This is a modification to solve pincussion effects, when using the PRO lens, especially required if using lens shifting..

also some may have some corner smearing which may only show in certain types of folded builds etc..

If your PRO LENS is OK,, dont follow this modification,,

Link to post describing details of disassembly and assembly of the lens along with spacer alterations

ok the where's and where forth's of probs of pincushioning of the pro triplet and corner focus problems that some have observed..

my view is that the pro triplet is the best thing since sliced bread,, absolutely no doubts,, and there is a very easy fix for these two problems.

for some reason,, the lens'es have been made with incorrect spacings, between the back lens and the centre double concave lens, which has been installed with a 12mm spacer,, i replaced this lens spacer with a 3.5mm rubber "o" ring,, and now I have an absolutely perfect corner focus and absolutely no pincussion

please i am not knocking the pro triplet,, it is a damn good lens for the price,,, so make no mistake,, it is good that the cure is very easy.

compared to the std 320mm lens which had far worse corner focus issues, the pro trippy was good,, but I wanted perfection,, it was mostly the pincusion effect that drove me to pull the lens assemebly apart, however I was surprised that the corner focus improved out of sight,, imagine my elation at this..



Notation the focal length has increased from 500mm, to approx 550mm

Anotation,,, dazz and I have been conferring on this point since 4pm today,, since I stated that i would rip the lens apart to solve the grrrrrrrrrrrrrrrrrrrrrrrrrrrr,,,,, pincusion effect as it was annnnnoooyyyyiing me,,,,

You took apart a $200 worth lens ?,

Anakin, stay strong.

anakin the force follows,,, as the good jedi be he.....

ummmmmmmmm I him told after the fact,,,,, Tis ok,,,,, IIIII cannnnn deaaalll with theeee Emperor,,,, I think !!!!

He only cracked one lens element, he still has two more good ones.
Should still work.

Good for you Elken! Im wondering if this isnt close to what they were doing with the DIYProjector lenses when they were offering that modification for 10 dollars. Any explanation on how you arrived at 3.5 mm? Still its a great find.

SJ

It was a scientifically calculated guess.
It was just the first thing he layed his hands on.
I’m currently using 4mm so I’ll have to try 3.5mm when I get a chance. I tried no spacer at all with bad results.

DJ

Thank you very much kv29.

Master elken, as thee goest so shall I followeth. The deep, black night approacheth the long awaited dawnism. All barriers fall to thee. Thy shall liveth in the collective memory of Lumenlab brethren for all of projected eternity. Now I gotta get my arse in gear!!!

Say, you got any free time to remove my plantar warts?

I can confirm that this mod does fix the pincusioning but I still have some focusing issues. But I believe the focus issue is still partially caused from misalignment of my mirror. Elken’s mirror is positioned half way between his triplet and LCD, where as mine is close to the triplet which magnify small variations.
I think I’ll have to convert to a straight through design to take the mirror out of the puzzle.

DJ

edit:
I’ll convert back to the folded design after I confirm the triplet focus.

My projector is now positioned 400mm further from the screen, which translates to a FL of 550mm.

DJ

Amazing!!!!!
Any pics and explanation for the process?
Thank you.

That is strange. I have no pincushioning and perfect focus with my pro lens in the straight though design... only time I had trouble was when I used a horizontal folded design.

I like the idea of increasing the focal length from 500 to 550... this would give me a smaller projection for the same throw... something i've been wanting as the screen is a bit too large...

cheers,
gs

interesting,,, no pincussion,, several have had it,, maybe different batches of lens's,,, hmmmmm

this lens had very defined issues,, and they have all gone completely reducing spacing between two rear lens's,, LCD side,

I will do a repeat set of pics to show differences tomorrow


This topic will be peared off this thread soon too,, as it has become a different subject,, today for me has been a hurdy gurdy day,, it all began with me almost doing full sets of LUXie LUmie measurements, spent two hours doing it then, went arhhhhhhh waste of time,, then got back to PRO lens familiarization, and started looking very close at its performance, and then picked up anomalies,, the rest is now history,,, just ask dazzzzzzer,, we have spent more time on phone today tonight than ever heheheheheheh,,, and nup he is not my type,,, he wears blue shirts,,, hehehe I like pink,,,, ummmm heheh on a girl tho

so moral of my version of a story of some kind,,,, follow ya instincts,,,, .... luxies can wait for another year.... me off on other goalies,,,, rainbows at the beginning rather than the end,,,,,, oh dear I need something yes big "D" it is censored heheheheh

You're running a WUX correct? I'd think most would benefit more by using a simpler technique for shrinking their projection. But it's the DIY spirit that wins out most of the time. We'll wait and see what DAZZ has to say swapping between straight and folded setups. That should be fun to see.

Edit: I'll see what I get some year too. Surely the inner lens spacing wouldn't vary much within production runs? Need more numbers.

wow, this is amazing elken, excellent work...hey gadget, as elken says, maybe a few batches got thru with the wrong lens spacer(or maybe even one of the lenses), I agree that 550mm woul be better... are you brave enough to take yours apart and check the spacers?

simpler? you mean just moving the pj closer? true, but in my case, unless I go rear projection my pj will need to be 9 feet away from the screen due to furniture and that extar 50mm would be a godsend(I'm pretty sure I'm going pro)....too bad rox isn't around, didn't he help design the pro with brainchild?
all this would certainly explain those people who ahve had big issues(christmasgt(I think) among others..)

I dare YOU to double-dog dare HIM.

Can you kinda look askance at the lens and get a feel for spacing? Prolly not.

Nah, powerstrip or whatever. Heck, can't you achieve a moderate degree of shrinking just with the front panel controls as well?

Edit: I'm still thinking of an analog monitor!

triple dog dare you,,hey, don't you have a pro?

doh! yeah, but that wouldn't work for hd from cable or satellite, just pc... yeah front controls can shrink my last panel about < 10% you're right

ok,,, instruction for it,,, in a tick,,, gotta get a drink,,,, hic hic cih

oh

I just walked down to get a glass of port,, and spied the screen running

The colour is even better and whites whiter

totally understandable too,,, better, crisper focus means that the RGB are focused evenly, resulting in purer whites,, I hope that made snese,, if RGB's are not in phase, the white is kakieee, in colour.. ummmm oh my

but the brightness is higher again, as the contrast too

... I wood tak da thriplit afart, ut mi tong iz shuk to thiz thagpole...

... you guys are evil !

I think the question of the wrong spacer may have come into question when Christmas GT was having trouble with his focus... and I believe he was using a straight design.

gs

i'd rather not have to adjust resolution from powerstrip for exactly this reason... I will soon (hopefully) be getting HD and want to be able to use the PJ without the use of a PC as there are no cards available to input HD signals into a PC...

ah... now i'm starting to see what's going on here... people need to get themselves a pair of "portglasses" to improve the screen image... in the US we generally refer to this as "beergoggles" and it's typically used to improve the appearance of individuals at a bar, rather than just the image on our screens !

(j/k folks)

elken, is there any possibility that the lens elements were installed backwards... would this make a difference ? I find it hard to believe that they could assemble the pro lens with a 12mm spacer rather than something closer to 4mm and not notice, but could see them installing a lens element backwards without noticing... Just some thoughts.... I really would have to take the triplet apart to measure the spacers to see if something is different...

gs

The DViCO Fusion does and a number of others like the Twinhan etc. I have DViCO here in PAL land, downconverts 1080i to 720p for my projector.

My Pro lens was from the first batch that arrived at LL and it has no pin-cushioning but it does have corner focus issues that I have minimised by putting the mirror fairly close to the LCD but there is still a small corner focus problem there and elken is right, that spacer is 12mm, I'll fiddle with a new spacer tomorrow.

This is a modification to solve pincussion effects, when using the PRO lens, especially required if using lens shifting..

also some may have some corner smearing which may only show in certain types of folded builds etc..

If your PRO LENS is OK,, dont follow this modification,,

Research and prepare well before proceeding with this procedure!!!

Ok,, instruction for taking the PRO trippism apart

first lay a very clean soft towel down on a well lit bench

place the triplet fange side down, then try and undo the slotted retainer, if it does not move easy take a small blade screwdriver and insert into slot,, but be very careful,, one slip lens gets scratched,, tap it in the direction of the ring,, counterclockwise,, if you cant move it,, make up a tool to fit cutting out enough to clear vertex of lens,, then it should come free,, it is not glued ( also when doing it up again,, DO NOT OVERTIGTHEN, optics should never be tight,, Expansion)

try to avoid rotating lens assm on towel,, as any grit will certainly scratch protruding vertex of lens

once you remove retaining ring, use a tissue,, oh put cotton gloves on too,, ( finger oil )

turn lens assm over, so flange is up,, but hold lens in till turned over.

when turned over lift housing and shake so whole lot falls out,, but be careful,, they will spill out if care not taken,, like a pile of slippery pancakes they be..

before you do a damn,, thing the previously prepared texta pen,, oops sorry forgot that one hehehehhe

mark arrows in a direction of your,, and dont be smart arse heheheh up or down,, Not sideways,, Hhehehhe umm sorry

this will make sure you dont mix up lens,, err also mark 1 2 3 ...

now the end lens which is a double convex has a spacer which most likely will be a 12mm alum... one is the one that needs to be changed to a 3.5mm or somewhere between 2.5 to 4mm..

dont move the pile of lens,, keeps the rest clean,, just lift the top one put a replacement spacer in place of 12mm one,, place the double convex one back, on the new spacer,, remember it has a direction,, one side has a bigger convex to the other,,, hence the arrow markings..

now I used a rubber "O" ring, I had to cut it as it was a tad too big, and used some heat shrink tbe to join it again,, not critical but clean.. but make it a tad bigger in diameter, to assure clean snug fit... and BOB's not my unckel and never bloody well will be

I hope that helps all and one
This hyper jump takes you to Live Pics of lens mod...................................http://www.lumenlab.com/forums/index.php?showtopic=14355&st=60#

Diagram Thanx to DAZZZLER

Click to view attachment

I tried every combo, including lens flips etc etc etc

the last bit was spacings,, all lens are installed in right direction,, IE all surfaces are matched,, but the collector is adouble convex is set for 500mm FL,, but not matched for correct pincussion/barrel distortion,, it must be closer to a 550mm by its figuring of radii which in turn would also affect our square so to speak extreme corner focus,, most opticians think in circles,, we use a bit more called the square outside the circle,,, so moral of story in there is speak so of,, geez I am talking a load of ,, ummmm you know

SAM or DAZZ,, maybe now is a good time to split this series, and call it PRO LENS MODIFICATIONS,, only if needed, by advanced,, or something like that,,, umm hehehe

Tell me which post number is the best to split it with and I will do it.

SJ

Gadget your un-pincushioned triplet is an interesting puzzle. I wonder how many others have no pincushion?
Just for reference I have one of the original two prototype triplets, the other Supraguy has, and I have tried it in a straight shooter and the pincushion was there as well. I PMed him about the pincushioning and he said he didn’t have it on the original tests. But I do remember him saying somewhere after changing some distances or other optical components that he did see some pincushioning.

I’m actually a little annoyed with myself I should have done this test along time ago, I must have been side tracked by pre-con’s, I wouldn’t have cut my fresnels down, Grrrr. Elken’s discovery has opened a can of worms, at least for me. I was originally going to implement lens shift and ceiling mount my projector but testing showed that the pincushioning was greatly exaggerated so I abandoned the idea. So now I’ll have to reconsider it because the new modified triplet should be able to do a good amount of shift as well as the bonus of extra FL.

Just when you think you are getting a grip of this addiction, you relapse again.
DJ

I would say post #966 trim the first sentence about soon to be etc,, only need the core of the start post..

Hey we are really lucky,, the fix if it can be called that is so easy, and gives such great results,, ummm other optics taken into account too..

I have to say, I have only been playing with a PRO for two,, days and was and is still in awe,, but this mod I did late this afternoon, was like going from standard def to high def in one single bound,,, well eight dissasmbles and reassembles of a trippy heheheheh to get secret,,,

and yeah yeah yeah ANAKIN knows,,, heheh ummm I told him after fact oooppsss knuckles wraps for me...

can someone comment on instructions,,, does it make usable sense

This is a modification to solve pincussion effects, when using the PRO lens, especially required if using lens shifting..

also some may have some corner smearing which may only show in certain types of folded builds etc..

If your PRO LENS is OK,, dont follow this modification,,

I have modified the first page ,,Thanx for shift..

You did the same damn thing I just did!!! I'm outta here!!!

typical,, in and out and gone,,,, thats our big "d" for ya....

I couldn’t find an O ring for use as the spacer so I made one from some 4mm flexible shielded audio coax. Just remove the wires from the centre and you will be left with the outer rubbery jacket. Cut it to length and use a piece of the inner wire, about 20mm long, to rejoin the end to make a ring. I also used surgical glove and only held the edges. Another pair of hands is also a good idea as they can hold the lens elements and not have to place them on cloth, less chance of contaminating with fibres.

A pic is worth a thousand words.
Click to view attachment

DJ

ummmmm hummmm dazzzy,, that right hand lens is a concave/convexism one,,,, technical picky heheheheheh


yeah that may be true

and it takes ten thousand words to describe a picieee too

daz can you insert that pic into post #26

Done

Here’s some interesting info that Elken and I discussed and observed:

When the original triplet was used in the general orientation it pincushion the image and very slightly blurred the individual sub pixels. It showed a small amount of field curvature, either the corners where in focus or the centre was in focus.

When the original triplet was flipped, it barrelled the image and the field curvature was excessive.

Elken’s modified triplet, with the 3.5mm spacer, shows excellent geometry and focus when used in the reverse orientation that we usually use, flange away from the LCD. I don’t think he has tried it installed the other way around mounted but I think he has tried it by hand. My modified triplet, with the 4mm spacer, shows improved focus and geometry when used with the flange facing the LCD. But flipped, with he flange away from the LCD, the geometry was improved but the focus was slightly less.

When I removed the spacer all together the focus in both orientations was very poor.

What this suggests is that 3.5mm or 4mm spacer may not be at its optimum yet. It may be a case of using small .1mm shims to finely tune it to its max.

DJ

I can confirm that this mod works and works well.

I used some flyscreen rubber hose stuff I had lying around. Never had pincushioning but this was from the first batch of Pro lenses. The edge focus has improved 1000%. Its still not perfect but that could be because of the mirror alignment and the projector alignmnet in relation to the screen.

Well done elken!!

wow this is great,, this gives us all such an edge,,, whew,, not just an exception here in my PJ,,

three now

geezz 3:02 am,,, kip time,, zzzzzzzzzzzzzzz

So, shortening the rear spacer makes the focal length of the lens longer? hmmm, I'd like to try this with the 18" opaque, I always wanted to get it close to the focal of the 550mm fresnel I'm using. How did you and DAZZ come up with the spacing?

Oh, and great job elken!

DAMNIT, now I have to take down my projector from the ceiling. Oh well. If this works I will be so happy. I will let you know tonight if I have any luck.

It will work

And maybe solve the problem of blurry corners on 17" Lcd's.

Ok WHO is gonna be the first bright spark with a lathe to make a proper,

ZOOM PRO LENS

Ohhh hehehe if ya make one make two,, I would love one




well !!!!!!!

Make a either 'a new housing or modify the existing,,

I tested it today,, and it works, I mounted the acromat part,, figure of speech ( the front two lens taped together so they didn,t fall apart, mounted them in a plumbing tube then left the single rear, problamatic lens in another tube that slide inside the other one, leaving a 1MM spacer to stop the lens clanging together, and hey presto,, a ZOOM lens that changes image size quite a bit,, IE that is height wise on a 4:3 screen five feet down to 3 feet,, of course the larger the image some pinning and loss of focus on corner,, but hey in 16:9 mode perfect


how do like them apples