135mm long-throw lense kit from diylabs

[Dazzzla]

Trev ya back, u been on a holiday

DJ

[ace3000_1]

I wish mate, been busy doing other things lol, im going on a holiday soon though . My projector will be finnished this year aswell , all on paper just a matter to find the time to build it now.

Trev

[Rox]

well, i have received more information about the lens but it is confusing me. Now they say that the 24 degrees field angle is at the side of the wall. And at LCD side it is 38.7 degrees field angle.

Well, can somebody tell me how is it posible? i guess the light could go in both directions so the more restrictive angle is the closer to the reality (i would say 24 degrees). Or we can do a midle angle with both and say it is overal that field angle;

(38,7+24)/2=31.3 degree field of view.

I just don´t understand it. I think the manufacturers don´t know exactly what am i asking for.

Thats what they told me;


if there are 24 degrees in any side, then this would be the most restrictive. Any suggestions? (I am yet in contact with them to clarify this)

[ace3000_1]

Rox, who drew the pic? you or them?

If its 24deg per side it should JUST work on a 15inch panel, i wouldnt expect mirricles though on the edges. I do realise this isnt the case though.

Trev

[Inkog]

That would explain the term "long throw" right? The angle of light leaving the triplet would be smaller than the angle entering the lens.

It sounds like that if you have the correct field fresnel, corner to corner focus and light distrobution should be possible.

[Rox]

I drow it with the information they gave me.

The angels are full angle, do not think they are half. The only confusion is that at LCD side (left) they said it is 38,7 full angle (19,3 + 19,3 half angles) but they say as well that on wall side (Right) it is 24 degrees angle (12+12) then if you do some math, you can see that there is image being projected on 38,7 angle so I wonder what does this 24 degrees on triple wall side field angle mean.
If the performances of the lens are only aceptable inside this 24 degrees, then the 38,7 degrees of LCD side has no sense. Please does anybody know what the hell is happening?

[Rox]

inkog then if the image enters from 38,7 degrees and outs from 24 degrees, what focal lenght have you got?

it is not compatible with only one focal and one magnification and one throw, you you understand it?

[ace3000_1]

The angle of light leaving the triplet would be smaller than the angle entering the lens.

Should be the same both sides bud, aleast of what ive seen in my lenses, vari triplets have a slight diff. That angle will only change if you move the lens closer or further from the lcd to focus, and it will still be the same on both sides at those magnifacations.

Trev

[ace3000_1]

inkog then if the image enters from 38,7 degrees and outs from 24 degrees, what focal lenght have you got?

That would have a negative focal if it was doing that, or the front ellement is less powerful then the back which imo is pointless for projecting an image unless you want a throw of 10m+ lol.

Trev

[Rox]

the focal of the lens would be positive always, but this long throw concept inkog has think about is not correct (there would be 2 focal lengh or two throws or two whatever, i mean that this system is not compatible (has no solution).

I also would say that the field of view angle needs to be simetrical to both sides. But i think that it could be that this angle they told me could be the angles where the aberrations have been minimized at this angle. (just a thought) I just want to know the field angle!!!!!!

what do you think about the midle point 31 degrees? can we accept this as field angle? anyway it is not 42 degrees (needed for 15" and 100" image)

I thought i had arrived to the field angle but now i think i have to start again Could you help me on it as well? maybe more people asking for it would do a faster correct reply (and your english would be much better than mine as well )

Rox, still on it.