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Scanning 4x5 Negatives; DPI Preferences
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bartbob



Joined: 30 Oct 2010
Posts: 102

PostPosted: Thu Sep 15, 2011 11:25 pm    Post subject: Scanning 4x5 Negatives; DPI Preferences Reply with quote

I'm searching for a decent scanner for my 4x5 B&W negatives. Something that will do a good job on negatives with images resolved in the 30 to 60 lines per millimeter range my lenses produce.

The largest prints I'll make from a 4x5 negative are 20 x 30 inches. From 120 film 2.25 x 2.75 inch negatives, 16 x 20 inch prints are about as large as I'll go. So I'm thinking that a scanner that does 1600 or 3200 dpi should do the job. Such scanners are out there for 70 to 140 bucks used. I think 1600 dpi should suffice so that's what I'm considering.

Question is, is 1600 dpi enough or should I opt for a 3200 dpi one?
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C. Henry



Joined: 13 Dec 2005
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Location: North East Georgia, USA

PostPosted: Fri Sep 16, 2011 3:50 pm    Post subject: Reply with quote

IMHO the 1600 dpi scanner should be adequate for what you intend from the 4 x 5 inch negatives however I believe you would need a 3200 dpi scanner to get good quality 16" x 20" prints from your 2.25" x 2.75" negatives especially if you want to crop the image in both horizontally & vertically.

C. Henry
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45PSS



Joined: 28 Sep 2001
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Location: Mid Peninsula, Ca.

PostPosted: Fri Sep 16, 2011 8:02 pm    Post subject: Reply with quote

The DPI rating should be the optical limit of the scanner not the interpolated.

All depends on the quality you want. 1600 dpi 11x14 max from 6cmx6cm, 6cmx7cm, 6cmx9cm; 16x20 from 4x5 if it is a near perfect negative.

Microtek 8700 or I900 will handle both film formats to the print sizes that you want as will many Epson.
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Henry



Joined: 09 May 2001
Posts: 1442
Location: Allentown, Pennsylvania

PostPosted: Sat Sep 17, 2011 12:47 am    Post subject: Reply with quote

You can scan at 1600 or 3200 but your file sizes will be enormous! I doubt if you need to go any higher than 800, possibly 400. Try it and find out for yourself what works best for your purposes.
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45PSS



Joined: 28 Sep 2001
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PostPosted: Sat Sep 17, 2011 1:40 am    Post subject: Reply with quote

http://www.scantips.com/calc.html

may be of some help.
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C. Henry



Joined: 13 Dec 2005
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Location: North East Georgia, USA

PostPosted: Sat Sep 17, 2011 3:11 am    Post subject: Reply with quote

Nominal 5" long side (4.75" approximate actual size) would give:
@ 400 dpi = 1900 pixels = 30" @ 63.3 dpi output.
@ 800 dpi = 3800 pixels = 30" @ 126.6 dpi output.
@ 1600 dpi = 7600 pixels = 30" @ 253.3 dpi output.
@ 3200 dpi = 15200 pixels = 30" @ 506.6 dpi output.
IMHO anything less than 150 dpi output just is not "Photo Quality" and I personally will not deliver any prints to customers at less than 180 dpi output and prefer to print at 250 dpi or more.
Large prints at "Photo Quality" resolution will always be large computer files even at maximum compression.

C. Henry (the other Henry)
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bartbob



Joined: 30 Oct 2010
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PostPosted: Sat Sep 17, 2011 5:22 pm    Post subject: Reply with quote

45PSS, thanks for the link to scantips. It pretty much covered what I'd done but in a much easier way to do it.

C. Henry, thanks for pretty much using the same numbers (scan dpi, print dpi and print size) I did to estimate what things would look like; that gave me confidence I was doing it right. I agree that around 200 dpi on prints is a reasonable minimum; that's about 4 lp/mm on the print.

Scanning at 1600 dpi optically can produce images with about 30 lp/mm. The lenses for my 4x5 aren't as sharp as surgeon's scalpels and their 40 to 50 lp/mm limits don't seem to make any sharper prints when scanned higher than 2000 dpi. Especially when a full frame enlargement's viewed at a distance equal to 1.5 times the print height; for example, a 20 x 24 inch print viewed at 30 inches. I had negatives scanned at 800 dpi that made pretty good 11 x 14 inch prints and even at 20 x 24 looked reasonable to me.

Someones got an Epson 1680 ******* near me and I'm going to check it out. It'll do 1600 dpi optically and scan four 4x5's at one sitting. It might be plenty good enough for me to use.
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45PSS



Joined: 28 Sep 2001
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PostPosted: Sat Sep 17, 2011 8:50 pm    Post subject: Reply with quote

Quote:
Someones got an Epson 1680 ******* near me

If it has the transparency adapter get it (if the price is right).
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bartbob



Joined: 30 Oct 2010
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PostPosted: Sat Sep 17, 2011 10:54 pm    Post subject: Reply with quote

45PSS wrote:
If it has the transparency adapter get it (if the price is right).
$90 including all the accessories; trans. adapter, four film holders, fire wire, all software CD's.
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45PSS



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PostPosted: Sun Sep 18, 2011 12:56 am    Post subject: Reply with quote

1600dpi will get you a decent 11x14 from 6x6 cm, 16x20 from 4x5.

Price sounds fair if it is in good condition.

The optics most likely need a cleaning (scans seem soft, not tack sharp). The mirrors are front surface and must be removed to access the front of the lens. Handle with care. The sensor must be removed to clean it or the rear of the lens. Exact position of the sensor board is critical (you may have to realign the sensor to get distortion free scans once it is removed). The ribbon cables are real sensitive and delicate. They may show they are making contact with an ohm meter but will not transmit digital information.

Windex, cotton balls/swabs (under side of bed glass), and heavy weight microfiber lens cleaning cloths (mirrors, lens, sensor) work well for cleaning the scanner's optics.
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bartbob



Joined: 30 Oct 2010
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PostPosted: Sun Sep 18, 2011 11:51 am    Post subject: Reply with quote

45PSS wrote:
The optics most likely need a cleaning (scans seem soft, not tack sharp).
I found a service manual online for a few bucks I could download if such cleaning is required. After looking at an exploded view (from a parts source listed on Epson's web site), it'll not be easy to do. I'll wait until I check some scans. But the scanner won't be bought without a money-back guarantee if it's not in decent condition.
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45PSS



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PostPosted: Sun Sep 18, 2011 8:11 pm    Post subject: Reply with quote

I had a Microtek 8700 Pro that started getting color streaks on B&W 2 years after I bought it. A complete cleaning did the trick with no other problems in the remaining 4 years I owned it.

My fall back Epson 1640su Photo took 3 years to go fuzzy and was very temperamental and finally quit after the second cleaning. I found another 1640su close by that needed cleaning and it is still working fine.

The plastics and adhesives used in manufacture gas out and leave a thin residue on all the surfaces. A service manual is not necessary to clean the optical path or align the sensor. Its all straight forward mechanical disassembly, reassembly. The sensor looks like a circuit board from the back that is mounted to a fixed plastic box. Alignment is nothing more than loosening the board mount screws and shifting the board .00005, securing, and retrying the scan. Any linear target or transparency can be used for an alignment target.

The HARDEST part is keeping dust out of the inside of the scanner.
The transparency unit is nothing more than a light source behind a translucent cover. It will not need servicing unless the lamp burns out or the attaching cord breaks.

To open a Epson for cleaning power it on, start a scan then unplug the power cord once the sensor/lamp box has moved off the home position by an inch or two. Leave the sensor block forward of the scanner lock when reassembling. The scanner will reset itself when power is applied the next time.
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bartbob



Joined: 30 Oct 2010
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PostPosted: Mon Sep 19, 2011 10:43 am    Post subject: Reply with quote

45PSS, thanks for the cleaning info.

But alas, the guy (a pro photog in Denver) with the Epson 1680 didn't have the transparency unit with it; it was his Epson 2450 that does. He said he'd sell me the 2450 instead. I looked online for reviews of the 2450 and they seemed pretty good. But I was concerned about my computers processing a huge TIFF file.

So I upscaled a 4x5 negative TIFF file scanned at 800 dpi to 2400 dpi to do some processing tests on my notebook running Vista with Photoshop Elements 8 software. Took a lot of time to crunch the pixels but that 97 Mpix 237 Mbyte TIFF file choked on it; twice, trying to save it as a 31 Mb JPEG file. I thought 2 GB of system memory and 66 MB for graphics was enough. This morning, it did save it reasonably fast.
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45PSS



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PostPosted: Mon Sep 19, 2011 9:36 pm    Post subject: Reply with quote

I'm running a 1.3gh Pentium 4 HT, 4 gigs ram, on XP with CS2. A 500mb tiff works fine a 1 gig chokes it.

Tiff is lossless, jpeg looses info every time you close the file as it recompresses it.

Do not have any other programs running, even background ones. Use your firewall to block all internet traffic or disable the internet connection while scanning or editing large files.

In Photoshop 7, CS2 you can set how much of the ram is used for photoshop. Default is 50%, setting it to 75% or 80% should leave enough for Windows to operate.
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bartbob



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PostPosted: Tue Sep 20, 2011 3:03 pm    Post subject: Reply with quote

I shut down all sorts of processes on my computers to do graphics. Too many background stuff can increase times by 1/3, sometimes a lot more.

I've found an Epson 3200 for a really good price and may get that one instead of the 2450. Preliminary tests editing a 173 MP, 480 MB TIFF file on Photoshop Elements 8 didn't hang up my computers at all.
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