How does this 1.25" Filter Holder prevent tilt in my imaging train?
By using T-2 (M42x0.75) threads to connect directly to other T-2 accessories, it creates a rigid, metal-on-metal connection. Unlike drop-in holders or nosepieces that rely on pressure screws, this threaded system ensures all components are perfectly aligned and locked in place, eliminating flexure even with heavy equipment like a cooled camera or filter wheel.
Can I use the Baader 1.25" Filter Holder with my 2" eyepieces?
Yes, but with a caveat. You will need the optional Baader Expanding Ring T-2f / M48m (#2458110) to adapt the T-2 threads to standard 2" filter threads. Be aware that using a 1.25" filter with a wide-field 2" eyepiece will likely cause significant vignetting (darkening at the edges of the view), as the filter is smaller than the eyepiece's field stop.
What is the advantage of this screw-in filter holder over a drop-in filter slide?
The primary advantage is stability. A screw-in holder becomes a structural part of the optical train, preventing any possibility of tilt or movement. Filter slides are convenient for changing filters quickly but can introduce minute alignment shifts that can affect flat-field calibration and edge-of-field star sharpness in demanding imaging applications.
If I use this holder with my ZWO ASI533MC camera and T-2 accessories, will it cause vignetting?
No. The sensor in the ZWO ASI533MC is a 1-inch square format, which is well within the illumination circle provided by a 1.25" filter. When used in a native T-2 threaded system, this filter holder will not cause vignetting with that camera.
Will this Baader filter holder work with a Q-Barlow lens?
Yes, the holder accepts accessories with standard 1.25" filter threads, including the Baader Q-Barlow lens element. However, due to the specific thread length on the Q-Barlow, it will only screw in about a quarter of a turn. This is sufficient to hold it securely for use.
When imaging Jupiter with my ADC and a heavy camera, why is this Baader T-2 holder a better choice than a standard 1.25" nosepiece?
For planetary imaging, maintaining perfect collimation and alignment through the entire optical train is critical. An ADC and a cooled planetary camera create a long, heavy lever arm. A standard 1.25" nosepiece held by thumbscrews can easily tilt, throwing off both the ADC's correction and the camera's focus across the sensor. This all-threaded T-2 holder prevents that tilt, ensuring the entire imaging system remains rigid and perfectly aligned with the telescope's optical axis.
