Thickness of ASI294MC Pro spacers

Alfonso

Hello, does anyone know the thickness measurements of the four spacers shown in the image, please help.

Kevin_A

Depending on what you received. They usually are 0.5mm, 0.19mm and 0.08mm. I have 4 cameras and each set varies slightly. In reality, close is probably as best as you are ever going to get as each of my cameras are supposed to have a sensor distance to flange of 6.5mm but my actual sensor to flange distances vary from 6.2mm, 6.4mm, 6.6mm, 6.7mm of backspacing. The sensors are not offset back all the same even with the same model. So the 17.5mm camera backspacing reference can actually be anywhere from 17.2 to 17.7mm depending on the camera. Mine are 183mc pro, 533mc pro, 585mc pro and 2600mc pro cameras. It is a royal pain when using very fast f2 telescopes.

Alfonso

Kevin_A, muchas gracias por tu respuesta. Saludos

Hara

Kevin_A How did you measured the sensor to camera flange distance?
All of those thin spacers are made of different thickness material, you have to measure all of them separately to get correct distances. Even if those are sold to you for example 1 mm ones, they can be anything at least from 0,9 to 1,1 mm, maybe more.

Kevin_A

Hara i measure all of my zwo shims and mark them. Each thick one can be 0.49, 0.50, 0.52 etc and same with the others. Regarding sensor BF distance… I measured the sensor backspacing using one camera as a reference that was accurate and measured with a digital depth gauge and then focussed pin point at infinity and then I recorded the physical distance on my FRA300 petzval scope using a digital vernier between the drawtube and the rear drawtube flange. I recorded that distance for a zero reference. I then installed my other cameras and recorded the physical distance of pin point infinity focus for each camera and noted the difference they are before or after the reference distance once achieving perfect focus. I verify focus with a mask as well as with EAF AF. I also used a manual lens that has perfect focus at the infinity mark using my reference camera just for verification and repeated the tests by shimming the exact previously recorded discrepancies on it and the focus was again exactly at the infinity mark on all of them when previous un-shimmed they were either before or after the infinity reference mark. I also measure focus in the exact same center of all the cameras with a mask to rule out tilt.