A Sekonic Adventure (Giant Stride for me . .)

[xpatUSA]

In a recent post, I mentioned that I've ignored external light metering up until now. But I've been playing around with the subject of "native" ISO on my cameras and impulsively purchased a Sekonic L-398 to assist in that endeavor. Anyway, it seemed to read high, so I looked into that as a side issue. Took a shot or two which suggested that it was indeed reading high. So, went a bit further to figure out how much it was over. Of the several ways to do that, I went outside, incident light-metered a tree then exposure-bracketed upward to a decent result. Also took a reflected-light shot with the camera metering just to compare.

Here's the results:



At bottom left we see the camera-recommended shot. Just tiny bit blown (arrowed). At right, the Sekonic-recommended shot, obviously under-exposed. At top left, I had worked down through the bracketed shots until I found the one that was just under being blown and, at top right, I took the next one up and backed off the highlight slider to recover that little blown highlighted area.

The top left image was one full stop over the Sekonic's recommendation; tempting to just apply that to future metered values. On the other hand, my camera does benefit from higher exposure rather than one with headroom and the top right looks better in the shadows . . .

So - I think I'll set the Sekonic to 50 ASA or less (leaving my camera at 100) and shoot some more and different subjects. like our white travel trailer (caravan) for example.

[Manfred M]

Ted - Your Sekonic L-398 is an incident light meter and your camera's light meter is a reflective light meter.

I assume you are metering the Sekonic by placing it on the subject and pointing it back to the camera position?

[xpatUSA]

Ted - Your Sekonic L-398 is an incident light meter and your camera's light meter is a reflective light meter.

I knew that, Manfred.

I assume you are metering the Sekonic by placing it on the subject and pointing it back to the camera position?

Yes.

[Manfred M]

There go two of the obvious reasons for the different readings.

I assume that you have "zeroed" the needle by doing a dark reading?

[xpatUSA]

There go two of the obvious reasons for the different readings.

I assume that you have "zeroed" the needle by doing a dark reading?

The zero was good and did not need adjustment.

The difference between the Sekonic and my lux-meter is really not a problem as we speak, because I'm still waiting for my TES-1334 lux-meter to show up. My intention is to use the ASA dial to offset any gain error after more testing.

The camera metering did very well I thought. I spot-metered the tree and it must have been pretty close to the so-called mid-gray. Almost like a living breathing gray card . .

[mikesan]

Just curious why the exif data in the lower right image (Sekonic metered shot) shows an Exposure bias of -1.3EV. Was this set in camera or in raw converter? And how (if at all) does this contribute to that image appearing underexposed?

[xpatUSA]

Just curious why the exif data in the lower right image (Sekonic metered shot) shows an Exposure bias of -1.3EV. Was this set in camera or in raw converter? And how (if at all) does this contribute to that image appearing underexposed?

It had me puzzled too, Mike! There was some bias in the other shots too. So I went and dug the X3F raws out of the trash and all was revealed.

Welcome to the world of Sigma . . .

For the test, I shot in manual. That bias is the amount by which the camera metering disagreed with my manual setting. Kind of makes kind of sense, sorta like.

So the Sekonic had recommended settings that gave a low exposure - because it read high for the incident light measurement. All I did was manually select the settings f/5.6 and 1/60 sec per the Sekonic recommendation, not sure I even looked at the camera metering for the Sekonic test shots.

There is also a little bias in the camera-metered shot which was done in aperture priority - that's because the metering goes in 1/3 EV steps but the actual numbers used in-camera are sometimes a little different . . to do with the jump from one step to another even though the metering is actually continuous, is my best guess.

[mikesan]

For the test, I shot in manual. That bias is the amount by which the camera metering disagreed with my manual setting. Kind of makes kind of sense, sorta like.

So the Sekonic had recommended settings that gave a low exposure - because it read high for the incident light measurement. All I did was manually select the settings f/5.6 and 1/60 sec per the Sekonic recommendation, not sure I even looked at the camera metering for the Sekonic test shots.

Understood. The Sigma world is foreign to me.
The remaining question is why would the Sekonic exposure differ that much from the camera's reflective metering and result in such an obvious underexposure. While holding the meter at the tree (and pointing at the camera) is it possible that your body cast a slight shadow on the meter?

[george013]

I don't know if this is of some help. With a Nikon in the manual mode the 0-point of the lightmeter bar is a corrected point: incl. a ev-correction. So if you shoot manual, have a ev-correction of -1.3 and the lightmeter bar is in the 0-point, then there's a correction of -1.3.

If you use another mode, than the ev-correction is visible in the bar.

George

[xpatUSA]

Understood. The Sigma world is foreign to me.
The remaining question is why would the Sekonic exposure differ that much from the camera's reflective metering and result in such an obvious underexposure.

Yes, In another post here I explained that, compared to a digital lux-meter that I already had, the Sekonic was reading at least 1 EV high and that was confirmed by a few shots I took before posting the OP in this thread. Right now, it's doing much better with the ASA at 40 and the camera still on 100 ISO.

While holding the meter at the tree (and pointing at the camera) is it possible that your body cast a slight shadow on the meter?

These past few weeks I have indeed read many articles that warn against that very occurrence but thanks for the tip. As I explained earlier I'm not real bothered and am still waiting for a new lux-meter to show up at the Post Office. I use a lux-meter for things other than photographic exposure and was in need of a better one anyhow.

[george013]

If you went out and shot first with the setting from the external meter and then with the settings of the camera, then the bottom right is the shot with the camera settings according to the time shown. You did shoot manual and had a ev correction of -1.3. If you adjust following the light meter in manual, then you've a -1.3 underexposed image. That's what I see. I don't think it's different as from a Nikon.

George

[xpatUSA]

As I explained earlier I'm not real bothered and am still waiting for a new lux-meter to show up at the Post Office. I use a lux-meter for things other than photographic exposure and was in need of a better one anyhow.

Oh, joy, The lux-meter is at the Post Office according to the tracking.



I'll collect it later and compare my other meters with it and then decide the fate of the Sekonic. If it still has a linear response and little to no zero error, I'll calibrate it and keep it.

Although the latest Sekonic L-398A battery-less model does have an amorphous silicon sensor it's quite expensive, even used.