Basic video projector question

[jbaugh]

I'm embarrassed to ask such a simple question. But how else will I learn?

I have purchased a video projector that has VGA and DVI inputs. It is currently connected to the computer by a 30 ft. VGA cable with a VGA to DVI adaptor to connect to the computer DVI port.

I believe we have it set up with a resolution of 1260 x 780 or something thereabout.

My question is:

Will I get substantially better projected image quality (particularly text) by purchasing a DVI cable and switching to the DVI input in place of the VGA? My friend has reasoned that since the output of the projector is analog there will be no noticeable improvement in image quality by using DVI versus VGA.

Thanks.
John

[gll99]

It would have helped if you posted the make and model number of your projector but in general....

The vga connector is analog and the dvi is digital. If you go from dvi to vga on the pj then the projector has to convert the signal to digital. If you go from dvi to dvi then no conversion is needed. It's also best if the ouput from the pc is at the projector's native resolution. That should produce the cleanest signal.

[IKnowNothing]

Having used a number of projectors over the last 5 or so year I have to agree with gll99.

For me the biggest effect on output quality is to ensure that the source is at the native resolution of the projector - much the same as laptops - and use as little of the digital zoom as possible. Changing the input has (in my opinion) little or no difference on the output (all other things being equal).

The only other thing I have found is that setting the projector up properly (brightness, contrast, aspect ratio etc) makes a big difference to perceived quality of the image - as does using a white screen!

[jbaugh]

Thank you for the responses. I apologize for giving such scant information about the projector. The fact of the matter is that I didn't actually buy the projector. It was purchased by another individual in my small church. I was asked to be responsible for connecting it to the Mac computer that we will be using for our audio/video needs. Since I am the only Mac person in the church I am trying to decide how to best proceed.

Unfortunately, at this time I don't recall the name or model of the projector. I was struck by how poor the documentation was that came with the projector. I looked all through the owner's manual and other descriptive material thinking that a projector would have a native resolution like a flat screen monitor has. But there was no "specification" list or any mention of native resolution. When attached to the Mac, a long list of resolution selections is possible through the Mac preferences. If one of the highest resolutions is chosen there is an error message that the settings are "out of range".

The one who purchased the projector hooked it up with a VGA connection. He led me to believe that was the only option. But when I climbed up to look at the mounted projector it clearly has a DVI connector.

I guess my basic question is, regardless of which projector you use, does it matter how the projector is connected to the computer in terms of video quality?
John

[gll99]

I guess my basic question is, regardless of which projector you use, does it matter how the projector is connected to the computer in terms of video quality?

Given the choice, digital is best so use the dvi connector.

As to the resolutions offered by the video card I would be careful. The computer may see the projector as a standard monitor and offer resolutions that the projector does not support or that the projector will need to convert. In the first case there will be no picture and in the latter the pj will convert the signal but it's not the optimal setup. As was said before find out the native resolution of the projector and send that from the computer to the projector.

There are other important factors maybe even more critical in a large space like an auditorium or church. Since it's often more difficult to control ambient lighting high contrast and brightness are critical. For discreet placement you usually need a longer throw distance with a good zoom to adjust the image size. Projector placement too can be an issue if it's not centered adjustments must be made for keystone correction.

Unfortunately extreme zooming or keystone adjustment reduce brightness and introduce distortions which could affect focus and text clarity across the viewable screen. For example, the top of the screen may be in focus but the bottom is not or the left side is focused while the right side is not. This is barely visible (if at all) when viewing video or images but is hard to miss when reading text.

IMO, many churches, meeting halls and auditoriums are probably environments most suitable for a rear projection unit and retractable screen.

[jagabo]

A 30 foot VGA cable might indeed degrade the picture. I would try moving the computer and projector closer together and using a short VGA cable to see if there is an improvement. Then you'll know if the long cable is a problem.

[edDV]

Go to the projector and write down the make/model number. Then tell us. Everything else is speculation.

A projector can have a DVI connector but only connect VGA (aka DVI-A). Long DVI-D runs >20ft also have issues.

[jbaugh]

I wish to thank you all for your input and suggestions. Today I will have physical access to the projector and I will gather all of the info you've requested.

Happy Easter.
John

[jbaugh]

The projector is a Planar PR5022 DLP.

The native resolution is 1024 x 768, which is the resolution we have chosen for it.

Should I stay with the VGA to DVI adaptor to connect to my Mac Pro DVI ? Or should I spend $75+ and switch to a DVI cable to make a DVI to DVI connection? Will I notice enough improvement in the video to justify the expense and effort?
John

[jagabo]

Borrow a short DVI cable from a computer. Compare the picture quality of the 75 foot VGA cable to the picture quality of the DVI cable. If there's a significant difference you know to use a 75 foot DVI cable.

[edDV]

The projector is a Planar PR5022 DLP.

The native resolution is 1024 x 768, which is the resolution we have chosen for it.

That projector does have both VGA and DVI-D inputs. The VGA input will accept native 1024x768, or down scale 1400x1050 or 1600x1200 to 1024x768. The manual is non specific about accepted resolutions over DVI-D. Use 1024x768.

This is a business conference room style projector intended for office lighting.

Specifications
http://www.planar.com/products/projectors/pr/pr5022/index.cfm

Manual
http://www.planar.com/products/docs/projectors/manuals/qsg-planar-pr5022.pdf

Install guide
http://www.planar.com/products/docs/projectors/manuals/qsg-planar-pr5022.pdf