What is the purpose of the Askar 185APO 1x Flattener?
The primary purpose of the Askar 185APO 1x Flattener is to correct for optical aberrations inherent in refractor telescopes, specifically field curvature. It ensures that stars are sharp and round across the entire imaging sensor, especially larger full-frame sensors, without changing the telescope's native 1295mm focal length or f/7 focal ratio.
How do I achieve the correct 55mm back focus with the 185APO 1x Flattener?
The 55mm back focus is measured from the base of the M48 male thread on the included adapter to your camera's sensor. Most dedicated astronomy cameras, when paired with a filter wheel and off-axis guider, are designed to meet this 55mm standard. For DSLR or mirrorless cameras, a standard 48mm T-ring is typically all that is needed to achieve the correct spacing.
Can I use 2-inch filters with the Askar 185APO 1x Flattener?
Yes. The flattener's M54-to-M48 adapter has an internal M48×0.75 filter thread. This allows you to screw a standard 2-inch astronomy filter directly into the imaging train before it connects to your camera.
Will this 1x flattener work with telescopes other than the Askar 185APO?
No, this flattener is optically matched specifically for the Askar 185APO refractor. Using it with other telescopes will likely result in poor optical correction and may not reach focus. For best results, always use the dedicated flattener designed for your specific telescope model.
Is the 185APO 1x Flattener or the 0.8x reducer better for imaging the Whirlpool Galaxy (M51)?
For a relatively small target like the Whirlpool Galaxy (M51), the 1x flattener is the ideal choice. It preserves the telescope's native 1295mm focal length, providing the maximum image scale to resolve details like spiral arms and dust lanes. The 0.8x reducer would shrink the galaxy on the sensor, making it less detailed.
What camera combination works with the 55mm back focus of the 185APO 1x Flattener?
A standard setup for the 55mm back focus would be a dedicated astronomy camera (e.g., ZWO or QHY) with a sensor-to-flange distance of 17.5mm, connected to a 21mm filter wheel and a 16.5mm off-axis guider. This combination totals exactly 55mm. Alternatively, a DSLR with a standard T-ring also meets the 55mm requirement.
