Svbony reducer not focusing

[redeye64]

Have just bought a Svbony SV503 102 scope and a SV193 reducer, when attached to a nikon d5300 l can't get focus - it's too long. The reducer is able to have the back half unscrewed which then allows proper focus but is considerably shorter than the 55mm back focus. Will this make a difference i.e. is the whole point of its "flattening" properties now out the window?

*The reducer has a 48mm flange where the nikon is m42 so l'm using a narrow adapter but even holding the camera face directly to the reducer it still is not reaching focus

[Drac0]

Hi Paul,

You will need to get yourself an M48 T-Ring. Going longer with the adapter (or shorter) will cause issues towards the edges of your images with distorted stars. I use this reducer on my Saxon 102 triplet with Canon cameras & it works very well when setup correctly, fantastic piece of budget gear.

Cheers,
Mark

[redeye64]

Thanks neighbour, l suspected that....l'll grab the skywatcher one
edit - Just found the Svbony one at aliexpress for $8......do me!

[redeye64]

Quick update - the reducer/flattener is actually too long when used with Nikon dslr's, aps-c ones anyway. The flattener luckily has a nose piece that unscrews and the shorter length focuses perfectly......problem is l don't know what the focus length is now to input into my ASIAR or other programs?

[iborg]

Hi Paul

Hopefully, someone else will give you a better answer, but, here is a suggestion.

I don't have an image handy to test this idea. First, put a best guess in for the focal length. Take a single shot, with plenty of stars, where in the sky doesn't matter and it doesn't need to a particularly 'clean' image.

Upload it to this site (https://nova.astrometry.net/upload), when it is analysised, the site will give you plenty of info about the stars in your image. It will also tell you what the angular size is. If you are lucky, the focal length will be there as well. Or at least enough information that it can be calculated.

Good luck

Philip

[redeye64]

Thanks Philip, l'll try it out when l get it set up :thumbsup: