What is the primary use for the Baader UFC S70 VariLock 15-20mm Extension?
Its primary use is for fine-tuning back focus in an imaging train that uses the Baader Universal Filter Changer (UFC) system. When your camera, filter wheel, and other adapters don't add up to the exact spacing required by your flattener or reducer, this component's 15mm to 20mm adjustable range lets you dial in the precise distance needed for optimal optical correction.
How do I set and lock the spacing on the UFC S70 VariLock?
The VariLock mechanism uses a rotating collar. To adjust, you slightly loosen the collar, extend or retract the barrel to the desired length (using the engraved millimeter scale for reference), and then firmly tighten the collar. This locks the extension at the chosen length, creating a rigid, slip-free connection.
When would I choose this 15-20mm VariLock over a fixed Baader UFC extension?
Choose the 15-20mm VariLock when you need to correct for small, precise spacing errors or when your required back focus doesn't match a standard fixed extension length. It is also invaluable when accounting for the optical thickness of different filters. Fixed extensions are simpler and potentially more rigid, but offer no adjustability.
Can I use the Baader S70 VariLock with non-UFC components?
Directly, no. The S70 dovetail interface is proprietary to the Baader UFC system. To integrate this component into a non-UFC imaging train, you would need to use Baader's S70 adapters to convert the dovetail connection to a standard thread size like M48, M54, or M68.
My corrector requires 55mm of back focus, but my camera and filter wheel only add up to 38mm. Can the UFC S70 VariLock help?
Yes, perfectly. You have a 17mm spacing gap (55mm - 38mm = 17mm). The Baader UFC S70 VariLock 15-20mm Extension covers this exact distance. You would set the VariLock to 17mm to achieve the required 55mm total back focus for your corrector.
I'm imaging with a fast f/4 refractor. Why is precise spacing with the UFC S70 VariLock so important?
Fast optical systems like an f/4 refractor have a very shallow depth of focus and are extremely sensitive to back focus errors. Even a 1mm deviation can cause elongated stars in the corners of your image. The fine adjustment of the UFC S70 VariLock is critical in these setups to precisely hit the tight tolerance demanded by the flattener, ensuring sharp stars across a full-frame sensor.
