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View Full Version : Dynamic Range of Portra and Ektar (for the Sekonic L758)



gmfotografie
7-Oct-2015, 02:04
Hi, im just try to set up my sekonic for those films.
for a the display... can anyone tell me (round about) the dynamic range for ektar 100 and portra 160.

(usually i meassure the darks and put them on zone iii and let the higlights go... never mind exactly where to put the higlights...;-) )

thank you ;-)

richardman
7-Oct-2015, 02:13
Whatever they are, they are HUGE.

jp
7-Oct-2015, 03:53
It's big, I just expose adequately for the shadows and not worry about highlights. The range is probably comparable with tmax 400 based on seat of the pants estimation.

Drew Wiley
7-Oct-2015, 08:41
They aren't necessarily generically huge latitudes by any means, at least if you expect quality results. Ektar has just about one stop of margin either side of what you get with a typical chrome film (not Velvia). Beyond this you risk crossover or other issues. Therefore placing shadow detail on Zone III is a good idea; but you can still blow out the highlights in high contrast scenes. If you expose Ektar with as much care as you do a chrome, you'll do fine, except in the sense of color balance in shadows, which is a slightly different subject requiring suitable color temp filtration at the time of exposure (it's a myth all this can be post-corrected in
PS). Porta films are a lot more forgiving, but a different softer look, with Portra 400 having more snap than 160.

gmfotografie
7-Oct-2015, 08:53
thank you all
...and let the highlights go is not really correct.

i usually messure the overall contrast and if it is about 5 to 7 stops, i dont calculate where the higlights will go... just put the darks on zone 2 or 3 and basta ;-)
so therefore i feel ok using the portra. i photographed only 4 sheets with portra with good results...outdoors.

im generelly not experienced in shooting indoors ;-)
never have done this before with film.....and tomorrow i will be in a nuclear power plant ;-)
hope to get some good results... will show it to you if its okay!

wombat2go
7-Oct-2015, 08:58
This image is on 120 film Ektar 100 taken early morning
https://app.box.com/s/mbi6jx0kykx6ga1h6as30l1xibslqy2n
It was scanned using Pacific Image PrimeFilmPro120 to a 16 bit tiff
Dynamic range from the dark car hood to the blue sky in Hex is approximately 0035h to F785h

That is a ratio (in decimal) of 1:1195

In decibel: 20log(1195) = 61.5 dB

in "D" units ( I think the old film dynamic range units) : 3.07

That dynamic range won't be observable unless a TrueColor ( 10 bit) monitor is used, and a 16 bit tiff is viewed in a 16 bit viewer

Edit ( forgot) In "stops" that is approximately 6 stops.

Drew Wiley
7-Oct-2015, 09:16
Well, my office monitor is not the greatest, but even here it's apparent you've got a thud in all the lower zones due to color balance issues. Next time try an 81A
filter over that kind of shot. Sure, you can post-tweak it a bit, but it will be hell to get clean hues over the whole range unless you get it right at the time of the
exposure itself. Once there's dirt in the shadows, it's tricky to get it out. Or just switch to one of the Portra products instead. It's a tradeoff. I know... I know. "Looks fine to me". That's because people are just expecting Ektar to look like yet another color neg film. It isn't. That's like driving a Porsche with a temporary
spare on one of the wheels. It's a performance film. Portra (esp 160) is more of a classic portrait film, engineered for "pleasing skintones" instead of overall
color saturation. These are all excellent products, but with very different personalities.

wombat2go
7-Oct-2015, 09:36
Thanks Drew.
Did you mean that an 81A filter would have helped the early morning color cast?
I have not used filters so far . I see the 81A effectively reduces the color temp by attenuating the blue range

Here is one using Porta 160 in bright daylight. Sand stone in Sydney. Graflex 2x3 with the Graftar 103mm
https://app.box.com/s/guawvk0g2ods4g0xlms00t42pvyrpovl

gmfotografie
7-Oct-2015, 10:52
great depth of field ...

Drew Wiley
7-Oct-2015, 11:06
Yes, that's correct. I always carry an 81A for overcast sky or mildly bluish shadow correction, and light pink sky filter (2A etc) for high-altitude UV issues or minor tweaking, and an 81C for deep blue shadows under open blue skies. Split lighting (some of the scene under deep shade, some under open direct sun) presents
a trickier problem requiring Zone III preflashing thru a warming filter. Ektar doesn't artificially warm the shadows like Ektar. This means it is capable of cleaner
natural hues overall (nice for landscape work), but will give cold shadows where they are truly cold. The other direction, skies can go cyan if not properly exposed. Controlling all this is no harder than what Hollywood photographers have done with neg films all along, or what chrome shooters routinely did whenever they wanted more realistic results. Otherwise, if this is an annoyance, just shoot Portra 400. It's a lot more forgiving but will yield a bit more of a classic color neg look. Portra 160 even more. Ektar is what you reach for when you want a color neg film that behaves more like a chrome in terms of contrast and clean saturation.

Drew Wiley
7-Oct-2015, 11:06
oop. Typo. Ektar doesn't artificially warm the shadows like Portra, I meant.

wombat2go
7-Oct-2015, 11:10
You should edit your post, as you correction is on next page.

Drew, Does exposure level (errors) affect the color balance of these C41 negs?

Corran
7-Oct-2015, 11:36
More important than any of this, in my opinion, is the scan (assuming you are doing a hybrid process, as most are these days for color).

You can have the most perfect color balance in the world and all the dynamic range possible, but a bad scan and poor edit will still look like crap. There's a million tales of "blue casts" with various negative films that have nothing to do with the film and everything to do with the scan.

For the moment you could do a lot worse than just setting your meter to 100 for both films and placing the deepest shadows at Zone III (or II for Portra if you want) and seeing how it goes.

Drew Wiley
7-Oct-2015, 11:45
Absolutely. As with other color neg films, if you must wing the exposure, slightly overexpose the film. But with Ektar you never want to go too far off box speed.
This is due to its high contrast (compared to other color neg films per se). What happens if you underexpose it, is that you get the shadows way down where parts of the respective dye curves overlap, so cross-contaminate. With deep blue shadows, this means that particular dye will be underexposed and the whole category of blue tones will be hard to resolve. I realize that landscape photographers often liked unnaturally blue shadows produced by films like Ektachrome 64. But with Ektar you get a kinda sickly cyan cast. Merely overexposing the film won't cure this, and will risk crossover at the upper end, in the highlights. You need to filter for it, selectively. The reward is far cleaner hues overall. It's a wonderful product to have, now that chrome films are getting scarce. But ya gotta understand it.

Drew Wiley
7-Oct-2015, 12:31
Coran - Ektar is different. It's prone to cyan issues in particular if either the exposure or color balance is significantly off. Bad scans are a different topic and the
source of all kinds of visual crimes. But one of the most frequent issues with scanning Ektar is the sample size and how this interacts with slope of the dye curves. In real-world terms, the smaller the film, the harder it is to get a good scan. Sometimes I'll order up a scan with my C-41 order in lieu of a contact sheet. Even a 50K flatbed does a miserable job with 35mm film; the sampling is just too coarse. But the same level of scan does just fine with 120 or larger film. (I never scan sheet film, because it's what I am most likely to print myself. But I do use smaller films for the sake of economical testing or mock-ups.) In other words, the very film most people are most likely to place in a cheapo scanner is 35mm, and therefore they habitually get weird looking results they incorrectly blame on the film. But the same half-assed scanner might give acceptable results with 4x5 film. This problem is so routine that it's given Ektar a
pretty bad rap among amateurs, esp the "I can fix anything in PS" crowd.

Corran
7-Oct-2015, 12:42
Well I've scanned a lot of Ektar, in 35mm up to 4x5, on one of those (originally) $50k flatbeds.

As you already stated, Ektar is bluish in the shadows - which very well may be "how it was in real life" but for me it really is too blue/magenta in the shadows. Balancing it out with levels/curves/etc. is of course doable. The cyan tones in the sky are also a signature Ektar look (that I don't like). I can fix anything in PS (HSL layers can do a lot) but I prefer shooting a film that's better looking for my vision in the first place. But this is about learning the materials. My comment has to do with the scans I see often that look like they were shot through an 80A filter.

As for 35mm vs. 4x5 scans, I totally disagree with everything you said. Other than the obvious resolution/grain differences, I see no differences in the colors for different formats.

Here's an Ektar scan for reference. The shadows were very blue and the sky more cyan than I like. So I tweaked it quickly in PS. This shows the typical DR of negative film, with full sunlit bank on the right and deep shadows on the left.

http://www.oceanstarproductions.com/photosharing/45c.jpg

wombat2go
7-Oct-2015, 12:54
Absolutely. As with other color neg films, if you must wing the exposure,

I admit I have been winging it. I have a vintage Pentax 3/21 spot meter but now I am not going to take it out in public due to its shape.
Pehaps I need a little Sekonic, but my budget does not nearly reach an L758 !

Drew Wiley
7-Oct-2015, 13:34
Of course, EVERONE disagrees with me on the web. Once someone sees some of my actual Ektar prints, that shuts them up FAST. They're pretty surprised just how
clean a palette I get. So you can either take my word or not. I don't care. But from a simplicity standpoint, you agree with me anyway, Corran, since you apparently prefer to peg the neg exp correctly in the first place too. But academically, once again, I have plenty of visual proof of scan vs scan format-wise.
Small film needs a better scan not only per resolution, but hue distinction.

Corran
7-Oct-2015, 13:36
Sure sure, well the offer is still open for you to send me a (small) print to evaluate. I'll send it back after.