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ETTR (underexposure) help sought

tjv

Active member
Hi guys,

First up, please let me state the following:

I have absolutely zero interest a debate about the relative merits of CMOS vs. the CCD back I'm using. I'm well aware of them and have read a lot about the new products coming through, even demoed a few for myself. What I am interested in is discussing how to get the most out of what I do have (Credo 60 on a Linhof Techno platform) in terms of preserving important hightlight information in high contrast scenes and getting better shadow information. Like for slide film, perhaps this is somewhat of an oxymoron...

Anyay, a bit of context.

I've been trying to shoot a cliff face including a bit of surrounding contextual information for a long-term project I'm working on. I'm trying to shoot a two shot, 6x13 panoramic stitch and am using an average lens in the Rodenstock 55mm APO-SD with a centre filter (2.5 stops... ouch...). Movements are quite extreme, so I'm suffering a lot with sharpness fall off. +/- 17mm horizontal shift, AND 10-13mm fall of the back. Always between f11-16.

Anyway, the shots I've taken so far have been frustratingly bad for many reasons, not least because I simply haven't managed yet to catch the scene under interesting light. I've tried and I've been there at times when it's beautiful in the flesh, but the foreground is always dark and if I'm to retain detail in the highlights, i.e. expose to the right with only very minimal clipping in the sky, the foreground falls very dark. Today looking at the histogram on the back when in the field I thought I'd managed to reach a good compromise exposure (although I knew the resulting shot wouldn't be very good from the get go,) with what seemed a tiny bit of space at the foot of the histogram and only a tiny bit of highlight clipping (viewing histogram on the back). I was looking forward to editing the photo and seeing what I could do with it, but on the computer my enthusiasm quickly dissapated when I lifted the shadows. Total mush, not helped by the falloff of the lens...

Anyway, attached here is a screenshot of an LCC file (when applying it I turn the vignetting correction off and just remove the colour cast to try keep the noise levels down,) the flat file preview (right frame, 17mm horizontal shift plus 10mm fall of the back), and a preview after some very rough editing. For this example I've used the Product curve in C1, along with the Pro Photo colour profile (the product profile, which usually looks good if quite low saturation, looked horribly dead.)





My question really is what would others do in this situation? Would you expose the image differently, i.e. force the highlights to white to improve the shadows, or do you have any special tricks in C1 to magically clean things up? I must admit that I'm not a C1 native and hugely prefer the Lightroom interface, so admit to getting frustrated quite quickly when trying to get the results I want. Would you resort to exposure blending and if so, what is the best way to go about doing this? I.e. is there good software that can do it in an automated sense like the photomerge function in PS, even with images to stitch as a pano?

Seriously, any advise appreciated.

TJV
 

jagsiva

Active member
Exposure blending maybe your best bet if you want to keep noise levels down. For the few times I've done it, I process the files in C1, then blend in PS (there are a number of methods available), then flat stitch in PS.
 

torger

Active member
I would use a grad filter. I have a H4D-50 and it's noiser than the Credo 60 so in those situations it's a must, unless multi-exposure and merge. As I'm a fan of the single-shot image I only do multi-exposure if I really must. It's rarely the noise as such that disturbs me, but the "dead color" which comes from under-exposure.

Don't worry too much about a wavy horizon or a tree sticking up. Apply a pretty strong (2-3 stop) sharp grad filter and shoot ETTR. Then you shoot also the LCC shot with the grad filter still on, and perhaps one more with the grad filter not there so you have both options.

I only shoot LCC with grad filter still on, but I'm not sure how well C1 handles that (I use RawTherapee or my own Lumariver HDR depending on situation).

In post-processing when applying the LCC the grad filter effect will thus be cancelled out. If the LCC algorithm is done right that will darken the image, if done wrong the highlights will be irreversibly clipped. I don't know how C1 works, you have to try.

Let's assume it's done right, then you can start working the file and enjoy the lower noise in the shadows. Usually I add back a virtual grad filter, perhaps weaker and with a wider transition. I prefer a base grad filter effect even with things sticking up like that tree, as it darkens the tree and keeps some of the natural back-lit effect experienced at the scene. This also makes the tree darker and noise there less problematic.

When grad filters are used this way in the field, they're only "exposure tools" rather than creative effects. This means that you can use sharper transitions and less careful placement as the effect will be canceled out in post anyway.

If the LCC algorithm has a clip problem you need to use the LCC without grad filter on, and then either keep the original grad filter effect in, or manually cancel it out with a reverse virtual grad filter which is possible but is a bit messy.
 

Paul2660

Well-known member
I also would use bracketing. I am not a fan of ND filters in the field as most times you scene does not have a perfectly flat line and thus trees or other objects will tend to be darkened.

Underexposures of the amount you have will tend to turn the details to mush as the camera is not receiving enough light to allow it to really register the subjects in the deeper shadows.

I would consider 2 brackets or max 3 as you are on a tech camera and shifting just to keep the work down.

You can combine the files manually in Photoshop, or use LR's HDR tool. LR's HDR tool does a great job but don't let the resulting image fool you, as it may appear too bright. There will be a lot of room left for work on the image.

Paul C
 
M

mjr

Guest
tjv, can you post a crop of a dark area with noise? I shot some similarly lit scenes the other day with the IQ260 and raising shadows to 100 and there's minimal noise. I can upload to show what mine produces if it would help.

Mat
 
I would use RawDigger to verify the highlight details and to help learning about the capability of the digital back. Your ETTR (maximum exposure without blowing out highlight) is correct.

In your use case you don't seem to be doing long exposure of sunset/sunrise then why not doing some bracketing for as much dynamic range as you want?

If you have to do it within a single exposure then a Sony CMOS helps (but as you've mentioned you have no interest in this I'm not going further on this).
 

Aviv1887

Member
Torger gives great advice that is certainly worth experimenting with. I would also try a grad filter but not quite 2-3 stop. Another small tip is to use Linear Curve in your Base Characteristic in C1. Always gives a bit more highlights.
 

vjbelle

Well-known member
I almost always use a 2 stop Lee graduated ND filter and would not be without it. I find the graduated filters much more versatile than the Hard series and have never had a situation where the filter interfered with non-sky areas. Regardless of the amount of DR I have I feel much more comfortable bringing up the shadows as little as possible. So, I'm in the Torger camp although all other suggestions are very valid.

Victor
 

ErikKaffehr

Well-known member
Hi,

I would suggest that try out "RawDigger" to find out about your exposures: http://www.rawdigger.com

With a tool actually showing the raw histogram from your images you actually see how they are exposed.

Personally, what I have seen is that Capture One and my P45+ are a bit disposed to protect highlights by underexposing the images quite a bit. Capture one adds quite a bit of brightening the images.

Doing bracketing and HDR (when needed) is a good option. Many times it may be possible to make multiple exposures and blend in Photoshop.

Best regards
Erik


Hi guys,


Seriously, any advise appreciated.

TJV
 

tjv

Active member
Thanks everyone who has taken the time to reply, I appreciate it.

To clarify the shot I posted above was the right hand frame of a two shot stitch (for 6x13 ratio, which is a bit odd but essentially a panoramic making use of the + / - 17mm click stops on the Linhof sliding back. The other part of the frame which I didn't post is mostly a cliff face that takes up 80% of the entire frame. I guess an graduated ND could be used here, but it'd be pretty cumbersome and painful to get right in fading light I imagine. Torger's technique sounds interesting, although I'd be super paranoid about blowing highlights after the LCC is applied. I guess practice would make perfect.

I essentially think I'm working against a few evils here.

The first is the DR of the sensor. Exposing as not to blow highlights then pushing shadows is not kind to colour depth or detail. The CF helps quite a bit compared to using the lens "naked", but noise is only one part of the equation.

Secondly, I'm making use of some pretty extreme shifts and this is really highlighting the weakness of the 55mm APO-SD. It's a really good lens with moderate shifts, but this is just too much for it and on top of losing detail to noise, I'm seeing a ton of detail smearing as the image gets out towards the edges.

Thirdly, the particular image I've been working on capturing is a good idea that doesn't necessarily translate into a classically good photograph. What's the saying? You can't polish a turd, but you can cover it in glitter? It's a good way to describe what I'm trying to do...


So, all things considered, I'm up against it unless I make some compromises...

The other day I did actually make two exposures of each shot, one image ETTR preserving all highlights without clipping, and a second two stops over. I tried using the LR HDR tool today to see how it looked but encountered weird errors and gave up. Most of all, even with cautious settings to allow for subject moment (it was a very still day but there was some movement in the leaves, etc.) I got weird edges around hard lines – with all the different settings – and to make matters worse the file kept corrupting. Anyway, I don't think was extreme enough in my bracketing to be of much use. I'll try again another time when I'm not under so much pressure to get the shot.

I've not used RAW digger before and am not so good at understanding what all the numbers mean, but I'd be happy to send anyone a RAW or two to look at if they were interested?

MJR, I'd be keen to share a RAW with you and visa versa if you're interested to see what I'm talking about for yourself. I'd post a crop here but the forum software keeps butchering / compressing things for some reason.

Thanks again and I'd be keen to see anyone elses samples of similar shooting situations posted here, too. It'd be good to see a thread that tackles this kind of shooting issue where people can learn new things without being told to dump their gear for the next best thing.

Thanks again,

Tim
 

Paul2660

Well-known member
Hi Tjv.

I read your info about the LR HDR.

If the message was "the file may be corrupted". Don't worry about that as you can still export the file if you get one that does not have any other issues.

This error is a known LR bug that Adobe has chosen not to fix as it's been known about since the release of the software in LR. I have just come to ignore.

Adobe has gotten bad about this IMO, releasing code with bugs that never seem to get resolved.

Paul C
 
M

mjr

Guest
I'm really not a fan of the LR HDR tool, I tend to use PS and lay 2 exposures over each other and mask to blend the highlights from one with the shadows from another, seems to be easier to me, just a different option.

Happy to swap some RAW's with you, just send me an email address, our sensors should be the same although I don't have the same lens.

Mat
 

Jack

Sr. Administrator
Staff member
My .02:

When scene contrast exceeds the DR of the camera, the best solution for me has always been two (or three) exposures blended; one for the shadows, one for the highlights (and if needed one for the mids). With all cams after the P65+, I am usually able to accomplish this with ONE capture just shy of blowing highlights, and multiple variants output from C1, then blend those variants in PS. I still prefer to blend in PS because the masking is so effortless, though C1's tool has improved significantly and is also an excellent option.

PS: FWIW, I personally find the visual line effect of SND filters distasteful and can see it in almost every image it's used in. I feel the same way about over "tone-mapping" halos.

/ :lecture:
 

torger

Active member
Due to my shooting style I don't run across DR problems very often, but I found one here where I've used a 2 stop grad filter, the effect canceled out in post, and then a new grad filter was applied (virtually), plus some light tonemapping. No super-beautiful light or anything in the scene (it was actually pretty dull), just testing out if it was possible to make natural-looking scene of a difficult lighting condition.

I can use sharp edge grad filters as I cancel out the effect in post via LCC, and apply a new virtual one with suitable transition and strength. If I would keep in the filter effect I would use soft transition filters more of course, and I would have to be more skilled placing the filters, which is a problem when for me as I use them quite rarely and thus it's hard to maintain skill.

Personally I find the most natural look of a tough DR situation is had if you combine techniques and apply a little bit of all. I combine grad effect with coarse dodge and burn and then modern detailed tone mapping. If you let one technique handle all DR reduction, it becomes too visible, that's at least my experience.

In the material I usually shoot I typically have quite soft light and then get by with only a soft grad filter effect and then I stay with that. A soft detailed tonemap would also work, but my personal taste is slanted towards a more traditional look, I like it when the image looks as if it could have been shot with film and traditional dark room techniques. I don't like a very clear visible transition though so if the grad becomes to visible I combine with other techniques.

Unfortunately I did find a good example of the tree sticking up over the horizon issue, but what my personal taste there is that the tree should indeed be quite dark, it gives a more natural look as the eye constantly adapts to the light depending on where it looks, and when you look into the sky the back-lit features will look dark. A soft-edge grad that darkens the tree above the horizon is good in my book, but it can't be too strong of course.

"Keeping details in shadows everywhere" and tonemap to do so I think is dangerous, it can easily start to look unnatural. Instead I try to think about the image in a more global sense and blackness here and there can contribute to the mood.
 

Attachments

Jack

Sr. Administrator
Staff member
Here is an example result of the above process, this image made from a single capture exposed for highlight retention which is the sky in the background. 2 variants are output from C1; first is basically "as-shot" for the sky, second is processed to elevate the foreground exposure pretty significantly, lifted 3-½ stops for this image IIRC. Of course contrast and color is balanced in both variants before blending. These two files are layered, and then masked for the desired balance between highlight and shadow layer adjusted to render what I feel is still a "believable" level of shadow detail.

 

GrahamWelland

Subscriber & Workshop Member
Hi,

I would suggest that try out "RawDigger" to find out about your exposures: http://www.rawdigger.com

With a tool actually showing the raw histogram from your images you actually see how they are exposed.

Personally, what I have seen is that Capture One and my P45+ are a bit disposed to protect highlights by underexposing the images quite a bit. Capture one adds quite a bit of brightening the images.

Doing bracketing and HDR (when needed) is a good option. Many times it may be possible to make multiple exposures and blend in Photoshop.

Best regards
Erik
I absolutely agree with Erik here. I found that when I ran my iq160 & iq260 files through raw digger that I was routinely under exposing by anywhere up to 1.5 stops compared to the raw file clipping points. It changed the way I used the CCD backs and ETTR. Also running tethered was an eye opener too as to how much more the images could be exposed.

with CMOS I'm going in the other direction because it seems likes there's less free headroom in the highlights but bucket loads of shadow information that is practically noise free.

As as per jack, a blend works even better than the highlight/shadows but obviously less convenient.
 

Jack

Sr. Administrator
Staff member
when I ran my iq160 & iq260 files through raw digger that I was routinely under exposing by anywhere up to 1.5 stops compared to the raw file clipping points. It changed the way I used the CCD backs and ETTR.
You can even see it in C1 at the flat defaults! You do for sure need to learn how to read the older IQ's histos -- they are not as intuitive to get right as one might think! Biggest issue I found with them is they are very sensitive to specular highlights -- like the Suns glare off green tree leaves or similar minimally reflective surfaces -- and that alone can cost you several stops up top.
 

ErikKaffehr

Well-known member
A small demo…

Hi,

Here is a small demo, let's start with an exposure that is perfectly OK (IMHO):

Here it what it looks like in Capture One at default settings and highlight warnings enabled:
Screen Shot 2016-05-18 at 14.18.54.jpg

Now, let's check it in Lightroom with default setting (my defaults, but it doesn't matter in this case (*) )
Screen Shot 2016-05-18 at 14.18.39.jpg

That file is not overexposed at all! Histogram says it is quite a bit from clipping!

Now let's check the ultimate truth, the raw file, using RawDigger:
Screen Shot 2016-05-18 at 14.16.48.jpg

Raw digger shows us that the green channel is clipped but in a small part of the sky. All part of the sky is probably recoverable.

Now, let's do some adjustment in Capture One, and we see that sky id fully recoverable.

Screen Shot 2016-05-18 at 14.19.20.jpg

So, what this story tells us that it is good to know our system and that the information in raw converters can be greatly biased. Using a tool that shows uninterpreted data, like RawDigger, is helpful in achieving that.


Best regards
Erik

(*) My defaults in Lightroom use a fixed WB, that has been established for daylight and I also use a self made profile that was generated by Adobe DNG Profile Editor.
 

Wayne Fox

Workshop Member
Just a note for those that might go through this thread in relation to Erik’s comparison of C1 vs LR defaults, one thing to be aware of (which can be good or bad) when Lightroom introduced it’s 2012 process, it added some preliminary “intelligence” for lack of a better term which analyzed your image and adjusted certain parameters. Lightroom tries to preset a white and black point based on the image. Unfortunately that adjustment is not reflected in the black and white sliders, which will always display 0, even if Lightroom has pulled those points in.

Here’s a before/after screen shot of an image, the left is the raw file in the 2010 process, the right the only change has been to move to the 2012 process. Note almost all clipping has been eliminated. the 2010 process was more like C1, meaning the user would deal with those end points through adjustment. as I mentioned, this can be good or bad depending on how you look at it.
 
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