Questions about Curve Surgery and Photogenetic Curves

Mellisa....

Don't take this the wrong way but I need to ask....

Why on earth would you want to use a custom curve in this piece of machinery?

In order to expose properly, you need to use EV compensation when you shoot as you can't possible have a curve that will allow proper exposure for everything you shoot.

It's like the little exposure tweak that Nikon has in the menu....if you ad -EV to hold highlights in this tweak..you're gonna squash the shadows at times. If you use a negative EV, you're gonna blow highlights. You really need to meter and compensate for the shot if you want the exposure as close to correct as possible.

I'm srry..I didn't mean to lecture :roll:

We need to get you schooled by RR  

 

Curves has nothing to do with exposure.

What you are saying, Jim, is somewhat equivalent to "we do not need different film, one size fits all".

 

Illiah..

Once I wrote it I was afraid you were gonna read it  

A) i've had 4 glasses of wine since coming in from the marsh.

B) I spent two hours last night trying to convince my neighbor (who just got a d2X cause mines takes pretty pictures) that sticking a negative tweak in her camera isn't gonna save the entire day...just a highlight here and there. It was very frustrating).

C) Illiah...let me ask you this......anything that can be accomplished with a curve can also be accomplished with processing can it not???

 

Re: Illiah..

Not in Capture. To do that, you need access to linear raw data directly. For now, only RML allows that. Manipulations in linear space are very powerful in shadows, and very gentle in highlights. Also, because of some infamous Capture bugs camera curve can help presrving highlights.

 

What is Curve Surgery? What is a Photogenetic Curve?

These are both new to me.

 

NEF format can't handle more then 1 curve - no place for second curve there.

Fotogenetic site is:
http://fotogenetic.dearingfilm.com/index.html

 

Iliah -

Where are those "infamous Capture bugs" documented - I'd sure like to know what those are so I can avoid them in the future if possible.

All -

My understanding so far is that a custom curve would affect only a JPEG file in camera (when shooting straight JPEG or a combined RAW-JPEG combo). The display of highlights and curves in their respective screens would also be influenced by a custom curve. The RAW data, however, is the same whether a custom curve is used or not. Is this not correct?

If so, shooting in RAW would seem to work better if you simply used the "Low Contrast" setting, since that would give the most accurate readings in highlights and histograms, then you could use whatever RAW conversions you wanted to in post processing.

Of course, if you shoot in JPEG only then a custom curve is much more important if you choose to use one.

Am I confused about this (or simply missing the point)??

 

I think there was a lot said about Nikon Capture sub par ability to get the highlights, as well as about problems with false highlight colouration.

Of course, those bugs were reported to Nikon Capture Development Team, and recently they responded by acknowledging the problem.

I never heard of publicly available documentation on Nikon Capture bugs.

For the record, I will be the last person to trash Nikon Capture.

 

Oh well, I was hoping there was something more concrete than that. I wasn't trying to imply that you were trashing NC, Iliah. I consider your input very valuable and feel like you are the local expert on topics concerning RAW conversion and representation.

What about my other questions? Shouldn't RAW be the same regardless of the curve (although if the curve encourages you to change your exposure, then of course it's a moot point)? And doesn't "Low Contrast" give you a better idea of exactly what's being captured?

 

I think at least several hundred people know precisely what is wrong in NC and why. It's quite simple, really.

Low contrast will not give you accurate render of highlights. I differs for different models, and even for different samples, but in most cases mapping 255 to about 240 is better.

The point why to use custom curve with such a mapping is that it also helps to overcome truncation in Nikon Capture. Of course, resulting render will be low contrast and will need some additional correction. You can try this one to see what happens:
http://www.pochtar.com/D2xCameraCurve.zip

RAW data depends on custom curve only in original D1. But the whole Nikon Capture processing depends on that curve for all cameras. So, you are presented with 6 processing modes, one of which is using custom curve while the others are with Nikon standard curves. Using Curve Surgery to switch the curves post factum and to edit them adds one more dimension of freedom - especially if you use blending.

 

Mellisa
RR is Ron Reznick he has held sessions for many on this forum , I personally have not attended one but when he is offering them again sure would like to attend either a Yellowstone or Bosque session

 

Re: Illiah..

Sorry if I seem to just pop in, but I find this thread very interesting. Just what is RML ?

 

Re: Illiah..

RML is RAWMagick Lite, our program to convert NEF and some othe RAW files to PSD/TIFF/JPEG

 

Be very careful with Custom Curves!!!

Melissa, Fotogenetic's Custom Curves are NOT for the D1 and D2 series...
To my perception, they were produced just to fix the underexposure issue of the D100 mainly. And I don't think there's such an issue with the D2H/X... :!: :!: :!:

 

Sorry, Panos, curves have nothing to do with underexposure   If it were so, expsure compensation will be quite sufficient, and no curves needed.