drum scan dpi - (large format)

okay, i am new to this tango drum scan stuff.

i am going to be sending off 2 negatives for a scan job.
i looked at west coast imaging (they seem reputable, correct me if i am wrong or offer your choices) and in their questions and answer's section, they say a 300mb file size is recommended for large format.

well, there is 4x5 and there is 8x10... and scanned at the same dpi, will result in a 4x file size difference.

i think it boils down to dpi as the main thing to consider based upon the largest print size you'll need...


so an example, let's say i plan to make a 40x50 print from a 4x5 somewhere down the road.... a 10x enlargement to produce the most stunning image with no digital artifacts.

what dpi should i be scanning with?

also, is 8 bit good enough for black & white scans? they have 16 bits available and they also say that 16 bit is overkill for color scans.

your thoughts welcome.

thanks.

-lc

8-bit is fine if you do not plan on doing any editing, i.e., if your negatives are perfect and just the way you like them. (Get 16 bit scans.)

can you explain why?

i can't see why it would be needed for things like cleaning up dust spots...

but i can see it where one adds contrast - lots of contrast and you end up with quantization bands - is that the main reason?

FYI, Calypso Imaging is equally reputable, and offers 16 bit for the same price as 8 bit.

As a drum scanner owner/operator I advise that you get more information to base your decisions on than what you can get from WCI. They are very tranny biased, and also tango biased (that's their scanner after all, you wouldn't expect them to say anything other than it's the be-all and end-all of drum scanners now would you?), and it used to say that in just about that many words on their website. I've haven't looked in a while so I don't know what's there now.

If you are looking to have negatives scanned, I would instead look to someone who actually likes and understands how to scan negatives. Consider for example fellow LF photography forum member Danny Burk (and no, I have no commercial ties with Mr. Burk). I should also note that there are a number of drum scanners out there that are sharper at higher levels of enlargement than a Tango. Danny has one of those.

You should also consider fellow LF photography forum member Ted Harris (no commercial ties with Mr. Harris either). He says his professional flat bed scans are the equal to drum scans and he may well be right; he certainly gets a lot of credit for his views from others on this forum who have used his services.

I'm just saying... More information rarely hurts.

As to file size. Ideally you'd want to have a file that requires no interpolation by the output device at final file size. Unfortunately there's not much of a standard for this. Epson wide format printers want 360 ppi, Lightjets want 120 ppcm (304.8 ppi), HP and Canon WF printers want 300 ppi, etc. And in practice this is nearly impossible to accomplish due to cropping at the scanner and in Photoshop, etc.

Then there is the argument over what scanner resolutions to use to get the image data off the film. There seem to be basically three main camps about this. One camp thinks you should scan at fairly low resolution to get the image detail without capturing any film grain (2400 ppi or so). One camp thinks you should scan at around film grain size (3600-4000 ppi or so). One camp thinks that you should scan at maximum scanner resolution and then down sample to your final print size (to reduce noise for example).

I'm not able or in fact willing to do the work to figure out which camp is "correct" if any of them are. That's left as an exercise for the reader.

What I do (and remember I'm doing my own scanning so this is easy for me) is to scan my 5x4 Tri-X and 160 Portra VC at full output size and 300 ppi. Another way to say this is 11x enlargement at 300 ppi. This gives me files of around 350MB (16 bit grayscale) and 1.1GB (16 bit RGB). I've printed a number of big canvas prints at 125 x 100 cm (about 50 x 40 inches) and this results in prints that are "nose sharp" in that they show the detail and sharpness when you walk right up to them.

This is what I want. I'm certainly not saying that this is the only way to do this kind of work. Clearly YMMV, a lot.

What I suggest you do is get the same piece of film scanned a few different ways. Make prints (sections from the full sized print). Compare the (sections of) prints (real, physical prints, not looking at it on a monitor). Decide what's worth it to you, and what isn't. That's really the only way you'll figure out what's going to work for you.

thanks, i believe i have enough information for now that is :)

I just had some scans done by WCI. I'm waiting on the Prints
to come back. After speaking with Ted Harris I have a greater
knowledge of what to look and ask for in the future. You would be
doing yourself a favor by speaking with him.
Good luck
Tom