Today high CRI LEDs are pretty common, amazingly a common white LEDs type contains phophorous to emit whilte light, like those good lamps...Originally Posted by Bernice Loui
Se here white LEDs section: https://en.wikipedia.org/wiki/LED_lamp
Also perfect scans can be made with 3 monochromatic sources, a 3D LUT would map all perfectly, see color separation to preserve color movies, using 3 BW films.
Here we go again, repeat of MTF plots... Tiresome, Amusing, Learning Resistant or ?
White LED spectrum plot. Phosphors used in LEDs are to increase light output, not significantly increase their output spectrum range. If you understood the Physics behind how an LED functions, there would be an understanding of this innate problem with LED as a light source technology.
Spectra plot for a Chroma 50 fluorescent tube (40FT12) originally from GE. This phosphor-fluroscence light source has been the industry standard for reference color illumination for decades and to this day.
Bernice
Hmmm, Bernice... Bernice...Here we go again, repeat of MTF plots... Tiresome, Amusing, Learning Resistant or ?
White LED spectrum plot. Phosphors used in LEDs are to increase light output, not significantly increase their output spectrum range. If you understood the Physics behind how an LED functions, there would be an understanding of this innate problem with LED as a light source technology.
Spectra plot for a Chroma 50 fluorescent tube (40FT12) originally from GE. This phosphor-fluroscence light source has been the industry standard for reference color illumination for decades and to this day.
Bernice
If you read well my post I was speaking about High CRI (Color Reproduction Index) LEDs, not about the spectrum you posted of a $3 bazar torch.
Please go ahead and learn a little what's a High CRI LED.
Anyway I'm pretty confident that a film scanner can use 3 pure monochromatic frequencies to get top notch results. In that case 3D LUTs may be required for calibrations for each film type, in fact each RGB reading would target a unique point in the destination 3D LUT.
So... in the same way we have high and low CRI phosphorous lamps we also have high and low CRI LEDs.
A proper LED illuminator is perfect for an scanner. Any doubt ?
I know my V850 scans photos if shot properly will rival a drum scanner and a purely digital i.age from my Canon 5DMKIII. I have a shot in bw of a mural that scanned extremely well and rivals any capability i have ever seen or read about In fact it is noise free which a dslr wouldn't be in phx this tag me of year given the exposure was 30 minutes. I use Vuescan and a better scanning wet mount. Eventually I will be making a comparison dlscanner to a digital capture of my film using a dslr and a 100 mm macro lens.
From my perspective the V850 would be the choice.
Which drum scanner?
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
Hello Peter,
Any drum is a way, way better scanner than a V850, dot.
... but a lot of times a LF scan from a V850 can rival the result obtained with a drum.
The situations were a drum shines is when we have uncommon high densities beyond 3.0D that we want to recover, and when we have detail in the negative that's beyond 40 lp/mm and we need that detail because we also want wall size prints.
Having detail in the negative that's beyond actual 40 lp/mm it's not easy or frequent: we need the scene with that detail, then we need a perfectly steady shot that's not easy outside a lab, then we need a sharp film like TMX of CMS 20 (TMY drops beyond 20 Lp/mm), then we need perfect focus and DOF, and a sharp lens working in his sweet point.
For example at f/32 a drum won't get much more image quality than a V850 simply because a sharper scan will only find blur beyond what a V850 can see.
Time ago a very interesting benchmark was made: http://www.largeformatphotography.info/scan-comparison/
I took the sample crop from a V750 and I edited it to make it match with the crop of a howtek 4500 drum, it is surprising that with some clicks... with Photoshop sharpening and curve edition... et voilà: the same !!!
You can download the crops from here (http://www.largeformatphotography.info/scan-comparison/) and do it yourself... no secret...
In another sample crop the V750 is not as good, but I think that the V750 scan was flawed because wrong range limits or because not using M-E, I think that with the V750 properly used it would also perform well.
Of course, no doubt that a drum is a way better system, by far, but in the same way that a Ferrary is not faster than a VW Beetle in a traffic jam also a V850 may rival a drum a lot of times, speaking about LF negatives, specially if BW of color negatives.
Pere:
You can spew all the semi-comprehended statistics you want, but they don't add up. Those noisy, artificially-sharpened-beyond-a-very-poor-real-world-mtf-performance scans from the Epson look really, really bad when seen in context and especially in print (even in small prints) alongside clean, properly natively 'sharp' (and 'sharpness' has very little to do with notional optical resolution numbers and a lot more to do with overall optical performance) from PMT drums. High end CCD can come close if treated sensibly (especially if you control the inversion manually in Photoshop afterwards). A clean 2000ppi will wipe the floor with a noisy, aberrated 2300ppi any day. I wouldn't trust the Epson's optical system beyond maybe 1200ppi & even then, it's noticeably softer (like a wide-open Verito vis-a-vis a Sironar N or S) compared to pretty much any PMT or high-end CCD.
If there was enough demand, Epson would probably make a better scanner, but it would likely be 5-10K EUR/USD/GBP.
Back to the topic in hand, my understanding is that, real world, there's not a significant difference between the 4990 & later Epsons apart from the lighting - choose the one that works well & is compatible with your computer. The theoretical difference is dwarfed by the other limitations of the hardware.
Interneg:
OK, forget my nasty semi-comprehended statistics...
... but download V750 and Howtek 4500 crop samples here http://www.largeformatphotography.info/scan-comparison/ and spend 1 minute with Ps to make it match like in post 16 http://www.largeformatphotography.in...1#post1447446:
Hey, man... how can it be possible that the result can be so close ? The Epson is not that bad, is it ?
This test also has no nasty math: https://petapixel.com/2017/05/01/160...s-500-scanner/
Look, as the format gets larger scanner performance is less important, in this way a V850 may not be the best choice for 35mm film, but the V850 is an extremly powerful for 8x10" negatives. For 4x5" the V850 simply outresolves the Hassy X5 by a narrow margin, while the X5 is better for MF jobs, and of course for 35mm jobs. The larger the negative format the V850 shines the more.
Then we have the high densities, and yes, if we want to recover 3.6D areas then any drum blows any flatbed. True.
But then it comes the color purity, clarity, beutiful tones and other bla, bla, bla... Well, take 3D LUT Creator and make a conversion LUT from a colorful negative, using as input the drum scan and the V850 scan. You killed all magic and all bla, bla. Now the V850 nails the same "tonality" and colors of the drum.
What I say is that the V850 is a serious device for LF, when densities are not excessive for a flatbed, a common situation. I've calculated that a drum scan would be benefical (over the V850 scan) in aprox 10% of my BW LF shots, but only if wall size prints were to be made.
Not again. Sorry but my passion for drum scanners doesn't allow me to ignore this as much as I really should. Epson is not as good as a drum scanner under any condition. It's not even close. It's far inferior and if you ever spent time with a drum scanner and Epson next to each other for several hundred hours like I have, the only logical way to describe an Epson is to call it a good machine for what it's intended. Never would I call or compare it to anything designed for professional use. It's awesome as an entry level consumer scanner but don't expect it to be powered with any unicorn magical force.
Pali
Exactly - and no amount of fixing-in-post will hide the flaws of the Epson - but it is a good entry point.
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