Portra 400VC versus Provia 400

[fju]

<p>Can someone tell me which of these films has finer grain? Thank you.</p>

[kevin_surfane]

<p>Provia 400X has an RMS of 11.</p>

<p>Portra 400VC has a PGI of less than 42.</p>

<p>The Converstion formula <a href="http://cacreeks.com/films.htm">RMS = (PGI / 0.5335) ^ (1 / 2.8669)</a> .Which gives Portra an RMS of less than 4.5. (The conversion formula is an approximation and it isn't perfect. There are plenty of sources of why grain comparison can't be done directly between slide and print films.)</p>

<p>Kodak also designed the film for scanning. I love Portra, but it's a bit pricy and film prices for both Fuji and Kodak are going up in January 2009 - so stock up.</p>

[kevin_surfane]

<p>Les;<br>

Here is the pertinent section from my link above:</p>

<blockquote>RMS 4.0 ~= PGI 28, RMS 4.5 ~= PGI 41, and RMS 5.0 ~= PGI 53, but the equivalence is not linear and there seems to be a lot of slop in the reporting of RMS numbers. (Or else RMS does not really measure perceived grainyness; blue sky dotting seems to be mostly a function of low-contrast resolution). Thanks to Michael K. Davis for this conversion formula: RMS = (PGI / 0.5335) ^ (1 / 2.8669).</blockquote>

<p>I have no idea how the original author derived that formula. I brought this up because this was the closest thing I could find that has a numerical comparison between the slide and print films. (I know: apple and oranges!) But I think in this day and age of scanning, the OP does have a valid question.</p>

<p>You've shot both the old VC and ProviaX - I haven't. And to be honest, even if I did, I proabably couldn't tell the difference. For example: I've shot both TMAX 100 and the new TMAX 400 and I can't tell the difference when I print them at 8x10. Maybe if I printed them at 16x20 I could. But when I have shot the old Portra 400, I was really impressed even with the cheap scans- and I am having some problems finding them so I can post - arrrrrrgh! I don't know if it matters, <em>everything</em> looks great at 72dpi on a monitor!</p>

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[fju]

<p>Thank you for your replies. Has anyone printed both at 20x30? </p>