[foamcows]

For those who have their kit up and running. Are you able to get crystal clear focus all the way to the edges? I cant, I get a similar problem to what we had with the varifocal lens but not as extreme. The center is in focus, the edges are just slightly out of focus. I also notice that the sides are kind of concave, the image is thinner in the middle, the corners are wider and taller by a half inch or so. It is not a major problem, just you can notice it.

I am using a 17 inch monitor. If my lenses are out of alignment then give me an idea how, I adjusted them for maximum and even brightness. The image is very bright, all the way to the edges, the lenses are facing the right direction.

[miedosoracing]

foamcows, on Jun 13 2006, 08:30 AM, said:

For those who have their kit up and running. Are you able to get crystal clear focus all the way to the edges? I cant, I get a similar problem to what we had with the varifocal lens but not as extreme. The center is in focus, the edges are just slightly out of focus. I also notice that the sides are kind of concave, the image is thinner in the middle, the corners are wider and taller by a half inch or so. It is not a major problem, just you can notice it.

I am using a 17 inch monitor. If my lenses are out of alignment then give me an idea how, I adjusted them for maximum and even brightness. The image is very bright, all the way to the edges, the lenses are facing the right direction.

Make sure the lens is in the right direction. I do remember Brain saying they look backwards when installed. Good luck.

[Durachko]

miedosoracing, on Jun 13 2006, 09:43 AM, said:

Make sure the lens is in the right direction. I do remember Brain saying they look backwards when installed. Good luck.

To add to this the pro lens is mounted with the widest part - the flange - closest to the LCD.

[GadgetSmith]

FYI... Flange side goes toward the LCD. (just clarifying miedo's statement)

More questions if you do indeed have the triplet oriented correctly... Are you using split/unsplit optics ? Any keystone ? Any folds in the light path ?

... any other information about your setup that may help troubleshoot would be good.

cheers,
gs

[foamcows]

It's your normal 17 inch pro haas kit, split lenses, no folds. Some keystone, it still has the focus issue when I dont have the projector tilted. The triplet is facing the correct way.

I am more wondering if I should expect better than I have, is the image capable of being perfect?

This post has been edited by foamcows: 13 June 2006 - 07:05 PM

[miedosoracing]

foamcows, on Jun 13 2006, 02:04 PM, said:

I am more wondering if I should expect better than I have, is the image capable of being perfect?

I wonder the same thing. I think it is gonna be hard to get a perfect pixel to pixel corner to corner focus, but others may be able to answer that, that use it currently. What Fresnels are you using. I believe a 650mm is what everyone is using. You are sure that you have the fresnels in the right order as well? light/330mm lens/650mm?

[GadgetSmith]

I don't know if you can easily try the unsplit design, but if you can, you will quickly see that you can attain perfect corner to corner focus... even small text is easily read... the capabilities of the lens has been well documented by other users...

Surely any keystoning you do will effect focus to some extent, but with it not angled you should be getting "very good" focus. If not, it could be that the field fresnel is a bit warped ? ... something else I've noticed is that when I was between using the Ushio S400DD and the EYE BT-28/HOR with the Ikea napkin ring reflector, I found that simply changing lamps would alter my focus... I was never sure why this was... the BT-28 always had better focus (at least that's how I remember it... so long ago it seems like... it might have been the other way around...) What lamp/reflector are you currently using ?

My opinion is that if you stay with the split design, you may always be trading away some focus... you may certainly get it to the point you are very happy with it, but may not ever be "perfect". Unsplit is pretty much the way to go for "perfect" focus as there is simply nothing between the LCD and triplet to alter focus. This may be more difficult to implement because of contraints on locating the PJ, etc...

gs

[miedosoracing]

GadgetSmith, on Jun 13 2006, 02:58 PM, said:

something else I've noticed is that when I was between using the Ushio S400DD and the EYE BT-28/HOR with the Ikea napkin ring reflector, I found that simply changing lamps would alter my focus... I was never sure why this was... the BT-28 always had better focus (at least that's how I remember it... so long ago it seems like... it might have been the other way around...) What lamp/reflector are you currently using ?

I've been saying that kinda of thing. I said my focus was different due to my light, and got laughed at. It does matter. I am not exactly sure except possibly the arc length, but every little thing can alter the focus.

And when I say corner to corner, I don't mean words etc per say . I am saying, pixels being clear and seperated all the way to the corner. :-)

This post has been edited by miedosoracing: 13 June 2006 - 08:53 PM

[Me2!]

foamcows, on Jun 13 2006, 07:04 PM, said:

It's your normal 17 inch pro haas kit, split lenses, no folds. Some keystone, it still has the focus issue when I dont have the projector tilted. The triplet is facing the correct way.

I am more wondering if I should expect better than I have, is the image capable of being perfect?

Your focus problem is more due to the split design than the lens.
Imagine a fresnel lens lying flat with teeth up. Light is coming up from underneath. Some light is reflected off the flat bottom and some is reflected inside the lens as it is about to exit. Your problem is the latter. The reflected light bounces off the teeth and goes back down at an angle pointing out from the center. It then hits the bottom of the lens and some bounces back up. This causes a smearing of the light that is most pronounced in the corners.

This happens in an unsplit as well but it doesnt matter much because it is before the image is made. It's just more light flying around at poor angles. It contributes a bit to dimmer corners. It is less likely to be angled to go throught the objective.

Most fresnels have this problem. Reflexite makes a non ghosting fresnel. It is very thin so the bounce doesnt get past the teeth. In other words it is not displaced out by much.

If Brain want to sell good fresnels for DIY he should get the film fresnel from reflexite.

[Rox]

foamcows, on Jun 13 2006, 09:04 PM, said:

It's your normal 17 inch pro haas kit, split lenses, no folds. Some keystone, it still has the focus issue when I dont have the projector tilted. The triplet is facing the correct way.

I am more wondering if I should expect better than I have, is the image capable of being perfect?

how is it going?

mmm, you said you had the triplet propperly oriented, you know it is the opposite way as the standard lens would go?

mmm, the split and the keystone expreselly would introduce some unfocus but I believe it should not be comparable to the old pro lens...

please can you update about your issue?

[Me2!]

I should add that Reflexite won a $4.5 million contract (U.S. Display Consortium, a public/private partnership) to develop fresnels and screens for rear projection back in 2000. Their film fresnel was a result.

http://display-optic...s_march2000.htm

These are probably the best projection fresnels around.

[foamcows]

sorry for the delay, between the stanley cup finals, nba finals, and world cup I have just been watching tv more than anything.

I have the ushio pusle stirke lamp with a norpro reflector. Would putting black tape on the edges of the fresnel closest to the triplet help any? I wish I could get away with the unsplit design, but I need the keystone adjustment. I also have a 712n monitor and I have not attempted the antiglare removal.

it is not as bad as the old pro lens, I can read the windows clock when displaying full screen. But it is noticeable. Maybe it doesnt help that I have a 13 ft diaginal image, it would only magnify any problems. I rarely watch it in full screen, when in widescreen it isnt as bad but you do notice the barreling.

I guess I should rephrase my question to help narrow down the problem.

Does anyone with a Pro Kit in the split design with slight keystone have a slight focus issue?

I would be happy just knowing I am not the only one and leave it alone.