I shoot in 4:3 with my xl1 to preserve quality. When I want to get a film looking touch I use a letter-box made in Photoshop, applying it in Premiere, through transparencies and so on.
But I have noticed a problem. When I use the letter box-alpha channel the image becomes lighter...loss of quality?
It´s very subtle but noticeable. any suggestions'

I say it depends on what effect you use to get the mask over
your video and how you made your mask in the first place.

Try one of my masks I use in Vegas, can find them here (www.visuar.com/letterbox/calc.htm).

Now these do NOT contain any alpha channels, so you must
indicate to Premiere that it is to use the (pure) white to show
the video. In Vegas I can easily tell it to do this. I have no idea
how you would do this in Premiere.

I have tried with your mask but the result is the same
I have tried also all the possibilities premiere offers to obtain transparencies
I insist, it´s very subtle, myself I have been using letterbox for a long time without seeing this loss of light.
Maybe I am losing my mind....
Thank you for your time!

I am not familiar with Premiere but if "cropping" is available, try to crop to 75% vertical. This should go faster too, because there is no processing (appart from de/recompressing) on the remaining video content.

I tried to use cropping in Premiere but the program didn´t obey me. Maybe this feature is not compatible with my pinnacle dv-500?
Finally, I have renounced the letterbox (and the film look)
It was just a wedding. Next time I see myself cutting frame by frame to obtain the black bars...
Perfectionism is so painful! (I am not proud of it, I swear! sometimes it is so close to stupidity!)
Thank you for your time, Andre!

I would not want to crop, personally, so I can still move the
footage vertically under the bars to get the optimal framing.

Josema: I've had similar problems when keying in Premiere. It looks as if the white isn't completely keyed out, but is left simi-transparent?

I do color correcting and add leterboxes in After Effects now. I use the basic "Color Key" filter on a pre-made 16:9 letterbox w/ white center and I key out the white (RGB 255, 255, 255). This works perfectly.

Also...in After Effects you can import a PSD and tell it what layer to pull in, or pull in merged layers. Of course, the black bars would have to have been created on a separate layer, with a transparent middle. Anyhow, I forget whether or not Premiere allows you to do this, but that might work.

Oh, and maybe you could try 32 bit TGAs.

I'd hate for you to have to do it by hand!

,Frank