well, i'll have to check with, well, whoever took over for Kelli to see if I can still get a replacement for my pro lens. Hmmmm, sales@ still works, i assume........ BTW - Hello Jonjandran.

I think i need to do the pro lens mod . The center is sharp and gradually looses focus. Watching movies looks fine.

Are these results similar to what you guys are experiencing? using a folded design

Hi,

I am also getting the same focussing problem, either corners OR center can be focussed, not both.

I tried modding my Pro Lens. But still unable to get perfect corner focus.

Consider the fact that I am using a 14.1 in LCD, short arc lamp, and projecting at a short throw (9 feet) to get a diagonal size of around 65-70 inches.

FYI - I am having an unsplit vertical design.

Using an FS mirror from eBay (vette4jj).

Is it becoz I am having the mirror closer to triplet than the LCD?

Also one more point: Since my box is a bit short, I am having the rear fresnel (220mm FL) at around 190mm from lamp arc. Is that an issue?

Distance between fresnels - 10 - 40 mm (i tried all distances).

Distance between LCD and Fresnel - 40 mm, since the chip attached to LCD needs to be reversed (towards fresnels in an L shaped orientation) I wont be able to reduce this gap during my testing. Will reducing this gap help? If yes, then I will try (but it will give me reversed image).

I will be posting pics soon in my Plog that I started today.

Guide me on what more information will be required from my side to get inputs from you all.

I got a 150w ceramic as well, and having corner blurry issues. How would i 'take advantage' of my lamp's short arc? moving the front fresnel closer to the triplet?

I would like to see what the triplet mod can do for me. I have some ghosting/smearing and still I have some little trouble to get perfect edge to edge focus.

Before I'm going to do it, I would like to know if it has any negative effects when dust comes between the lenses.

I can answer this. The first time I reassembled my lens it was filthy sick with pieces of lint. I mean really bad. I couldn't pick out any artifacts at the screen. This being said I still HIGHLY RECOMMEND you use all means at your disposal to keep the lens internal elements scrupulously clean. Wear powder-free or lint-free gloves of some kind. Work in a clean area. Keep a can of compressed air handy to get rid of the odd speck. And be very careful and patient when taking it apart and putting it back together. I chipped one of my lenses rather badly (but again it made no difference like the dust). I've since taken it apart and cleaned out all the crap because I simply couldn't stand looking at it all the time.

Very few pro lenses actually appear to be "bad". This is a real mystery. So, make certain you've exhausted all other possible causes of your dissatisfaction before proceeding to mod it. And let us know how things work out.

Ok thanks. I will do my very best to do it all clean.

Although you are probably right to say: first try all other things but you know, I'm just vewy vewy curious

So I'm just going to do it

I already started. This is going to be my new spacer:



It's a challenge though. The only thing I have is a crooked saw . I got a tip from a friend of mine. I think this is how I'm going to do it:

Since it has to be about 3,5mm (as I understood) i'm gonna do my best to saw it as straight as possible at 4-4,5mm. Then I will lay down some sand paper at the table and rub the ring on it. Hopefully this will bring it down to about 3,5mm at all sides.

Any other ideas?

Do you believe in the power of prayer?

Like I said - let us know how it turns out.

tommy,,, use a rubber o ring much easier,, with anything that is not clean and flat could possibly crack the lens edges

I used the plastic insulation from ordinary electrical wire. I joined the two ends with another piece of insulation that fit neatly inside. This makes it easier to trim slithers off the length to get it fitted snuggly into the triplet housing.
Dust inside the lens won’t be seen on screen. The triplet resolves an image of the LCD not an image of the triplet. You can even place your finger in front of the triplet and not see it projected, it will dim slightly though. As Durachko said, keep it clean if you can.

DJ

Thanks for the comment. I couldn’t find a rubber ring big enough in diameter. The isolation rubber of electric wire could do the job but I think using that plastic material which is already at the right size would be better. So today I finished fabrication. Let me show you some pictures.

First I tried to cut (with a metal saw) the ring to about 4mm, as straight as I could:



The result was a pretty uneven sized ring. About 3,5 to 5mm. So I had to bring that down to about 3,5mm at all edges. I tried to do this with sandpaper however that seemed impossible. First it was very hard to get a grip to this small ring. Second with my hands it was impossible to cut down only the parts that should be. So I had to come up with something. I created this tool:



Pff damn it’s hard to explain in a foreign language.. Knowing the wood (MDF) is perfectly flat I thought that pressing the ring down would result in a situation were only the 5mm parts would firmly touch the sand paper. That way only the 5mm parts would be cut down.

Like this (up side down):



Well it was pretty successful. In the end the ring was about 3.1mm all places. There was a variation of about 0,1mm. So it isn’t perfect but good enough for testing. I could measure it pretty accurately with a beautiful tool from my neighbour:



Continues with a new post:

I blackened the inside with a black marker and then I could begin. It’s actually quite simple and it’s done in a minute:

Old situation:


I removed the upper lens (this one faces the tft) and the spacer below. I put on the new spacer and put the lens back:



The other spacer moved to the front and here I am ready to go:


So what did it do with the projection.

Well at first I discovered the triplet has to be furthered away a lot to focus at the same distance. So I had to construct something to keep the triplet steady:



Continues with a new post:

Ok now the image:

Size:
Of course it has become smaller. I guess about 20%. Although it’s still big enough, it’s just a little bit to small for my taste.

Focus:
Well it seems the focus is just the same as it was. When I bring my lamp back to about 220 mm there is a big difference between corner and centre focus. However (just as it was before modding), bringing the distance down to about 195mm gives me a pretty good corner to corner focus however I think I can still detect a small difference between centre and corner. But the triplet is not mounted probably so it’s pretty hard to tell.

Smearing/ghosting:
It seems the ghosting (white letters that glow to the left or right in a dark background) has increased. I hoped it would decrease, but clearly it did not. When I twisted the triplet to the left (horizontally) the ghosting increased to the left but dissolved at the right, and vice versa. However holding the triplet perfectly centred meant at both sides there was still some noticeable ghosting.

It’s not all bad. There is some improvement! First my projection looked a bit like this:



I believe to recall this is referred to 'the pincussion effect'?

Well at this point the projection looks a bit like this!:



So somewhere in between it should be perfectly straight

What am I going to do next:
Well bringing the distance between the first and the second lens down to 3.1-3.2mm is just a bit too much (so the distance is a bit too small ). I want to try a new spacer which will be about 5mm or bigger. Also I want this spacer to be even with a variation less than 0.001mm so I will have to find a rubber O-ring. Hopefully with that spacer my triplet can be mounted to the enclosure because I’m not planning to adjust my focus mechanism. That way it’s also better to see what it does to the corner to corner focus. Moreover I hope the ghosting to be reduced.

get a rubber o ring bigger abd cut it, i used plastic tubing to join the ends,, (spagetti tubing) edge image smearing is mostly caused by misaligned optics

Just a little tip for joining the o-rings... use Super Glue! Make sure it is cut properly because once it's stuck together the o-ring 'becomes' one piece again!
We use this tip in making our own o-ring sizes all the time where I work, it's so strong that when you pull on the o-ring it won't break where it's joined.
I just thought I would pass this along as it will make the o-ring the same size without an apparent 'connection'.