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Please look at the anamorphic thread to see how some of those lenses were actually made in the past. Here is a picture of a computer optimized wide angle cooke triplet which should work with LCD of 17 inch wide screen format. It has 450 mm FL and 40 degrees total field of vision. I will post design information and the lens can be scaled down for use with 15 inch LCD and lower FL. Find an optician who will sell you two 75 mm diameter +0.75 Diopter lenses.
Here is a zip file which is a microsoft word document that has the technical drawings and spacing information for this lens design. If anyone out there needs this file in another word processor format just ask and I can probably put it in any major format as long as the wordprocessor can insert EMF format. If I've done this correctly...it is a 15" LCD to be projected....approx 10 foot projected image...and 16 foot distance to the screen...which suggests a 21.3" focal length. Of course, you can also find more creative ways to mount your optics, such as using a 2 inch steel electrical conduit with a screw-in coupler to make a functioning focuser.
Best triplet lenses Reviews
I'm using a 15" LCD and have a 220mm fl and a 317mm fl fresnel lenses. The screen I'm projecting to is huge...approx 122". The focusing duplet I have is way off base...image is 2-3 times bigger than the screen when projected from 16 feet. If I were going to build a duplet from eyeglass lenses, can you offer this noob a bit of help on the diopter needed and spacing. AS can be seen in this spot diagram for the glass 40 degree triplet it can focus down to about 44 microns of spot size on the paraxial axis.
(Lenses designed with this have a 30 degree field of view.) I usually just use the chart at the bottom of the page. I know that a 1000 mm + 1000 mm duplet works very well with a 15" LCD. The field angle is about 32 degrees. With a shorter focal length and a 15" LCD, the field angle increases so it may not work as well. If you use a smaller LCD, then the field angle may decrease. You could try making one with off-the-shelf CR-39 plastic lenses to see if it works for your projector.
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I have compared it to a four element optimized glass tessar lens and the tessar is slightly better giving a 32 micron spot for the paraxial axis. For most application the slight improvement of the tessar over the cooke triplet does not justify the cost and added complexity. For us it shouldn't matter too much as the cooke has twice the on-axis resolution that we need. When a lens is used to focus parallel rays of light, the focal length is the distance from the lens to the point of focus. This means that for a single element camera lens, the focal length determines the distance the lens needs to be from the film or sensor.
When a lens designer starts a design, he has a set of goals. Telescope objective designers don't care how their lens performs with light entering at a 20 degree angle, because it will be mounted in a long tube with a tiny eyepiece at the other end. Rays coming in at more than 1 degree will never make it to the eyepiece. A particular telescope objective might work okay with a 20 degree off-axis ray, but it might not. The mechanics involved in making lenses is often more challenging than the optics. One possibility is to go for a reusable, interchangeable-parts approach.
HTS 203A0 10x 21mm Chrome Triplet Jeweler's Loupe with Leather Case
Running it will generate three part files, one for each lens. Based on our research, we have found these excellent products to be well worth the money and should be able to meet your needs. It's important to do your research before buying any new product.
Ive looked into it hezz, $2k for the tooling on each lens for custom lenses, that price quote was from edmunds, and i dont see it much cheaper then that anywhere else. To anyone who has downloaded the drawing files there is something you need to be aware of. It has to do with the sign conventions for numbers that the optical design software uses.
A good brand will always produce quality products, so a product with an established name should be good enough for your needs. Please enable JavaScript to view the comments powered by Disqus. Mark Parrish is a consummate designer and a prolific producer of DIY astronomy products. You may eventually want to get a small altaz or equatorial telescope mount for your telescope. The easiest method is to make a simple wooden stand for the lens and another with a sheet of white card fixed vertically to it. The first stage of the build requires you to measure the focal length of your lens.
Comfort– Comfort is the other primary factor we took into consideration when evaluating triplet lenses. After all, the more comfortable a triplet lenses is, the less likely you will dislike it. To overcome this, modern telescopes have ‘doublet’ lenses that use two different glass elements to bring most of the colours to focus at the same point.
This cancellation is not perfect either, so, Cooke Triplets are usually restricted to applications requiring only moderate speed and field coverage . My last camera was build with 2 box of cardboard and only one meniscus lens and seem like work so fine but this project i can't move the body for focus. For remedy this problem i'd like to project a lens like Cooke Triplet or other simple schema to focus more easy and adapt this lens to different kind of body that i'll build.
We are not yet diffraction limited and there are certainly more steps one can take but we stop here. Any significant improvement would most likely involve lens splitting, glass choice, and/or aspheres. As one can see in the design, using only spherical elements with relative common glass choice, it performs well on- and off-axis.
This shows that astigmatism is actually the most dominant aberration with 87.3 waves of wavefront error shown by the \(W_\) term. Coma is the second most dominant with -38.9 waves of error as shown by the \(W_\) term. Remember this is just a listing of the third-order aberrations. While specific aberrations are difficult to quantify from the spot diagram, Zemax calculates specific Siedel coefficients and converts them in terms of wavefront error with units of waves. Also, I can't avoid the small apertures and diffraction.
Because the curvature is so small it may appear as a straight or negative surface on a drawing. There won't really be much work to do, unless he is grinding extra-large glass lenses for you. Stock lens blanks should just be sitting on somebody's shelf already made up and polished. If you are lucky enough to have access to bellows, you have an ideal focuser for homemade lenses. The last step is to generate the three lenses needed for the triplet using the values from the patent along with the focal length. Swing out loupe design protects the loupes lens when it is carried and acts as a handle when you use the loupe.
Here is a zip file of a solidworks e-drawing of the lens solid model. The glass ones are expensive - $16.56US each, but the acrylic ones starting on page four of the positive meniscus lens section are made of acrylic and cost only $8.79US each. There, you’ll be able to see many more examples of homemade lenses and the images they produce. Once again, spherical aberration resulted in soft, “glowing” images.
Could also be a bit of effort in getting the glass types required, although you have more flexibility then you would think as you do not specifically need FPL-51 or FPL-53. I'd look into using an old camera lens (eg. nikon f mount) in reverse. Posting something on this thread to get it out of the arcives for a time as someone has found possible builder of the lens. Rather than having custom lenses made you could even use piece together a lens system with used eyeglasses for nothing. There is also the possibility of having the lenses mounted in a water tight lens housing and using index matching liquids between the lenses. Done properly this can work as good or better than AR coatings on the lens.
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