Powerbook And Projectors

DMA3763

Registered
Hello,

Sometimes when I use a VGA projector with my PB G4 1.5Ghz with DVI video out, the resolution of my screen changes. This is with the "mirror" mode.

I know I can select separate resolutions for both the PB and the projector with the display menu, but that doesn't always work. With some projectors it is impossible to get a "workable" resolution on the PB screen.

I have a new PB with a DVI video output, but it has always been like that with my previous machines; some projectors are just a pain. Windows PCs don't seem to have this problem.

Is there a way to keep the PB screen resolution unchanged all the time in mirror mode?

Also, as this PB has a DVI output I must use the DVI-to-VGA adaptor. Last week I noticed that with a Pionner wide screen display (plasma type), vertical lines were distorted (noisy). My colleagues didn't have that problem with their Windows PCs.

Thank you.
 

Zammy-Sam

Desertchild
The native resolution of your 15'' powerbook screen is 1280x854. When you plug a second screen to your powerbook you have two options: 1. splitt screen mode and 2. mirror mode. You can switch between these modes using the F7 key. When you use the mirror mode, your 15'' powerbook screen switches to the default resolution of your external screen or video device. If that is set to 640x480, your powerbook will use the same resolution. If the projector supports higher resolutions such as 1024x786, you should change the default resolution of that screen to 1024x786 using the Display settings in System Preferences (use option+F1). Now your powerbook screen will run at 1024x786 which will look a lot better than 640x480. The next time you plug the same projector the resolution should be 1024x786. However, I wonder why you are using the mirror mode. For keynote or powerpoint presentation there are some very useful features in the splitt-screen mode such as notes and a timer or a preview of the next slide while there will be a fullscreen presentation over the projector.
 

DMA3763

Registered
thank you for the feedback.

I am using the mirror mode because we often do work live with a projector; such as fine tuning presentations... using the split screen option is cumbersome as tools are not in the same screen.

I am also curious to understand why Windows laptops don't seem to have the screen resolution issue; they just do F7 and all is done.

Finally, I am also curious to understand why I had quality problems (noisy lines) when using the Pionner flat screen display; once again, my friends didn't have that problem with a straight VGA connection (remember I need to use the DVI-to-VGA connector interface).

thanks.
 

Zammy-Sam

Desertchild
DMA3763 said:
thank you for the feedback.

I am using the mirror mode because we often do work live with a projector; such as fine tuning presentations... using the split screen option is cumbersome as tools are not in the same screen.

I am also curious to understand why Windows laptops don't seem to have the screen resolution issue; they just do F7 and all is done.

Finally, I am also curious to understand why I had quality problems (noisy lines) when using the Pionner flat screen display; once again, my friends didn't have that problem with a straight VGA connection (remember I need to use the DVI-to-VGA connector interface).

thanks.
Actually the Mac does the same thing as the PCs. Once you enter the mirror mode, the screens are "mirrored", which means that they both use the same resolution. It now depands on the native resolution of the laptops lcd, how the picture quality looks like. Given this example: the beamer supports 800x600 and the native resolution of a pc-laptop lcd is also 800x600. In the mirror mode the picture will look sharp as it is the lcds native resolution. On your powerbook, which has a much higher resolution, the picture will no more look nice in 800x600. LCDs are not like crt screens that show a sharp picture in lower resolution. LCDs should run at their native resolution otherwise the quality will suffer. This is the rule for all lcds.
Another aspect is that your powerbooks lcd has the ratio 15:10. Most standard resolutions are at 4:3 (1024x768, 800x600, 640x480). Simulating such different ratios will reduce the picture size and quality.
By the way, did you know you can use the F7 on your powerbook as well? Try it and you will see that the only reason why your powerbooks picture doesn'T look so nice in the mirror mode is the high resolution of your lcd and the different ratio.
 

ksv

web developer
If the projector has a DVI or VGA output, you could connect it to another CRT display that will use the same resolution as the projector.
 

Viro

Registered
Zammy-Sam said:
By the way, did you know you can use the F7 on your powerbook as well? Try it and you will see that the only reason why your powerbooks picture doesn'T look so nice in the mirror mode is the high resolution of your lcd and the different ratio.
One thing I've noticed when running in mirror mode on my Powerbook 12", is the screen will change it's resolution to match that of the external display (CRT/LCD/projector/etc).

The picture quality on my laptop's LCD doesn't change, as instead of making the screen fit the entire LCD at a lower resolution, I end up getting a small picture (at for example 800x600) with thick black borders filling up the rest of the screen. Picture quality doesn't suffer at all.

Your mileage might vary, since this was on a 4:3 aspect LCD which is what the Powerbook 12" has.
 

DMA3763

Registered
Zammy-Sam said:
Actually the Mac does the same thing as the PCs. Once you enter the mirror mode, the screens are "mirrored", which means that they both use the same resolution. It now depands on the native resolution of the laptops lcd, how the picture quality looks like. Given this example: the beamer supports 800x600 and the native resolution of a pc-laptop lcd is also 800x600. In the mirror mode the picture will look sharp as it is the lcds native resolution. On your powerbook, which has a much higher resolution, the picture will no more look nice in 800x600. LCDs are not like crt screens that show a sharp picture in lower resolution. LCDs should run at their native resolution otherwise the quality will suffer. This is the rule for all lcds.
Another aspect is that your powerbooks lcd has the ratio 15:10. Most standard resolutions are at 4:3 (1024x768, 800x600, 640x480). Simulating such different ratios will reduce the picture size and quality.
By the way, did you know you can use the F7 on your powerbook as well? Try it and you will see that the only reason why your powerbooks picture doesn'T look so nice in the mirror mode is the high resolution of your lcd and the different ratio.
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I tried several projectors and get terrible results on the projector screen. However, I also tested with an external monitor (Sony with DVI interface) and the picture is excellent with the DVI interface and quite good (but you can tell the difference) with the DVI-to-VGA interface.

I am very disappointed by the bad quality obtained with projectors (always with VGA interfaces) and I wish there would be a way to use VGA projectors with at least average quality images.
:(
 
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