Larger sensor, smaller depth of field

For me as a landscape and nature photographer, one of the disadvantages of using a full frame camera is the fact that the larger sensor yields a narrower depth of field. Or rather: it seems to. The crop factor of smaller sensors is the culprit: we could say that it does apply to the aperture, too. A very simple example: make a photo of a really really long alley with a compact camera. You will have NO problem at all to have everything from the nearest trees to the farthest tiny spots on the horizon in focus. A compact camera's sensor is so small that you have infinite depth of field most of the time (unless you focus really really close). Now try the same with a DSLR with a larger sensor...

Here's a second (or third, or something) attempt of making a photo of the beautiful Weissbach (white creek) near Inzell in spring. Depth of field-wise, it's a failure. Stopping down to f/11 with the telezoom lens was not enough to get everything in focus - even in the web version you can see a slight softness at the top of the frame:

Weissbach (NIKON D700, 1/5s @ ISO 100; f/11, 70mm)

I need to change my habits and get used to that! Stopping down to f/11 on a crop sensor would give me more depth of field than on the full frame sensor (f/11 x 1.5 crop = f/16.5), and I followed some fierce discussions on the internet (in forums, where else:-) why that is so, and how, and the level on which these discussions were held were rather high, with a lot of laws of optics and whatnot involved. With this post I will try a different approach and explain this as simple as possible (with a terrible lack of illustrations, I must admit).

If you look at the above photo again and think of the part of it that you would see on a camera with a crop sensor at the same focal length (!) it's very easy: the frame is cropped, and you see less of it (for the above photo, it's the equivalent field of view of a 105mm focal length: 70mm x 1.5 crop). The critical area at the top of the frame that is soft and slightly out of focus would simply not be there! Looking at it the other way around, there's simply "more picture" around the original frame of a crop sensor (I want to take my explanation approach from that side).

Here's where the "trying to explain it really really simply" part starts:

To understand what is going on we must understand what "depth of field" really is, and how it happens. Commonly, the "depth of field" is understood as being that part of a frame that has acceptable sharpness. Everything outside this area if more or less blurry (and btw.: how that blurriness looks is called "bokeh"). So that's what depth of field is.

And how does it happen? Strictly speaking, the focal plane is always just that - a plane, but not an area, or a field. There's one single distance, no matter what your aperture is, where everything is perfectly in focus - the focal plane.

But as the light rays pass through the lens, they are "focused" - and how much they are focused depends on the size of the aperture. We could say that the smaller the opening of the aperture is, the more light rays are "squeezed together" so that they form a point instead of blur at the resolution of the medium (sensor, film), and thus create the effect (illusion) of sharpness over a larger area or field. If the aperture is wider open, more of these light rays "wander off" in other directions, they are not "bundled" to form points on the medium, but remain blurry.

The Wikipedia article on Depth of field has a better explanation (of course), quote: "Decreasing the aperture size reduces the size of the blur circles for points not in the focused plane, so that the blurring is imperceptible, and all points are within the DOF."*

End of the "trying to explain it really really simple" part. :)

The first look through the viewfinder of my D700 was enlightening: there's simply "more unsharpness" "surrounding" that area of the frame (from a crop sensor) that is sharp. To squeeze the light rays together so that they reach those outer areas of the full frame sensor (again: because these outer areas are not there on a crop sensor) as "sharp", you have to stop down more.

The question remains: do we really need to know all the background and explanations to make photos? In my opinion: no. Knowing that I need to stop down more on a full frame sensor is enough.

Cows! D700 Dynamic Range Example

I uploaded this photo to my Picasa Web Album yesterday and it has received very friendly praise and comments in a relatively short time (thank you to all of my followers!). It also serves as a good example of how much of a "buffer" the D700 has in the shadows, dynamic range wise (to underline the claim that I made in a post a couple of weeks ago), and at which quality.


Cows chewing the cud (NIKON D700, 1/400s @ ISO 200; f/11, 12 mm (in 35mm)

As usual, when I made the photo I tried to not blow out the highlights, to be able to get back to what you can see above - in the final version, I brought down the blue luminance a good amount to make the difference between the clouds (or rather: vapor trail leftovers) and the skyblue bigger, and this wouldn't work with a blown out blue channel. Here's the unprocessed photo without any edits:

Cows chewing the cud (unprocessed) (NIKON D700, 1/400s @ ISO 200; f/11, 12 mm (in 35mm)

There's a good amount of noise in the brown areas of the cows' fur, but it doesn't matter for the web version, and it wouldn't matter for a 30x45cm print, either.

Needless to say that what I actually saw with my own eyes was more like the final, edited version! It was a bright and sunny day, the sun had just disappeared behind these trees, leaving this part of the Finsterbachalm in the shadows - but from the exposure settings you can see that it still was very bright and these cute cows where of course not in the dark like that. :)

PS: yes, that's the Sigma @ 12mm - did I mention it's barrels of fun? :D

Wider

With the change to a full frame camera I was lacking some wide angle. My 12-24 Nikkor was a DX lens, and while it can be used from something like 18-19mm on for full frame too, it's just not very convenient to have an overall zoom range of (wow) 6mm. I sold it and replaced it with the Sigma 12-24 - exactly the same focal range, but for full frame, w00t! I can use it on the S5pro with it's crop sensor just like the Nikkor.

Sigma seems to be somewhat specialized in wide angle lenses. They have a very interesting line-up of wide angle lenses for both full frame and crop sensors (the unbelievable 12-24mm for full frame
is available for crop sensors too with their 8-16mm ultra wide angle zoom).

I made an evening walk around Burghausen's Wöhrsee with Toni + camera + lens the day the Sigma arrived here, and what can I say... it's simply amazing, barrels of fun!


Wöhrsee + Pulverturm (NIKON D700, 1/50s @ ISO 280; f/11, 12 mm (in 35mm)

The above photo was made from exactly the same spot where I also made the photo in the post "Feeling like a nerd" (about first time tripod experiences).

The minimum distance to focus is only 28cm - which means you can bring the front element of the lens as close as something like 10cm to a subject you want to have in focus:


Flower (NIKON D700, 1/50s @ ISO 360; f/4.5, 12 mm (in 35mm)

Yes, wide open the corners are extremely distorted and blurry, but it's one of the effects of wide angle that I really like. With being able to get that close (and wanting to do that for that typical wide angle effect) it's useful to stop down the lens a lot, and in the range of f/11 to f/16, the corners are good for a wide angle that is as extreme as the Sigma.

Sidenote: it seems that SeenBy has closed their US office, or at least their US website. Navigating to seenby.com results in an "authorisation required" request in the browser. That's pretty lame and unprofessional if you ask me. A simple redirect to their EU website seenby.eu would have done the trick. There's no notice about the US office on their website either. It's a pity. And I have to update all the links to my photos here in my blog and who knows where else... :-/

Kreuzweise gegenständig

"Kreuzweise gegenständig" (NIKON D700, 1/80s @ ISO 360; f/3.8, 105 mm (in 35mm)

The title of this post describes the arrangement of leaves on these flowers in German. These white milky orbs on top of the plant are actually drops of rainwater.

I wonder if it's justified to call the ongoing meteorological "situation" here in Germany "weather" at all, or if "nightmare" isn't more fitting - I mean... it's almost the end of June and it's raining, and cold, and I just checked - Germany still *is* on the northern hemisphere!

Grey skies and rain and not exactly a tempting photographic subject around here (might be different in the mountains, were clouds hanging low in the valleys or rising from the forests are creating a wonderful, sometimes eerie atmosphere), so I continue with what I've done when I was waiting for spring: focus on the details. I've really put that macro lens to good use by now, I think.

Three Trees (what do you want to show?)

Three Trees (NIKON D90, 1/125s @ ISO 200; f/11, 127 mm (in 35mm)

For a while now, I've been submitting photos to SeenBy, and most recently I filled up my account with the 20th photo that was approved. The 20 photos that were accepted by SeenBy are about 30% of the total photos that I submitted for review. 20 photos are their limit - if I want to submit new photos I have to delete older ones.

Which is a quite interesting challenge, because it includes questioning one's own approach to the selection of photos. You can show photos in public that you like, or you can show photos in public (of which you think) that others (will maybe) like them. More than once, I've been surprised at the feedback on photos which I kind of "showed only for the sake of completeness" and wouldn't have considered being interesting, worth looking at, worth printing, etc. myself. Sometimes, the feedback that I receive makes me reconsider a photo. And many many times, looking back at older photos, I notice how my taste and my own selection criteria have changed.

And in a similar way... while I begin to understand what the SeenBy editors are looking for, it's of course tempting to go the easy way and submit photos that have a higher possibility to fit their selection criteria.

I often find myself pre-occupied ("inspired") with a certain vision of an image in my mind. Something that "works". At that point it is important to remember: I'm not making photos for the SeenBy editors, or for any audience at all. I'm making photos for myself. It's not a job! It's a hobby and a passion. As I described it in my previous post - being out in nature with the camera, enjoying a beautiful scenery and exploring it photographically is fun and the most enjoyable part of the whole thing. And if the resulting pictures (that I decide to show to the public) are appreciated by my audience, it's all the better.

[the question that arises is of course: without all the feedback and applause that I received for my photos, without all the friends that I made and the people that I met, would I still do it? Show my photos in public just like that? Without ever knowing if someone looks at them and likes them, or not? I don't know. But I think it's better to not ask that question, and simply go on doing what I like. :)]

Puritanism

Puritanism, n. - "the haunting fear that someone, somewhere might be happy."

OK, that's not the real definition of Puritanism. :-P But it's somewhat fitting when I look at all the talk about photography, and discussing photos, especially in web forums, and especially there where amateurs meet.

These discussions are very often about "Oh, I'd crop a little bit here and there" - "where does that color come from, have you checked your white balance?" - "it looks a bit soft, were you using a tripod?" - "the light on her left shoulder is too harsh" ...et cetera, et cetera. In other words: mostly nonsense, anemic, narrow-minded picking at details, refusing people artistic freedom and expression... and most of all: neglecting the FUN that photography is!

Why do I say that? Todays walk with Toni after work led me to my beloved forest at the Huckinger See in Austria, and I took the camera and two primes with me, really lightweight, the "oh, just in case" situation where you take the camera with you without having anything specific in mind.

And it was so enjoyable! I find it very refreshing to free myself from all the eagerness, earnestness, the pressure of "I-want-to-create-something-NOW" or "wow this is a spectacular place/situation, I'd better make some terrific photos now!".

So no tripod, no heavy backpack (loaded with lenses and filters and accessories), no wide angle lens, no macro lens, no telezoom lens, no zoom lens at all! After I began with some "going nowhere" snapshots here and there I began to try different things, looking at things from different angles, left the track, and I came home with about 50 photos (that includes lots of trying different apertures and exposures, and about 50% of them are disposable, immediately). Here's the one photo that I like to show - I love it!

"Elder over brook" (NIKON D700, 1/80s @ ISO 640; f/2.8, 35 mm

Yes, I myself am an amateur too. And I plead guilty as charged, for lecturing my fellow amateur photographers about the usage of raw data, tripods, and whatnot, every now and then. I'm sorry. But then again... it's so hard sometimes to draw the line - when is criticism allowed and useful, when is it really helpful, and when is it just... Puritanism? Hmmmm. Philosophical ponderings for the weekend. :)

IMHO: AF-S VR Nikkor 3.5-5.6/24-120mm

This is the lower left corner at 24mm and f/11. It's the newer production with 7-digit serial number made in Thailand. Do I have to add anything more when you look at this?


Click to see the original (827x827) crop - that's about 30% of the height of a 12mpx frame, so... not exactly a "neglectible" problem for me.

Well, the long story... I wanted a little bit more wide angle and a little bit more versatility in a single lens after hauling too much glass around on my recent hike to the Wimbachgries (I'll maybe add more about that in another post). And of course, the 24-120VR Nikkor sounds like a very good lens for exactly that purpose. In theory.

In practice, the corners in the range of 24-35mm are rather unusable unless you stop down to f/16 (yes, sixteen!), and even then, they're still somewhat soft and blurry. Since that wide end was the reason to get that lens, it does not fit my requirements at all, and I returned it. Maybe I got a bad one? I don't know, and I do not intend to find out.

I hope that the rumors are right that Nikon will release a new 24-105VR at this years Photokina. I can wait and will use my cheap, plastic, 30€-used 28-80mm instead. It's certainly better at the wide end!

Looking sideways (and normal)

After what felt like weeks and weeks of rain, it's suddenly super warm and summer hot here in Germany - too warm for hiking in the mountains. Fields and grass are bursting with growth, and pollen... I haven't felt the effects of my pollen allergy that strong for quite some years. It's nice to stay at home in the relatively cool apartment, blinds half closed, sip some coffee, take it easy... and maybe grab the camera later for some evening light.

Two days ago, I grabbed the "good old" S5pro, the 35mm and the 105mm lens and made an evening walk with Toni and camera. Using the S5pro with the comfort of it's exposure latitude that I described in my previous post filled me with a bit of melancholy - so at first, I wanted to entitle this post "looking back", but I figured that it's not really fitting. The S5pro is simply a different camera.

I made a good amount of macro photos - or should I say macro attempts? The viewfinder of the D700 and it's continuous shooting speed are simply better for handheld macros - but it became obvious only when I came home and reviewed the photos on the computer. :-P This photo doesn't qualify as macro at all, but I quite like how it turned out:

Evening in the meadows (FinePix S5Pro, 1/60s @ ISO 250; f/2.8, 105mm DX

For the look of the above photo, I applied a good amount of negative clarity in Lightroom and compensated the loss of contrast with an increase of the highlights. After a little playing around I applied a split toning preset called "cool warmth" (from x-equals.com once more, read that nice article - it's about split toning, the download link is at the end of the article.)

I picked the 35mm lens in addition to the macro lens because at it's 35mm equivalent field of view it's a 52.5mm or in other words "normal" lens. And I don't know why, but that focal length is really really attractive for the occasional and lightweight walk-around with the camera.

When I bought my first prime, I made the mistake and bought the 50mm/1.8 AF-D Nikkor - because it is extremely cheap of course, and because "having a fast prime" was something that seemed desirable. The problem (that I didn't realize) was that on the D70s with it's 1.5x crop sensor (Nikon calls it "DX" and it's often called "APS-C" size, too - but Canon's 1.6x crop sensors are also called "APS-C"... oh well), the 50mm prime is of course more like light tele or portrait length with it's 75mm-alike field of view. When I used it as a walk-around lens, it was not very enjoyable because it felt "too long" just very very often.

When I lent my 35mm/2.0 AF-D to a coworker over the weekend he tried it on his D5000 - only with manual focus, but (coming from analogue SLRs which he used something like ten years ago) he immediately knew what was wrong about his choice of the 50mm/1.8 (yes, he had that one, too) and he bought the 35mm/1.8 DX prime immediately.

Conclusion: if you want to start enjoying the fun of a prime, have a look at the right "normal" focal length (field of view equivalent to that of a 50mm lens on film or a full frame sensor). For the DX sensors, that's something like 28-35mm, for the 4/3 sensor league it's something like 20-25mm.

Wimbachgries

Yesterday the weather was really excellent and I made the long planned hike to the Wimbachgries and Wimbachgrieshütte (originally wanted to go there with Shuwen but we just visited the Wimbachklamm gorge because a heavy rainfall started just as we arrived and parked the car).


"Wimbachgries" (NIKON D700, 1/125s @ ISO 320; f/11, 19 mm)

The Wimbachgries (sorry, Wikipedia only has a german article) is a really exceptional area: the mountains surrounding the upper part of the valley are made of dolomite and they slowly but steadily errode into a giant gravel "stream". It does carry water, but only during snowmelt it surfaces. Most of the year the water flows underground, and only surfaces at a dam near the valleys entry (the dam is there also to stop the enormous amount of gravel "flowing" farther down) where it formed the Wimbachklamm gorge.

The photo is also an example for my previous post about the dynamic range/highlight differences between the S5pro and the D700. It was made with an exposure bias of -1 EV to preserve the highlights, and at home I pulled up the shadows a lot in Lightroom (Fill Light +83; amongst other edits, of course).

Besides that, it is also a good example of the shortcomings of the sRGB color space: the blue is simply wrong when exported from Lightroom, which is especially notable in the walls of the mountains. :-/

PS: I've adjusted the blue for the JPEG/sRGB export version and replaced the image. What you see now is mostly what I want you to see. :)

D700 vs S5pro - Exposure Latitude

I'm not really keen on writing this article anymore - when I had the D700 for the first few days I couldn't help but being disappointed with the D700 and it's "normal" sensor. After the first couple hundred exposures with the D700, I could certainly say that the S5pro is SUCH a CLEAR winner. Fuji's SR sensor is a strike of genius, period. It seems that no other sensor than Fuji's can provide the smooth and "natural" highlight shoulder/rolloff for photographers thanks to the "two sensors per pixel" speciality - if you haven't used a Fuji with the SR sensor, you may not understand what a fundamental difference that really is, but if you remember the "old days of film" and how highlights slowly turned into overexposure (heck, even the most basic photos made with a compact camera and film from the supermarket had it!), you know what I am talking about (just look at that old holiday pictures you made on film with a compact camera, like I did:-). Compared to that, digital clipping is harsh, a brick-wall, ugly - and Fuji's sensor addresses exactly this problem.

But as the weeks passed by and I used the D700 more and more, I understood that the dynamic range difference is not that dramatic. After I began using UniWB and controlled my exposures more carefully with the histograms I can say that the fundamental difference between the two cameras is where the dynamic range difference comes from: the S5pro has it's extra bits in the highlights, the D700 has it in the shadows (and a good part of it is maybe because of it's huge pixels - after all, the D700 has "only" 12 megapixels on a full-frame sized sensor).

I've prepared some example photos. I don't include them in this post but uploaded them to an unpublic Picasa Web Album instead (just follow the link). I added captions to explain what you're seeing.

The question of course is: which concept is better? And I am absolutely convinced that the Fuji approach is the better solution. Why?

For someone who uses only JPEG and expects pleasing and natural images out of the camera, it provides a "highlight safety" that is simply essential. Nikon addresses this problem with it's Active D-Lighting technology, but I must admit I haven't played with it much (it doesn't make much sense if you shoot raw).

Knowing that the D700 often clips the highlights in scenes with high contrast, the only solution for me is bracketing over three frames: normal, -1 and -2. Just to be on the safe side with the highlights. Which means more work at home: three files per photo, and then checking which exposure is "perfect", highlight-preservation wise, at home. :-/

So furthermore and more importantly: exposure-wise, the S5pro is really a "fire and forget" camera no matter if you're using raw data or JPEG - take a walk on a sunny day and try to capture the average scene with a bright sky and some foreground stuff. Nikon D700: dial in -1EV exposure compensation and you're good to go (if you shoot raw!). Fuji S5pro: just shoot. It's just depressing to experience that. I forgot how comfortable and worry-free it is to shoot the S5pro. It simply requires "less fiddling around" with the camera and that is a luxury I've learned to value very much...

Stop! In the name of light...

The original motto for my weblog was to describe my findings and experiences exploring (digital) photography, hoping that other beginners would be able to benefit from it and maybe, just maybe, would be spared of one or the other unpleasant experience. :-)

Some of my recent posts may have been very camera specific (hey, I bought a D700, and I love it, it rocks!) and/or technical (the UniWB stuff). The topic I want to cover in this post is something rather "basic" - but I remember how it kept me puzzled for quite a while, and when I finally understood what it's all about (I was like "duhhhhhh!"), it helped me so much to handle my camera better, faster, and with more confidence that this post is of a personal concern. I try to give an explanation in really really simple words - I hope it works. :-)

I can't remember how many times I've read and heard about "fast" lenses, about "stopping down", about "one stop" more (or less) light, "one more stop" of usable ISO, and so on, and so on (and in German, instead of "stop" people usually say "Blende" - aperture - and it puzzled me just the same). I wondered: what the hell IS a "stop" actually?

The simple answer: a change (increase or decrease) of one stop (no matter how, I'll explain it right below) means that we allow either double or half the amount of light to work for us. Double the amount if the exposure time gets longer, and half the amount if the exposure time gets shorter.

I myself understood the idea best when I looked at the "full" aperture progression, because the aperture is clearly (more or less) "in the way" of the light as it passes through the lens onto the sensor or film. It's not so much in the way if it is wide open and lets a lot of light pass through, and it's very much in the way if we "stop down" a lot so that the opening through which the light can pass is really really small (hint: in the Nikon world, all lenses have a small lever on the end that is mounted to the camera - it can be moved with the finger and when you do that, it's very clear then what the aperture does.)

Now, if we start at f/2.8 (which is common for expensive and "fast" zoom lenses), the series of apertures that follow are 4, 5.6, 8, 11, 16, 22. Those are full stops. With the aperture blades closing farther and farther from one full stop to the next, only half the amount of light can pass through to the cameras sensor (or film) for each of these so called f-stops.

So if you "stop down" the lens from f/2.8 to f/4 (yes, this is one stop) you let only half the amount of light pass through the lens, and to get a proper exposure, you have to double the exposure time - let's say from 1/100s to 1/50s. If you stop down twice (which, starting from f/2.8, would mean you end up with an aperture setting of f/5.6) you need an exposure time that is four times as long - let's say 1/25s instead of 1/100s.

It's a bit of an abstraction when these "stops" are used for exposure times and sensor sensitivity, but the concept is just the same. If you're looking at a relatively dark scene, you might want to tell your camera to underexpose "one stop"*. So you'd set 1/100s instead of 1/50s (without adjusting the aperture), letting only half the amount of light get to the sensor (or film) because the shutter is open only half as long.

And if it's used for the sensitivity of the sensor (or film): ISO400 is one stop faster than ISO200. And ISO800 is two stops faster than ISO200. Using ISO400 instead of ISO200 means that the sensor will capture twice the amount of light (if the exposure and aperture stay unchanged).

How did this help me when I operate my camera? Well, most cameras allow adjustments to the aperture, exposure and ISO in steps of 1/3 of a stop (most Nikons can be configured to use 1/2 stop instead, but it's not the factory default).

So, if I make a photo and notice that it is underexposed (when I check the histogram on the camera's display), I simply use the main command dial of my camera to dial in one stop of overexposure, and it's 3 clicks of the dial, each 1/3 stop. Or, if I cannot use a longer exposure time, I might need to raise the ISO sensitivity by one stop: I press the "ISO" qualifier button and again it's 3 clicks of the dial, each 1/3 of a stop. Or, if I can sacrifice the depth of field, I can open up the aperture, and again it's 3 clicks for one full stop. I don't have look at the actual number, I simply go click-click-click (in either direction, and for any of the three exposure, aperture and ISO sensitivity) and I know I now have either halfed or doubled the amount of light reaching the sensor or film.

Click-click-click. That's one stop. It's really that simple. I wish someone would have told me. That's why I wrote this article. If it helps just one fellow photography fan out there, I will be very happy.

*) why? because the camera doesn't know you're looking at a relatively dark scene - it always assumes you're looking at an averagely lit scene