SVBONYFocal Reducer, M54X1 Field Flattener, Telescope Accessory for SV503 102mm ED Telescope

The quickness of the delivery and the ease it was to attach to the units.

Surprisingly only because the cost is so low for a well built focal reducer. Using this with a 100mm ED F9 refractor gives me a round tight stars to the edge of a flat field using my CMOS camera with a 15mm diagonal chip.

I wasted precious clear skies and good seeing experimenting with this flattener reducer and could not find good results. At the recommended 55mm backfocus, there is not enough in-focus on the sv503 102 to come to focus. That is, until I discovered that the nose piece of the flattener is removable. Removing the nose piece is the only way to get the required in-focus while keeping the requird back focus. Svbony do not mention this, so it took some experimenting. The video they posted as an answer to a customer question *will not* result in a flat field. To be clear, you need to remove the nose piece by unscrewing it, and use an extension tube to get the 55mm backfocus. Shorter distances may come to focus with the nose piece, but you won't get a flat field.One wonders why they include the nose piece at all if using it will not actually work with telescope it's designed for and only adds confusion.

great little focal reducer. a must have if you plan to take pictures with your scope. Don't forget to get a camera adapter for your camera. the focal reducer has 48mm threads not the standard 42mm, so make sure your order the correct camera adapter.

Using this at 980mm Fl f/7 with an SBIG8300 Kodak sensor.Seems to work well and is acceptable for my purposes and the price paid.