SBIG STF-8300 (Used)

STF-8300

The STF-8300 cameras are based on ON Semi’s KAF-8300, 8.3 megapixel, full frame CCD.  This CCD array has 3326 x 2504 pixels at 5.4 microns making it ideal for both short fast optics in high resolution (unbinned) mode, and for longer focal lengths it can be binned binned 2×2 or 3×3.  The CCD has both antiblooming and microlens technology to improve the effective Quantum Efficiency of the sensor.  As a result it can be used in a wide variety of optical configurations.  The camera electronics are USB 2.0 for fast download rates and rapid focus mode.  The small light body accepts both C-mount and standard 35mm Nikon camera lenses.  A built-in mechanical shutter is included for automatic dark frames. In addition to its imaging capabilities, it can also be used as a guider.

Large High Resolution Imaging CCD

The KAF-8300 CCD is approximately 18 x 14mm and has a diagonal measurement of about 22 millimeters.  With its relatively small pixels and large image area it is ideal for wide field imaging with short fast telescopes and camera lenses and at the same time is flexible enough to be used on long focal length Schmidt-Cassegrains.  The STF-8300 camera can be used with a filter wheel in any of several binning and partial frame modes for monochrome, color or narrowband imaging.

The sensor is capable of being operated binned 2×2 (10.8 micron pixels) or 3×3 (16.2 micron pixels), and supports subframing for rapid image download.  This versatile camera allows a great deal of flexibility in accommodating different optical systems, imaging conditions, and targets. For these reasons, plus the camera’s small size and breakthrough price point, we feel the STF-8300 is an ideal camera for those stepping up to a cooled low noise astronomical CCD camera from a DSLR, and a superb second camera for advanced users.

The KAF-8300 is available in both monochrome and one-shot color versions.

Even-Illumination Shutter

A mechanical shutter is included to facilitate dark frames.  This is a necessity for anyone operating remotely, even if remotely means a few feet away from the telescope.  Adding a shutter to a camera design increases the cost and size of the camera body but we feel these trade-offs are worth the added convenience and functionality.  Since the early days of the original ST-7 camera, SBIG has been providing even-illumination shutters in our cameras; something not found in the majority of other cameras made for astrophotography.  “Even-illumination” means that the shutter mechanism is designed to open and close in such a manner that it does not change the proportion of light falling on the sensor due to the shape or motion of the shutter itself.  This is what one finds for instance with an iris type of shutter that opens-up starting at the center and closes over the center last.  In the STF-8300 we use a simple and very robust shutter wheel with a fan-shaped aperture of the same design that we have employed in the ST series cameras for over 20 years.  Another benefit of the rotating disk type of shutter is that it has only one moving part – the motor.  These motors are extremely reliable and can operate for millions of exposures without failure.  In over 20 years with thousands of cameras in the field taking millions of exposures, this shutter design has proven itself better than we can describe.  Our design is proven and reliable.

TE cooling

The STF-8300 now comes in the enhanced dual-stage cooling version STF-8300EN, which provides a typical regulated cooling delta of 40C to 45C.

Due to this CCDs extraordinarily low dark current, the dark current becomes insignificant compared to the read noise even at temperatures of -15C.  In one test two 15 minute dark frames taken at -10C were subtracted; the total noise remaining was ~15 electrons, which included both dark current noise and read noise.  This is exceptionally low.

Desiccant Plug

As we described in our article, Preventing Frost, SBIG cameras are designed for simple user maintenance to prevent any buildup of moisture over time in the chamber.  All seals very gradually leak, and camera chamber seals are no exception.  The extremely dry and cold environment inside the chamber will gradually pull in tiny amounts of water, until eventually frost patterns appear on your images.  If left uncorrected the moisture could eventually cause corrosion damage.

Many camera manufacturers simply hide a desiccant pack in the chamber, and when it eventually saturates out the camera must be promptly returned for service at significant expense.  Our cameras include a removable desiccant plug, which can be easily baked in your kitchen oven to recharge them.

Thew new cooling-enhanced STF-8300EN camera includes the new Mega Desiccant Plug.  The Mega plug doubles the amount of desiccant, which means you can operate your camera for twice as long before recharging the desiccant.  When operating in high humidity environments, we recommend recharging your Mega plug every two years.

Dark Current Characteristics

According to ON Semi, the dark current of the KAF-8300 is less than 200e- at 60 degrees C with a dark current doubling temperature of 5.8 degrees.  This means that for approximately each 5.8 degrees C that one warms the CCD, the dark current is doubled, and for each 5.8 degrees C one cools the CCD the dark current is halved.  Extrapolating this to -10C we can calculate the maximum dark current we can expect to find at that temperature.  In fact, ON Semi’s specifications are usually very conservative when it comes to dark current, and this value can vary from chip to chip by 50% or more and still remain within the allowed specification.  When we measured the 8300 CCDs we found many to be less than half of ON Semi’s allowed specification.  This is also typical of what we have seen in other ON Semi CCDs.  In our tests we measured the dark current in some samples to be as low as 0.01 electrons at -10C.  Again, these are extremely low dark current values for a full frame CCD.  Even at zero degrees C the typical dark current is well below 0.2 electrons!  At -10C the average of our current production units is around 0.04 electrons making it the lowest dark current of any ON Semi sensor currently sold by SBIG.

Quantum Efficiency

In the past, one of the drawbacks in using sensors with small pixels and antiblooming structure has been the trade-off of some quantum efficiency.  However, ON Semi’s microlens technology has largely made this trade-off a thing of the past.  The KAF-8300 uses microlenses to focus more light on each pixel that would otherwise be lost due to the opaque antiblooming gate structure of the sensor.  As a result, the KAF-8300 antiblooming protection can handle up to 1000X the full well saturation and at the same time this CCD has a quantum efficiency comparable to that of a full frame sensor without ABG.  Moreover, the QE curve for this full frame sensor has a peak in the middle of the visual spectrum and good sensitivity well into the red and near IR.  The QE at the important wavelength of H-alpha is nearly 50%.

Linearity

Linearity is measure of how flat the CCD response is to light with increasing exposure times.  For instance, an ideal CCD will record exactly twice the signal in a 20 second exposure as it does in a 10 second exposure from a constant light source.  This is particularly important in photometric studies where the CCD is used as a tool for measuring light at various wavelengths to determine the temperature of stars.  In our testing STF-8300 linearity was within about 1% of linear up to 50,000 counts (binned 2×2).

USB 2.0 Interface

Thanks to the fast USB 2.0 interface, the STF-8300 will download a high resolution, full frame image in less than 1 second, and is much faster still when focusing using subrames or binning. This makes it very easy to find and center objects, as well as to quickly achieve precise focus.

I2C Accessory Port

The 9-pin I²C port allows the use of our filter wheels with the same interface.  The power and commands for the filter wheel all come from the camera through this port; there are no other cables or power supplies needed to operate the filter wheel.  SBIG offers custom 8-position filter wheels for the STF-8300 camera, which are thin enough accept a lens adapter for shooting filtered images through any Nikon or Canon 35 mm lens.  Automatic exposure sequences may be set in advance for hands off acquisition, or the user may control the filter wheel for each exposure if desired.

Standard Autoguider Output Port

The guider port on the STF-8300 is the standard “ST-4 style” 6-pin modular telephone connector, which is connected to the user’s mount when using the camera as an autoguider.  The drivers used in the STF-8300 design are opto-isolated, so that no external relay box is required with any mount.

Solid Machined Construction

Although small and light, this camera is built to last.  The front plate, main body, and rear plate are each machined from solid aluminum block for maximum strength and then hard anodized over a special bead blasted finish for durability.  Connector labels are laser etched and will never wear off.

12VDC Operation

The STF-8300 comes with its own universal AC power supply.  This supply will operate from 100-240VAC and provides 12VDC at 3.75A to the camera.  The STF-8300 also has a built-in voltage regulator and can therefore be powered directly from any unregulated 12V (10 – 14 volts) source such as a battery for operation in the field.  The universal AC power supply is relatively small (1.2×2.3×5.2 inches, 30 x 58 x 132mm) and light weight (9 ounces, 254 grams).   However in the event that the user needs to locate this supply more than  6 feet (~2m) from the camera, an 8 foot (~2.4 m)  low loss extension cable with matching locking connectors is available as an option.  SBIG also sells a 12VDC battery cable with alligator clips and a cigarette lighter adapter plug.

Integrated Filter Wheel Option

Due to the large size of the 8300 CCD, 1.25″ filters can vignette the corners at faster f/ratios.  This may be acceptable at f/7 or longer focal lengths, but at shorter focal lengths the effect becomes greater.  Also, the STF-8300 cameras are ideally suited for use with camera lenses, and we wanted to make a system available that would accommodate the back focus requirement for typical 35mm camera lenses with a filter wheel attached to the camera.  For this reason SBIG designed 5-position and 8-position filter wheels specifically for the STF-8300 cameras that will hold 36mm filters for unvignetted images at any focal ratio, and at the same time accommodate 35mm camera lenses.  These filter wheels plug directly into the I²C port on the STF-8300 camera and do not require separate power or control cables.  Fully automatic function is controlled by the same software that controls the camera.  Full sets of 36 mm LRGB and narrowband filters are available.  For those users with slower optical systems, or when used with STF models with smaller imaging CCDs, 1.25 inch filters are acceptable and SBIG offers 1.25″ inserts for these 36mm filters.

Adaptive Optics Now Available

The STF-8300 is compatible with the StarChaser SC-2 off-axis guide camera (for STF-8300C the Filter Wheel Spacer is required).

The StarChaser SC-2 has an adjustable pick-off mirror, and a built-in CMOS guide sensor with adjustable focus. This provides easy-to-use off-axis guiding in a single compact package.

The SC-2 can independently operate the AO-8A Adaptive Optics unit.  This brings AO technology to the STF product line for the first time!  Save and buy both together – see below.

Advanced Software Included

All SBIG cameras purchased on or after September 1, 2019 come with our MaxIm LT software – a $200 value!  MaxIm LT is a special version of our venerable MaxIm DL software that provides complete control of your camera, filter wheel, and autoguider, plus advanced image processing capabilities.  If you wish you can upgrade to MaxIm DL Pro to get complete observatory integration and even more processing and analysis capabilities.

Each STF-8300 camera system includes the following:

• Rugged camera body with rack handles and 2″ nosepiece
• KAF-8300 imaging CCD
• High speed USB 2.0 interface
• I²C bi-directional accessory port for integrated filter wheel control
• Standard guider output port (ST-4 style with internal opto-isolation)
• Internal mechanical shutter
• Dual-stage cooler for STF-8300EN
• Large Cooling Fan
• User rechargeable desiccant plug
• Tripod mount 1/4-20 threaded side plate
• 15 foot USB cable (third party USB extenders available)
• Telescope interface cable (for guiding)
• Universal 100-240VAC Power supply
• MaxIm LT camera control and image processing software
• Hard carrying case with pre-cut foam for your camera and small accessories
• One Year Warranty Parts and Labor on the CCD
• Two Year Warranty Parts and Labor on the camera other than the CCD

Optional Accessories

• FW8-8300, Eight-position 36mm Filter Wheel
• 36mm LRGB and Narrowband Filters
• Canon and Nikon lens adapters for use with or without a filter wheel
• 12VDC Power Cable:  8 foot (2.4 meter) power cable with cigarette lighter plug and battery clips
• 12VDC Extension Cable:  8 foot (2.4 meter) Low Loss, 12V Power Extension Cable with locking connectors.
• T-to-C Adapter

Note:  If connecting this camera to an OAG-8300 or StarChaser SC-2 without a filter wheel, you will need a Filter Wheel Spacer.