Size is critical
I agree that either 550 or 600 mm focal length can work very well in an unsplit design. But a split design puts the field fresnel at least 50 mm closer to the projection lens. I think a 550 mm fl fresnel would work much better in a split design for this reason.
But Rox is absolutely right that either one will work with a little bit of lamp adjustment. There are some problems with using the 450 mm fl triplet still being sold by one or two DIY projector stores, but there are other lenses that can be used. It is also possible that the supplier could change the design of this triplet to give our community a lens with a wider field. In any case, 450 mm fl is about right for a long throw projection lens.
The most important feature of a new fresnel will be the size: It has to be large enough so that everyone building a long throw large format projector can use it. If you make it too small, then 3dlens will lose some of the potential customers.
I agree that either 550 or 600 mm focal length can work very well in an unsplit design. But a split design puts the field fresnel at least 50 mm closer to the projection lens. I think a 550 mm fl fresnel would work much better in a split design for this reason.
But Rox is absolutely right that either one will work with a little bit of lamp adjustment. There are some problems with using the 450 mm fl triplet still being sold by one or two DIY projector stores, but there are other lenses that can be used. It is also possible that the supplier could change the design of this triplet to give our community a lens with a wider field. In any case, 450 mm fl is about right for a long throw projection lens.
The most important feature of a new fresnel will be the size: It has to be large enough so that everyone building a long throw large format projector can use it. If you make it too small, then 3dlens will lose some of the potential customers.
Re: Size is critical
Sincerelly i doubt it. (it would bee great if they could do it, but if they change the FOV angle, then i guess they need to change the EFL also( so they keep the same housing) so it won´t be 450mmEFL.
JCB; Having the enough knowledge of projectors design should be just enought to understand what elements are needed there. Don´t you agree? Didn´t you told me you had 55cm separation between lcd and triplet's rear? (this means 55+2+6=63cm field fresnell works fine on your setup) but maybe you plan on larger throws for future designs...
I don´t care being 550mm fresnell, it will work nice for me. (but i think it has sense all this i am saying)
Guy Grotke said:
Sincerelly i doubt it. (it would bee great if they could do it, but if they change the FOV angle, then i guess they need to change the EFL also( so they keep the same housing) so it won´t be 450mmEFL.
JCB; Having the enough knowledge of projectors design should be just enought to understand what elements are needed there. Don´t you agree? Didn´t you told me you had 55cm separation between lcd and triplet's rear? (this means 55+2+6=63cm field fresnell works fine on your setup) but maybe you plan on larger throws for future designs...
I don´t care being 550mm fresnell, it will work nice for me. (but i think it has sense all this i am saying)
I would say 550 is a great focal length for the fresnel. Higher than this will work but is not necessary at all.
With 550 you can use 15, 17, and even 19 inch screens if the fresnels are large enough. So for 3Dlens producing one single 550 especially for DIY projectors will be the best option.
With 550 you can use 15, 17, and even 19 inch screens if the fresnels are large enough. So for 3Dlens producing one single 550 especially for DIY projectors will be the best option.
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