Wrong Aperture in EXIF - and a picture with my new M8.2!

[Vern Dewit]

Advertisement (gone after registration)

I've used many cameras over the past few years (I'm a gearhead and fully admit it ) but it's been a while since a camera was this much fun! I bought a lightly used chrome M8.2 and two ex++ lenses, the 28mm 'cron and a 75mm summarit. I'm hoping to add an 18mm zeiss some time this year when the bank account recovers from shock.

 

I've done some landscape shooting over the past two days and noticed that my reported lens aperture seems to jump all over the place in the EXIF (using LR 3B2) - is this something that has happened to anyone else? It's on my 75 summarit but obviously I'd know if I was changing the aperture and I wasn't! Camera was on 2s timer, discrete release and manual exposures.

[andybarton]

The camera can only guess at what the aperture is as there is no way for the lens to communicate the aperture to the body.

[Vern Dewit]

Sorry for posting pictures here... I guess that makes sense about the aperture. I wonder why it bothers to even guess!

[stunsworth]

I wonder why it bothers to even guess!

 

The camera needs to know the approximate aperture to correct the image when using UV/IR filters on wider lenses.

[ho_co]

And it gives us Leica nerds something else to complain about. Er, I mean, discuss.

[cbretteville]

You can't complain to Leica about the guestimated aperure. They decided not to publish it (because it is inacurate at times). I'm to blaim for that as I'm the one that published how to find it.

Carl

[Redridge]

Advertisement (gone after registration)

The camera can only guess at what the aperture is as there is no way for the lens to communicate the aperture to the body.

 

How does the camera guess? its a totally mechanical thing (aperture ring) with no feedback going to the electronics.... If its a guess Im assuming the exif is mostly right about the aperture, but how is that possible. Sounds like alot of complicated code to write on the FW. TIA

[ho_co]

Camera looks at lens ID to find out maximum aperture.

 

Camera looks at meter reading to figure out how much light is getting through the lens.

 

Camera uses that little blue dot on the front just above and right of the Leica Red Dot to read the ambient light.

 

From that, it comes up with a 'best guess.'

 

At first, Leica didn't want software to reveal the estimated aperture because they were afraid people would complain about its inaccuracy.

 

Then they realized people were complaining anyway because the information was stored with the file but inaccessible. So they made it available.

 

And they were right, people complain because it isn't accurate.

 

 

A case of "Damned if you do, damned if you don't," I guess.

[Redridge]

Camera looks at lens ID to find out maximum aperture.

 

Camera looks at meter reading to figure out how much light is getting through the lens.

 

Camera uses that little blue dot on the front just above and right of the Leica Red Dot to read the ambient light.

 

From that, it comes up with a 'best guess.'

 

At first, Leica didn't want software to reveal the estimated aperture because they were afraid people would complain about its inaccuracy.

 

Then they realized people were complaining anyway because the information was stored with the file but inaccessible. So they made it available.

 

And they were right, people complain because it isn't accurate.

 

 

A case of "Damned if you do, damned if you don't," I guess.

 

Thanks.... so If its not coded the guess just gets worse. This guessing thing is bad... lots of data (look up table, per lense) per amount of lights it sees vs ambient light. The FW must be a nightmare to write.

[wilfredo]

I have an M8 loaner from Leica and I've noticed this too. I can't say I ever noticed this with my own M8 which is with Leica at this time but it is not anything terribly important to me.

[cbretteville]

Then they realized people were complaining anyway because the information was stored with the file but inaccessible. So they made it available.

 

Actually they didn't, Sandy McGuffog worked with one of the developers in Adobe's LR team to get the information into LR, it is based on my research.

Carl

[billmary]

I process my DNG images with Safari, on an Apple iMac. The max aperture for the lens used is given but the actual aperture is shown as a " - ") on my "extended photo info". I don't see any estimated aperture.

 

Bill

[stunsworth]

I process my DNG images with Safari, on an Apple iMac. The max aperture for the lens used is given but the actual aperture is shown as a " - ") on my "extended photo info". I don't see any estimated aperture.

 

 

That's because software you are using - are you sure it's Safari - isn't interpreting the field in the Exif data. It was only recently that Lightroom was changed to display its interpretation of this information despite the fact that it had been available since the M8 was launched.

[andybarton]

Welcome to the forum, Bill.

 

You can't process DNGs with Safari, as it's "just" a web browser, but you may be able to view them. I will check that when I get home. I know that Safari will show tiffs as well as jpgs, but I didn't know it could display DNGs as well.

[gwelland]

You can drag DNG's into Safari but not open them directly via File->open. My guess is that it's using the built-in jpg preview.

 

Safari will render a file://...../image.dng path ok.

[andybarton]

Is that with Safari on a Mac or on a PC, Graham?

 

Safari on the Mac will probably use the core OS-wide code to render images, rather than something built-in tp the app itself.

[gwelland]

Is that with Safari on a Mac or on a PC, Graham?

 

What's a PC?

 

Actually it looks like it's rendering the jpg built in of some type. I just tried it with a NEF, RWL and NRW raw files and only the DNG file seems to render in a drag/drop. The built-in raw rendering works with all of these within Finder.

[billmary]

Appreciate the interest and the help. Here's what I do: I open iPhoto on my iMac. I shoot in DNG. I put the SD card into a card reader. The photos show up within the iPhoto "box" (The computer shows "Safari" on the upper left, just next to the "apple" icon.) A message appears to says "No images appear that meet download criteria". I click OK on that message and then the computer allows me to download the images. Each image says it is DNG. I then edit the images using the iPhoto editor, and save them in iPhoto. Best I can tell they stay in DNG form unless I change them for e-mail, etc.

Would appreciate comments and help,

Thanks,

Bill

[ho_co]

Actually they didn't, Sandy McGuffog worked with one of the developers in Adobe's LR team to get the information into LR, it is based on my research.

Carl

 

Carl--Thanks for the correction.

 

It wasn't in any way my intention to downplay your and Sandy's efforts in deciphering the fields.

 

I do recognize that the two of you are largely responsible for what we know about the M8's and M9's files.

[Advertisement]

Hallo,

Look here: Leica M

[cbretteville]

Howard,

No offense taken

Carl