DIY solar projector question

[Mr niall]

Hello there

I was wondering, when it comes to solar projection, how do you determine how far away to put your projection screen from your eyepiece? Or does it matter?

I mean - what I'm assuming is that the projected image just gets bigger and bigger the further away that you put your projection screen? Is that right? 

Am I right in further assuming that the further away you put the screen - and therefore the bigger the image - the less definition you see? So say for example I was projecting a lovely sunspot (fat chance at the moment!) onto a surface, would there be a point where the sunspot would go from having nicely designed edges to being a vague greyish blob on the projection screen as you moved it away and it got bigger and bigger?

Does aperture therefore make a difference? 

Many thanks

[Mark Daniels]

Hi

i made a projector using an old telephoto lens. Works well. To the back of the lens  i added a extension tube so i can use lenses of different size. I placed the projection screen 12 inches from lens. With a 25 mm lens i get a disc of 2 inch diameter with a 10 mm i get a 5 inch disc. The apeture doesnt effect size it just brightens or darkens image

hope this helps👍