ok, my first 3 elemnts that i recomend to start with are those close to the ones you will found on your 135 triplet.
The idea was to increase the focal lengh and therefore the FOV.
But since you told me your desired focal is 450mm then the lens elements focals can´t be as large as I told you.
I downloaded the oslo (lens design program) and found it is more complex than thought. I need some days to understand how does it work, (i have not time right now so do not wait to me 😀).
guy grotke has worked with it before, he does know much more about it.
if you just take the 80 triplet and look at the shapes of the three lenses, you still need to know what materials are made of (the refraction index) if you don´t know it, you can´t do anything.
The idea was to increase the focal lengh and therefore the FOV.
But since you told me your desired focal is 450mm then the lens elements focals can´t be as large as I told you.
I downloaded the oslo (lens design program) and found it is more complex than thought. I need some days to understand how does it work, (i have not time right now so do not wait to me 😀).
guy grotke has worked with it before, he does know much more about it.
if you just take the 80 triplet and look at the shapes of the three lenses, you still need to know what materials are made of (the refraction index) if you don´t know it, you can´t do anything.
I would assume that the poly with the ar coating will be the best all though we offer reflection free and nikon ar? reg ar is always going to be free for me though so it would be better to start with that. so you think something closer to the 135 would be better then with the triplet off an overhead? that doesnt make sense to me if the diameter to the lens is bigger on the 135 and the fov is still small it would seem to me we would need much bigger curve?
forget about the diameter. think on 80mm diameter, but if you copy the shapes from the 135 triplet, you will have 450mm focal again and the same narrow unusable field angle.
you have to change the shapes, but try to compensate it (if you make a positive lens stronger maken a smaller curvature radius, then you need to make the negative stronger as well so the total focal of the system remains at 450mm). Also think that one of the most important things on the field angle is the triplets barrel lengh, your 135 triplet is huge, it is a tunel for the light so it is not posible to design a wider lens with such a long tunel. The lumenlab triplet is much more thicker and it help increasing the field angle. Lets say that we don´t want this tunel effect.
you have to change the shapes, but try to compensate it (if you make a positive lens stronger maken a smaller curvature radius, then you need to make the negative stronger as well so the total focal of the system remains at 450mm). Also think that one of the most important things on the field angle is the triplets barrel lengh, your 135 triplet is huge, it is a tunel for the light so it is not posible to design a wider lens with such a long tunel. The lumenlab triplet is much more thicker and it help increasing the field angle. Lets say that we don´t want this tunel effect.
this is making a little more sense. I am sorry I really am starting from scratch with this I work with lenses all day but dont really do anything but throw them on the polishers, I used to edge them but again the machines really do everything. I also downloaded aslo and will play with it this wknd so maybe I can figure some of it out with it in front of me. I can have pretty much anything done with a 80mm lens so that shouldnt be a problem we just have to find out if it is physically possible to do what we are trying. can you explain to me what the third lens does in a triplet? I know guy grotke has made duplets and I have heard that a triplet is better but I dont understand what they do or why. well I am going to work so I will ask some ?s there.
a duplet is made with two positive lenses.
a triplet gives better image than a duplet.
a triplet is made with 3 lenses (2 positive focal and 1 negative focal)
the shapes and the materials are those that make the minimal aberrations to the image. There are lot of aberrations (cromatic, aspherical, coma, barrel...)
the lens placement (inter-lens distances) do affect to the focal lengh as well. Thats what oslo does, you place the needed specs and it does al the work for you. But you will see it is a complex program.
a triplet gives better image than a duplet.
a triplet is made with 3 lenses (2 positive focal and 1 negative focal)
the shapes and the materials are those that make the minimal aberrations to the image. There are lot of aberrations (cromatic, aspherical, coma, barrel...)
the lens placement (inter-lens distances) do affect to the focal lengh as well. Thats what oslo does, you place the needed specs and it does al the work for you. But you will see it is a complex program.
http://www.surplusshed.com/pages/item/l3043.html
This has a nice long focal length, not very wide however 66mm's . How would it work? Eek 6 inchs long too
This has a nice long focal length, not very wide however 66mm's . How would it work? Eek 6 inchs long too
ok didnt find much out at work today just that we need to figure out how to use aslo so that we know what we need. I am going to look at it a little this wknd if you figure anything out rox let me know. The more I think about this I really believe it will work I thought that we would have trouble cuz of the throw but I have seen many many lenses come through with curves way beyond anything we will need so it is really a matter of finding a good starting point and working from there. I really do not understand how the 135mm triplet would be a good starting point honestly I think it would be way off, we are going to need a much larger curve, smaller lenses and shorter distances between elements? well let me know if you think of anything I want to work on this and may tear my 135 apart this wknd.
do you understand how the focal length will change with each focal length of each element? I dont understand how you will calculate 450 each lens wont be 450? sorry I dont know how any of this works if you could explain or list some basic lens formulas that would be great.
gguertin145,
If you look back in the archives there is a 450 mm FL wide angle triplet that I designed. The file gives the exact lens materials and geometries. I think it would be a good start.
I will try to find the thread for you.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=27471&highlight=
Hezz
If you look back in the archives there is a 450 mm FL wide angle triplet that I designed. The file gives the exact lens materials and geometries. I think it would be a good start.
I will try to find the thread for you.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=27471&highlight=
Hezz
very interesting I actually think I had read that before along time ago. the differences here I am not going to be making these lenses by hand I need to know the dimensions and curves and power and all that stuff to have it made at work. I know it may not turn out on the first try but thats ok it will not cost me alot of money to get the lenses at least it shouldnt. I see that you know how to use oslo and understand lens design much better then I do if you can come up with anything me and rox are looking at the program but I know I am lost so it would be a long while before I am able to see or understand all of that. if you think you can come up with a good set of lenses to start with for a triplet with powers and curves we have decided on the 80mm diameter
guygrotkes dir for a duplet ou can just get a couple of +1.0 Diopter lenses in as large a diameter as you can get, AR coat them, and then mount them about 40 mm apart in a tube.
now with a triplet we are adding a neg lens does anyone know how this will affect things? we are looking for good starting points so anyone that knows anything about lenses please say something.
guygrotkes dir for a duplet ou can just get a couple of +1.0 Diopter lenses in as large a diameter as you can get, AR coat them, and then mount them about 40 mm apart in a tube.
now with a triplet we are adding a neg lens does anyone know how this will affect things? we are looking for good starting points so anyone that knows anything about lenses please say something.
Could you tell me Hezz why is it 40 degrees field angle defined?
could you tell me also the focal lengh of each elemnts?
i have done a stimation based on the curves and the refection index;
1)304mm focal
2)-93mm focal
3)217mm focal
please you will have more accurate teorical values, could you tell me?
could you tell me also the focal lengh of each elemnts?
i have done a stimation based on the curves and the refection index;
1)304mm focal
2)-93mm focal
3)217mm focal
please you will have more accurate teorical values, could you tell me?
gguertin145 & Rox,
All of the technical information needed to build the lens is in the zipped word file in that thread. You will need to download that zipped word file. WIth that information you can calculate the exact FL of each lens. It has been too long since I did this lens and I think it has 40 degree total FOV corrected to a high degree.
THe FL of each lens is less important than how the curvature of each surface interacts with the next one to help correct abberation or make it worse.
I am interested in how good this lens will perform but I think that it needs to be further optimized for more exact conjugate distance of the average HT room. IT was done in Zemax and was adapted from an existing design. Oslo I tried but the user interface is terrible and for me I did not want to learn to use that software.
All glass types and curve geometries are defined in the document. As are the exact spacings of the lenses.
However there is one problem that I need to resolve. And as I recall this lens was optimized with infinate conjugates on the object side. I tried to optimize with a more accurate conjugate distance but have not yet been able. A lot of optimization variables have to be set correctly to get the design going in the right direction. With the lens designed for the finite conjugates of the HT room it may be that the FOV can be increased but I don't know.
Trying to calculate these things manually is too much work as to get an optimized system you will have to make millions of calculations of system variables. The computer can do this in a few minutes. It would take you a lifetime.
Rox, if you can take a large e-mail attachment of say 35 megs I will send you a nice surprise. Then you can play with lens design all you want.
Hezz
All of the technical information needed to build the lens is in the zipped word file in that thread. You will need to download that zipped word file. WIth that information you can calculate the exact FL of each lens. It has been too long since I did this lens and I think it has 40 degree total FOV corrected to a high degree.
THe FL of each lens is less important than how the curvature of each surface interacts with the next one to help correct abberation or make it worse.
I am interested in how good this lens will perform but I think that it needs to be further optimized for more exact conjugate distance of the average HT room. IT was done in Zemax and was adapted from an existing design. Oslo I tried but the user interface is terrible and for me I did not want to learn to use that software.
All glass types and curve geometries are defined in the document. As are the exact spacings of the lenses.
However there is one problem that I need to resolve. And as I recall this lens was optimized with infinate conjugates on the object side. I tried to optimize with a more accurate conjugate distance but have not yet been able. A lot of optimization variables have to be set correctly to get the design going in the right direction. With the lens designed for the finite conjugates of the HT room it may be that the FOV can be increased but I don't know.
Trying to calculate these things manually is too much work as to get an optimized system you will have to make millions of calculations of system variables. The computer can do this in a few minutes. It would take you a lifetime.
Rox, if you can take a large e-mail attachment of say 35 megs I will send you a nice surprise. Then you can play with lens design all you want.
Hezz
This isnt something I could make very many of I said that in the begining but the lenses themselves arent that expensive to buy either? So this is more to see if it will work or not? I am really not sure to answere your question. Once we have a working model it wouldnt cost much to replicate it yourself, I think the biggest drawback was spending the money on different lenses to test it, I am not looking to sell a lens.
gguertin145,
Yes it is a word document and you may have to open it in word XP version. It will not open in wordpad or in word perfect even though they can supposedly do a doc. format. The document has too much special formatting information in it.
THe document contains lens profiles for each lens that are specifically designed for optical engineers to make the lens. The optical technicians will understand the documents as they are quite simple once you see how they work.
THey will have to custom grind the lenses unless they are willing to make molds for you. If the latter is the case then I suggest that we make sure this lens is exactly right before they do it. IF they make the molds the molds will be very valuable and can be used by the company to make inexpensive replicas so more lenses can be made. However, for a one off they are more likely to be ground.
As the lenses are large you better make sure thay they can make lenses of this size. THe largest is about 6 - 7 inches in diameter.
I would like to get Rox to help on this if he would like since he is very interested in designing the perfect lens. THe main issue is that we need to reoptimize the lens system for the near exact conjugates of the HT setup.
It is unlikely that off the shelf lenses will be available in the required sizes and any deviation from the prescription will severely effect the correction.
I tried to open the file in another word processor but was unsucessful. You will have to use word XP. IF you are not able to get the file I will make another that is more easily assessible.
Hezz
Yes it is a word document and you may have to open it in word XP version. It will not open in wordpad or in word perfect even though they can supposedly do a doc. format. The document has too much special formatting information in it.
THe document contains lens profiles for each lens that are specifically designed for optical engineers to make the lens. The optical technicians will understand the documents as they are quite simple once you see how they work.
THey will have to custom grind the lenses unless they are willing to make molds for you. If the latter is the case then I suggest that we make sure this lens is exactly right before they do it. IF they make the molds the molds will be very valuable and can be used by the company to make inexpensive replicas so more lenses can be made. However, for a one off they are more likely to be ground.
As the lenses are large you better make sure thay they can make lenses of this size. THe largest is about 6 - 7 inches in diameter.
I would like to get Rox to help on this if he would like since he is very interested in designing the perfect lens. THe main issue is that we need to reoptimize the lens system for the near exact conjugates of the HT setup.
It is unlikely that off the shelf lenses will be available in the required sizes and any deviation from the prescription will severely effect the correction.
I tried to open the file in another word processor but was unsucessful. You will have to use word XP. IF you are not able to get the file I will make another that is more easily assessible.
Hezz
i have have been playing with oslo, but can´t find yet the spot size calculator.
Let me ask you, how many surfaces did you enter manually and how many were calculated by computer optimization procces?
also, could you tell me if the lens spacement was automatically defined by the computer or you started with this spaces as well as lens thicknesses?
Also would like to know the field angle definition, in the oslo program, there are two rays entering the triplet, one is parallel to the axiz and the other is with the desired angle (field angle) but i believe it is not the field angle definition. I would like to check those spote sizes for both cases (axial ray and angled ray), but have found some oslo free program limitations on working it out.
Let me ask you, how many surfaces did you enter manually and how many were calculated by computer optimization procces?
also, could you tell me if the lens spacement was automatically defined by the computer or you started with this spaces as well as lens thicknesses?
Also would like to know the field angle definition, in the oslo program, there are two rays entering the triplet, one is parallel to the axiz and the other is with the desired angle (field angle) but i believe it is not the field angle definition. I would like to check those spote sizes for both cases (axial ray and angled ray), but have found some oslo free program limitations on working it out.
they wont be making molds I am sure of that so hopefully it can be done with lenses we have. I am trying to open it in word xp, and it still doesnt work. If we altered one lens to something in stock the others should be able to be modified to something else also to make up for it right? Hopefully we dont have to just thinking. If you could give me the specs to your lenses I may be able to order them today or tmw I just cant find them. I need the powers, curves all that stuff can you just send me the specs for the lenses I need to get?
here you have all the information form the hezz's document (I can open it with my wordprocesor).
the powers of each lens are in function of the shapes, so knowing the curvatures, no need to ask for power. it is very important to use those materials (SK16 , F2) if is not posible, make sure to use the closest material (same index refraction and V- number or abbe number). Good luck
the powers of each lens are in function of the shapes, so knowing the curvatures, no need to ask for power. it is very important to use those materials (SK16 , F2) if is not posible, make sure to use the closest material (same index refraction and V- number or abbe number). Good luck
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