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01-11-2020, 11:30 AM   #1
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Sekonic L478D have I got it right?

I have read the reviews and some of the specs of this meter (I think I got the model # correct) it is the 478D I have been reading about.

It seems this meter has DTS (data transfer system) in which you can some how down load your camera’s algorithm for metering into the meter so they are both on the same page so to speak? Is this correct?

In the online brochure it states you should calibrate your meter to the camera buy taking shots of a grey card with the lens you most use and I assume making adjustments to the meter? Then I see a guy on youtube use the thing right out of the box not following any of the above steps.

Could someone explain to me if the above steps are necessary and why they are necessary? I have tried to figure it out on my own but I am not having any success.

Thanks
Mike

01-11-2020, 01:13 PM   #2
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One answer is not all manufacturers use the same reflectance (midtone) for metering--values range from 10% to 18%. (18% is Kodak gray card, but that is not universal, and the gray card is used at a intermediate angle between camera and surface, so it is likely closer to 12%, as I recall.) And I guess you may want to have light meter and camera using the same, but the camera uses reflected light, and the exposure meter (I am guessing) will be most useful in incident mode. And given the differences I would doubt such a calibration procedure is so useful. More important would be taking photos and comparing the meter and the camera taking value.
01-11-2020, 01:18 PM   #3
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QuoteOriginally posted by rml63 Quote
I have read the reviews and some of the specs of this meter (I think I got the model # correct) it is the 478D I have been reading about.

It seems this meter has DTS (data transfer system) in which you can some how down load your camera’s algorithm for metering into the meter so they are both on the same page so to speak? Is this correct?

In the online brochure it states you should calibrate your meter to the camera buy taking shots of a grey card with the lens you most use and I assume making adjustments to the meter? Then I see a guy on youtube use the thing right out of the box not following any of the above steps.

Could someone explain to me if the above steps are necessary and why they are necessary? I have tried to figure it out on my own but I am not having any success.

Thanks
Mike
I use the L758DR which is an earlier 1degree spot or incident meter. The DTS software allows you to calibrate the meter exactly (1/10th stop) to the way your camera system responds to light and save a camera profile (or several) to the meter. To achieve this there are a few ways including purchasing the very expensive (for what it is !) Sekonic exposure target or use either the Macbeth Colour Checker target or the X-Rite Colour Checker Passport (my preference).

Roughly the process of profiling the meter to the camera is:

Take a series of exposures as recommended by the software (a simple three shot or a mor accurate 5 shot) varying exposure as instructed.
Import the shots into the DTS software and run the process
Set clipping points and warnings as required.
Then attach meter to computer and download profiles direct to meter.

For more information about the practicalities seek out tutorials by Joe Brady e.g.:

I think that most camera systems meter calibration point is between 12 - 13%. But as matrix and centre weighted metering is weighted towards manufacturers preferences and algorithms applied to interpret these preferences then actual figures may vary according to mode. Spot reading is the only way to be sure measuring and exact ROI.


An example would be that reading a highlight area and increasing exposure by +3EV to reach the clipping point would mean that the system calibrated to 12.5%. If the system was to be calibrated to 18% (I think unlikely!) then you would have about +2.47EV before your metered area reached clipping

Attached example of output of DTS software profiling the meter for spot reading showing a DR of 12 EV with clipping reached at around +3.5EV above meter indicated ROI
Attached Images
 

Last edited by TonyW; 01-11-2020 at 01:45 PM.
01-11-2020, 01:20 PM - 1 Like   #4
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QuoteOriginally posted by rml63 Quote
I have read the reviews and some of the specs of this meter (I think I got the model # correct) it is the 478D I have been reading about.It seems this meter has DTS (data transfer system) in which you can some how down load your camera’s algorithm for metering into the meter so they are both on the same page so to speak? Is this correct?In the online brochure it states you should calibrate your meter to the camera buy taking shots of a grey card with the lens you most use and I assume making adjustments to the meter? Then I see a guy on youtube use the thing right out of the box not following any of the above steps.Could someone explain to me if the above steps are necessary and why they are necessary? I have tried to figure it out on my own but I am not having any success.ThanksMike
Hello Mike.

I have the Sekonik L-358, that is the previous generation, so I don't know if what I'm going to tell you will help you or not.
I have the option to calibrate my photometer, if needed. I've using my photometer during years so I have a bit of experience, but it doesn't mean that I am any expert.

The calibration of my photometer is way simpler compared to the DTS system. I just can set a kind of exposure compensation. At present I have my photometer set at -0.3EV, so this value have to fit all the cameras I have.
But why do you need to calibrate a photometer? As I understand, a photometer is factory calibrated. The problem is that your camera sure is not telling all the truth when you set the ISO. As far as I know, the K3-II's ISO is around 0.3EV below real ISO, but really not sure 100%. This is why my photometer is set to -0.3EV, to match my camera real ISO. I don't know in deep the DTS, but I think this is a kind of profile to make adjustements on your photometer's measures to match your camera.
As an example, let's suppose I have my K3-II and I make a measure with my photometer at ISO 100, let's suppose I get 1/100 & f4.0 on my photometer. But, as my camera ISO is fake, when I set ISO 100 on my camera, the real sensor ISO is 80, so I should set my camera at 1/100 & f3.5 instead of 1/100 and f4.0.
But this is more complicated than that, maybe my camera's ISO 200 is accurate, ISO 400 is not, etc. So this is what I understand DTS profiles correct. Every camera have some inaccuracies regarding ISO, that are fixed with a profile, but I think they should be small.
In my case, I don't have profiles, just a global adjustment. By experience I have found that setting -0.3EV adjustment on my photometer gives me accurate exposures, notice that this is not a really huge deviation.

How do I do such adjustments/calibration ? I have a SpyderCube, that I found very useful to get correct WB but also to get medium tones, shadow, highlights, etc. So I prepare a lighting, take a measure and take a pic of my spidercube, and see if the grey part of the spider cube is about in the half of the histogram, just that.

Notice that also your lens is not telling you the truth, photo lenses lose a bit of light. A 2.8 lens can be actually f3.2 or so. I think only cinema lenses gives you the real f. In my case, I have a K5 + DA 50-135 and K3-II + sigma 17-50 combinations. If I get a picture at the same ISO, speed and F settings, pictures are slightly differents in exposure/tone. Also, you shoud consider your RAW converter, that can be using a curse when it sets the tone of your picture.

Can I use the photometer without any calibration? I think you can, sure you get a small deviation, but this deviation will be always constant, that is, you'll notice always a bit of underexposure or overexposure. If it's the case, then you can think about calibrating it... or just forget about it and correct it in post. I made a calibration maybe once a year or once every two years, just to be sure everything is OK.


Maybe some other users can share it's experience with photometer's use and calibration.


Regards.

---------- Post added 11-01-20 at 09:26 PM ----------

QuoteOriginally posted by TonyW Quote
For more information about the practicalities seek out tutorials by Joe Brady e.g.:
I learned a lot with this guy about measuring with photometers, mixing ambient and flash light, etc.
He also looks like a nice person.

01-11-2020, 03:51 PM - 2 Likes   #5
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Reviews and Youtube vids are no substitute for hands-on experience.
Any of the Sekonic multispot/duplex meters are neither toys nor fashion accessories for today's digital cameras, expensive as they are, this profiling bit is only used in applications requiring precise colour rendition e.g. medical and scientific, and requires much more knowledge than simply plugging in the meter to a PC. All of the professional-line Sekonics (e.g. L758D) have a stable, consistent baseline (factory) calibration, but with user options such as baseline shift and additional exposure shifts for such things as filter factors, additive/subtractive metering, centre-weighted or mean-average weighted and the most critical of all, exposure steps (0.3, 0.5 and 1.0) and method of averaging. These things are far more important than profiling, as they govern how the meter responds to the scene and illumination.

At a bare minimum, your skillset should comprise of a working knowledge of the Zone System (for traditional imaging and understanding placement of values, both of which have application in digital imaging) and digital colourimetrics for production (the matching of colour profiles from camera to PC to printer, your own or across a network). My L758D is bereft of external calibration -- not even a grey card [I use the palm of my hand] or a Macbeth CC [I use a psychedelic, tie-dyed sarong!]), yet neither I nor my clients would want anything more from the photographs.

Sekonic has made a hue and cry about the supposed essential usefulness of using a multispot meter (e.g. the L758D/DR among) for profiling a digital camera, but in active practice, it is not that simple, and today's camera's do not need it, nor will photographers actually benefit without the investment mentioned in skills, above. Thus, without significant investment in baseline working skills with a multispot meter, it is likely to be discarded somewhere along the way, even though in the right hands a meter can expose far better than the camera can, particularly analogue (film, any type, be it negative or transparency).

Digital camera metering systems have such complex metrics that a separate, undeniably expensive meter, is superfluous and an added (and likely undesired) layer of complexity. What is the objective with the meter? How, and in what way would it improve the camera's efforts?

The profiling bit of Sekonic meters is extremely small and seldom used in the wider scheme of their professional working application (it may be done once and once only in specific commercial or scientific areas), It's worth noting also that Sekonic multispot meters have a baseline calibration of 12.6% (reflected) spot and 16.2% incident; this variation alone from the gospel standard of "18% grey" should be sufficient heads-up of the complexity that awaits in those first steps of acquaintance.
01-11-2020, 04:40 PM   #6
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Precise colour rendition is not part of the profiling process with Sekonic meters and DTS software - the software and for that matter the meter does not understand colour, only luminance values can be measured by the meter and those values interpreted by the DTS software to produce a meter profile

It is also important to understand that you cannot profile your camera with the Sekonic meters. What you are doing with the DTS software is programming the Sekonic meter by supplying a profile that has recorded how the camera system responds and records light hitting the sensor.

Last edited by TonyW; 01-11-2020 at 04:45 PM.
01-11-2020, 08:27 PM   #7
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Well all of the replies were very helpful and certainly cleared up some of the misconceptions I had about using a light meter. I shoot landscapes mostly and I bracket a lot of my shots or adjust something in the exposure triangle , I thought a light meter would speed this process up. Am I wrong in that assumption?

Tony I watched that video very helpful, Thanks.

Moren your explanation of how you use and calibrate your light meter is close to what I had in mind.

Mike


Last edited by rml63; 01-11-2020 at 08:29 PM. Reason: Addition
01-12-2020, 01:41 AM   #8
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QuoteOriginally posted by rml63 Quote
I shoot landscapes mostly and I bracket a lot of my shots or adjust something in the exposure triangle , I thought a light meter would speed this process up. Am I wrong in that assumption?
If you are shooting B&W film and and use carefully controlled temperatures and precise chemistry, with to the second development times and utilize masterful optical printing technique, will the meter speed things up? perhaps. In skilled hands a multi-spot meter is harder to fool than the most well designed metering system*. Digital imaging sensors introduce a lot of variables with differing colour filter arrays, response curves and the myriad of proprietary additions/subtractions each manufacturer puts the data through before it is written upon the memory card. Simply measuring scene luminance,capturing it, and mapping it to the intended output space is a trivial affair.

It all depends upon your intended output. If you intend to print your work in order to sell it, buying a high quality pigment inkjet printer, selecting a high quality paper(s) and an appropriate colour calibration suite is always a wise investment. If your printing process is mis-calibrated, a lightmeter won't help in making your work more attractive to clients.


* What is important is to understand and predict scenarios where the cameras metering system is most likely to get things wrong: and be able to use the meter as a reference luminance target to get the "correct" exposure when compromising variables are present.

Last edited by Digitalis; 01-12-2020 at 01:49 AM.
01-12-2020, 07:36 AM   #9
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QuoteOriginally posted by morenjavi Quote

How do I do such adjustments/calibration ? I have a SpyderCube, that I found very useful to get correct WB but also to get medium tones, shadow, highlights, etc. So I prepare a lighting, take a measure and take a pic of my spidercube, and see if the grey part of the spider cube is about in the half of the histogram, just that.
I'd never heard of the SpiderCube, typically using greycards. Did some reading and it looks like a definite time saver, quite accurate too. but gosh pricey for what it is. As luck would have it a seller on eBay has two brand new ones only $18.49 each. I bought one so there's still one left for another PF member
01-12-2020, 08:47 AM   #10
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QuoteOriginally posted by gatorguy Quote
I'd never heard of the SpiderCube, typically using greycards. Did some reading and it looks like a definite time saver, quite accurate too. but gosh pricey for what it is. As luck would have it a seller on eBay has two brand new ones only $18.49 each. I bought one so there's still one left for another PF member
I'm sure you will like the Cube. $18.5 is a great price. I bought mine 5 years ago and I paid 30€ + 10€ shipping. I still use it and I think it's still accurate. The feature I use the most is the WB measurement. As It has two faces, if you are using a tipical main + fill light setup, you can see if there is a difference in temperature between main and fill. You can't do it with a plain grey card.

I had a grey card set before the Cube (white+grey+black), very cheap. At first, the card were accurate, but a year after, it was totally off, a disaster.

Your Cube should be useful for at least 5 years .
01-12-2020, 08:53 AM   #11
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QuoteOriginally posted by morenjavi Quote
I'm sure you will like the Cube....
The feature I use the most is the WB measurement. As It has two faces, if you are using a tipical main + fill light setup, you can see if there is a difference in temperature between main and fill. You can't do it with a plain grey card.

Your Cube should be useful for at least 5 years .
Great idea, so thanks for the tip. I have a range of lights, but all from the same series so supposedly all with the same white points, but I emphasize supposedly. Determining whether that's accurate will be yet another use for it.

Thanks so much for mentioning the SpiderCube.
01-12-2020, 07:14 PM   #12
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QuoteOriginally posted by rml63 Quote
I shoot landscapes mostly and I bracket a lot of my shots or adjust something in the exposure triangle , I thought a light meter would speed this process up. Am I wrong in that assumption?
The quickest method is when there is a blue sky meter it. The longer one, that ends up allowing you to judge w/o a meter, or how much to bias the reading, is to memorize the cheat sheet that used to come w/ film, which is based on the sunny f/16 rule and the adjustments for cloudy bright, cloudy dull, etc. And take photos using it and see.
01-12-2020, 10:59 PM - 1 Like   #13
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QuoteOriginally posted by rml63 Quote
Could someone explain to me if the above steps are necessary and why they are necessary?
The calibration steps are not necessary.

They would be useful if you wanted to know by using the light meter only whether your camera's dynamic range could manage certain light levels.

Arguably, a calibration would also improve the absolute accuracy of a reading with respect to a camera's exposure characteristics, but since "correct exposure" is a technical term and will rarely coincide with artistic intentions, such absolute accuracy is much more relevant to scientifically correct exposures than it is to real (as in "regular") photography.

I use my L-478D with a K-1 without any calibration and it is working just fine (as expected).
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