Slide copying - adjusting in RAW

Finally I have a question worthy of this group. I have a large 35mm slide collection, mostly in Fujichrome 100/200. I have started copying them with a Konica/Minolta 5D and an old Tamron 35-80 SP macro lens. Although I have PS CS2, I am still learning (could be a big clue there). I have no complaints about sharpness. Exposure is OK. What is not working is contrast. Copies habitually have blown highlights and murky lowlights recoverable only with individual attention in Camera RAW (and I sure hope to avoid going into Photoshop proper to fix this). I am not surprised by this, considering the media involved, but the question is - how can I copy several thousand slides without fiddling with each and every one of them to get this contrast under control?

TIA - Chuck

Chuck,

A great question. So what is your source of illumination?

It should be that if you sort your slides according to the shoot with lighting conditions for each group similar, you should at least be able to get setting for each group optimized by loading all that group in RAW and optimizing one and then applying that to all the other similarly lit and contrasted images.

There are slide feeders for various film scanners you can use. There are also very high end scanners that can handle a huge number of slides in one go and correctly expose each one, but that, I believe $20,000 or so!

Still, some of the $200-500 flat bed scanners do the same thing.

It's the workflow that is a killer!

I have merely taken to sorting slides and scanning a few as needed. I'd love to find a solution for my fading slides that didn't require 20,000 dollars or hours!

Asher

Asher - I'm using an electronic flash, dialed down to 1/16 power, covered with several layers of white Kleenex. As you can see, this is a low-budget operation. The slide holder is home-made, mounted on an old enlarger stand. I don't want to invest in a new, auto-feed scanner - copying with the camera goes pretty quickly.

Applying global adjustments is sort of what I had in mind, but I have no idea how carefully I need to sort the images in order to make a given group of them amenable to the same adjustments. Plus, hearing about how others make basic adjustments would be helpful too.

Copying slides to slide-copy film was pretty involved. It helped to pre-flash the film, something pretty obscure to the home user. I'm hoping there is a similar "trade secret" to making digital copies.

-- chuck

Chuck Bragg said:

Copying slides to slide-copy film was pretty involved. It helped to pre-flash the film, something pretty obscure to the home user. I'm hoping there is a similar "trade secret" to making digital copies.

Click to expand...

Pre-flashing digital is not a good idea. The brighter you record whatever is black, the more noise there will be when you correct it back to black in post-processing. The reason is that with digital, the noise is weakest in the shadows, near black, in an absolute sense, even though it is strongest there, relative to signal. Any extra light for your blacks means more absolute noise.

John - pre-flashing was only an example of an arcane technique for reducing contrast from the Ancient Days of Film. I wouldn't expect it to work on electrons, but somewhere out there is The Secret.

-- chuck

Chuck Bragg said:

John - pre-flashing was only an example of an arcane technique for reducing contrast from the Ancient Days of Film. I wouldn't expect it to work on electrons, but somewhere out there is The Secret.

Click to expand...

How much light is striking the camera side of the slide? There shouldn't be any. If there is any ambient light on the slide from the camera side, that would be like pre-flashing, making black impossible.

If you still get low contrast that way, then perhaps the black of the slide really isn't black enough for digital, and then you must use the "shadows" slider in ACR, and find a good default setting for it for slides. Might be 10, instead of the default 5. You might look to create a curve, instead, but whatever you do, save it as the default until you are finished converting the slides.

Chuck Bragg said:

I have no complaints about sharpness. Exposure is OK. What is not working is contrast. Copies habitually have blown highlights and murky lowlights recoverable only with individual attention in Camera RAW (and I sure hope to avoid going into Photoshop proper to fix this).

Click to expand...

Chuck, the issue you are facing is (assuming otherwise correct technique) one of dynamic range mismatch. Slide film, with a useful density range of roughly 10 stops (Dmax-Dmin ~= 3.0), just barely fits the 10-11 stops offered by the CCD in your camera.

Slide highlights should be exposed for almost (but not really) clipping. To then get away from the murky shadows, I'd suggest an HDR approach involving something like 2 individual exposures merged into 1 High Dynamic range one. You would need at least 2 stops difference between exposures. Three (like in auto bracketing) 1-stop (or 1 and 1/3rd) difference exposures might work even better in capturing the non-linear density curves of film. Just make sure that the histogram of the longest exposure stears clear from the left side of the range. Slight clipping of the shortest exposure is not a real problem in HDR's, but a waste of DR.

A (Windows) program like Photomatix can do batch-processing of several types of Raws, to simplify the workflow. I haven't tried Photoshop CS3 beta yet, but hopefully its HDR handling has improved over CS2.

Bart

Hi Bart,

Is Photomatix more capable than CS2 HDR?

Also is it available as a standalone?

I'm thinking that such a program would be a choice for me once I buy a Pwerbook Pro.

Asher

Hi Asher,

Recently, I have been experimenting with HDR using both CS2 and Photomatix. The latter is available both as a stand-alone program and a plugin.

My humble opinion is that Photomatix delivers better results than CS2 (if used properly), but I'm sure that there will be others who disagree . You need to understand the HDR concepts a bit to utilise it correctly. Overdoing things is rather easy whereas it should remain "believable", otherwise one gets "plastic-looking" results.

I am seriously considering buying Photomatix since I was able to salvage a few hopeless photos using it which could not be saved by CS2.

Cheers,

Cem

Hi Chuck,

Can you tell us a bit more about how you set-up and align the camera and slide?
Have you, by any chance, looked at one of these devices (the second one on the page)?

https://secure.soligor.com/index.php?id=89&L=1

It can be mounted on a DSLR using an adapter ring, after which there is no light entering the camera from anywhere but via the slide.
I have been looking for users' experiences but couldn't find any.

Cheers,

Cem

Asher Kelman said:

Is Photomatix more capable than CS2 HDR?

Click to expand...

Well, it's more mature than the first incarnation of CS2's HDR. Maybe the CS3 version has been improved.

Also is it available as a standalone?

Click to expand...

Photomatix is available as a stand-alone program, but that one isn't color managed yet. The Plug-in version benefits from Photoshop's on-the-fly display color management, but it (for the moment) lacks the latest options available in the stand-alone version.

Photomatix also offers several workflow benefits, and it has a better tonemapping function than PS. What I like about the plug-in is that it does its tonemapping on the 32-bit/channel HDR, without converting it to 16-b/ch. That allows to tweak the result when changing the mode to 16-b/ch in Photoshop.

Tonemapping the huge Dynamic Range into the limitations of 8-bit/channel images is what poses the real challenge, and constraint is key. It is easy enough to go overboard with the settings (as the samples on their site show), just pull back on the amounts till it looks natural again.

Photomatix also offers several exposure blending options, something that can be helpful when e.g. blending different versions of a single Raw file, or when stacking exposures to reduce noise. It also produces decent HDR files, partly because of the built-in alignment options.

Again, maybe CS3 has gotten it's act together on this subject, I've yet to try it. Sofar, Photomatix has been a good step in the right direction for me, with potential to get even better. Uwe Steinmueller has published an essay on Photomatix, and even offers a discount on the purchase price.

As for the scan challenge, HDR in general allows to improve the dynamic range by promoting the captured data to real 16-b/ch with low noise in the shadows, without the need for tonemapping, but it's still an option.

Bart

Chuck Bragg said:

Asher - I'm using an electronic flash, dialed down to 1/16 power, covered with several layers of white Kleenex. As you can see, this is a low-budget operation. The slide holder is home-made, mounted on an old enlarger stand. I don't want to invest in a new, auto-feed scanner - copying with the camera goes pretty quickly.

Click to expand...

Cleanex or other tissue paper will do little diffuse a light source. Such paper will waste flash power (get you down to 1/64 or 1/128 power) but to actually diffuse the light you will need to make the light source larger rather than making it dimmer as you are doing now. To diffuse light some type of bouncing will work well. I would suggest a sheet of white foam core as it is easy to position although a paper plate or piece of white paper out of your printer would work. Then white balance to your flash off of the reflector (i.e., the reflected light is your light source so balance to it).

Beyond that, ensure you have your lens parallel to the film and ensure the lens is open moderately wide (f/8 to f/10). Muddy shadows and blown highlights could partially be diffraction at f/16 or smaller.

But the trick here is diffusion is only achieved by making your light source wider. A Sto-Fen Omni-Bounce achieves this by sending light in many directions ( Omni) to bounce back from many directions (wide). Out of doors an Omni-Bounce primarily just wastes flash power like a ND filter. The tissue paper does little to help you here either.

Chuck Bragg said:

Copying slides to slide-copy film was pretty involved. It helped to pre-flash the film, something pretty obscure to the home user. I'm hoping there is a similar "trade secret" to making digital copies.

...

John - pre-flashing was only an example of an arcane technique for reducing contrast from the Ancient Days of Film. I wouldn't expect it to work on electrons, but somewhere out there is The Secret.

Click to expand...

Oh, that preflash worked really well with electrons if it worked at all (chemistry). The modern sensors are solid state devices while the old celluloid one use sensors were wet chemistry devices. But they all used electrons to store incident electromagnetic radiation.

enjoy,

Sean

Cem, I used to have a device like the Soligor but this time decided to buy a used macro lens (more than one use for me) and fit a slide-holding unit to it. Unfortunately, the lens I chose is too large in front for the bellows unit, so my first attempts have not been shut off from ambient light. Some time today I'll fix that and try again.

Sean, I'll try the diffusion methods you suggest.

Bart, I tried the Photometrix free version, which helps a lot. The problem is that it doesn't solve the workflow issue. I'm trying to get the image in as good shape as possible in RAW, applying some global corrections - if that proves to be insufficient, then that's the breaks, and Photometrix is a good tip.

-- chuck