Yes, you can use a 1.25-inch lens with a 1.25-inch to 0.965-inch adapter, but there are some considerations to keep in mind. The purpose of the adapter is to allow you to fit the larger 1.25-inch eyepiece to a telescope or device that originally takes the smaller 0.965-inch eyepieces. If you attach a 1.25-inch eyepiece to this adapter, you should be able to physically fit the lens and achieve a functional connection.
However, there might be a few potential issues:
Optical Performance: The adapter might affect the optical path slightly, altering the quality of the images you see. The use of an adapter could introduce vignetting, where the image is slightly dimmed or cropped, especially if the adapter adds length to the optical path.
Compatibility and Alignment: Ensure that the adapter securely holds both the eyepiece and connects firmly to the telescope’s focuser. Misalignments might affect viewing quality and focusing ability.
Light Loss: The transition through the adapter can result in a slight loss of light due to additional surfaces that the light has to pass through. If the interior of the adapter is not well designed to minimize reflections, it could degrade image quality.
Focus Adjustment: The adapter adds distance to the overall path. Therefore, you may need to make adjustments to the telescope focus to achieve a sharp image.
For casual observers, these issues might be minimal, but for critical observations, especially involving faint objects, they might be more pronounced. Overall, the adapter serves as a handy solution for utilizing more modern 1.25-inch eyepieces with older equipment designed for smaller eyepieces.