Hi guys,

I'm looking to work on my projector this weekend, but firstly i've got to get some design issues out of the way.

I will be following the simple projector plan (http://www.lumenlab.com/protectedwiki/Simple_Projector_Plans) exactly but will not bolt everything down until i like the end result. My questions are:

1)
If i follow the designs to exactly and fit the focusing lens statically (i.e no room for adjustment), will that be ok? What will be the size of my projection and how far must i position the projector from the screen?

2)
Will having a fixed focusing lens allow me to adjust the sharpness of the image (reduce blur)?

I've seen so many good projector designs here and am extremely motivated on making my own and hopefully, with the forum's help, will get results like the ones i've seen

Any help will be much appreciated. Thanks guys

That will depend on the distance that you fix the len at. It's probably best to adjust the lens to the distance/size that you want, or at least do some experimentation before yo finalize everything.

The only focus adjustment you would have is to move the projector towards and away from the screen, unless you leave provision for the lens to move. See the LumenLab focal length calculator for an idea of screen size and distance. DO NOT PLAN YOUR SCREEN AND PROJECTOR PLACEMENT BY THIS TOOL. It is approximate, based on theoretical values. Your LCD is not going to be exactly 15", placement of the field fresnel or dozens of other variables will alter your results. There is no practical way to take into account all of the possible variables until you've actually built the projector.

You can get excellent results, but you're going to have to do some experimentation first.

A recommendation, if you REALLY only want a fixed lens mount: Make your box a bit longer than it needs to be. Mount hte lens in a panel, and move it until it's where you want it. mark the box, then cut it to that length. Affix the lens panel to the front and it's done. Personally, I think there's enough options for a reasonable focusing mechanism to allow you to alter it.

Thanks alot dude! I'll have a crack at it once it's up and running.

Make the light adjustable.
Make the Fresnel nearest the triplet adjustable.
Make the Triplet adjustable (for focus).

and it's pretty close to 1:1, so if you want a 6' wide screen the proj will be 6' away. You should sit, iirc, about 1.6 from your screen, so if your screen is 10 feet wide you should sit 16 feet away.

Also please read and use the search as you are not the first to ask those questions.

Enjoy.