Hi all.
I notice this question has been asked before, 4 years ago and still hasn't had a reply:
http://www.diyaudio.com/forums/optics/120388-long-throw-zoom-lens-attachment.html
So I thought I'd ask a similar question to see if there is anybody out there...
I recently bought a projector that will remain un-named as it has got a lot of bad reviews (Abus HD-12 Pro) which I actually like, except for the racket of the fan. and its inability to decrease image size except by moving the projector back and forth.
Yes, I should've bought a more expensive one, but my redundancy package wouldn't go that far..
All I want to do is move the thing back about a metre (into a convenient cupboard with a window - which I have yet to cut out, but keep the projected size the same. Long throw lenses are over £1000 which is a bit harsh as the projector cost less than £200. It uses a 5 inch LCD screen and all I can tell you about the lens is that it has a 68mm diameter at the front - I haven't found any info on focal lengths etc. on the web to date.
I have the projector 3.18m from the wall which gives a projection size of 100 inches (2.54 metres) diagonal. I want to move it back to 4.16 metres and keep the 100 inch projection size, the size would be 130 inches (3.3 metres) diagonal at that distance.
Not knowing a thing about lenses, is there anything in the Optics Shed that I could fit on the front or the back of the existing lens that won't put my mortgage payments in jeopardy? Could I alter the existing lens with a hacksaw, hammer and Duct tape? Would a chat with a friendly optician (if I find one) help?
Is there distances inside the projector I need to measure to help someone come up with a solution? Will a picture help? Is the Earth flat? Will I ever get another job that'll pay for a long throw lens?
Any (polite) suggestions would be appreciated.
All the best,
Fitch.
I notice this question has been asked before, 4 years ago and still hasn't had a reply:
http://www.diyaudio.com/forums/optics/120388-long-throw-zoom-lens-attachment.html
So I thought I'd ask a similar question to see if there is anybody out there...
I recently bought a projector that will remain un-named as it has got a lot of bad reviews (Abus HD-12 Pro) which I actually like, except for the racket of the fan. and its inability to decrease image size except by moving the projector back and forth.
Yes, I should've bought a more expensive one, but my redundancy package wouldn't go that far..
All I want to do is move the thing back about a metre (into a convenient cupboard with a window - which I have yet to cut out, but keep the projected size the same. Long throw lenses are over £1000 which is a bit harsh as the projector cost less than £200. It uses a 5 inch LCD screen and all I can tell you about the lens is that it has a 68mm diameter at the front - I haven't found any info on focal lengths etc. on the web to date.
I have the projector 3.18m from the wall which gives a projection size of 100 inches (2.54 metres) diagonal. I want to move it back to 4.16 metres and keep the 100 inch projection size, the size would be 130 inches (3.3 metres) diagonal at that distance.
Not knowing a thing about lenses, is there anything in the Optics Shed that I could fit on the front or the back of the existing lens that won't put my mortgage payments in jeopardy? Could I alter the existing lens with a hacksaw, hammer and Duct tape? Would a chat with a friendly optician (if I find one) help?
Is there distances inside the projector I need to measure to help someone come up with a solution? Will a picture help? Is the Earth flat? Will I ever get another job that'll pay for a long throw lens?
Any (polite) suggestions would be appreciated.
All the best,
Fitch.
Interesting question, but this part of the forum gets so little traffic, you know.
As a projectionist myself, I know that longer lenses - within reason - are easier than short ones. Fortunately for me, I can just pick what I need off the shelf.
I wonder if you couldn't play a bit with multiplier lenses meant for cameras? They can be found online for reasonable prices, or maybe you know someone who can lend you one?
As a projectionist myself, I know that longer lenses - within reason - are easier than short ones. Fortunately for me, I can just pick what I need off the shelf.
I wonder if you couldn't play a bit with multiplier lenses meant for cameras? They can be found online for reasonable prices, or maybe you know someone who can lend you one?
well, basically, you would just have to attach a bi-convex lens to you projector ...
but ...
it would have to be calculated through, i'm talking of: focal lengths, diameter, distance to the projector ... also, a single bi-convex gives terrible errors, so an achromat lens would be the least thing to do ... but, honestly - i really do not have the time to calculate that thing right now, as i'm approaching my final exams here ... sorry
still, if you are lucky, the achromat lens which comes out after that calculation may be a standartised one, so you can buy it for less than 100 bucks from companies like qioptiq; you would only have to attach it somehow in the right distance and being aligned to the optical axis
again, sorry for giving such an unsatisfying answer, i wish i could have helped you more
but ...
it would have to be calculated through, i'm talking of: focal lengths, diameter, distance to the projector ... also, a single bi-convex gives terrible errors, so an achromat lens would be the least thing to do ... but, honestly - i really do not have the time to calculate that thing right now, as i'm approaching my final exams here ... sorry
still, if you are lucky, the achromat lens which comes out after that calculation may be a standartised one, so you can buy it for less than 100 bucks from companies like qioptiq; you would only have to attach it somehow in the right distance and being aligned to the optical axis
again, sorry for giving such an unsatisfying answer, i wish i could have helped you more
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