Is Epson 4870's exposure adjustable?

[steven_woody]

i heard many non-professional scanners are absent of provition of user

adjustable exposure. is it the case for Epson 4870? suppose i am using VueScan

or similar which alllow the exposure adjustment in software interface itself.

 

thanks.

 

-

woody

[greg lockrey]

By setting the black point and white point on the "levels" histogram, you can control the exposure. ???

[steven_woody]

really? i think the b/w points setting are merely post-scan controls.

[Tim_Lookingbill]

Yes, sort of.

 

Go into Configuration>ColorTab>adjust gamma between 1-3 in

the Color Control. It adjusts previews similar to Nikon's gain, but

I'm not sure if it is doing it in software or hardware, but I suspect

software.

 

Look at the input histogram in the Levels adjust panel to see if it

shifts with each gamma change in Color Control. You'll have to

hit Auto then Reset to induce the gamma change.

[steven_woody]

> You'll have to hit Auto then Reset to induce the gamma change.

 

sorry, i cant understand what does this mean.

[stu dall]

Steven. The only thing I can think of is to adjust the gamma setting. The default setting is 1.8 and I think you can take it up to 3.0.

Increasing it will bring out shadow details more, if you are finding that the scan is a little dark overall in the first place. I would give 2.2 a try, and work from there. Stu.

[steven_woody]

when talking about gamma setting, do you refer to Epson Scan or VueScan ? in an intuitive thinking, gamma changes contrast rather than exposure. you know, when incress gamma, some pixel values will increase in a cost of others get decreased. on the other hand, if you increase exposure, no pixel value will decrease.

 

i am looking for exposure not gamma unless 'gamma' is a wrong term used in these software interface.

[stu dall]

Epson Scan. I actually use the Silverfast Ai, but they all have gamma settings which can be adjusted. Give it a try, and see what you think. The obvious alternative is to 'Prescan' and make some curves adjustments, or bring the histogram up; or make all the adjustments in PS postscan. Of course the initial starting point is to have your monitor calibrated, and your scanner correctly profiled.

[mag_miksch]

IMO the Epson 4870 cannot adjust exposure on a hardware level, what I know is that KM 5400 has a button to increase the lightsource. <br>

My Canon 9950 can be set to "long exposure pass" by Vuescan, but I am not clear if this is done on soft- or hardwarelevel<br>Regards<br>Martin

[ole_hjalmar_kristensen]

Cannot say anything about the 4870, but my 4990 definitely use longer time to scan dense film (if I have set black & white points and gamma), indicating that it adjusts the exposure time. The time to do a preview scan does not depend on the density. I rarely bother with Silverfast AI btw., the professional mode in Epson scan is good enough to get in the ballpark, and is much more convenient to work with than Silverfast, IMHO.

[ronald_moravec1]

Exposure setting is software controlled in the profesional mode.

 

You can use the auto expose at the mid point in control box icons

( first icon) or prescan and use the density+rgb control. Save and recall the setting in the box at the top. Name it and type over current setting.

 

You can also prescan and apply the curve control. The curve works just like photoshop curve and you can save the setting and recall.

 

I never scan film in anything other than profesional mode and have saved settings for all the different color neg films I use.

 

The other modes are used for document scanning.

 

Be sure to remove the cover inside the lid so the back light works and plug in the cable in the back to power it. You will be able to select film rather than reflective scan. Set this up before turning on the scanner and software.

 

Take the time to learn the software. It does everthing.

[greg lockrey]

I agree with Ole. I happen to use both the Epson 750V and 10,000xl. Silverfast with film has an advantage in that multi-pass/multi-exposure is possible eliminating noise and getting a wider latitude. The Epson scan I prefer on reflective material since it's easier to determine white and black points with the eyedroppers in levels and I can get to a more "accurate" color balance.

[roger_smith4]

Wow, quite a collection of bad advice. I think the last three responses are worth trying to understand.

[steven_woody]

> IMO the Epson 4870 cannot adjust exposure on a hardware level

 

can anyone confirm this?

[Tim_Lookingbill]

Steven,

 

"You'll have to hit Auto then Reset to induce the gamma change."

 

After entering the new gamma choice in Configuration, in

Professional Mode panel in EpsonScan, under Adjustments,

click the first button that has the ball symbol. This is the Auto

setting, then hit Reset.

 

You now have an uncorrected preview without any Epson output

settings applied except what the new gamma setting does to

overall density which may be lighter or darker depending on what

gamma was chosen.

 

If you hit the Auto button again, a new set of default corrections

that are based on the new gamma setting will be applied and

will look different from the previous Auto settings used under the

old gamma setting.

 

The gamma settings in EpsonScan don't behave the same exact

way as applying gamma on a monitor or curve edits on an image

in PS. The gamma setting is only used by EpsonScan to set

density parameters for its Auto settings. If you want a sort of

linear flat uncorrected representation of this gamma setting, you

have to click the Reset button after you click Auto to update the

new gamma's affects on the preview.

 

For instance I can get very flat wide open lightened scan of color

negs setting the gamma to 3.0 in Configuration which opens up

more detail that couldn't be seen using 2.2 or 1.8. These gamma

numbers apply a sharp contrast to shadow and highlites

plugging up these areas when I use Auto and giving very dark flat

previews if I choose Reset.

 

My take on this is you can't edit what you can't see. 3.0 gamma

allows me to see everything and apply my own tonal curve to the

entire scene from the blackest black to whitest white using

EpsonScan tools. The density of the original medium being

scanned will also influence what gamma number needs to be

applied to reveal more hidden detail.

 

Now doesn't that sound like gain to you?

[roger_smith4]

"My take on this is you can't edit what you can't see. 3.0 gamma allows me to see everything and apply my own tonal curve to the entire scene from the blackest black to whitest white using EpsonScan tools. The density of the original medium being scanned will also influence what gamma number needs to be applied to reveal more hidden detail.

Now doesn't that sound like gain to you?"

 

No, not at all, you're just talking about software edits. Hardware exposure should be constant for color negatives once set correctly as the density range for color negatives is very small. The rest is how you "decompress" that data to fill the histogram- you can bias it towards highlights or shadows as you demonstrate.

 

THe 4870 probably scans at different exposures- try scanning a negative and then a slide leader (solid black) at the same resolution and time them to see how long they take. The real question is how do you adjust hardware exposure times and I have never used your scanner or software.

 

Try the trial version of Vuescan, hit lock exposure, and see if it lets you set different values (i.e. 1, 2 (twice 1), 3, etc). Email Ed Hamrick and he can tell you the range of acceptable values for your scanner if you don't know (mine is whole numbers from 1-6).

[Tim_Lookingbill]

Roger,

 

What's the advantage of this Vuescan lock exposure over what I

just described using EpsonScan's gamma setting. All I want is

even lighting throughout the negative. No appearance of contrast

or of shadow detail fading into the murky blackness and

highlites to flat white.

 

How's hardware going to make a difference?

[roger_smith4]

Changing hardware exposure settings enable you to stay above the noise floor for the scanner. Are you familiar with "exposing to the right" with digital cameras? Same concept.

For color negatives this shouldn't be an issue as you can scan them at a constant exposure and shouldn't have scanner noise in the highlights unless the scanner has a very poor dynamic range. B&W negatives and slide film is a different story and changing hardware exposure can be an essential tool.

 

The edits you describe would probably be better done in Photoshop at 16 bit precision, but to each his own. I prefer to set white and black point and overall image contrast in Photoshop to maximize image quality.

[steven_woody]

last night, i played serveral hours with my 4870 scanner and i think i can answer the question by myself:

 

1) the 4870 *is* exposure adjustable and VueScan's 'lock exposure' supports this. changing the number of 'lock exposure', the VueScan's raw histogram changed its shape.

 

2) by carefully adjusting exposure of every different frame with different density range, i can get a far better raw histogram than i did in before, which span as more as possible tones without clipping.

 

thanks for all your kind help!

 

-

woody

[Tim_Lookingbill]

I tried a demo of Vuescan and couldn't find the same input

histogram that EpsonScan has. Are you sure that's an input

histogram or output?

 

If it's true input RAW the entire histogram moves across the

graph linearly without changing shape when you lighten or

darken the preview.

 

EpsonScan has both input and output, but to see output you

have to click the button for it which is kind of slow in responding.

That histogram will change shape for all channels in response

to the software edits applied on output.

[steven_woody]

VueScan does not call them input and output, it calls them Raw histogram and Image histogram. Only the Image histgram reflects changes in user settings in the 'color' tab, including b/w points, curve contrast, etc.

 

for the Raw histogram, AFAIK, only exposure setting changes its shape. but, it's not perfect linear as you said. actually, when you change the exposure, the shape moves faster in the 'white' end than it does in 'black' end ( supposing i am talking about positive film ), this is because increasing/decreasing exposure will put more effects in the thinner parts of the film than on the thicker part of the film. so, if you increase exposure, the shape of raw histogram will span more tones on the scale while keeping its overall shape mostly.

 

ps. i am still not sure, in the Epson Scan, changing gamma equals to changing exposure without any side effect. did anyone do some works confirming that?

 

thanks.

 

-

woody

[roger_smith4]

Woody's right on how Vuescan works. Go to prefs and then histogram and you can cycle through the histogram choices (not sure if the demo lets you do this). I'm glad to hear that changing hardware exposure is working for you. Also, consider the combine multiple exposures feature for dense slides- I heard positive feedback about this but haven't tested it myself. The old "long-exposure pass" feature had terrible artifacts.

 

Tim, I did see something on the Epson site about the scanner having 7 levels of brightness, but it's still not clear to me if brightness= hardware exposure changes. You'd probably have to scan at nominal and then +7, disable other autocorrections and look at the histograms in Photoshop.

[steven_woody]

how do you know that there are 7 levels of brightness? can you show us your method? thanks.

 

-

woody

[Tim_Lookingbill]

Roger,

 

I'm not familiar with Epson's 7 levels of brightness and there's

no setting in EpsonScan indicating this unless the levels refers

to the gamma numbers from 1.0 to 3.0 in increments of plus or

minus .1.

 

All data indicators within EpsonScan is preview driven meaning

the output histogram follows the preview shown. Using

ICM/Colorsync is the only exeption and it only works with positive

film and reflective.

 

The only way I can see what input resembles preview wise is to

manipulate the output histogram with edits to mimic input for

each channel which I've done and it resembles something

completely different from any preview made with Epson's internal

profile and/or Automatic Settings.

 

The histograms pretty much match up shape wise with PS's.

[roger_smith4]

"I'm not familiar with Epson's 7 levels of brightness "

Come on guys, do a search on your hardware- it's not even my scanner.

http://files.support.epson.com/pdf/pr48pr/pr48prpg.pdf

 

See page 1.