Which DPI for creating digital negatives?

[ChristopherCoy]

at the risk of me being pedantic, it would probably help you tremendously to spend a little time gaining some understanding of what those numbers mean. More knowledge is rarely a bad thing, and there are people on here that are willing to help you gain that knowledge if you ask questions.

I've tried. Believe me, I've tried. I'm not that kind of learner though. Unless its put to me in a visual aspect like Matt did earlier, or I physically do something, it's extremely hard for me to learn something new. I just don't learn well by simply reading.

 

[ChristopherCoy]

AHA! Visuals.

https://www.scantips.com/interpol.html

 

[ChristopherCoy]

So maximum resolution of the V330 is 1500dpi, even though they advertise 4800. Does this mean that the 4800 number is 'interpolated', or as understand it, has pixels added by the scanning software to increase the size?

And if the resolution of the V330 is 1500dpi, that means that the best detail the scanner and 35mm negative can provide is going to result in about a 4x6 image correct? Even though I CAN scan it to be 3300x4200 (11x14), there wont be any more detail than the 4x6 image because A.) the 35mm negative doesn't contain it, and B.) the scanner/software has to make up for the lacking information? Anything larger that 11x14 is where things start to get blurry because of the added/averaged pixels/dots that the scanner has to "fill in the gaps with"?

And if I'm figuring correctly, at 1500ppi, the sweet spot for dpi is 375. 4x6=1500x2250

 

[MattKing]

While the scantips site is a really good resource - one that I would recommend you study - it is important to realize that some of the specific references in it can be dated.
For example, "The entire photo scanned at 300 dpi would be excessively large for our monitors. 6x4 inches scanned at 300 dpi would produce an 1800x1200 pixel image."
That was probably written when 1024 x 768 was an expensive, high resolution monitor.

 

[Mainecoonmaniac]

AHA! Visuals.

https://www.scantips.com/interpol.html

Very useful. Just like zooms in cameras. There's optical and digital zoom. With scanners, there's the optical resolution and resolution that is interpolated. In interpolation is not necessarily bad, but it comes down to how well the software could do it. I've seen some amazing interpolation with AI technology. Here's a deep dive.

 

[ChristopherCoy]

While the scantips site is a really good resource - one that I would recommend you study - it is important to realize that some of the specific references in it can be dated.
For example, "The entire photo scanned at 300 dpi would be excessively large for our monitors. 6x4 inches scanned at 300 dpi would produce an 1800x1200 pixel image."
That was probably written when 1024 x 768 was an expensive, high resolution monitor.

Yeah, I caught that. Especially because now we have 4K monitors and such. I figured this was written back i the days when monitors weren't flat.

 

[MattKing]

So maximum resolution of the V330 is 1500dpi, even though they advertise 4800. Does this mean that the 4800 number is 'interpolated', or as understand it, has pixels added by the scanning software to increase the size?

And if the resolution of the V330 is 1500dpi, that means that the best detail the scanner and 35mm negative can provide is going to result in about a 4x6 image correct? Even though I CAN scan it to be 3300x4200 (11x14), there wont be any more detail than the 4x6 image because A.) the 35mm negative doesn't contain it, and B.) the scanner/software has to make up for the lacking information? Anything larger that 11x14 is where things start to get blurry because of the added/averaged pixels/dots that the scanner has to "fill in the gaps with"?

It is considerably more complex and nuanced than that.
It isn't that the 35mm negative doesn't have more information, it is that the scanner has trouble differentiating between the smallest details.
So where you might have an imaged blade of grass in your negative, with a nice sharp edge between it and the background, the scanner might resolve more of a gradual and slightly blurred transition between that blade of grass and the background behind it.
When it comes to perceived sharpness, it is the edges that have the greatest effect. And it is the edges that scanning tends to blur, and sharpening tends to repair.

 

[ChristopherCoy]

I think I've identified one source of my confusion.

A 12mpx file is about 4000x3000 PPI/DPI.

I was thinking that 4000 PPI essentially meant that there were 4000 pixels in each inch of an image. So for say an 8x10 images, I'd end up with 40,000 pixels on the short side.

 

[MattKing]

I think I've identified one source of my confusion.

A 12mpx file is about 4000x3000 PPI/DPI.

I was thinking that 4000 PPI essentially meant that there were 4000 pixels in each inch of an image. So for say an 8x10 images, I'd end up with 40,000 pixels on the short side.

And you would be correct.
But trust me, you want to avoid thinking of file sizes except when considering issues like file storage and computer processing times/capacities. There is nothing more frustrating than labs that quote file sizes (rather than pixels) in their price lists for scans.
For everything other than issues of file storage and computer processing times/capacities, think/work in terms of pixels from the scanner and in the computer, and dots from the printer.

 

[brbo]

S
And if the resolution of the V330 is 1500dpi, that means that the best detail the scanner and 35mm negative can provide is going to result in about a 4x6 image correct? Even though I CAN scan it to be 3300x4200 (11x14), there wont be any more detail than the 4x6 image because A.) the 35mm negative doesn't contain it, and B.) the scanner/software has to make up for the lacking information?

Well, yes. With your scanner you can get the pixel numbers, but they will not be, erm, sharp.

I've made a scan of the resolution target scanned at 4800dpi on my Epson 4990 (aprox. 2000dpi real resolution) and Minolta 5400 scanner (5400dpi scanner, but scanned at 4800dpi to demonstrate what a true 4800dpi scanner would produce).

Epson:


Minolta:


If you download the full size scans and look at them at 100% or even greater you'll see the difference...

 

[ChristopherCoy]

If you download the full size scans and look at them at 100% or even greater you'll see the difference...

There's no need to look at them at 100%. Sitting here a foot from the screen its very clear that the bottom is sharper, and there's more "grain" in the white areas. But this is one of those gray areas where the 5 foot rule applies... for me at least. The average person, including myself, doesn't have to compare two images side by side. If you're standing in a gallery looking at photography, the curator doesn't put the first print next to the final print for the viewer to compare.

Although, if these are at 4800, viewing them at 100% makes them WAY larger than I'd ever print at this point anyway. at 100% those two squares are what 16x16 or larger?

 

[Adrian Bacon]

So maximum resolution of the V330 is 1500dpi, even though they advertise 4800. Does this mean that the 4800 number is 'interpolated', or as understand it, has pixels added by the scanning software to increase the size?

And if the resolution of the V330 is 1500dpi, that means that the best detail the scanner and 35mm negative can provide is going to result in about a 4x6 image correct? Even though I CAN scan it to be 3300x4200 (11x14), there wont be any more detail than the 4x6 image because A.) the 35mm negative doesn't contain it, and B.) the scanner/software has to make up for the lacking information? Anything larger that 11x14 is where things start to get blurry because of the added/averaged pixels/dots that the scanner has to "fill in the gaps with"?

And if I'm figuring correctly, at 1500ppi, the sweet spot for dpi is 375. 4x6=1500x2250

you have the native sensor resolution, which is 4800 dpi. There is a lens in front of that sensor. The lens does not resolve 4800 dpi worth of detail. It resolves about 1500 dpi of detail. Think of a scanner as a specialized camera, because that is what it is. When you scan something, you’re just taking a picture of it.

now, just like a digital camera, the sensor has a native fixed resolution. Just like with a digital camera, how much detail you resolve onto the sensor is controlled by the lens. Just like taking a picture with a digital camera, it’s best to capture at the native sensor resolution, then scale it up or down in software later to meet your storage or output needs. If you have a low end lens on your camera, you still capture at the native resolution, you just have less fine detail than you would if you had a higher quality lens that resolved more resolution. The only difference with a scanner is that you can’t change the lens.

Matt gave some pretty good guidance for starting out in a previous post in terms of working out which resolution would be best suited for what you’re trying to do.

 

[MattKing]

There is a lens in front of that sensor. The lens does not resolve 4800 dpi worth of detail. It resolves about 1500 dpi of detail.

What Adrian said, plus one really important fact.
Included in that "lens" (or rather optical system) is a relatively thick hunk of glass - the platen glass.
That glass does not help!

 

[ChristopherCoy]

What Adrian said, plus one really important fact.
Included in that "lens" (or rather optical system) is a relatively thick hunk of glass - the platen glass.
That glass does not help!

I wonder why someone hasn't invented a negative holder that allows you to remove the glass from the scanner.

I also wonder why laws allow companies like Epson to advertise inaccurate specifications, if they really aren't true.

 

[Adrian Bacon]

What Adrian said, plus one really important fact.
Included in that "lens" (or rather optical system) is a relatively thick hunk of glass - the platen glass.
That glass does not help!

very true. It’s tends to add flare and diffraction, neither of which are helpful.

 

[Adrian Bacon]

I wonder why someone hasn't invented a negative holder that allows you to remove the glass from the scanner.

you’d have a mighty big dust problem if you removed the glass. It’s already hard enough to keep dust under control.

 

[MattKing]

I also wonder why laws allow companies like Epson to advertise inaccurate specifications, if they really aren't true.

Well, they are true, just not particularly useful.
Sort of like cars that have a speedometer designed to show a maximum speed of 160 mph/250 kph!
Or clothing ads that show the clothes worn by runway models.
The resolution numbers in those specifications are accurate in terms of the electronic capabilities of the sensors and the capabilities of the stepper motors.

 

[brbo]

The average person, including myself, doesn't have to compare two images side by side. If you're standing in a gallery looking at photography, the curator doesn't put the first print next to the final print for the viewer to compare.

Well, you've answered your own original question...

If my goal is to take 35mm negatives, scan them, and print them on transparency for platinum printing, is it necessary to pay hundreds of dollars for a scanner with 7200dpi?

So, no, it's not necessary to pay hundreds of dollars. I bet a lot of people don't care about ANY of the technicalities that went into the print and also don't care how good they are. But there ARE people who know how good a print can look.

I wonder why someone hasn't invented a negative holder that allows you to remove the glass from the scanner.

I also wonder why laws allow companies like Epson to advertise inaccurate specifications, if they really aren't true.

There are scanners that don't scan through glass and there are scanners who scan through plastics (and are better than anything else). It's the sum of all parts.

And Epson hasn't lied to you. They just didn't tell you everything.

 

[Adrian Bacon]

Well, they are true, just not particularly useful.
Sort of like cars that have a speedometer designed to show a maximum speed of 160 mph/250 kph!
Or clothing ads that show the clothes worn by runway models.
The resolution numbers in those specifications are accurate in terms of the electronic capabilities of the sensors and the capabilities of the stepper motors.

same thing with camera makers. A canon 5Ds is 50MP. Canon does not make a single lens you could put on that camera that actually resolves 50MP onto the sensor.

 

[ChristopherCoy]

In relation to the resolution, this is where things kinda get but into the "it doesn't bother me" bucket. This is a screenshot from a Nick Carver youtube video. In the video he's talking about the little feet on the negative holders where if you take them out its minus, if you have them in and pointed to zero its "normal focus", and if you turn them all another direction is a "plus focus". So the feet either lower or raise your holder to better focus the scanner.

But the difference in these are so minute, that unless you see them side by side like this, you'd never know the difference. At least I wouldn't. Same with the resolution photos that were posted earlier.

And so I usually don't worry about minuscule things like this.

 

[Les Sarile]

I wonder why someone hasn't invented a negative holder that allows you to remove the glass from the scanner.

I also wonder why laws allow companies like Epson to advertise inaccurate specifications, if they really aren't true.

Actually, the Microtek Scanmaker i900 had a film holder you inserted below the glass. Was a promising concept - no glass in the way, until testing showed it was not an improvement on the Epson V700 which it was competing with at the time.

With regards to "inaccurate specs", there must be enough there to have withstood a class action lawsuit. I recall in the 80's we had this new IT manager who measured all of our CRT monitors and wanted to return them because his measurement did not match the advertised screen size. The CRT itself was the correct size but with the bezel on - as well as limitation of the graphic card frequencies, the actual viewable size was much less.

BTW, now that you have the scanner, you should give it a try and see if it meets your needs.