Unveiling the QHY5III715C and QHY5III678M: Test and Impressions

Unveiling the QHY5III715C and QHY5III678M: Test and Impressions

Author: Michael Wong

Review on QHY5III678M and QHY5III715C


The focal ratio that allows planetary imaging to achieve the optimal sampling rate is five times the camera pixel size in micrometers. In the past, camera pixel sizes were approximately around 3-5 micrometers, resulting in optimal focal ratios between 15-25. Even when using a native F/10 Schmidt-Cassegrain Telescope (SCT), a Barlow lens was necessary. However, now cameras with pixel sizes of 2 micrometers or lower have emerged in the market, leading to optimal sampling rate focal ratios of 10 or lower. This allows us to directly capture planetary images using an SCT or even an F/7 refractor telescope at their native focal points.

I have received these two cameras for quite some time, but the weather in Hong Kong has been unfavorable. Yesterday evening, we had a rare clear sky, and I conducted a preliminary test of the two cameras: the QHY5III678M (2-micrometer pixel size) and the QHY5III715C (1.45-micrometer pixel size)

QHY5III678M Test

The QHY5III678M performs exceptionally well in terms of signal-to-noise ratio in the visible spectrum, definitely surpassing the QHY5III290M and QHY5III462C. The initial impression of using it with an IR685 filter is also very good. I will not try it with a methane filter until Jupiter rises higher. Its frame rate is not as high as the QHY5III290M or QHY5III462C and is similar to other QHY cameras with a Type-C interface. It can reach approximately 100 FPS on my 6th generation i7 laptop with a 700 x 700 ROI. The overall impression of the QHY5III678M is no less than, or even better than, the QHY5III200M. Combined with the advantage of not requiring a Barlow lens when using an SCT, it is undoubtedly a winner. It will become my primary monochrome camera.

QHY5III715C Test

The QHY5III715C is a pleasant surprise. It is extremely affordable, yet its sensitivity is comparable to, or even better than, the QHY5III462C. The camera has an IR-blocking window, so I haven’t tried IR imaging yet. I will replace the window later and attempt IR imaging. If you are looking for a planetary imaging setup without the need for a Barlow lens or a filter wheel, this is definitely a good choice. Although I don’t have a QHY5III678C, I have a camera of the same model from another manufacturer. It seems that the color version of the 678 performs better in terms of signal-to-noise ratio, but considering the price and pixel size, the QHY5III715C is definitely the winner.

The New Era of Planetary Imageing without a Barlow Lens

After a long period of technological development, we have now entered a new era of planetary photography that no longer requires a Barlow lens. This will greatly enhance the convenience for astronomy enthusiasts in the field of planetary imaging. In the future, we have every reason to anticipate the emergence of more cameras with smaller pixel sizes and higher sensitivity, providing us with even more exciting astronomical photography experiences.


Review: A Second Look on QHY5III678M


I had the wonderful opportunity to revisit and test the QHY5III678M during the few days surrounding Jupiter’s opposition. Over the course of three consecutive nights with bice seeing conditions, I thoroughly explored its capabilities, and now I am delighted to share my experience and impressions.

My telescope of choice is a 14-inch Schmidt-Cassegrain Telescope (SCT), a reliable instrument for planetary imaging. Traditionally, achieving optimal sampling in planetary imaging necessitates the use of a 2x Barlow lens. However, thanks to the QHY5III678M’s small pixel size, I could forgo the Barlow lens entirely, granting it a significant advantage over other models like the QHY5III462M and QHY5III200M. The camera’s ability to capture fine details and achieve high-resolution imaging without the need for a Barlow lens is truly commendable.

The QHY5III678M truly excels in delivering exceptionally low levels of noise and high sensitivity. Equipped with a Starvis 2 chip, this camera effectively suppresses noise even at high-gain settings, resulting in clean and crisp images. During my imaging of Jupiter, I achieved optimal results with a gain of only 20% and a 10ms exposure time using an F/10 imaging configuration. The low noise levels exhibited by the QHY5III678M are comparable to other cameras featuring Starvis 2 chips, solidifying its performance.

Furthermore, the QHY5III678M impressively demonstrates good infrared (IR) sensitivity, further enhancing its capabilities for planetary imaging. I conducted tests using an IR685 filter, and the camera effectively captured infrared light, yielding pleasing results.

Of particular note is the QHY5III678M’s exceptional sensitivity to methane band (CH4) imaging. Utilizing bin 1, a 25ms exposure, and 80% gain, the camera produced excellent results that were comparable, and in some instances slightly superior, to those achieved with the QHY5III200M. This capability significantly reduces the total exposure time required for CH4 imaging, making the QHY5III678M an invaluable tool for planetary imagers.

In conclusion, the QHY5III678M is an outstanding imaging camera, specifically tailored for planetary astrophotography. Its ability to reach the resolution limit without the need for a Barlow lens, coupled with its low noise levels and high sensitivity, ensures the capture of intricate details within planetary objects. The camera’s impressive IR sensitivity and its outstanding performance in methane band imaging further elevate its value for planetary imaging enthusiasts. If you are a dedicated planetary astrophotographer in search of a top-notch camera, the QHY5III678M undoubtedly represents a worthwhile investment.