hi there i just bought fresnels from this url http://www.3dlens.com/shop/fresnellens.php
*Page magnifier x2
*Full page magnifier x2
*Pocket fresnel magnifier x2
well fresnels ok but they're very thin. is that a problem?
should i use more thick lenses?
Full Version: Is this fresnels ok?
We use fresnel lenses BECAUSE they're thin.
You will, however, require a projection lens.
The pocket magnifier fresnel is promising as a collomator, with a 120mm FL, it's about as good as you're going to get for collecting light from your lamp. It appears to be large enough for a 4.8" LCD as well. (If it does not cover the entire viewable area of the LCD, you can't use it.)
The page magnifiers aren't ideal, but ought to work as a collector lens, it will depend on what you plan to use as a projection lens.
The frensel lenses are usually only used as a part of the light engine, and not as projection lenses.
You will, however, require a projection lens.
The pocket magnifier fresnel is promising as a collomator, with a 120mm FL, it's about as good as you're going to get for collecting light from your lamp. It appears to be large enough for a 4.8" LCD as well. (If it does not cover the entire viewable area of the LCD, you can't use it.)
The page magnifiers aren't ideal, but ought to work as a collector lens, it will depend on what you plan to use as a projection lens.
The frensel lenses are usually only used as a part of the light engine, and not as projection lenses.
QUOTE (SupraGuy @ Oct 20 2009, 05:00 PM) 
We use fresnel lenses BECAUSE they're thin.
You will, however, require a projection lens.
The pocket magnifier fresnel is promising as a collomator, with a 120mm FL, it's about as good as you're going to get for collecting light from your lamp. It appears to be large enough for a 4.8" LCD as well. (If it does not cover the entire viewable area of the LCD, you can't use it.)
The page magnifiers aren't ideal, but ought to work as a collector lens, it will depend on what you plan to use as a projection lens.
The frensel lenses are usually only used as a part of the light engine, and not as projection lenses.
You will, however, require a projection lens.
The pocket magnifier fresnel is promising as a collomator, with a 120mm FL, it's about as good as you're going to get for collecting light from your lamp. It appears to be large enough for a 4.8" LCD as well. (If it does not cover the entire viewable area of the LCD, you can't use it.)
The page magnifiers aren't ideal, but ought to work as a collector lens, it will depend on what you plan to use as a projection lens.
The frensel lenses are usually only used as a part of the light engine, and not as projection lenses.
These fresnels i have are soo thin. They're like thick papers. You're right about thickness but i don't know maybe i should try these with another light source. i just tried with the halogen desk lamp and the paralel lights seems a little distorted to me.
Anyway here is my plan
I think that you need to do more reading on precondensers and reflectors. There's a reason why we user spherical reflectors by preference, and that use of a precondenser is simply wrong. In fact, there is no possible way for hte precondenser to act like what you've drawn in that diagram.
Here's a thread from DAZZZLA on a super precondenser. It uses 2 lenses but minus the smaller one and you still get the idea of how the larger one works in design.
QUOTE (SupraGuy @ Oct 20 2009, 10:51 PM)
I think that you need to do more reading on precondensers and reflectors. There's a reason why we user spherical reflectors by preference, and that use of a precondenser is simply wrong. In fact, there is no possible way for hte precondenser to act like what you've drawn in that diagram.
I've seen this plan on a website and it seems logical to me.
Rays coming from the reflector are parallel. So they will reflact like they were coming from the focal point.
And rays coming from the direct light is spherical. If it stands in the focal point of the condenser rays will be going parallel.
whats wrong here?
QUOTE (nefarkederki @ Oct 21 2009, 03:24 AM)
I've seen this plan on a website and it seems logical to me.
Rays coming from the reflector are parallel. So they will reflact like they were coming from the focal point.
And rays coming from the direct light is spherical. If it stands in the focal point of the condenser rays will be going parallel.
whats wrong here?
Rays coming from the reflector are parallel. So they will reflact like they were coming from the focal point.
And rays coming from the direct light is spherical. If it stands in the focal point of the condenser rays will be going parallel.
whats wrong here?
It's the rays you described leaving the plano/convex (pcx) lens, they don't diverge out but rather converge in. See diagram.
Click to view attachment
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.