Product Questions and Answers
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Could you also confirm that the desiccant plug is included in the camera box.
Many thanks for your attention.
A technical drawing of that version can be viewed under:
Both the desiccant tube and the desiccant plug are in the scope of the delivery.
Note: This information was originally listed incorrectly in QHY’s manual that it did have an IR cut window but was later confirmed by QHY that it’s AR only and has been corrected in the manual.
Zum Thema USB settings im SharpCap-Manual:
USB Traffic This controls how fast the camera will try to push data over the USB bus.
Setting a lower value will try to move data faster and give higher frame
rates. Setting a value that is too low can cause:
• dropped frames
• a collapse in frame rate
• or even no frames at all
Ja, es hat einen Einfluss, wie ich sehen konnte! Falls jemand bekannt ist, der speziell hier genauer Bescheid weiß, wäre ich dir für einen entsprechenden Hinweise dankbar. Auch im Internet gibt es viele Hinweise, aber nichts spezifisches für die QHY-Kamera. Zumindest noch nicht gefunden.
Einen langen Thread, in dem auch das Thema USB Traffic behandelt und diskutiert wird, finden Sie hier: https://stargazerslounge.com/topic/389405-qhy268m-qhy268c-users-thread-please-share-your-knowledge-and-tips/
Die von Ihnen gewählte Einstellung von Gain 200 ist auf jeden Fall viel zu hoch. Der Fullwell-Wert und die e/ADU gehen hier gegen Null. Auch die Dynamik leidet bei einer so hohen Gain-Einstellung enorm (nur noch ca. 7Bit). Diese Einstellung hat also nur Nachteile.
Werfen Sie am besten noch einmal einen Blick auf die Übersichten der verschiedenen Charakteristiken bei den jeweiligen Gain Werten. Diese finden Sie auf der Produktseite unter "Die vom Nutzer wählbaren Auslesemodi".
Für helle Objekte wie Sternhaufen oder helle Galaxien wird ein Gain-Wert von 0 / Offset 25 empfohlen. Gerade bei hellen Sternhaufen möchte man einen möglichst hohen Full Well Wert erreichen, damit der Sensor nicht direkt gesättigt wird und die Sterne somit ausbrennen. Hier ist auch der Extended Full Well 2CMS Modus sehr interessant.
Bei dunkleren Objekten, Langzeitbelichtungen mit Schmalbandfiltern oder dunklem Himmel kann der Gain Wert auf 56 erhöht werden, um vom geringeren Ausleserauschen zu profitieren. Insbesondere für die Deep Sky Fotografie ist der Auslesemodus 1 (High Gain Mode) bzw. High Gain 2CMS sehr vorteilhaft, da er ein geringes Ausleserauschen und eine hohe Dynamik bietet.
Alle Gain Einstellungen über 56 sind für die meisten Anwendungen nicht mehr sinnvoll, ab Gain 100 sind fast alle Werte nahe Null.
QHY268 M/C BSI Cooled Medium Size APS-C Camera
Ultra High Resolution, 26 Megapixels, APS-C format
QHY268 is a 26 Megapixel back-illuminated cooled color CMOS camera with 16-bit A/D and 3.76um pixels. The QHY268 is available in both a monochrome and a color version. The sensor size is 23.5mm x 15.7mm (28.3mm Diagonal)
The QHY268M is the first monochrome CMOS camera with an APS-C sensor. The chip has the same functions as the flagship QHY600M:
- USB Re-connection with 12V ON/OFF
- Extended Full Well and Multiple Read Modes
- Random thermal noise suppression
- 20Gb optical fiber transmission (PRO-Version)
- 1GB / 2GB oversized DDR3 memory
- Large programmable FPGA (only PRO)-Version, under development
- Water-cooled option
PRO version can optionally (at extra cost) be delivered with 2 x 10 Gigabit fiber interfaces and a QHY PCIE Kit (#1931116 , € 3050,-) for faster data download. HOWEVER - a grabber card is not necessary to operate the camera, since it is likewise capable to work under USB3.0 connection. Some users may own two or more ethernet compatible cameras but only do operate one camera at a time. In this case just one grabber card needs to be ordered. But for multiple cameras, each to operate with 2X10GB simultaneously, then the same number of grabber cards are needed. More information about the Gigabit interfaces can be found here
The QHY268PRO supports the Trig in/out and the GPS function. There is a 6-pin GPIO connector on the back of the camera. The PRO version can be connected with the QHY GPS Box (#1932500 , € 540,-) to transfer the high precision GPS time stamp to the image head.
Heating plate placement on the QHY268 M/C Camera:
Since June 2023, the position of the heating board of the QHY268M, and since August 2023 of the QHY268C, has been raised by about 5mm, which will decrease the likelihood of fogging. This change will not affect the back focal length calculations or any other function. The mono cameras will use the same adapter kit as before.
Note on the FCCT II for QHY268M/C Camera: The QHY268 mono and color camera with new postion of the heating board (hotplate was raised by QHY by about 5mm) is unfortunately NOT compatible anymore with the Baader FCCT (Filter Changer Camera Tilter) for RASA 8" and QHY cameras (various versions available) .
Mechanically, an adaptation of the FCCT II to the new version of the QHY268M/C is still possible, but due to the adaptation of the heating plate, the backfocus in connection with the FCCT II has shifted by 5 mm. Thus, the optical backfocus can no longer be maintained. We are currently working on an FCCT III to ensure compatibility with the QHY268M/C again. However, the completion will still take some time. The previous versions of the QHY268M (before June 2023) and QHY268C (before 15th August 2023) are still compatible with the FCCT II.
Change in Standard Body Style of the QHY268C Camera:
Since January 2023, the QHY268C body configuration will be the same as the QHY268M camera. That is, both the mono and color cameras will have bodies with the short back focal length design. Previously the QHY268C body had the round dovetail ring on the front. However, the short back focal length design is being made standard for both mono and color 268 cameras in response to dealer and user requests to make the QHY268C more compatible with third party filter sliders, electric focusers, etc. This change is entirely mechanical and results in the QHY268C having only 14.5mm of backfocus instead of 24mm with the dovetail ring and centering ring attachment (CAA-Adapter). In addition to the new mechanical configuration, the QHY268C SBFL now includes a new G1 adapter kit as a standard accessory ( see QHY Adapter Systems). When you need to connect Canon or Nikon lens, you only need to get one Canon/Nikon adapter, not a “kit” like D2 or D3 anymore.
The chip chamber of the QHY268C SBFL is now just as effectively protected against fogging as was the case with the long version with ring dovetail - and those who want to have it completely safe can also add the larger desiccant tube from QHYCCD. QHY calls this now omitted component with the 45° undercut "tilter" because you can rotate the whole camera body with it - but not "tilt" it. The term "ring dovetail" that we still use for such quick clamps, on the other hand, originates from the telescope production of Carl Zeiss Jena and referred there to the so-called "changers" (=quick clamps) that also allowed a rotation of the connected accessories. We still manufacture these changers according to the original Zeiss drawings, but with much more precise fitting dimensions. Please have a look at our heavy-duty quick-change systems, which are available in the connection variants T-2, M48, M68 as well as PlaneWave SecureFit.
Native 16-bit A/D, 65536 Levels
The QHY268 is the CMOS camera with native 16-bit A/D on-chip. The output is real 16-bits with 65536 levels. Compared to 12-bit and 14-bit A/D, 16-bit A/D provides higher sampling resolution. System gain is less than 1e-/ADU with low noise and no sampling error.
Full Well Capacity of 51ke- to > 75 ke- Low Gain Mode
One benefit of the back-illuminated CMOS structure is improved full well capacity. This is particularly helpful for sensors with small pixels.Even with unbinned 3.76µm pixels the QHY268C has a full well capacity of >51ke-. By using one of the binning modes, this can be increased to > 75 ke-.
Ultra-Low Read Noise of less than 2 Electrons at High Gain
The QHY268 PHOTO Version (M and C) has less than one electron of read noise at high gain and 6 FPS high readout speed. The QHY268C PRO has only one electron of read noise at high gain and 6,8 FPS high readout speed.
One electron of read noise means the camera can achieve a SNR>3 at only 3 to 4 photons. This is perfect performance when conditions are photon limited, i.e., short exposures, narrow band imaging, etc., making this large area sensor ideal for sky surveys and time domain astronomy.
Low Dark Current, TE Cooling, Round Body
The QHY268 has extremely low dark current using SONY's Exmor BSI CMOS technology. In addition, the camera uses QHYCCD's proprietary thermal noise reduction technology and 2-stage TE cooling to reduce the dark current noise to extremely low levels.
Best Match for RASA System
The round body and sensor size make this camera ideal for RASA and Hyperstar systems.
The Photographic and Professional Model of QHY268 M/C
Choose between three models: The Photographic Model QHY268 M/C PHOTO or the Professional Model QHY268C PRO. Image quality is identical between the two models.
Photographic Modell QHY268 M/C PH (PHOTO: Professional Model QHY268M/C PRO:
- 6 FPS, full frame, 16-bit images
- 6.8 FPS, full frame, 8-bit image
- Support for ROI at higher frame rates
- 1 GByte DDR3 memory
- 2×10Gigabit optical fiber interface*
- Programmable trigger in/out
- Advanced timing interface for GPS
- 6,8 FPS, full frame, 16-bit images
- Support for ROI at higher frame rates
- Customizable FPGA
- 2 GByre DDR3 memory
*requires a QHY PCIE Kit (#1931116 , € 3050,-) for faster data downloa
6 Selectable Readout Modi (#0 to # 05)
Readout Mode is a new function for the QHY cameras. Different Readout Mode have different driver timing etc and lead to the different performance results. Each readout mode has its advantages and disadvantages. QHY600/QHY268 currently has three readout modes. QHYCCD may add more modes in the future. The Readout mode currently supported by QHY ASCOM Camera Driver and SharpCAP software and the N.I.N.A software. You can find the list box in the software.
Mode # 0
This is the standard readout mode for most applications. A a gain of 25 to 26, the readout noise is only about 7 from 2,5 e-. The readout noise is doesn't change much for a gain between 0 and 25 as well as for a gain between 26 and 60. That's why most users will probably chose either gain 0 or gain 26, because the full well capacity decreases at a higher gain than 26, as well as the dynamic range. At fast optics like f/2 (e.g. RASA), a gain of 0 will probably be most useful. For slower telescopes under a dark sky (and thus longer exposure times), gain 26 is recommended, so that you can profit of the lower readout noise.
# 1 – High-Gain-Mode
This mode is characterised by a low readout noise and a slightly smaller full well capacity. Just like in the standard mode #0, there is a sweet spot for high or low gain. In this mode, the readout noise goes from 3,5 e- to 1,5 e- between gain 55 and 56.
# 1 – Expanded Fullwell-Mode
This mode achieves the highes full-well-capacity. The readout noise is almost independent from the gain setting approximately always at 7 e-. The dynamic range is almost always between 13 and 14 f-stops.
Mode # 3
Mode # 3 is very similar to mode # 2, but at a constantly lower readout noise between 4,5 e- and 5,5 e- (instead of 7,5 e- in mode # 2).
Here are the plots for the different modes:Further detailed information can be found the website of QHYCCD :
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