Jump to content

Unexpected results when testing the X Vario light meter


Recommended Posts

Advertisement (gone after registration)

Having noticed that my (wonderful) new Vario tends to overexpose more often than I'm used to, I decided to test the camera's light meter using the Sunny/16 rule. Using a high quality 18 percent grey card in direct sunlight, I made a series of measurements that raise more questions than I myself can answer, so I'm hoping some of you may be able to help.

 

The idea is that the camera, using aperture priority, should pick a shutter speed equal to the ISO value. Instead, with spot metering, the shutter speeds are double the expected value:

  • ISO 100 : 1/200
  • ISO 200 : 1/400
  • ISO 400 : 1/800
  • etcetera

With centre-weighted metering the results are different (though they should be the same, having taken care to fill the frame with the grey card):

  • ISO 100 : 1/160
  • ISO 200 : 1/320
  • ISO 400 : 1/640
  • etcetera

Now to make things even more complicated, I found that in manual mode, the on screen exposure meter reads zero at a third set of values:

  • ISO 100 : 1/125
  • ISO 200 : 1/250
  • ISO 400 : 1/500
  • etcetera

With this final test, there was no difference between spot and centre-weighted metering, which presents us with yet another riddle...

 

Can anyone explain this? Or try to replicate these results with their Vario, just to rule out that I have a faulty item? Also, I'd welcome advice about adjusting exposure strategies in light (pun intended) of these irregularities. I use spot metering most of the time, and my thinking about exposure is largely in terms of Adams' Zones. 

Edited by Mandemaker
Link to post
Share on other sites

First of all, Sunny16 is a rule of thumb which is not legally binding for digital cameras. It's certainly fine for photographing on film and it's perfectly good for an informed guess.

 

You say that your camera overexposes with respect to what you expect, given the Sunny16 rule. However, the exposure times you name indicate an underexposure by one f-stop. 1/200sec admits half as much light as 1/100sec.

 

The different values the camera arrives at between spot metering and center-weighted metering do not - in practice - matter much, being much less than a third of a stop. I have no idea as to the cause of the difference. When I do similar tests in my office, I see no difference in the metering results. However, I take great care not to change my position with respect to the light source and the grey card (which is the door of a cupboard in my case). Just moving by a few centimeters will result in a quite different reading.

 

I can't explain the difference you obtain between manual and automatic exposure, either, as I can not reliably reproduce it. Again, the position of my body with respect to the light source and the gray card has the largest influence.

 

On the whole, I'd think your X Vario performs perfectly well. When trying to apply the zone system, I think you'd to well to perform a few tests in order to determine how much light the sensor needs for rendering zone X.  That's IMO the most important thing to determine so as not to blow your highlights. That's commonly called ETTR, "Expose To The Right".

Link to post
Share on other sites

Thanks. Maybe I was unclear: I first noted too many shots were overexposed, when what I saw on the exposure meter while shooting made me expect differently, and then I decided to test the meter using the Sunny/16 rule. I think what happens is that the exposure meter displays values more or less consistently ⅔ stop lower than they should be, while the camera when in aperture priority mode does somehow choose the right shutter speed. In other words, the visible exposure meter 'undermeasures'. I find that if I try to read the meter bearing in mind that its reading is ⅔ stop too low, I get more predictable results.

 

By the way, ETTR is not a viable approach in full manual mode with this camera, because the histogram is then quite useless. Instead, measuring the brightest important part of the scene (now adding ⅔ stop) and placing it in the appropriate zone does work.

 

Incidentally, unless the cupboard catches direct sunlight and is painted exactly 18 percent grey, and very matte, the method you used does not seem reliable.

Link to post
Share on other sites

Incidentally, unless the cupboard catches direct sunlight and is painted exactly 18 percent grey, and very matte, the method you used does not seem reliable.

The cupboard test was not designed to test the accuracy of the light meter within the camera. It was designed to test the light meter for consistency and it does exactly this.

Link to post
Share on other sites
  • 4 weeks later...

Having noticed that my (wonderful) new Vario tends to overexpose more often than I'm used to, I decided to test the camera's light meter using the Sunny/16 rule. Using a high quality 18 percent grey card in direct sunlight, I made a series of measurements that raise more questions than I myself can answer, so I'm hoping some of you may be able to help.

 

The idea is that the camera, using aperture priority, should pick a shutter speed equal to the ISO value. Instead, with spot metering, the shutter speeds are double the expected value:

  • ISO 100 : 1/200
  • ISO 200 : 1/400
  • ISO 400 : 1/800
  • etcetera

With centre-weighted metering the results are different (though they should be the same, having taken care to fill the frame with the grey card):

  • ISO 100 : 1/160
  • ISO 200 : 1/320
  • ISO 400 : 1/640
  • etcetera

Now to make things even more complicated, I found that in manual mode, the on screen exposure meter reads zero at a third set of values:

  • ISO 100 : 1/125
  • ISO 200 : 1/250
  • ISO 400 : 1/500
  • etcetera

With this final test, there was no difference between spot and centre-weighted metering, which presents us with yet another riddle...

 

Can anyone explain this? Or try to replicate these results with their Vario, just to rule out that I have a faulty item? Also, I'd welcome advice about adjusting exposure strategies in light (pun intended) of these irregularities. I use spot metering most of the time, and my thinking about exposure is largely in terms of Adams' Zones. 

I have been shocked in my now three months with the camera how good the light meter is. After playing with my tenedency to "underexpose" a little (I have Sigma cameras and always trying to avoid blowing the highlights), I have come to trust the X Vario implicitly. The only change I like is a little extra shapening on the color RAW images when needed. 

So perhaps you have a problem with the camera; again I am not an expert, but there is seems very little you have to do with an X Vario image if correctly exposed. 

 

BTW I shoot manual ALL the time. 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Hansa
      Many owners have experienced a broken battery clip with their X1, X2, X-E, X Vario or X camera (the small grey plastic retaining clip inside the battery compartment). Leica service in The Netherlands was kind enough to send me a new clip for free. While putting it in, I looked for a way to prevent this from happening again. I think the problem is caused by the rather heavy battery which, after a few years, is too much for the quite fragile clip to handle when the camera is put down on a solid object such as a table or other impacts. There is a space of a few mm. between the clip and the inside of battery door. The battery door does not support or hold the battery, but only covers the compartiment. The clip takes full impact of the battery mass on each impact. Because of this design, after a few years the clip usually breaks. An easy way to prevent this is to attach a small piece of sticky foam rubber on the inside of the battery door. The foam rubber pushes the battery up and relieves the clip. Any impact is cushioned by the rubber damper. Ergo; no more broken battery retainer clips. 

      Hello guest! Please register or sign in to view the hidden content. Hallo Gast! Du willst die Bilder sehen? Einfach registrieren oder anmelden!
    • By HP203
      Hallo zusammen,
      Ich bin zurzeit am überlegen, ob ich mir für meine Sony Alpha 7 und eine noch anzuschaffende R 8  R Festbrennweiten oder ein Vario Zoom (wir lassen dieses mal die Diskussion ob es nun das 28 - 70 mm oder das 35 - 70 mm werden soll weg) kaufen sollt. Zurzeit verwende ich an der a7 nur das Standart 28 - 70 mm Zoom welches als Kit Objektiv dabei ist. Da dieses jedoch einen weniger guten Manuellen Fokusring hat und ich es heute, genau ein Jahr hat es gehalten, aufgrund einer sich von selbst im Gehäuse gelösten Linse wieder zum Händler zurückbringen musste. Das ich mir eine R 8 kaufen möchte habe ich nun eigentlich schon entschieden. Ich hatte nun auch schon mehrmals die R8 meines Vaters mit einem 38 -70 der letzten Generation und einem 80 - 200 in der Hand und wollte danach eigentlich meine A7 gar nicht mehr verwenden. Da ich also nun mir eine R 8 anschaffen möchte und ich für diese eine Optik brauche überlege ich nun ob ich mir Festbrennweiten oder ein Vario Objektiv zulegen sollte, welche ich dann eventuell auch an der alpha 7 nutzen möchte.
      Kann mir da jemand weiterhelfen?
      HP203
    • By Steve Ris
      Hi everyone.  
      Just bought an X Vario and I normally use a lens hood.  I can't find any of the original or JJC replacement 18774 available anywhere.
      Does anyone have any experience of other hoods at all?  I was wondering if the LX100/D-Lux hood would work without vignetting for example.
      Any suggestions?
    • By farhiz
      Whenever I get the urge to replace my X Vario I re-read this, https://photo.imx.nl/camera/styled-10/. And the urge disappears.
    • By firoze
      Marine Drive, Mumbai. Also know as the Queen’s necklace.
      X Vario

      Hello guest! Please register or sign in to view the hidden content. Hallo Gast! Du willst die Bilder sehen? Einfach registrieren oder anmelden!
×
×
  • Create New...