Digital BW, The Print

Scott,
Their are several things to look at.. Lets look at stuff backwards ..First at the printer level it prints using one of a few selections from your printer or RIP menu.. Typically Epson printers prefer to get fed 360 dpi at what ever the image size your printing for normal images.. That's not to say that you can't send 180 dpi and obtain an acceptable image. 
Ok now lets bounce to the scans.  If your workflow is to scan all your 6x6's at 2400 dpi.. assuming you have good transparencies  or negs that looks like that is your limitation. a 2400 dpi scan of a 6x6 @8 bit is only 30.6 MB If you scanned in 16 bit it's 61.3 MB .. Their is typically much more information in that 6x6 so you want to get at it and the way to do that is in the scan process.So your 135mb file I assume is interpolated up.. That does work to some degree but interpolation does not create more information it just tries to keep what you already have and none of that stuff works perfectly.  So the answer would be to do the original scan at a higher resolution say 5600 which will give you a 166MB file in 8 bit..  By the way if you know your going to be doing some serious file manipulation do your scans in 16 bit. 
We always scan our transparencies or negs at the largest size we feel we'll ever print @ 300 or 360 dpi. So we do get some large files. I looked at the web site Mike posted.. That is true what they are saying but lets look at it.. If you have a base file that is say 5 x 7 @ 100 DPI then you tell photoshop to turn it into 1000 dpi you have not changed any of the information you have merely taken the existing information and converted it to a smaller dot pattern so no change in the final output with images output at the same size. 
So if you want to see the difference so that you can get and see it ....do this.. Choose a tranny or neg that has some good line detail in it..maybe something that has some architecure in it.. or?? you choose.. something that has good detail and line work.. Scan the same image twice ..first your way at 2400 dpi then a second time at my suggested 5600 dpi.. ( make sure your scanner is capable of scanning optically at that dpi)  Do the same process on each working the images up.. including any croping you may do..  Size both images to 36" width when your done you should end up about 360 dpi for the 5600 scan .. and about 150 for the 2400 scan... Print both images ( make 36 inch prints or crop down to something that will work fo ryour equipment)  then compare them.. If their the same then go directly to Home Depot and buy a chain saw and cut your scanner in half...then start looking for another one. :-))..  Just kidding.. Anyway the scanner plays a big part in this equation. We use drum scanners here. Many of the flat beds that are out there have optical limits that just won't get you there. Hope this made sense..

jimbo


  ----- Original Message ----- 
  From: Scott 
  To: DigitalBlackandWhiteThePrint@yahoogroups.com 
  Sent: Sunday, July 10, 2011 3:08 AM
  Subject: [Digital BW] dpi and printing quality


    
  Hi All,

  I was reviewing some of my scans and noticed that there seemed to be a big difference in dpi on a lot of my final photoshop outputs. There are lots of variables, but in a nutshell, I looked at two separate prints, both done on an epson 1400 with eboni inksets. One showed at 675 kb and 72 dpi, the other 135mb and 1200 dpi. I scan all my negs at 2400 dpi as part of my workflow.

  Here is the part I don't get. the 675kb print is equal in quality to the 135mb print. I have even had it printed on 24 x 28 paper, with no loss of quality.I am scanning 6x6 negs

  So the question is, does the dpi that is displayed in photoshop relate at all to print quality? What am I missing in my workflow?

  Scott



  

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