Negative copying, macro lens and camera histogram - OMD Em1 mkii

[Wairoakid]

I am copying BW film negatives with my Em1 mkii and 60mm macro lens. The film is in a neg holder and I am using Kaiser Slimline Plano as a light table. I am using a Kaiser copy stand. The film is placed with the emulsion facing the camera.
I am very pleased with the quality of the shots, I do a Hi-Res shot (50m) as well as "normal" ORF file at 16m.

I am using the camera histogram to make sure that I am getting as many gray tones as possible spread from 0-255. I use DX Photolab 4 to process. The negative result is turned to positive by just reversing the Curve completely. I have to use Fastview to flip horizontally though as DX Photolab 4 does not have this tool.

However as the film is a negative I am assuming that the right hand side of the histogram which normally shows the amount of White (255) in a positive shot is actually showing the amount of Black and vise versa.

Am I correct in this assumption?


Is there any way of getting the camera to show a positive image on the screen BEFORE I take the shot so the histogram is correct as to distribution of tones.

Thanks for any help

 

[Armoured]

You might want to try tethering to computer. That way you could do test shots and reverse. Offhand I don't know if any tethering software allows you to see reversed images live, which would be ideal. But with a good workflow or automation,you'd probably be able to get reversed results quite quickly

 

[Wairoakid]

Thanks for replying
I might try that- have to reconfigure the room

My main concern is whether the camera histogram is providing the correct information as I am using it to get the maximum tonal spread when it is reading the negative.
I am assuming that the information in the histogram is reversed. Given the histogram plots plots pixel count against luminance value then what I am seeing as the highlights area in the camera will be the dark tones when the negative is reversed on the PC screen but the proportion of the overall number of pixels will remain the same as it did before reversal.
I presume that the change to positive operation removes 255 from each pixel value and then makes it a positive value. i.e 0 becomes 255 and 50 become 205 and 255 becomes 0.

Looking at histograms for the same shot in both negative and positive in the PC the positive histogram appears to be a mirror image of the negative positioned in the same place in the luminance axis.

So I think I can rely on the camera histogram to provide information but I need to remember that the left is the right when the picture is made positive so I don't want the highlights blowing out.

 

[ac12]

Old fashioned solution.
Put a file card, as a reminder, next to the camera saying "Hightlight on the left, shadows on the right."

 

[Brownie]

However as the film is a negative I am assuming that the right hand side of the histogram which normally shows the amount of White (255) in a positive shot is actually showing the amount of Black and vise versa.

Am I correct in this assumption?

Edited: Never mind. I misunderstood the question

 

[Armoured]

My main concern is whether the camera histogram is providing the correct information as I am using it to get the maximum tonal spread when it is reading the negative.
I am assuming that the information in the histogram is reversed.
...
Looking at histograms for the same shot in both negative and positive in the PC the positive histogram appears to be a mirror image of the negative positioned in the same place in the luminance axis.

So I think I can rely on the camera histogram to provide information but I need to remember that the left is the right when the picture is made positive so I don't want the highlights blowing out.

Yes, that is what is meant by negative, and that basic approach is correct.

Obviously there are details and tricks like the orange cast on colour negatives, and anything digital is applying some processing that may be a bit different, etc., but for all practical purposes, it's the inverse of the histogram.

 

[Wairoakid]

Thanks for all the comments

 

[Armoured]

Old fashioned solution.
Put a file card, as a reminder, next to the camera saying "Hightlight on the left, shadows on the right."

Right next to my "pants first, then your shoes" reminder.

 

[Mack]

RawDigger has the ability to output a TIFF file directly from the RAW data. I believe it is the only one to do so. Still camera images look very flat looking at them much like some video RAW fiiles do.

Your camera will output a JPEG and who knows how it is cooked via the internal.embedded profile it made. Additionally, all these editors seem to have their own 'personal thoughts' on "How it should best look." Many (e.g. Adobe) like to boost the middle tones by default.

 

[Wairoakid]

As I understand your point the camera will be outputting a jpeg in the viewfinder so I can't rely on the in camera histogram to correctly show the tonal spread of a raw?

 

[Armoured]

As I understand your point the camera will be outputting a jpeg in the viewfinder so I can't rely on the in camera histogram to correctly show the tonal spread of a raw?

Probably one could write PhD's on this in math terms. In short form: the extremes at each end should roughly match between the jpeg and raw histograms. The relative amounts (the way the curve of the histogram is shaped) will differ somewhat depending what adjustments you have dialled in and what OM has baked into their jpeg formulae.

BUT: the bigger difference is how much in-between data, 8-bit vs 12 or 14 (I forget which OM uses). There's more data there to mess about with without it showing more weird artefacts eg you might be able to bring more detail out of shadows than you could from the jpeg. Depending what your use is, in this context, have the camera save raw and jpeg, and if you like the jpeg, use that. If you need to make extensive edits, use the raw - it might require a bit more work to get where you want (including replicating or getting closer to how the jpeg looks if that's your goal), but you'll have somewhat more latitude before the processing becomes evident.

 

[Armoured]

I should note, I'm simplifying above. There are other effects in jpeg like sharpening that may have more or less obvious impacts on how things like film grain are picked up etc. Some of this will just be expérimentation.