a minimum of 5 amps current. Anything less, or attempts at "sharing" the power supply with other on-board electronics, results in dramatically increased likelihood the camera could malfunction due to low voltage.
Despite these deficiencies, the ZWO ASI2600MC-Pro is the camera of choice. It is ideal for capturing very detailed and dynamic images of the night sky; and does so with less noise, more dynamic range, and with finer detail than its DSLR cousins. CNPAstronomy has managed to produce a few 'fine' astronomical images since acquiring one, due in large part to the incorporated innovations. If one can muster the $resources required; it comes highly recommended.
So, why acquire / use this camera over the modified Nikon DSLR used up to this point? ...it's a great question. Another more general re-statement of the same question can be seen regularly across the online forums... "Why use a dedicated astronomy camera? Doesn't a DSLR perform just as well?" These questions go directly to the heart of the typical next logical step one might consider on the trek forward to improving image quality. These cameras aren't $cheap; one must be diligent to learn and weigh all the Pros and Cons before making the choice to acquire one. The answers are derived from many aspects of the basic elemental function of digital camera operation, particularly when used for long-exposure nighttime astrophotography.
1) As mentioned elsewhere, DSLR cameras are designed for the short, sub-second exposures typically associated with daytime photography. When forced into the world of long-exposure AP, they can be made to perform as intended; but, they do so with some shortcomings. ...the first and foremost of which is electronic noise in the resulting images. Many, many image processing techniques have been developed in recent years to deal with this noise; and, many of them are very effective. But arguably, the most universal truth about AP image processing says, "less is better". There have been more than a few images destroyed by too heavy of an approach to removing noise caused by the camera. If one can significantly reduce the production of noise at its source, then much less attention has to be given to it later in post-processing. Dedicated astro-cams like the ASI2600MC-Pro are designed for long exposures. One aspect of this design is the inclusion of an on-board cooler built directly into the sensor assembly to keep the sensor cool during operation. (This is actually a new-tech redesign of the forerunner CCD cooling technology.) When a DSLR is used as intended for daytime short-exposure photography, there's not much need to cool the sensor. The short exposures simply don't produce much heat in the sensor. But when used in the long-exposure world of AP, DSLR sensors can get quite hot, and the ensuing noise levels increase significantly as a result. The source of the heat is the bias current used to energize the sensor, turning it 'on' to perform its function of capturing and converting light photons to electronic signal. The issue can be particularly pronounced in the summertime when outside ambient temperatures stay elevated at night making it difficult for a camera to dissipate its heat. Modern, cooled astro-cams are designed to mitigate this malady. The ASI2600MC-Pro, in particular, is renowned for its reduction in noise levels, particularly the noisy build-up often seen either around the edges, or in the form of 'banding' across the middle of DSLR images called "amp-glow".
2) The manufacturer of the sensor (Sony IMX571) has developed the capability for camera builders to plug-in to a new "Back-Lit" technology; and, ZWO has taken full advantage of it. This technology allows the captured data to be read from the sensor pixels in parallel and bundled into large "packages" before sending them off for external storage and processing. This is as opposed to the sequential reading of older-tech DSLR sensors. The result is much faster reading of the data, further reduction of heat, and significant reduction in "Read Noise" lowering the total overall noise generated by the camera.
3) The IMX571 renders color in 16 bit hexadecimal wording. This compares to 8 bit for older DSLR cameras (more than ~10 years old); and, 12-14 bit for newer DSLR's. This translates into more accurate color rendition and nearly complete elimination of color banding by the 2600MC-Pro. ...both of which can be problematic for a DSLR.
4) The full-well depth capacity of the pixels on the IMX571 is rated at 50 ke- ; being a measure of the amount of electronic signal the pixel wells can "hold" (in between read-outs) before they completely saturate and spill-over to adjacent pixels. This has a bearing on the amount of "bloat" frequently seen in the stars of AP images. Stronger control of this bloating (deeper pixel wells) results in "tighter" stars and finer overall detail.
5) The ASI2600MC-Pro boasts an 80% quantum efficiency. ...being a measure of how completely it converts photons of light to electronic signal. This is extremely high; much better than the best DSLR's that run in the range of 55-65% efficient. (...older models can run as low as 35%.) This higher efficiency translates into better dynamic range in the resulting images.
6) The astro-modification process performed on many DSLR cameras to remove the daytime photographic IR-cut filter definitely helps 'improve' a DSLR for use in AP. But the dedicated, cooled astro-cams come with this improvement already built-in by default. In particular, the ASI2600MC-Pro comes with a nighttime astronomical (...not daytime photographic) UV/IR-cut filer with anti-reflective properties permanently fixed in front of the sensor. ...it serves two purposes - 1) to provide UV/IR-cut capability (...further reduces star bloat), and 2) to provide protection from dust on, and physical damage to the sensor.
7) One small feature that is often overlooked is that the ASI2600MC-Pro has a dew heater mounted just outside of the UV/IR-cut filter to prevent dew accumulation on the outside of the filter glass. It's somewhat counter intuitive to think that there is a cooler built in to the sensor assembly, and a heater built into the front end of the camera; but, that's exactly what it has. They are physically separate from each other so one has no real impact on the other. But with that said, there is no need to put-on a dew heater strap in front of the camera, particularly in the wintertime, because of this feature.
8) Finally, and as already mentioned, the ASI2600MC-Pro is not a $cheap camera. But with that said, it DOES represent a SIGNIFICANT reduction in $cost from the CCD technology that was so popular thru the 2000's and 2010's. ...so much so, in fact, that CMOS has successfully relegated the CCD to only the research and scientific communities; removing it almost completely from the amateur consumer market. It is from this perspective that it can now be said, CMOS is easily within reach of the common man.
Some of the shortcomings of the ASI2600MC-Pro include the inability to store images on-board. A separate computer with data storage capability (a laptop PC, miniPC or astronomical computer like the ASI-Air or Primaluce Eagle) has to be connected to capture and store the images. Also, the ASI2600MC-Pro has a completely electronic shutter. No mechanical shutter is present (...there is no shutter 'button'). While helping to reduce the amount of "shake" caused by moving mechanical parts, this electronic version cannot be actuated without being connected to an external computer loaded with software appropriate for operating the camera. And finally, due mostly to the on-board cooler and dew heater, the ASI2600MC-Pro is somewhat of a power hog. It requires a dedicated 12vdc power supply capable of delivering a minimum of 5 amps current. Anything less, or attempts at "sharing" the power supply with other on-board electronics, results in dramatically increased likelihood the camera could malfunction due to low voltage.
Despite these deficiencies, the ZWO ASI2600MC-Pro is the camera of choice. It is ideal for capturing very detailed and dynamic images of the night sky; and does so with less noise, more dynamic range, and with finer detail than its DSLR cousins. CNPAstronomy has managed to produce a few 'fine' astronomical images since acquiring one, due in large part to the incorporated innovations. If one can muster the $resources required; it comes highly recommended.