iPad and shooting tethered with phase or other digital device.

[bob carnie]

I use the digital colour meter that you find in any Mac under Utilities . This meter is set at CIE Lab and I find it very handy for reading density's and colour, for a variety of purposes and reasons. Scanning software usually is in RGB and not LAB so I use this meter when scanning as well to keep track of density numbers using the LAB meter.

My associates use phase and digital cameras quite often and I am always watching them hooking up the laptop and shooting tethered.

So here is my question, Can one put the Digital Colour Meter on lets say a mini mac or I Tablet and be able to read LAB numbers..

Specific.. LAB numbers, not RGB, not CMYK , and yes I do have a very good reason to wonder about this.
I am pretty agile on my Macs, but as I said my associates do all the commercial photography here, even though I am part owner of most of the gear I have never used a digital camera other than simple P&S or camera on my phone.

I am thinking of purchasing a tablet, and learning how to use the digital camera and these thoughts about placing exact density numbers have potential for me. I think this could have major benefits for various workflows that I use to put tones on paper or film.

I make enlarged silver film from digital files and the thought of placing exact tonality's to film density turns my crank..

thoughts?? experience??

[Mark Woods]

I have a densitometer and use it both on color neg and B&W. Is that what you're talking about?

[bob carnie]

No its not Mark... I am talking about an easy way to measure a scene tethered to a digital camera by reading LAB numbers, lets say a betterlight 4x5 so its large format related.

Currently I watch our studio photographer work tethered to a laptop loaded with PS and he will take info pallette readings of the highlights and shadows and by controlling his exposure makes sure key end points are within highlight with detail and shadow with detail. By shooting a Macbeth Card he also neutralizes the white , mid grey and black within the scenes he is working on.

My interest is in outdoor landscape, urban and rural and would like to be using a digital device to do this but the thought of being loaded down with Camera, Tripod and laptop is a bit daunting.
With the new tablets and a digital colour meter app I think one could measure values and be very predictable. I think this could be very practical and save one the hassel of carrying around a laptop on top of the regular equipment.
On the opposite end of the scale when working with supplied artwork one could take LAB or RGB measurments of the original and make sure that your workflow allows these known colours are reproduced.. Or at least as close as the inks, and papers that you are using will allow.
I have a Eyeone Spectrometer that I think will allow me to do this , but I am trying to figure out a way of tethering to a camera and getting my readings using a simple app.




I have a densitometer and use it both on color neg and B&W. Is that what you're talking about?

[bob carnie]

Thanks Greg

I considered a mac mini, I think what I am looking for is the most compact system that when tethered to a digital camera can allow me to look at the curves and their information as I shoot.

We are already using a mac laptop with PS to do this in the studio but it really is not portable.


As far as I know there aren't any apps for the ipad that would do this. The only input available for the ipad is the dock port with either a VGA adapter or HDMI adapter. The Mac Mini would work, but it would need a monitor, so a laptop would work better in that regard.

[David A. Goldfarb]

It's not large format, but with a Canon DSLR, a WFT grip, and a portable wireless hotspot (MiFi, Verizon Jetpack, etc.), you can get images into anything with a web browser, including an iPhone or an iPad, without requiring a laptop. I've done that much with my 5DII and an iPhone, and before that with a 40D and an iPod Touch. You can view the image live, adjust the exposure and other parameters and fire the shutter, and you can download images, so that gets you halfway there.

There are apps that will let control any imaging device that can use a WiFi enabled memory card from a web browser or a phone (I think ShutterSnitch is one, and there's one for Canon) without a dedicated WFT module (so potentially with a LF back that can take a WiFi enabled memory card), but when I looked into these, they all required a laptop as the server, even if you weren't doing anything else on the laptop, and at that point you might as well just tether to the laptop.

Next question is whether there's an app that will let you look at your downloaded image (I highly doubt there's an app that would let you do this with a live image) and get LAB values from points on the image. I haven't seen this feature available on the various image editing apps I have on my iPhone. I don't know if there's something for the iPad that can do this. There are apps that will give you curves and histograms, though.

Then if it did work, it's kind of a slow process via wireless. You've got to make sure everything is connected on the network (easy once you've set it up, but sometimes the setup is tricky), and then you're transfering all this data to the iPad/iPhone, and then you've got to download the image (or maybe a smaller version, so you shoot RAW + small JPEG) and open it in some editing program, find your LAB values, adjust, take another shot, download, open that one, lather, rinse, repeat. Seems easier just to take a couple of spot meter readings and shoot.

[bob carnie]

Thanks David

I wish there was a spot meter that could give me LAB values, I posted this question a year back with no luck.

You are right a slow process for what I see as a gain in control but as you say a lot of work.

[David A. Goldfarb]

Okay, I did a quick search, and there are apps like "Color Expert" that will give you standardized color values in RGB, CMYK, Pantone, and such, from an image (you have a magnifying glass cursor to pinpoint the pixel you want to read), and there is at least one converter called "Color 2 Color" that will convert RGB or CMYK to LAB values.

So the workflow with that combination of apps would be--make the exposure and transfer a small jpeg to the iPhone/Pad, open in Color Expert to get a value for whatever color interests you in the image, convert that value to LAB in Color 2 Color.

In the world of apps, many developers are small and open to suggestions, so if I were interested in such a thing, I'd probably write to the developer of "Color Expert" and ask if in a future update, they could offer CIE LAB values.

[bob carnie]

thanks David I will do just that.
I think that it would be a great feature to us using a digital camera and reading exposures, for print geeks like myself.
Do you think the fact of sending a small jpeg make any difference than sending the raw data that our studio guys get when tethered?

Okay, I did a quick search, and there are apps like "Color Expert" that will give you standardized color values in RGB, CMYK, Pantone, and such, from an image (you have a magnifying glass cursor to pinpoint the pixel you want to read), and there is at least one converter called "Color 2 Color" that will convert RGB or CMYK to LAB values.

So the workflow with that combination of apps would be--make the exposure and transfer a small jpeg to the iPhone/Pad, open in Color Expert to get a value for whatever color interests you in the image, convert that value to LAB in Color 2 Color.

In the world of apps, many developers are small and open to suggestions, so if I were interested in such a thing, I'd probably write to the developer of "Color Expert" and ask if in a future update, they could offer CIE LAB values.

[David A. Goldfarb]

Well, presuming the small file is in the same color space as the large file (Canon's options are Adobe RGB and sRGB) the questions would be whether the app could handle the RAW file, and whether you could deal with the transfer time of a larger file in the field. In the studio at least the light is stable, and you're not waiting for clouds, wind, people walking through the shot, etc., plus tethered by wire is faster than wireless.