Choosing Equipment for EAA and Astrophotography Systems Part 4: Astronomy Cameras

■ About dedicated astronomy cameras

Basically, please assume that the larger the sensor size, the higher the performance. Also, the larger the area per pixel (pixel size), the better the high-sensitivity image quality. Therefore, for the same sensor size, models with lower pixel counts have better high-sensitivity performance. This can be said to be the most important performance for photographing dark celestial objects.
However, when viewed as an image, higher pixel counts look more detailed, and the image quality is less likely to degrade even if cropped to some extent. Where you choose to balance these conflicting performance characteristics depends on individual considerations such as the target celestial object, focal length, sensor size, resolution based on aperture, and viewing size.
For astrophotography, since long exposures are performed, a cooled camera is recommended.

Considering control via ASIAIR, ZWO cameras are currently the only choice.
If you are using a laptop and SharpCap, cameras from Player-One or SVBONY are also options. (SVBONY's SC001 and SC311 have built-in WiFi functions and can send still images and videos to a smartphone, but they cannot be used for EAA because the app lacks a live stacking function. Currently, they cannot be used with SharpCap either.)

■ Choosing a camera to match the celestial object

As written in the basics section, an important indicator when choosing a camera is the sensor size multiplier. It is important to choose an astronomy camera by considering the sensor size multiplier so that the combined focal length is optimal for the target celestial object.
The sensor size multipliers for each camera are: Full-frame 1x, APS-C 1.5x, 4/3 size 2x, 1-inch 2.7x, 1/1.2-inch 3.24x, 1/1.8-inch 4.86x, 1/1.9-inch 5.13x, 1/2.8-inch 7.56x, and 1/3-inch 8.1x.
If you are photographing celestial objects of vastly different sizes with the same telescope, it is a good idea to have multiple astronomy cameras with different sensor sizes and swap them according to the object.

(In the case of planetary photography, cameras with a pixel size of 2.9μm are often used. In that case, it seems that the telescope is often set to a combined F-number of about F20 to F40 using a high-quality Barlow lens.)

■ About back focus (flange back)

When attaching a correction lens such as a flattener or reducer to a telescope, or if a correction lens is built into or behind the telescope's drawtube, or if the telescope has a short drawtube extension, the distance from the camera's sensor surface to the rear end of the telescope must be 55mm. Unless this back focus is approximately 55mm (±2mm is within the acceptable range), the performance of each correction lens cannot be utilized.
In the case of ZWO, there are cameras with 17.5mm and 12.5mm. For the 6.5mm one, the included extension tube is 11mm, so attaching it makes it 17.5mm. Therefore, a ring with a remaining length of 37.5mm or 42.5mm is required.
* For telescopes that do not use correction lenses, extension rings are not necessary. Adjust by extending the drawtube.

・Drawtube thread diameter

The rear end of many telescopes from overseas manufacturers is M48.
(Askar, Sharpstar, WilliamOptics, SkyWatcher, SVBONY, Celestron, etc.)
On the other hand, domestic manufacturers have various standards; Takahashi is M54, Vixen is M60, and Borg is M57, so a ring to convert to M48 is required.
The astronomy camera connection part is often M42 (thread pitch P0.75). (In the case of ZWO full-frame cameras, it is M54)
(The M42 mount standard for old MF SLR cameras has a thread pitch of P1.0, so please be careful not to make a mistake when purchasing a ring. Astronomical equipment almost always uses a P0.75 thread pitch.)

・About extension rings

ZWO cooled cameras come with extension rings.
In the case of ZWO non-cooled cameras, extension rings are not included, so the following 2-3 rings are required.

① ZWO T2-M48-16.5 M42-M48 extender ring 16.5mm
② ZWO T2-EXT-21 M42-M42 extender ring 21mm
③ 5mm ring from the 8-piece extension tube set for astronomical telescopes (M42×P0.75) (Required if the astronomy camera's flange back or back focus is 12.5mm.)

With the three items ① to ③ above, the optical path length from M48 to M42×P0.75 becomes 42.5mm.
③ is unnecessary for cameras with a flange back of 17.5mm.
Instead of the 16.5mm ring in ①, a ZWO OAG (Off-Axis Guider) can also be used.
Instead of the 21mm ring in ②, a filter drawer (ZWO FD-M42-II, SVBONY SV226, etc.) or ZWO EFW can also be used.

Alternatively, there is a method to use SVBONY's SV109 (24-35mm variable) to connect an M48-M42 adapter and the 15mm piece from the above 8-piece extension tube set to make an optical path length of 42.5mm.

◆ Non-cooled color (For EAA. Recommended for beginners)

ZWO ASI585MC

1/1.2-inch 8.14 megapixels (3840×2160)
Flange back 6.5mm, body weight 126g, 61,200 yen

My top recommendation, if you can stretch your budget a little, is the ASI585MC.
The 1/1.2-inch sensor size expands the range of telescope choices. Since the pixel count is 4K, I would like to use it with a 60mm class telescope. It has a reputation for high sensitivity in the infrared range, making it the perfect camera for EAA or photographing nebulae. The pixel size is 2.9μm.

ZWO ASI664MC

1/1.8-inch 4.15 megapixels (2704×1536)
Flange back 12.5mm, body weight 126g, 45,900 yen

The runner-up is the slightly cheaper ASI664MC. The sensor size is 1/1.8-inch with 4 megapixels, and the pixel size is 2.9μm. Since the area per pixel is slightly larger, it has high sensitivity and is resistant to noise. This is also a camera with high sensitivity in the infrared range. It is also suitable for planetary photography.

ZWO ASI662MC

1/2.8-inch 2.07 megapixels (1920×1080)
Back focus 12.5mm, body weight 126g, 22,900 yen

For a low-budget introduction to EAA, the ASI662MC is a safe bet in terms of price.
Although it has a low pixel count, the pixel size is 2.9μm, making it a sensitivity-focused camera that is easy to handle. However, perhaps due to the sensor's high sensitivity in the infrared range, actual images tend to look quite red.
Since the sensor size is 1/2.8-inch, you will need a telescope with a fairly short focal length. (This is the sensor used in the Seestar S30.)
Conversely, you can take advantage of this sensor size when targeting smaller celestial objects. It has become a standard sensor size, especially for planetary imaging.

ZWO ASI385MC

1/1.9-inch 2.13 megapixels (1936×1096)
Back focus 12.5mm, body weight 120g, 51,000 yen

Although this is a previous-generation sensor, the 3.75μm pixel size is larger than the current generation's 2.9μm, boasting high sensitivity and low noise. (Same pixel size as the APS-C ASI2600MC PRO)
However, since it seems prone to amp glow, taking dark and flat frames might be essential.
If you can buy it cheaply, this model is also highly recommended for EAA.

ZWO ASI294MC

4/3-inch 11.69 megapixels (4144×2822)
Back focus 6.5mm, body weight 140g, 107,300 yen

If you want to get a good camera from the start, the 4/3-inch ASI294MC with its larger sensor is versatile and has a proven track record, so choosing this one is a good idea. It also expands your options for choosing a telescope. The pixel size is very large at 4.63μm. It can be used effectively for both EAA and astrophotography.

ZWO ASI678MC

1/1.8-inch 8.14 megapixels (3840×2160)
Back focus 12.5mm, weight 126g, 45,900 yen

This is the sensor used in the DWARF3.
The pixel size is quite small at 2.0μm, but if you want high resolution, it might be an option.
Because it has low sensitivity, it might be difficult as an entry-level EAA camera.

ZWO ASI178MC

1/1.8-inch 6.0 megapixels (3096×2080)
Back focus 12.5mm, body weight 126g, 42,900 yen

With a 1/1.8-inch sensor and a pixel size of 2.4μm, it is a balanced model with somewhat low sensitivity and decent resolution. It seems usable for low-cost astrophotography.

ZWO ASI183MC

1-inch 20-megapixel (5496×3672)
Back focus 6.5mm, body weight 140g, 76,600 yen

This is a 1-inch high-resolution, low-sensitivity sensor. The pixel size is 2.4μm, the same as the ASI178, so it seems a bit difficult to handle.
Recommended for those who want to take photos of bright celestial objects and need high resolution.

ZWO ASI715MC

1/2.8-inch 8.4-megapixel (3864×2192)
Back focus 12.5mm, body weight 126g, 30,500 yen

With a 1/2.8-inch sensor and 8 megapixels, the pixel size is quite small at 1.45μm, making it low-sensitivity and difficult to handle. However, taking advantage of its small sensor size, it is sometimes used for photographing planets and small, bright celestial objects.
It is not at all suitable for electronic assisted astronomy, so I cannot really recommend it to beginners.

◆ Cooled Color (For long-exposure photography)

For long-exposure astrophotography, a cooled camera that can reduce thermal noise from the sensor is recommended.

ZWO ASI2600MC Pro

APS-C 26-megapixel (6248×4176)
Back focus 17.5mm, body weight 700g, 230,000 yen

If you are going to spend a high amount on a cooled camera anyway, I think the APS-C size ASI2600MC Pro is within reach. If you buy this, you won't have any complaints for a while, right?
The pixel size is 3.76μm.
For those who are serious about astrophotography, I recommend the monochrome version (ASI2600MM Pro).
There is also the ASI2600MC Duo, which has a built-in guide camera (equivalent to the ASI220MM-Mini).
In addition, there is the ASI2600MC AIR, which also has built-in ASIAIR functionality. (This can significantly reduce wiring.)

ZWO ASI071MC Pro

APS-C 16-megapixel (4944×3284)
Back focus 17.5mm, body weight 640g, 170,300 yen

This is an affordable(?) APS-C size, lower-resolution version. The pixel size is 4.78μm, which is slightly larger in area than the ASI294MC PRO below. It is also perfect for electronic assisted astronomy.
There is a 1μm difference in pixel size compared to the ASI2600MC PRO. Although the pixel count is 10 million pixels lower, it is a difficult choice between prioritizing sensitivity and dynamic range versus pixel count. The ASI2600MC PRO is a newer generation and incorporates a zero-amp glow circuit. The ASI071MC PRO is equipped with 256MB of DDRIII to suppress amp glow caused by transfer delays, but it is slightly inferior.

ZWO ASI294MC Pro

4/3-inch 11.69-megapixel (4144×2822)
Back focus 6.5mm, body weight 410g, 153,300 yen

For a cooled camera, the standard choice is the 4/3-inch ZWO ASI294MC Pro. It offers a good balance between sensor size and pixel count. The pixel size is 4.63μm, which is larger than the ASI2600. However, the sensor is now from a slightly older generation.

ZWO ASI533MC Pro

1-inch 9 million pixels (3008×3008)
Back focus 17.5mm, body weight 470g, 122,600 yen

If you are on a budget and want a cooled camera, the ASI533MC PRO is recommended for its good balance. However, it has a somewhat unique 1:1 square aspect ratio. The pixel size is 3.76μm, the same as the ASI2600MC PRO.

ZWO ASI2400MC Pro

Full-frame 24 million pixels (6072×4042), back focus 17.5mm, body weight 700g, 460,200 yen

It has a low pixel count for a full-frame sensor, but it is a high-sensitivity model that boasts a large pixel size of 5.94μm.

ZWO ASI6200MM Pro

Full-frame 61.17 million pixels (9576×6388), back focus 17.5mm, body weight 700g, 582,899 yen

Go ahead and get the top-of-the-line full-frame model.
If you're going full-frame anyway, maybe try monochrome for SAO composite imaging?
The pixel size is 3.76μm, the same as the ASI2600MC PRO, but it is four times more sensitive than the RGGB filter color model.

ZWO ASI183MC Pro

1-inch 20 million pixels (5496×3672)
Back focus 6.5mm, body weight 410g, 121,500 yen

A 1-inch high-resolution camera. This is for those who need high pixel counts in a low-cost cooled camera. Since the pixel size is small at 2.4μm, it has lower sensitivity for a cooled camera. It is a viable option if you are targeting bright celestial objects.

ZWO ASI585MC Pro

1/1.2-inch 8.29 million pixels (3840×2160)
Back focus 17.5mm, body weight 470g, 91,900 yen

This is the most affordable cooled model. While its pixel size of 2.9μm is small for a cooled camera, it is equipped with the latest sensor that features high sensitivity in the infrared range. It is also suitable for planetary imaging. If you don't have a large budget but need a cooled camera, this might be the best choice.