Hi everyone. I recently put an order in for several 15.5"x15.5" fresnel lenses with 13" focal length. These lenses are made specifically for 15" LCD panels, but should work with panels as large as 17" widescreen format! Currently we are offering them as a non-profit group buy for $30 per lens (includes 2 fresnel lens halves). We really need to meet our goal of 20 more orders by the end of this week, but would certainly welcome more. I'll sell any quantity to any person or business, and we'll ship anywhere in the world that the USPS will go to. Please email me for more details (can be accessed via the "email" button below). Thank you for reading, and enjoy!
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Update
Here is a more concise run-down of the info...
Size: 15.5 x 15.5" (15x15 largest effective square)
Focal Length: 13" (326mm)
Groove Pitch: 2 per mm (same as most other high-end OHP lenses)
Price: $29.99 for group buy. Will ship worldwide.
ETA:May, 2004
If you have any questions, email me or post them here 🙂
Here is a more concise run-down of the info...
Size: 15.5 x 15.5" (15x15 largest effective square)
Focal Length: 13" (326mm)
Groove Pitch: 2 per mm (same as most other high-end OHP lenses)
Price: $29.99 for group buy. Will ship worldwide.
ETA:May, 2004
If you have any questions, email me or post them here 🙂
Correct me if Im wrong
I thought you would need fresnel's both being different focals.
If this is to be true then how would one focal length be of any use?
I thought you would need fresnel's both being different focals.
If this is to be true then how would one focal length be of any use?
The two lens halves do not need to be of different focal length. The top fresnel should be roughly the same FL as your projection lens (objective lens), but the rear has no specifications. Shorter focal lengths are prefered for the rear lens so that it will collect more light, but in this case that would make the lens about $20 more expensive and I don't have the capital to invest in a new lens design right now unless someone wants to partner with me for the group buy. 13" is a fine focal lengh though - very typical and usable.
If anyone emailed me today (April 1), please re-send your email ... I accidentally let my mailbox get full so I didn't receive a few emails from other people. Thank you for understanding.
I sent you some money through penpal for an order, could you have missed that too, if so what should I do?
David - I got your order just fine, but hadn't seen that email until now. Don't worry - Paypal will accept the payment and I'll still record it even if I don't get the email confirmation, but thank you for checking anyway.
Mesage to everyone: There has been some confusion about this lens. You will actually receive 2 fresnel lens halves per 1 order. So you are basically getting a split fresnel lens, which is preferable since you can use it in either split or combined configurations. It is plenty big to use a 17" widescreen with split fresnel lenses.
Mesage to everyone: There has been some confusion about this lens. You will actually receive 2 fresnel lens halves per 1 order. So you are basically getting a split fresnel lens, which is preferable since you can use it in either split or combined configurations. It is plenty big to use a 17" widescreen with split fresnel lenses.
Possible increase in lens groove count
Would anyone be more interested in these fresnel lenses if they had 50% higher (0.3mm between grooves)? The manufacturer hasn't cut the lens mold yet, so there's a potential that I could talk them into a higher groove count without any increase in price. Please post ASAP if you have an opinion - THANK YOU!
Would anyone be more interested in these fresnel lenses if they had 50% higher (0.3mm between grooves)? The manufacturer hasn't cut the lens mold yet, so there's a potential that I could talk them into a higher groove count without any increase in price. Please post ASAP if you have an opinion - THANK YOU!
hi alan, i was wondering why you did not spec a higher ring
count. i think since most will use this split, the higher pitch
would be a big help. my little commercial projector that has
a fresnel in the image path, has a very high ring count. much
higher than an ohp. tony
Maybe Cruser could chime in. He has had experience with
higher ring count lenses.
count. i think since most will use this split, the higher pitch
would be a big help. my little commercial projector that has
a fresnel in the image path, has a very high ring count. much
higher than an ohp. tony
Maybe Cruser could chime in. He has had experience with
higher ring count lenses.
That means also that you could shorten the focal on the rear frensel without a higher price?
Also whats the specs on the acrylic? how transmisive is it?
Trev
above all considerations the shorter fl should be priority but if thats not an option the higher ring count would be good too for the field lens
my findings with the 0.5 vs 0.3 pich fresnels is the 0.5 produces more light and the 0.3 gives a cleaner image
seing the fl of these fresnels are 13" the higher ring count may hurt the overall image as far as brightness is concerned but im down to test a few either way
my findings with the 0.5 vs 0.3 pich fresnels is the 0.5 produces more light and the 0.3 gives a cleaner image
seing the fl of these fresnels are 13" the higher ring count may hurt the overall image as far as brightness is concerned but im down to test a few either way
Ordering
I have tried to email you and tried to order from your site and I cant. I would like the lens but cant seem to get you the pre order payment. Please give more details on the ordering process.
Doug
I have tried to email you and tried to order from your site and I cant. I would like the lens but cant seem to get you the pre order payment. Please give more details on the ordering process.
Doug
Potentially Changing the Rear Focal Length
Hi all - sorry it's been a few days since I've been on the forums. The ring count will probably remain .5 grooves/mm in light of the information posted by cruser and since there isn't really much demand for the higher count. I cannot make the rear focal length shorter without increasing cost since currently I'm able to use the same lens mold for front and rear lenses. It would initiall add about $1500 to my cost for the lenses to offer a different focal length rear, but the cost to manufacture each lens pair would remain constant. If any one or group of people wants to help raise that capital, I'm very willing to do that. Anyone who has already purchased a pre-order would have the option of receiving any combination of 8" or 13" focal length halves without changing their purchase.
Doug, sorry for not emailing you back - I found your email just now and will reply immediately. If anyone else is having trouble pre-ordering, please email me. Thanks!
Hi all - sorry it's been a few days since I've been on the forums. The ring count will probably remain .5 grooves/mm in light of the information posted by cruser and since there isn't really much demand for the higher count. I cannot make the rear focal length shorter without increasing cost since currently I'm able to use the same lens mold for front and rear lenses. It would initiall add about $1500 to my cost for the lenses to offer a different focal length rear, but the cost to manufacture each lens pair would remain constant. If any one or group of people wants to help raise that capital, I'm very willing to do that. Anyone who has already purchased a pre-order would have the option of receiving any combination of 8" or 13" focal length halves without changing their purchase.
Doug, sorry for not emailing you back - I found your email just now and will reply immediately. If anyone else is having trouble pre-ordering, please email me. Thanks!
Re: Potentially Changing the Rear Focal Length
Alan I think my email filter bounced you email so try this one dnt32@yahoo.com
As for tyhe fresnel I would like the best large fresnel possible if it cost more tand 30 bucks ok I wanted in on the large fresnel with cruser but the I didnt have the funds at the time. now I have them and is ready to buy.
diylabs said:
Alan I think my email filter bounced you email so try this one dnt32@yahoo.com
As for tyhe fresnel I would like the best large fresnel possible if it cost more tand 30 bucks ok I wanted in on the large fresnel with cruser but the I didnt have the funds at the time. now I have them and is ready to buy.
Really. Figure out what it would cost to have the 2 diff focals, per set. I think most people in the know were rather surprised at the low low 30 dollar price tag on these lenses ur getting.
So even if I had to pay double that to have the proper focals, it would be worth it.
Cruser, I'm sure you can pipe up on this one. Didn't you pay upwards of 100 bucks for the fresnels for your hdtv pj u built with the SGI?
Granted, ur pitch count for the field fresnel was higher if I recall, but still, 30 or even 60 bucks seems like a good deal for large fresnels.
So even if I had to pay double that to have the proper focals, it would be worth it.
Cruser, I'm sure you can pipe up on this one. Didn't you pay upwards of 100 bucks for the fresnels for your hdtv pj u built with the SGI?
Granted, ur pitch count for the field fresnel was higher if I recall, but still, 30 or even 60 bucks seems like a good deal for large fresnels.
Heya faith, personally without the transmisity specs i wouldnt buy them, anything under 92% transmisive is a waste of time as it will chew one hell of alot of light, there is more to it just then the ring pitch, the transmisity would have to be the first to look at, rings second, focal last, also from my experience with frensels, a frensel that uses the same focal on both lenses acutally is darker then a frensel that has 2 diff focals, why who knows but thats what ive seen.
Trev
Trev
I would WITH OUT A DOUBT pay double for the shorter focal
Yes i did pay 100 for each lens and from what i see on the screen it was worth every penny
i would pay 60 for the set without blinking actualy ill take a couple sets
Yes i did pay 100 for each lens and from what i see on the screen it was worth every penny
i would pay 60 for the set without blinking actualy ill take a couple sets
That's exactly what I figured Cruser. I'm ONLY interested if he decides to go with diff focals. But even so it's a good deal for such bigguns.
Hey Alan, how bout contacting your manufacturer and ask them what the transmissiveness is for these fresnels, as Trev suggested? While you're at it figure out what it would cost us to have the diff focals, instead of just one, per set.
Hey Alan, how bout contacting your manufacturer and ask them what the transmissiveness is for these fresnels, as Trev suggested? While you're at it figure out what it would cost us to have the diff focals, instead of just one, per set.
Faith and everyone else, I'm glad that you appreciate the low price. I'm essentially selling the first 100 lens pairs or more AT COST to generate more interest in them and also to help quickly recomp my investment (it wasn't cheap ordering a new lens design). If anyone cares to donate to help out with this, let me know for sure! 🙂
You guys are right that a different rear focal length would make it brighter - not because it would be different, but rather because it would be SHORTER, and thus nearer to the lamp. I can make it an option on my website to purchase a 15.5x15.5" fresnel lens pair with 8.6-9" rear focal length and front focal length of 13" for a total of $50 plus shipping if there is enough interest. I could also reduce that price a bit for people ordering multiple lenses, though I'd have to sit down and calculate the specific scheme.
If you are interested in a dual focal length 15.5"x15.5" fresnel lens for $50, please email me and/or post a reply (email is best if that's okay with you)
As for the transmisity of the fresnel lens, I recall 95% or better for each fresnel half, though I am not sure whether having a shorter rear focal length would affect that. What I do know is that having a larger surface area means that this newer fresnel would potentially collect about 50% more light than a 12.2"x12.2" fresnel lens even if the newer lens had 5-7% less transmisity, which I am fairly certain it will not since the acrylic and thickness is the exact same for each lens design.
I have an email into the manufacturer to find the exact transimisty, so I'll try to post it here as soon as he lets me know. Post or email more questions if you have any. Thanks everyone!
You guys are right that a different rear focal length would make it brighter - not because it would be different, but rather because it would be SHORTER, and thus nearer to the lamp. I can make it an option on my website to purchase a 15.5x15.5" fresnel lens pair with 8.6-9" rear focal length and front focal length of 13" for a total of $50 plus shipping if there is enough interest. I could also reduce that price a bit for people ordering multiple lenses, though I'd have to sit down and calculate the specific scheme.
If you are interested in a dual focal length 15.5"x15.5" fresnel lens for $50, please email me and/or post a reply (email is best if that's okay with you)
As for the transmisity of the fresnel lens, I recall 95% or better for each fresnel half, though I am not sure whether having a shorter rear focal length would affect that. What I do know is that having a larger surface area means that this newer fresnel would potentially collect about 50% more light than a 12.2"x12.2" fresnel lens even if the newer lens had 5-7% less transmisity, which I am fairly certain it will not since the acrylic and thickness is the exact same for each lens design.
I have an email into the manufacturer to find the exact transimisty, so I'll try to post it here as soon as he lets me know. Post or email more questions if you have any. Thanks everyone!
Excellent. For 50 dollars a set, I'll take a set at least, maybe 2. I'll have to let my buddy know and see if he want a set(non forum member). When will you need the loot by?
Also, since you're dealing with the manufacturer, can you ask them to NOT join the halves?
Also, since you're dealing with the manufacturer, can you ask them to NOT join the halves?
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