Stellarvue's universal field flattener is designed for cameras with sensors that are full frame and smaller. We have versions that work with each of our telescopes. The flattener is our exclusive design and these are built right here at Stellarvue. These are designed and fabricated to tight tolerances to minimize spherical issues that are all too common.
Important information about back-focus: Many people new to astronomy confuse camera back-focus with telescope back-focus or with focus in general. They are not the same thing. Camera back-focus is the distance from the attachment thread on the camera to the camera's sensor. There is an industry standard recognized by the makers of DSLR cameras and some CCD/CMOS camera makers. That standard is 55mm.
For example, a Canon or Nikon DSLR with a t-ring attached has a camera back-focus of 55mm. Some makers of CCD/CMOS cameras understand that this is an industry standard distance. So they provide extension tubes that place the sensor 55mm from the attachment thread. If your camera is not set for 55 mm you should contact us and we can recommend the necessary extension tubes and spacer rings to use so you will have the proper spacing between the flattener and your camera's sensor.
Remember, this has nothing to do with focus! If your flattener is not at the precise distance from the sensor it may still come to focus but the field will not be flat. You need the proper spacing between the flattener and the camera sensor to get the best correction (sharpest stars).
Attachment threads: This flattener threads into the focuser using an M68X1 thread. The thread on the other side of the flattener is our standard M69X1 female thread. We have various adapters, extensions and spacer rings as needed.
Flattener Options: As mentioned above, the flattener gives optimal performance when it is spaced a specific distance from the camera sensor. This distance varies depending on the focal length of the telescope. We do show some options above that make it easy if you are using a DSLR with M48 t-ring or you have a ccd or cmos camera that has a 55 mm back focus and uses an M48 attachment thread (such as ZWO). In this case you merely select the telescope you have and the necessary extensions/adapters will be included.
So let's assume you have an SVX152T refractor and a DSLR with an M48 t-ring. You merely select the SVX152T/180T option above and you are good to go! But let's say you have a camera with a different thread and/or it has a different back focus. In this case you will need to buy the flattener only and get the necessary extension tubes and adapters. In this case, read the paragraph below.
Attachment to the camera system: The flattener lens assembly itself has a long back focal length to accommodate a variety of cameras. That distance varies depending on which telescope is used. The optimal performance of this flattener will be achieved when the flattener is the specified distance. Here is the distance the back (camera side) of the universal flattener will need to be from the camera sensor when used with our various telescopes:
SVX080T - 105.5mm
SVX102T - 97.3 mm
SVX102TR - 97.3 mm
SVX130T - 93.4 mm
SVX152T - 90 mm
SVX180T - 90 mm
We have a large number of adapters and extensions we have machined. We generally can get you at the proper spacing with what we have in stock. So look up the specs on your camera system and give us two pieces of information we will need to get you up and running:
1: The attachment thread of your system such as M42, M48, M54, 2.156-24, 3-24, etc.
2. The exact distance in millimeters from the attachment thread to the sensor on your camera.
This is all we need to get you the parts you require to use this flattener.
Important note: When we say the exact distance to your sensor it is not merely the back focus of your camera if you are using other accessories (such as a filter wheel, OAG, etc). It must be the total distance from the sensor to the connection point which includes camera and all accessories.
Please contact us by email if you have any questions: firstname.lastname@example.org.