AVS Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
216 Posts
Discussion Starter · #1 ·
I have finally set ceiling mounted my JVC RS10 which has allowed my to complete my CIH setup. I have a Panamorph modified (to avoid ghosting) UH380 at a throw distance of 11.6 feet (throw ratio is 1.66). I am getting a slight but real decrease in sharpness with lens in place. It still looks good, but I want as good an image as possible.


I realize my setup is not ideal (both TD and TR). As this is my first attempt at CIH, I just want to make sure it isn't how I have the lens mounted/setup.

1) Basic question - Does it matter which way the prism is facing (hard to explain but it can be mounted with prism facing right or left). Panamorph manual seems to imply is doesn't matter if I am reading it correctly.

2) I adjusted the focus with the lens in place, but it still seems slightly less sharp than with no lens. Is this just a matter of my short throw distance? I know the sweet spot seems to be 14-17 feet. Is there a corrective element designed for shorter throws?

3) For those using the UH380 or UH480, would you say that sharpness is identical with or without the lens for you? When I put up the focus grid with lens in place, it still looks pretty sharp, but the picture appears a bit sharper when I remove the lens.


Any advice?
 

·
Registered
Joined
·
5,601 Posts
Yes, get a cylindrical anamorphic ala the Isco III.



I have never seen a prism based anamorphic that doesn't degrade image quality to some (possibly very slight) degree.


Of course, there is also a slight price difference between an Isco III and a prism based anamorphic.....


Vern
 

·
Registered
Joined
·
8,958 Posts

Quote:
Originally Posted by tds1 /forum/post/15492117


I know the sweet spot seems to be 14-17 feet. Is there a corrective element designed for shorter throws?

It does not appear so. In your case you might be best to remove the corrective element. Your TR is quite short, so you would already be experiencing some abberations like Pincusion. Removal of the element may mean that you get Astigmatism, but you have to ask you self what is worse, an out of focus image or an image that get slightly out of focus towards the edges?


Vern has made comment about the cylindricals and for good reason. They have continiously adjustable astigmatism correction becuase their front (or rear) elements can shift in or out to re-focus the image. Prisms lenses can not do this regardless of they have a corrective element of not...


Mark
 

·
Registered
Joined
·
736 Posts
I could see a notable improvement in sharpness and clarity when I upgraded from UH380 to 480. Currently, cannot see any sharpness reduction due to the lens. There is slight sharpness reduction towards the edges, however, this is the case even without the lens (for vw60).
 

·
Registered
Joined
·
5,169 Posts
CAVX,

Re: Panamorph conversion kits (you mentioned these in another thread):


I just received the standard UH-480 lens, which is designed for a throw up to 17' 5". My throw is 20’-5” (about 3’ further). I do see that my "pixel focus" is not as sharp (when I go up to the screen) as it is with the lens off. However ...at my seated position (14’ from 120" wide screen) w/ lens - the picture looks extremely sharp and very focused. In your opinion - would having a conversion kit installed sharpen/focus the image further and be actually noticeable (to my eye) from my seated position? Or is the increase in sharpness (focus) only going to be noticeable at very close (under 1') distance?


Vern,

I would appreciate your expertise as well (by the way - ISCO III was out of my price range - I was lucky to swing the Panamorph in these economic times
)
 

·
Registered
Joined
·
216 Posts
Discussion Starter · #6 ·
Thanks to all for the advice. Moving to a UH480 or ISCO III is unfortunately not a viable option, but I can understand they would be an improvement. I can live with the quality of the picture if that is the best the lens can do, but want to make sure I have maximized my setup.


CAVX, I do have pincushion, but I have zoomed the image enough that is seems tolerable. I would try removing the corrective element if it is a reversible procedure (meaning if I prefer it how it currently is). How hard is this to do with the UH380 (i.e. how would you go about doing that?)? Also, my UH380 was modified to avoid ghosting with the JVC projectors. I don't know what the modification by panamorph really was. Could this be why I am seeing a slight sharpness decrease?


Don't get me wrong, the picture looks really good with the lens in place. But like others here, we are always seeking the best possible.
 

·
Registered
Joined
·
8,958 Posts

Quote:
Originally Posted by John Ballentine /forum/post/15494748


In your opinion - would having a conversion kit installed sharpen/focus the image further and be actually noticeable (to my eye) from my seated position? Or is the increase in sharpness (focus) only going to be noticeable at very close (under 1') distance?

Whilst I have not had the oppertunity to "test" all the correction elements, I do know that when using a lens that can be made razor sharp for a given throw that the increase in image sharpness is noticealbe. Panamorph have released 5 different correction elements becuase they want their customers to be able to get pixel clarity at all throws. Yes you will see a difference, but you will also need to consult Panamorph about which correction element is right for you...

Quote:
Originally Posted by tds1 /forum/post/0


CAVX, I do have pincushion, but I have zoomed the image enough that is seems tolerable. I would try removing the corrective element if it is a reversible procedure (meaning if I prefer it how it currently is). How hard is this to do with the UH380 (i.e. how would you go about doing that?)? Also, my UH380 was modified to avoid ghosting with the JVC projectors. I don't know what the modification by panamorph really was. Could this be why I am seeing a slight sharpness decrease?


Don't get me wrong, the picture looks really good with the lens in place. But like others here, we are always seeking the best possible.

Understandable. The corrective element sits in the rear of the lens and you can remove it by first removing the 10 or so 1bolts that hold the lid on usig the supplied 1mm allen key. Just take note of the way the corrective element is facing as you do not want to put it in backwards should you feel the need to re-install it...


Mark
 

·
Registered
Joined
·
5,601 Posts
Yes, the proper corrective element for your throw will definitely help.


The major difference between the cylindrical style lens and the prism style lens is that the astigmatism adjustment on the cylindrical is continuously adjustable and can be tuned to perfection, whereas the prism style correction elements are only perfect for one specific distance within the range they cover.


But that's a lot better than no element or an incorrect element for your throw.


Vern
 

·
Registered
Joined
·
216 Posts
Discussion Starter · #9 ·

Quote:
Originally Posted by Vern Dias /forum/post/15502179


Yes, the proper corrective element for your throw will definitely help.


The major difference between the cylindrical style lens and the prism style lens is that the astigmatism adjustment on the cylindrical is continuously adjustable and can be tuned to perfection, whereas the prism style correction elements are only perfect for one specific distance within the range they cover.


But that's a lot better than no element or an incorrect element for your throw.


Vern

That would seem to bring about the question as to whether Panamorph has a reason for not having a corrective element specifically designed for shorter throw distances. I would have to think that at least one of the reasons people choose CIH setups is because they cannot achieve that 2.40 screen size by zooming (at least that is the situation in my case). That would seem to be a common problem with shorter throw distances. I think I will at least give them a call to see what they say as well. I am somewhat hestitant to open the UH380 - my last attempt to "repair" our dishwasher resulted in requiring it to be replaced.
But, I am very tempted to give it a try. I guess the question is, is using a corrective element designed for 14-17 feet better than having no corrective element at a distance on 11.5 feet?
 

·
Registered
Joined
·
8,958 Posts

Quote:
Originally Posted by tds1 /forum/post/15503185


I guess the question is, is using a corrective element designed for 14-17 feet better than having no corrective element at a distance on 11.5 feet?

The corrective element is to correct astigmatism which is likened to a slight defocus towards the edges of the screen whilst the centre is in focus. Right now, (based on what I gather from your posts) your image is out of focus, so if you remove the element, whilst you will introduce astigmatism, at least the centre of the image can be in focus.


The point is, the corrector is designed for a specific distance. If you are outside that distance, the corrector is not working for you anyway...


Mark
 

·
Registered
Joined
·
5,169 Posts
Quote from Panamorph:


"The UH480 lens is engineered to give optimum sharpness and full graphics level performance when mounted between about 14.5’ to 17.5’ from the screen. This was a deliberate design choice, as experience has shown us that the vast majority of projectors are installed within that mounting distance. Mounting the lens within those limits will reveal full 1080P pixel level sharpness even with critical test patterns.

Practically, however, the UH480 lens can be used from about 12 to 22 feet without any noticeable loss of sharpness with even high definition movies.


For those wanting “pixel level” performance at distances greater than 17.5’, we offer optional UH480 Long Throw Conversion Kits at additional cost."


What do you think about the "bolded" statement about throw ratios up to 22" w/no noticeable loss in sharpness (my throw ratio is 20'-5")?
 

·
Registered
Joined
·
968 Posts

Quote:
Originally Posted by tds1 /forum/post/15503185


That would seem to bring about the question as to whether Panamorph has a reason for not having a corrective element specifically designed for shorter throw distances. I would have to think that at least one of the reasons people choose CIH setups is because they cannot achieve that 2.40 screen size by zooming (at least that is the situation in my case). That would seem to be a common problem with shorter throw distances. I think I will at least give them a call to see what they say as well. I am somewhat hestitant to open the UH380 - my last attempt to "repair" our dishwasher resulted in requiring it to be replaced.
But, I am very tempted to give it a try. I guess the question is, is using a corrective element designed for 14-17 feet better than having no corrective element at a distance on 11.5 feet?

I recall reading a post from Shawn at Panamorph that you can combine/stack two of the longer throw conversion elements to achieve better focus performance at throws as short as 11 ft. The issues are the lens housing does not support this, and the cost of the corrective elements is not cheap.


I am using a UH380 at 12.5 ft (1.85 TR), and the focus is pixel perfect for the center of 1/3rd the screen, and softens gradually towards the edges, effecting vertical lines more than horizontal. I have to be very close to the screen to notice the drop in focus though, and from my normal 10 ft. view distance I can't see it.
 

·
Registered
Joined
·
968 Posts
After a quick search I was able to find the post from Shawn about combining corrector elements:

http://www.avsforum.com/avs-vb/showt...6#post11633706


"Short throw distances are far less common in home cinemas these days. However, long throw converter elements can typically be combined to provide optimum performance for shorter throws. For example, our UH380CD element can be added to the UH380 standard lens for the highest clarity at just over 10 feet. Note again that these are fine tuning adjustments, but they are readily apparent with single pixel test patterns at 1080 resolutions."
 

·
Registered
Joined
·
216 Posts
Discussion Starter · #14 ·

Quote:
Originally Posted by f300v10 /forum/post/15508091


I recall reading a post from Shawn at Panamorph that you can combine/stack two of the longer throw conversion elements to achieve better focus performance at throws as short as 11 ft. The issues are the lens housing does not support this, and the cost of the corrective elements is not cheap.


I am using a UH380 at 12.5 ft (1.85 TR), and the focus is pixel perfect for the center of 1/3rd the screen, and softens gradually towards the edges, effecting vertical lines more than horizontal. I have to be very close to the screen to notice the drop in focus though, and from my normal 10 ft. view distance I can't see it.

Very interesting. Yes the cost of that corrective element looks quite expensive. I think I need to take a step back a bit and get to the most basic question (as this is my first FP setup). How does one obtain pixel perfect focus (regardless of lens in place or not). I have just been using the focus grid that the RS10 has, but it seems like a very inexact procedure. Is there another way of obtaining more exact focus?
 

·
Registered
Joined
·
968 Posts

Quote:
Originally Posted by tds1 /forum/post/15510026


Very interesting. Yes the cost of that corrective element looks quite expensive. I think I need to take a step back a bit and get to the most basic question (as this is my first FP setup). How does one obtain pixel perfect focus (regardless of lens in place or not). I have just been using the focus grid that the RS10 has, but it seems like a very inexact procedure. Is there another way of obtaining more exact focus?

If there is a procedure to obtain exact focus, I don't know what it is. My PJ (Benq W5000) has manual focus, so I spent a lot of time walking back and forth to the screen until I got the focus as good as I could. If the RS10 has power focus (I think it does) then you should have an easier time of it.
 

·
Registered
Joined
·
8,958 Posts

Quote:
Originally Posted by f300v10 /forum/post/15510539


If there is a procedure to obtain exact focus, I don't know what it is. My PJ (Benq W5000) has manual focus, so I spent a lot of time walking back and forth to the screen until I got the focus as good as I could. If the RS10 has power focus (I think it does) then you should have an easier time of it.

That comment about no loss of focus for HD film is accurate as PC desk tops tend you to need a slight adjustment to look razor sarp, but a film still looks good. My BenQ 5000 is from one of the ealier batches (had FW 1.08 out of the box) and I have discovered some interesting things along the way such as focusing for film is best done using the menu in the centre of thje screen - when that is sharp your pretty good to go, but also that this unit does not seem to have uniform focus from side to side so focus at the center seems to work best for me.


When using a test pattern grid of single display pixels, I also noticed that only one plain (H or V) can be in focus as one time with my prims lens. Is this a limitation of prisms? I would say yes. So it is a case of finding what looks best on generated text and then except what you see for a film. I mean I can all the grain on the film transfer, so it is pretty sharp...


Mark
 

·
Registered
Joined
·
7,220 Posts
For my Sony when I think it's in focus, I actually go up 5 clicks and then down 10 clicks to see if that focus point is really "centered". If so, then back 5 to dead center.


If not, I adjust and try again.


In other words, is the out of focus the same on each extremes?

If so, then at mid point you are as "focused" as possible.

(I'm assuming liner steps in this narrow /near focus range)


I've found this simple trick helps me get the best focus I'm capable of.
 

·
Registered
Joined
·
216 Posts
Discussion Starter · #18 ·
So I spent some time with the focus last night, and I think now I am more confused (or surprised at the result). First thing I did was focus as accurately as I could without the lens in place. Then I moved the lens in place and tried to refocus to see if the "ideal" focus point was the same. It's pretty close, but it consistently appears to be a different "ideal" focus point than when you focus "ideally" without the lens.


Then I put on The Dark Knight BR using the focus point obtained by ideally focusing with the lens in place. Using this focus point, the picture looks extremely sharp, and to be honest at this focus point I can't tell any difference in sharpness by using the lens or not - both look equally sharp. I should probably complete the test and see if I can sharpen the "without lens" picture even more, but I am afraid to tinker with this current focus setting since there is no way to save it.


In short, I seem to have obtained a very good focus setting by setting my focus through the anamorphic lens first rather than setting the focus without it. To my eye, the through the lens sharpness and without the lens sharpness look equal in the center of the picture at this focus setting. It has certainly sharpened my CIH picture to the point that I am happy with it this way. But it has me wondering, is there some slight adjustment I need to make to my projector mounting that would explain why this is occurring?
 

·
Registered
Joined
·
5,601 Posts

Quote:
When using a test pattern grid of single display pixels, I also noticed that only one plain (H or V) can be in focus as one time with my prims lens. Is this a limitation of prisms?

No, it's the fact that your astigmatism correction is off. It does relate to prisms in that a prism style lens is perfectly corrected for atigmatism at one and only one throw distance (per correction element if your lens uses one). So if you have the luxury of altering the throw distance, you could experiment to try to find that magic distance for your particular lens.


However, a cylindrical anamorphic with continuously variable astigmatism correction is the better solution (if you can swing the $).


Vern
 

·
Registered
Joined
·
5,169 Posts

Quote:
Originally Posted by tds1 /forum/post/15515800


So I spent some time with the focus last night, and I think now I am more confused (or surprised at the result). First thing I did was focus as accurately as I could without the lens in place. Then I moved the lens in place and tried to refocus to see if the "ideal" focus point was the same. It's pretty close, but it consistently appears to be a different "ideal" focus point than when you focus "ideally" without the lens.


Then I put on The Dark Knight BR using the focus point obtained by ideally focusing with the lens in place. Using this focus point, the picture looks extremely sharp, and to be honest at this focus point I can't tell any difference in sharpness by using the lens or not - both look equally sharp. I should probably complete the test and see if I can sharpen the "without lens" picture even more, but I am afraid to tinker with this current focus setting since there is no way to save it.


In short, I seem to have obtained a very good focus setting by setting my focus through the anamorphic lens first rather than setting the focus without it. To my eye, the through the lens sharpness and without the lens sharpness look equal in the center of the picture at this focus setting. It has certainly sharpened my CIH picture to the point that I am happy with it this way. But it has me wondering, is there some slight adjustment I need to make to my projector mounting that would explain why this is occurring?

Interesting. I just focus without A-lens in place. I assume this focus is also ideal when A-lens IS in place (as per Panamorph). But I might try what you did - focusing w/ A-lens in place first. If I have a choice - I would actually rather have the scope picture (w/A-lens) be the sharper option.
 
1 - 20 of 23 Posts
Top