CurtPalme.com Home Theater Forum

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Finally, I can take my hands on a set HD-145N lenses for my PG xtra which is equipped only with HD-6C ML lenses (from PG plain).
I wanted HD-145 lenses for a long time, but now I am hesitant. Everyone says that the HD145 has better edge focus, however I managed my HD-6s perfectly focused in the corner as well, also the HD145 haloing less (now this would worth the effort), but everyone says the throw is different -now this is the biggest problem. I am short of space, I only have 152cm (60") wide screen (174cm/68" in diagonal) the distance of the projector is 225cm (88"). I've breeded 720p-72Hz timings for maximized raster usage, and have about 1,5-2cm (6/10"-8/10") safe margin on the tube edges. I don't want any smaller screen, although I have space for bigger screen and is welcome, but I can't pull the pj back any further.
So what can I expect from a HD-145 sizevise? I found that the HD145 has about 1,4x width throw, but that's what I already have, so can anybody tell me what can I expect?

mc86 · Posted: Wed Sep 26, 2012 2:38 pm Post subject:

what is your time frame? I could take a physical measurements for you simply using the green tube on my ECP for you sometime within the next few weeks. My ECP has the HD-6C ML on it now AND I have HD-145Ns on hand, too. I will be making the very same change next summer as part of my planned soft edge blend. So I'll eventually need to know in advance of that project...so this helps me, too.

Obviously, the actual tube face of the 07MS is not the same as your NEC's tube, so I couldn't provide actual throw distances for your machine, but I could provide relative data that could be scaled. There would certainly be nonlinearity in the size multiple as a function of distance from center of tube face -- as such, I'd take measurements every 8in or so for both cases at three throw lengths. A translation function could then be easily fit given the knowledge of the actual size of the image on my tube's face. You'd then have to extrapolate for the width of your tube face using my data. Make sense? That is, I don't think one can say the throws differ by a constant multiple over all widths of tube face or throw lengths. This might take me three hours or so, I'm guessing.

Matt

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Thanks, there is no need to hurry. I think I'll get the lenses on the next week or so, but I've never got better picture out of this set like nowadays, so I'm affraid it would be very hard to achive this point of perfection, after messing with the lenses just for fun. Not to mention that as I've seen the HD145Ns have differently tinted filter elements than HD6s so a color recalibration would also required -but for testing this could be ignored though. So I'll think twice before do anything... Smile

HaydnG90 · Joined: 22 May 2006 Posts: 1356

How does the throw of the HD6's compare to the HD8's? I had the latter on my floor mounted BG808s. When I switched to the HD144's I had to move the pj about 5" closer to the screen for the same sized image. This suited me just fine since I could reclaim the sweet spot and sit behind the pj and still enjoy the immersive, big-screen experience.

mc86 · Posted: Wed Sep 26, 2012 3:36 pm Post subject:

Ah OK, interesting. I'll try and get to this in the coming weeks, but it might take longer given status of cliffy's meet-up and other factors. On my ECP I'm planning on switching from tinted glycol and clear HD-6Cs to clear glycol and tinted HD-145s, so re-doing color will have to happen (greyscale is not correct now anyway) for me regardless. I have mixed feelings about the trade-offs on all this and may end up putting clear HD145s on it...not sure.

Once other concern I have about using the 145s is that smaller throws for the same image size means increased keystoning of the image on the tube face...and this becomes increasingly drastic as the throw length decreases. Thus, keeping with the less-wide lens could be beneficial to image-on-tube geometry and not maxing-out keystone.

Matt

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

HD8 has longer focal length than HD145, but unfortunately it doesn't help me.
There is a USPL document about lenses in the "all about the lenses" thread, I attached here too, there they say that the (plain) HD145 is fully compatible (including throw) with HD-6D, and HD6D is mechanical upgrade of the HD6C, however I read somewhere HD6C and D have different throw. Actually comparing the focal length of HD145 and HD6C would help a lot, and it can be measured by it's own.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Okay, the HD145Ns are here. I just put them on...

Drum roll....

I got 1 cm (less than a half inch) smaller picture (in width) with untouched raster than with HD-6, of course the convergence still needed to be touched up, but it was about a 15 minute work.
Haloing is indeed less noticeable, aaand the sharpness... well for me it's just a little bit sharper, the difference is not that huge as I expected from others' opinion, however the scanlines in 720P are now visible from closer inspection.