Newbie seeks advice on resolution

Smorton · Jan 9, 2016

First post to this forum. I bought a Plustek film scanner (35 mm) and I have been scanning slides and negatives.

I scan at 7200 dpi. The files are so huge that they take up an incredible amount of room. A typical 35 mm slide or negative is 528 Mb.

I thought if I scanned at the highest resolution the scanner allowed it would be best but now I can see that I might have to try to buy SeaGate or some similar company to accommodate this.

Is there a best practice for this type of thing. The slides/negatives are old travel and family things.

I also have some 2.25 negatives to scan. I bought a Cannon 90000 F Mark II. I have not tried scanning with that. With black and white can I simple put the negatives on the flatbed glass and scan or do I need to use the film holder or even purchase one of the custom film holders.

Lastly, I have some valuable (at least to me) 5 x 7 b & white negatives. Is there any way to scan these without anymore investment in scanners? Any good place to send them where you can feel secure about getting them back?

Any input highly appreciated.

Thank you.

Smorton

Doyle Thomas · Jan 9, 2016

resolution choice depends on how you plan to use the image (ie print size) a 7200dpi printed at 360dpi is 7200/360 = 20 inches without interpiation. scanning at the max optical res of the scanner keeps all options open
keep in mind that post edit (layers) will increase file size. if you only plan to do screen display you can get away with a lot less res. you could scan for screen at 720

With black and white can I simple put the negatives on the flatbed glass and scan or do I need to use the film holder or even purchase one of the custom film holders.

bw or color don't matter what does matter is how flat the film is and the depth of field of the scanner~expermemt

Lastly, I have some valuable (at least to me) 5 x 7 b & white negatives. Is there any way to scan these without anymore investment in scanners? Any good place to send them where you can feel secure about getting them back?

if you have a good light table you can place your 5x7 on it and photograph it then invert.

Smorton · Jan 9, 2016

Thanks for the response.

I am sorry if I am dense, but I am uncertain what you mean by : "bw or color don't matter what does matter is how flat the film is and the depth of field of the scanner~expermemt."

Any chance you could expand on this. I am very new to this.

Thank you.

Smorton

John_M_King · Jan 9, 2016

I am not familiar with Plustec scanners but what you could try if the software lets you, is to set the scan resolution at 300 then set the size of the required output size to the shortest side of any print you intend making. So scan at 300, then to get a print of approx A3 size adjust the output image size to 12" x 18". That way you will get an approx file size of 45mb for colour and something less than 30 for B&W

Smorton · Jan 9, 2016

Many thanks
Smorton

Doyle Thomas · Jan 9, 2016

it does not matter if you are scanning color or black & white except that gray scale is smaller file size than color. in both cases if the film is not flat it can cause distortion and out of focus areas. placing the film directly on the glass can sometimes cause what are called Newton Rings (look it up) that are hard to fix in post. a holder lifts film off the glass and helps flatten, some holders have an adjustable hight to allow you to find the sharpest point of focus.

when scanning color there are 3 channels red, green, and blue. in gray scale there is only 1 channel so the file size is only 1/3 + overhead than that of RGB

what John says is good if you are printing to a Cannon or HP printer, if you are going to an Epson use 360. you could go ahead and make the scan at 7200 and then resize in post to reduce file size and edit time. you can always throw away pixels but you can never get them back although ON ONE's perfect resize does a pretty good job. that's why I said scanning at the max optical res of the scanner keeps all options open.

if you can afford a 5Tbyte HHD you will be good to go for a long time but ALWAYS HAVE A BACKUP! using the Cloud is an option but slow.

Smorton · Jan 9, 2016

Thanks for the help!!

Smorton

Alan Klein · Jan 9, 2016

What is the actual resolution of the scanner? Scanning at higher resolution only creates larger files. Just because the scanner says it provides 7200dpi doesn't mean the scanner is actually sampling resolution larger than let's say 3200 or 2200 or whatever. I'd scan at the largest resolution the scanner actually catches. Then rez-up in post processing if I need to enlarge the photo with more pixels. The scan will be faster and the files will be smaller.

StoneNYC · Jan 9, 2016

Don't bother scanning larger than 2400dpi on that scanner, it just doesn't have the capability for more, regardless of the options on the screen.

That's your answer really in simplest form without getting too techy.

I honesty doubt that it can do 2400, more like 1800 or 1200, but 2400 will give you some flexibility (again the reasons get too techy, "resampling" "downscaling" reasons.

2400 35mm will give you maybe an 11x14 print, but 8x10 will look sharper. 5x7 just do 1200, they will be good for very big prints at 1200.

Good luck!

Sent from my iPad using Tapatalk

Doyle Thomas · Jan 10, 2016

that's why I said scanning at the max optical res of the scanner

Smorton · Jan 10, 2016

Is it a pretty bad scanner?

Don't worry about hurting my feelings.

Smorton

StoneNYC · Jan 10, 2016

Smorton said:
Is it a pretty bad scanner?

Don't worry about hurting my feelings.

Smorton

No it's not, 35mm can only resolve so much, digital has gone way beyond that so our perception of sharpness has changed. Except for super expensive scanners ($1,000-$20,000) the lower ones are all going to be roughly the same frankly.

Certain films like Ilford PanF+ and Kodak Tmax100 can resolve very high, but most 400 speed films will be a bit grainy. Remember "back in the day" most people made 4x6 and 8x10 prints, maybe some 11x14 but rarely, except professionals, so you don't need much to make an 8x10, we are just used to much bigger on the computer screens. You'll do fine with yours, if you want more detail start shooting 120 format film in 645 or even better 6x6/6x7 framing.

If it's any consolation I shoot 120 645 format for models and 8x10 sheet film for landscapes.

But that's a slippery (and expensive) slope.

Smorton · Jan 10, 2016

Thanks for the input.

Smorton

Prof_Pixel · Jan 12, 2016

The scanning resolution is just 'one hand clapping'. What really counts is the total pixel size of the image. For most applications, a 16 megapixel file is all you will need.

StoneNYC · Jan 13, 2016

Prof_Pixel said:
The scanning resolution is just 'one hand clapping'. What really counts is the total pixel size of the image. For most applications, a 16 megapixel file is all you will need.

How does 16mp translate in a scanned DPI number? Thanks this is interesting.

Alan Klein · Jan 13, 2016

Prof Pixel: Is 16mb for BW 35mm? When I scan at 2400dpi, 48 bit color, saved in TIF, file sizes are:
35mm color= 35-45mb.
6x7 medium format color= 175-240mb.

If scanning BW, 6x7 is around 75mb.

Prof_Pixel · Jan 13, 2016

StoneNYC said:
How does 16mp translate in a scanned DPI number? Thanks this is interesting.

It's easy. The smaller the image, the higher the scanner dpi you use.

Prof_Pixel · Jan 13, 2016

Alan Klein said:
Prof Pixel: Is 16mb for BW 35mm? When I scan at 2400dpi, 48 bit color, saved in TIF, file sizes are:
35mm color= 35-45mb.
6x7 medium format color= 175-240mb.

If scanning BW, 6x7 is around 75mb.

Note I said 16 megapixels and NOT megabytes.

StoneNYC · Jan 13, 2016

Prof_Pixel said:
It's easy. The smaller the image, the higher the scanner dpi you use.

Sorry if my question was unclear, that's not what I'm asking, I'm asking how do you know what 16 megapixels is with a scare, I have no idea how to figure out what that translates to in the DPI choices.

Is 1200dpi, 2400dpi or 4800dpi equivalent to 16mp?

Prof_Pixel said:
Note I said 16 megapixels and NOT megabytes.

Right, but what does that mean for scanning? They don't give MP as options so it's hard to know what it is equivalent to.

Thanks for helping us understand.

Prof_Pixel · Jan 13, 2016

The 16 megapixel value is approximate

Let's say you have a 4 x 5 image. If you scan it at 1000 ppi, you get 4,000 x 5,000 = 20,000,000 pixels (20 megapixels).

If you wanted to get 16 megapixels exactly:
4 x 5 = 20
16,000,000 / 20 = 800,000
square root (800,000) = 895
4 x 895 = 3580
5 x 895 = 4475
3580 x 4475 = 16,000,000
The chances are 1000 ppi is the closest your scanner gets to 895 ppi

For a 35 mm image:
1 x 1.5 = 1.5
16,000,000 / 1.5 = 10,666,667
square root (10,666,667) = 3,266
1 x 3,266 = 3,266
1.5 x 3,266 = 4,899
3,266 x 4,899 = 16,000,000
The chances are 4800 ppi is the closest your scanner gets to 3266, but 2400 ppi is probably good enough. It would give you 8.640 megapixels

Make sense?

StoneNYC · Jan 13, 2016

Prof_Pixel said:
The 16 megapixel value is approximate

Let's say you have a 4 x 5 image. If you scan it at 1000 ppi, you get 4,000 x 5,000 = 20,000,000 pixels (20 megapixels).

If you wanted to get 16 megapixels exactly:
4 x 5 = 20
16,000,000 / 20 = 800,000
square root (800,000) = 895
4 x 895 = 3580
5 x 895 = 4475
3580 x 4475 = 16,000,000
The chances are 1000 ppi is the closest your scanner gets to 895 ppi

For a 35 mm image:
1 x 1.5 = 1.5
16,000,000 / 1.5 = 10,666,667
square root (10,666,667) = 3,266
1 x 3,266 = 3,266
1.5 x 3,266 = 4,899
3,266 x 4,899 = 16,000,000
The chances are 4800 ppi is the closest your scanner gets to 3266, but 2400 ppi is probably good enough. It would give you 8.640 megapixels

Make sense?

Yes! Thanks for the math this helps!! Hope it helps the OP too.

MartaSr · Sep 1, 2016

I see.......you blokes are dual addicted... glass AND computers. I used a mac once & liked it.

Sort of like a dirty admission eh ?

Newbie seeks advice on resolution

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