Photons Missing In Action

Started Nov 24, 2009 | Discussions
Grevture Veteran Member • Posts: 4,188
I am constantly amazed ...

... by some posters lack of imagination in realizing that different people might use cameras in quite different ways

HiRez wrote:

Marianne Oelund wrote:

krisw wrote:

go take pictures

The 600,000 that I took last year are not enough for you?

You can't be serious about that, can you? 600,000 pictures in one year? That's 3-4 shots per minute, 8 hours per day, every day of the year.

I recently saw a number of similar replies in a thread over at the Canon forum over numbers of images taken with different cameras (and the life expectancy of shutters). Some people seem confused by the shooting habits of even a modest sports shooter like myself clicking away at a rather pedestrian 100-150k images/year.

Just this last Tuesday, I was talking at length with a event shooter who has for the past years regularily been shooting nearly a million images per year. And no, he does not do much of his post processing himself. And yes, many of his images do not get any post processing at all. And yes, he has a shelf in his office with a number of worn out Eos 1D Mk2 and Mk3 cameras. And a couple of recently added D3 bodies ... I know this is a very extreme and rare example, but photographers really come in all sizes and shapes, and they indeed do use their equipment in quite different ways.

Mariannes shooting habits are fairly well documented in these forums, since she has been friendly enough to take time to share her experiences and findings in a wide range of photographic subjects over the years - AF performance, battery capacity, camera durability, astro photography, stackling of TC's and also more scientific minded explorations into lenses and sensor like this current thread. Just to mention a few subjects.

I for one really apprecieate that Marianne takes time to share from her vast experience and from the results from her scientific and engineering curiosity.

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I don't suffer from insanity, I enjoy every moment of it!

By the way, film is not dead.
It just smell funny

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HiRez Regular Member • Posts: 458
Re: I am constantly amazed ...

Good explanation, Grevture, but wow, that's crazy! That has to be terabytes worth of storage space...plus redundancy for backup. Sheesh. And what happens when you try to load that many images into a Lightroom or Aperture library? Doesn't it choke?

Grevture Veteran Member • Posts: 4,188
Going further off-topic

HiRez wrote:

Good explanation, Grevture, but wow, that's crazy!

I would say a million images a year is unusually much, half that number, or 600k as in Mariannes case is probably not even that unusual among event shooters. My numbers (100k+) are reflective of the fact I am a half time photographer, half time writing journalist ...

That has to be terabytes worth of storage space...plus redundancy for backup.

Yes, and?

A 1TB disk is less then $250 these days. For a working photographer with tens of thousands invested in photo gear, then add salary for yourself, transportation, insurance and a million others costs ... Storage is far from a major obstacle. The bigger impact is the time involved in dealing with all images in a secure and organized way.

Sheesh. And what happens when you try to load that many images into a Lightroom or Aperture library? Doesn't it choke?

I managed to choke up Lightroom 2.x pretty bad from time to time, but between Lightroom 3.x and going from 8 to 16 GB of RAM in my main computer, nope.

Even my poor old beat up four year old laptop deal pretty gracefully with the large amounts of images passing through it. Though when working with images on the laptop, I usually try to import in smaller batches as I go along and also avoid building 1:1 previews. And equipping that laptop with a SSD drive gave a significant boost.

When shooting large amounts of images, you workflow become important. Here I would love to hear from other high volume shooters how they organoze their work - I am pretty happy with my current workflow, but reading about how other deal with 200-400-600k images a year could be helpful and interesting.

But that should be dealt with in a separate thread since it has nothing to do with the original topic of this thread - which is vere interesting by itself.

I think it is well past time to call it quits on the off-topic branch ...

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I don't suffer from insanity, I enjoy every moment of it!

By the way, film is not dead.
It just smell funny

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tmdowd Contributing Member • Posts: 661
Re: Photons Missing In Action

I don't know Marianne from a hole in the wall, but I surmise from her post that she is passonate about photography and very generous with her feedback. Her post explores a topic that I would never consider and I thank her for bringing it to light.

Thank you Marianne for your quality post. I look forward to more from you.
(However, I can't say that I totally grasped this one.)
--
Tom D
http://thomasdowd.zenfolio.com/

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Mr Physics
Mr Physics Contributing Member • Posts: 716
Interesting study

Thanks for your rigorous testing Marianne.

I'm assuming from the dates of your original posts, that DxO didn't include the T-stop value with their reviews of lens at some point. And why don't the lens manufactures include this data? It seems to be an important measure of quality. If I purchase a f/2.0 lens to use in a low lighting situation, I'm interested in knowing how much of the available light gets to the sensor.

Do you somehow extract your data from the raw files? How do you know what the magnitude of the color signals are "supposed" to be vs their actual values? I have a suspicion that the raw data is actually "cooked" somewhat in firmware (see a related thread below and Gonzorro's experiences specifically)
http://forums.dpreview.com/forums/read.asp?forum=1034&message=37878784

I'm interested in exploring how I could examine the raw data output of a given image. Is there some sort of software assists in this (e.g. input a .NEF file and outputs photo detector magnitudes into a file usable by a spreadsheet?
I admire your intellectual curiosity.
Best Regards,
Tony P

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_sem_ Veteran Member • Posts: 5,032
Re: That was not called for

lovEU wrote:

I don't know why LGO pulled out this old thread...

Anyway, good to dig it out once in a while. Found that aperture calibration is much less precise than what I used to think, guess I'm not the only one.

noirdesir wrote:

Just to make sure we are talking about the same thing, I meant that if a f/2 lens actually was an f/2.1 lens and you tried to measure the accuracy of f/2.8 stop you would measure a delta of 0.8 stops between them or in other words conclude that the f/2.8 aperture is 1/5 stop too bright (always assuming naturally that the ratio between f and t-stop is the same for both apertures which is what you assumed already). Now, if the camera new that a lens actually had a f/2.1 aperture wide open it would adjust a nominal f/2 and 1/100 s not to f/2.8 and 1/50 s but to 1/56 s (eg, in aperture-priority mode).

For a practical example, consider the Tamron 60/2.0 macro (DX). A very nice little macro-portrait lens, but does not really seem to show that F/2.0 IMHO, at least not in Nikon mount.

Leonard Migliore
Leonard Migliore Forum Pro • Posts: 17,111
Some clarifications

sem wrote:

lovEU wrote:

I don't know why LGO pulled out this old thread...

Anyway, good to dig it out once in a while. Found that aperture calibration is much less precise than what I used to think, guess I'm not the only one.

The aperture calibration may be correct; Marianne's results are about the amount of light that gets through, which is a different thing.

For a practical example, consider the Tamron 60/2.0 macro (DX). A very nice little macro-portrait lens, but does not really seem to show that F/2.0 IMHO, at least not in Nikon mount.

This is something else entirely. When a lens is extended from infinity focus, the effective aperture changes because the lens is further from the sensor and f/number is the focal distance over the opening diameter. For some esoteric reason, Nikon reports this. Look at any of your other lenses; you generally won't be able to get your listed aperture at the minimum focus distance. You should see f/2 on the Tamron at infinity focus (but you hardly ever call for f/2 outdoors).

Canon doesn't do this, so when my MP-E65 is set to 5X, it still reads f/2.8 even though it's actually about f/16.

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Leonard Migliore

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_sem_ Veteran Member • Posts: 5,032
Re: Some clarifications

Leonard Migliore wrote:

The aperture calibration may be correct; Marianne's results are about the amount of light that gets through, which is a different thing.

See 2. in the OP. Surely is a different thing, but very closely related in practice.

This is something else entirely. When a lens is extended from infinity focus, the effective aperture changes because the lens is further from the sensor and f/number is the focal distance over the opening diameter. For some esoteric reason, Nikon reports this. Look at any of your other lenses; you generally won't be able to get your listed aperture at the minimum focus distance. You should see f/2 on the Tamron at infinity focus (but you hardly ever call for f/2 outdoors).

Canon doesn't do this, so when my MP-E65 is set to 5X, it still reads f/2.8 even though it's actually about f/16.

You got me wrong, I was referring to the declared nominal aperture, I know the effective aperture displayed on Nikon decreases when focusing close. But the issue with this lens is evident at inf focus, when the two values are the same. Tamron already made a correction for the odd exposure behaviour of the initial batches (underexposure mostly all over the range), but I think they have merely kind of addressed the calibration-exposure issue without removing the max aperture constraint. So at the widest aperture the lens still produces relatively underexposed images that do not show the expected reduction of DoF.

JP Scherrer
JP Scherrer Forum Pro • Posts: 10,645
@ Marianne Oelund: Lens brighter than announced !?!

Hi Marianne ! First of all, thank you very much for the time spent on measuring, testing, etc... lenses and cameras !

Now... I bought a 300mm. f/4 AF-s a few weeks ago (and enjoy it thouroughly BTW)... I noticed one thing: it's the ONLY lens to which I have to use the Exposure Compensation Button on my D700 ! Fortunately, the correction is on the "good" side, ie. I must ADD 0.7 EV to have a properly exposed image ! ...I tried the 3 metering systems and all apertures/shutter-speed combinations: same effect everytime ! So, it seems that the lens is indeed BRIGHTER than f/4 !!!

I never had to compensate the exposure with any other lens before (you can check my lens in my profile/plan) !

How do you explain this ?

Of course, I'm NOT complaining about this, much for the contrary... LOL !

TIA for you opinion !


J-P.

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JP Scherrer
JP Scherrer Forum Pro • Posts: 10,645
...and I must add.....

....that the +0.7 EV correction is ALSO needed when I use the 1.4x converter !!!

Great, isn't it ? That makes me "gain" almost one stop, whis sometimes (allways?!?) is very usefull !


J-P.

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binary_eye Veteran Member • Posts: 4,290
Re: @ Marianne Oelund: Lens brighter than announced !?!

JP Scherrer wrote:

I must ADD 0.7 EV to have a properly exposed image ! ...I tried the 3 metering systems and all apertures/shutter-speed combinations: same effect everytime ! So, it seems that the lens is indeed BRIGHTER than f/4 !!!

Why would the need to apply positive exposure compensation suggest the lens is brighter than advertised? If anything, it suggests your subject is brighter than middle gray.

Regardless, metering is done through the lens (TTL), so differences in transmission vs. nominal aperture are accounted for.

Jim Keye Senior Member • Posts: 2,197
Re: @ Marianne Oelund: Lens brighter than announced !?!

binary_eye wrote:

JP Scherrer wrote:

I must ADD 0.7 EV to have a properly exposed image ! ...I tried the 3 metering systems and all apertures/shutter-speed combinations: same effect everytime ! So, it seems that the lens is indeed BRIGHTER than f/4 !!!

Why would the need to apply positive exposure compensation suggest the lens is brighter than advertised? If anything, it suggests your subject is brighter than middle gray.

It seems to suggest the lens is 2/3s of a stop slower than advertised, regardless of subject.

metering is done through the lens (TTL), so differences in transmission vs. nominal aperture are accounted for.

Well...not always. First, sometimes metering is done externally. Also, there are a great many instances when people use manual exposure. When you switch lenses you have to change exposure also. Sort of a PITA when you're in a hurry, not to mention you have to decide between changing ISO, shutter, and f-stop to achieve the correct exposure again. Each affect things differently, especially if you're using a flash or a flash-ambient mixture, have the flash set on manual mode, etc. etc.

JP Scherrer
JP Scherrer Forum Pro • Posts: 10,645
Correction : my bad... I meant MINUS 0.7 EV !!!

(nt)

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JP Scherrer
JP Scherrer Forum Pro • Posts: 10,645
@ binary_eye !

binary_eye wrote:

Why would the need to apply positive exposure compensation suggest the lens is brighter than advertised? If anything, it suggests your subject is brighter than middle gray.

CORRECTION: I meant 0.7 EV, of course ! Still, I took A LOT of pics, with different subjects/background lighting and the -0.7 EV was still doing it's job !

Regardless, metering is done through the lens (TTL), so differences in transmission vs. nominal aperture are accounted for.

??? Hein ??? so what ?

???
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JP Scherrer
JP Scherrer Forum Pro • Posts: 10,645
@ Jim Keye

Jim Keye wrote:

Why would the need to apply positive exposure compensation suggest the lens is brighter than advertised? If anything, it suggests your subject is brighter than middle gray.

It seems to suggest the lens is 2/3s of a stop slower than advertised, regardless of subject.

Ooops ! I corrected it: of course it was MINUS 0.7 EV !!! ...which make the lens brighter than f/4 !

Why would the need to apply positive exposure compensation suggest the lens is brighter than advertised? If anything, it suggests your subject is brighter than middle gray.

Well...not always. First, sometimes metering is done externally. Also, there are a great many instances when people use manual exposure. When you switch lenses you have to change exposure also. Sort of a PITA when you're in a hurry, not to mention you have to decide between changing ISO, shutter, and f-stop to achieve the correct exposure again. Each affect things differently, especially if you're using a flash or a flash-ambient mixture, have the flash set on manual mode, etc. etc.

I tried all possible arrangments: apertures, shutter-speed, different subjects vs background/foreground lighting, S-mode, A-mode, M-mode, you name it ! Everytime the image was correct with -0.7 EV !

Still wondering... and enjoying !


J-P.

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binary_eye Veteran Member • Posts: 4,290
Re: @ binary_eye !

JP Scherrer wrote:

binary_eye wrote:

Regardless, metering is done through the lens (TTL), so differences in transmission vs. nominal aperture are accounted for.

??? Hein ??? so what ?

So suggesting the lens is "brighter than f/4" based on the camera's meter implies a misunderstanding of how the system works.

Jim Keye Senior Member • Posts: 2,197
Re: @ Jim Keye

JP Scherrer wrote:

Jim Keye wrote:

Ooops ! I corrected it: of course it was MINUS 0.7 EV !!! ...which make the lens brighter than f/4 !

Gotcha.

Why would the need to apply positive exposure compensation suggest the lens

Well...not always.

I tried all possible arrangments: apertures, shutter-speed, different subjects vs background/foreground lighting, S-mode, A-mode, M-mode, you name it ! Everytime the image was correct with -0.7 EV !
Still wondering... and enjoying !

To be clear: I'm not suggest that how you're metering has any impact on how the lens behaves or transmits lite. Your 300 f4 maybe very weill be 2/3s of a stop faster than marked. Nothing you do will ever change that.

What I'm referring to is situations where you're changing lenses and plan on using the same exposure. Unfortunately you can't because the lenses aren't at the same t/stop, despite being marked as the same f/stop. So you have to change shutter speed, aperture, or ISO--or flash settings--to keep the exposure the same. In some scenarios, changing any of these has other impacts on the photo besides just correcting the exposure.

OP Marianne Oelund Veteran Member • Posts: 7,768
Metering anomaly
1

JP Scherrer wrote:

Now... I bought a 300mm. f/4 AF-s a few weeks ago (and enjoy it thouroughly BTW)... I noticed one thing: it's the ONLY lens to which I have to use the Exposure Compensation Button on my D700 ! So, it seems that the lens is indeed BRIGHTER than f/4 !!!

That does not follow. What you are observing, is only a metering problem; by adding the -0.7EV, you are correcting the error.

You can confirm this by photographing a blank wall that's evenly illuminated, with your 300/4, and then another f/4 lens wide open (note: 200-400/4 VR is not recommended for this comparison), keeping all camera settings manual and unchanged. Then compare the histograms (reading the furthest-right values shown, since the dimmer values are due to vignetting, which varies between lens models).

How do you explain this ?

I've never used the 300 f/4, so I do not have any experience which I could offer as explanation. I have noticed, however, that exposure metering can be affected greatly by the optics used.

JoeBlackFox New Member • Posts: 9
Re: Metering anomaly

I encountered with the same problem using my 18-105 kit lens.
It overexposes 1/3 stop at f/5.6 and higher.

I emailed to Nikon's support and called to Nikon's service center, they told me that exposure error of 1/3 stop is acceptable and it's feature of the lenses. But I don't think so.
Did anybody fix lens aperture inaccuracy in Nikon's Service center?

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