Can different filters make a difference to focus point

[Fay]

I put the Atik 314 put together for focus with the Leitz 180mm lens. i am sure i had the correct adapters in the imaging train, which included a filter wheel. i have not done this for quite a long time, but the camera would not focus.


the only difference I can think of was I put in a Baader 7mm ha filter, which I think is a  thicker glass, but when I originally had the adapters made for this setup I was using an Astronomik 12nm ha filter.

Could this have been the problem why it will not now focus? although I dont remember the Astronomik filter being considered in the imaging train details at the time

Thanks

Fay

[MarkS]

Have you tried without any filter?  Thicker glass will affect the focal plane distance but I always confuse myself about which direction.

[The Thing]

Have you tried without any filter?  Thicker glass will affect the focal plane distance but I always confuse myself about which direction.

I would have thought it would be a tiny amount.

Fay, you'll just have to try different combinations. Was it past inifinity? - if so you probably have too long an imaging train. When you have the right setup take a picture and keep it with the lens

[RobertM]

Fay,

Most definitely it can or rather it definitely does.  The focal length can be changed by 1mm or more depending on whether you have no glass or thick glass.  That's why sensors have to be shimmed when astro mods are carried out.

Robert

[Fay]

Thanks all, the answer is for me to get out there for some testing!!

[RobertM]

Fay,

I think you should have a much better chance of reaching focus with the Baader filters

Robert

[Fay]

It is the Baader filter that i am querying