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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.
And unlike what you might expect from a lens at about f/ 1.2, there is no thin plane of focus that snaps in. Instead, there seems to be a very broad area from about 7 feet to 14 feet that has nearly the same degree of focus. Of course, the low contrast, halos, and soft focus can all be put to good use as long as you are not looking for the crisp images produced by commercial lenses. Choosing the appropriate triplet lenses can be tough. However, if you consider these factors, your job will be easier.
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You might be able to make it work by adjusting the lamp-to-condensor-fresnel distance to make the rays going to the field fresnel into a slightly diverging cone. This increases the distance from the field fresnel to the focussed image of the lamp arc. Depending on how we address the mechanics of the lens, focal lengths in the range of 60 – 200 mm are good candidates for DIY camera lenses. The general approach we will take is to draw a 2D profile of half of the lens on the XY plane and then create a revolve boss around the X axis. The X axis is the optical axis (i.e. the center of rotation for the lens).
Align these on a flat surface so the view through the lens is projected onto the card. This point is the objective lens’s ‘principal focus’ and the distance from here to the centre of the lens is called the ‘focal length’. We are now at the paraxial thin-lens starting point for the Cooke Triplet. Surface 3 is not useful since rays are going from and into the same glass, so we will delete that. Then we will go ahead and add 4 mm of thickness to the elements and 2 mm of thickness to the airspaces.
HTS 203A0 10x 21mm Chrome Triplet Jeweler's Loupe with Leather Case
The starting point of the first-order design is to imagine the Cooke Triplet as a pair of air spaced achromatic doublets. The second achromatic doublet has exactly the same radii of curvatures as the first except with opposite signs. In fact, the lenses I am considering are reportedly from an enlarger, one purpose built for printing multi-image school portraits, as in 4 up, 8 up, etc. I know there are better quality lenses for macro, but I must have lenses with very small diameters ( mm), and these fit the bill. Peter Drew May 19, 2017 I've not made triplet objectives but I've made triplet refractors from scratch using "bare" supplied optics. The largest was a 300mm F15 triplet for a large Camera Obscura which produced a 2.5 metre dPeter Drew May 22, 2017 When I said you could have them I meant FOC.
The good thing about building a small refractor telescope is that they’re light and portable, making them idea for taking to dark-sky sites. We create a merit function using the Zemax Optimization Wizard with attempts to minimize the root-mean-squared spot size radius calculated from the centroid, with 3 rings and 6 arms. We also insert an optimization operand, EFFL, to control the effective focal length of 50 mm. The 2D Layout shown below shows significant coma aberration in the caustic of the off-axis fields.
Adjustable Focus
One is to take the plans to an optical design firm and have them custom grind the lenses for you. The other is to make the lenses yourself by hand and then have them coated somewhere with the AR coating. I was hoping that someone out there had better access and funds to try to have one made. In the future I may try and redesign the lens for use with plastic lenses that can be hand made more easily but there is no reason that the lenses could not be made by hand. I may try and come up with a method that is doable in the future.
Is there any difference between "zoom" lens and standered? Or is it just getting the correct focal lengths for each lens? Keep checking back i will post my results on the design that you specified. Im in the middle of midterms so it may be a week or more tell i post again. Creating two reference planes for the front and back of the lens will help with aligning them to create the triplet.
The heart of any refractor is its convex glass objective lens, which is mounted close to the front of the hollow telescope tube. A triple convertible lens is a lens that provides three focal lengths in one. The front element has one focal length, the rear element a different focal length, and by screwing them together the whole intact lens has a shorter focal length. For example, some Schneider Symmars from the early 1950s and before were designed like this. Triple convertible lenses can have other designs as well.
The only positive aspect of that is that with the lens so diffration limited, maybe the lens performance does not have to be so great to start with. I happen to operate the CNC lathe our company uses and am very interested in the possibility of manufacturing my own lenses. Metals are what we mostly deal in with stainless steel as the most common , although I have done some telfon machining.
I'm not going to anything with them and they would only get lost or broken in due course.Peter Drew May 19, 2017 I nearly did as well, it was a steal at the price. Create a new assembly and add the three lenses in the order lens1, lens2 and lens3. Align the front plane of lens2 7.89mm from the back plane of lens1.
Old style macro extension tubes, such as a set of Nikon K rings, provides a shortcut. One side of the K2 ring mounts to the camera and the other side has a thread that fits 52 mm filters. This 52 mm thread is a convenient standard to use for quickly connecting multiple lenses, spacers, focusers, and diaphragms into a working lens . Here is a 75 mm lens along with some aperture rings. Note that the achromat was friction mounted to three 58 mm rings that were recycled from some junk filters. A 52 to 58 mm step up ring allows this lens to fit my 52 mm standard.
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.
Project the light from the lamp through the lens and onto the paper. Adjust the distance between the lens and the paper until the image is at its sharpest. Now just measure the distance from the lens to the image on the paper.
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