Focusing on Reflections in Water as it relates to a landscape image

[Brownbear]

Hi Bruce,

Yes, I'm just trying to learn how to relate them all to photographing a landscape and the point of focus so I can see it immediately in a vista and not have to think about it so much, and be able to do so while thinking of different lens (especially wide angle) or performing calculations (live view will take care of the latter)... Aperture, distance (subject and background) and focal length.

Thank you.

Christina, do you know the 3 variables that influence DOF?



Bruce

[rpcrowe]

Actually there are four variables that influence DOF: Focal Length, Distance Focused on, f/stop AND CIRCLE OF CONFUSION for the format you are shooting.

Rather than getting into some involved photographic theory suffice it to say that an image from a small sensor needs to be enlarged to a greater degree than the image from a large sensor and thus needs to be sharper to begin with.

We always hear that a larger sensor (say full frame) has a more shallow DOF than a smaller sensor (such as the Canon 1.6x). That is only true however when the larger sensor is placed closer to the subject to get the same framing as the smaller sensor or if the larger sensor is used with a longer focal length to get the same framing as the smaller sensor.

If they are shot from the same viewpoint, with the same focal length, the larger sensor has a greater DOF than the larger sensor. As an example:

200mm @ f/2.8 focused at 10 feet
full frame DOF = .12 feet
1.6x crop DOF = .08 feet

If the image recorded by the larger sensor is shot using a longer focal length lens from the same distance to match the image shot with a shorter focal length from that distance; the larger sensor will have a more narrow DOF. As example

I shoot a 1.6x crop camera using a 50mm lens focused at 10 feet @ f/2.8: DOF will be 1.29 feet
I shoot a full frame sensor using the equivalent focal length (80mm) focused at 10 feet @ f/2.8: DOF will be .79 feet

[Brownbear]

Hi Richard,

Thank you. I didn't realize that the circle of confusion was a factor but it is aptly named. Focusing on a certain point on a landscape is very new to me - up until most recently (say 2 months ago) I just placed my focus point on the subject of interest in the landscape.

Thank you for the extra detail as related to sensor size.

Would it be possible for you to explain ones best options the focal point in a landscape image when one is using a wide angle lens and wishes to photograph a subject in the immediate foreground - with a simple clear explanation.

ie; as per my example if one was photographing a view with mountains in the background and whales breaching or a dog playing in the ocean right in front of you. (and where I would wish to place my focal point)

I'm thinking that because of the distance of the mountains in the scene (reinforced by Mike's exercise) that the mountains would be in sharp focus anyway. I performed the calculations (seen in my original question) but I can't seem to relate the results for the perfect focal length (as calculated 11.2 mm) to this vision of an image.

Thank you.

PS


I recall an image of Frank's in which he had a couple sitting on a bench immediately in front of him, and a grand vista beyond in which everything was in beautiful sharp focus that also had wonderful depth of field. So in this particular image if he placed his focal point on the couple, would the choice of aperture (even if it was a large one) not make a significant difference because the mountains were far away... That said if I remember correctly there were islands in the middle of the image in which case the aperture choice would be important but a middle aperture might do just fine? Or did he place his focus 1/3 of the way into the image and use a smaller aperture that would extend 1/3 of the way back to his camera, ensuring the couple would be in sharp focus?

Actually there are four variables that influence DOF: Focal Length, Distance Focused on, f/stop AND CIRCLE OF CONFUSION for the format you are shooting.

Rather than getting into some involved photographic theory suffice it to say that an image from a small sensor needs to be enlarged to a greater degree than the image from a large sensor and thus needs to be sharper to begin with.

We always hear that a larger sensor (say full frame) has a more shallow DOF than a smaller sensor (such as the Canon 1.6x). That is only true however when the larger sensor is placed closer to the subject to get the same framing as the smaller sensor or if the larger sensor is used with a longer focal length to get the same framing as the smaller sensor.

If they are shot from the same viewpoint, with the same focal length, the larger sensor has a greater DOF than the larger sensor. As an example:

200mm @ f/2.8 focused at 10 feet
full frame DOF = .12 feet
1.6x crop DOF = .08 feet

If the image recorded by the larger sensor is shot using a longer focal length lens from the same distance to match the image shot with a shorter focal length from that distance; the larger sensor will have a more narrow DOF. As example

I shoot a 1.6x crop camera using a 50mm lens focused at 10 feet @ f/2.8: DOF will be 1.29 feet
I shoot a full frame sensor using the equivalent focal length (80mm) focused at 10 feet @ f/2.8: DOF will be .79 feet

[Brownbear]

Adding on a sample image to explain what I'm trying to understand.


Frank's image is the 10th posting in this thread.

Learning Landscapes - Please post your BIG picture dramatic landscape images

I see that the couple is not in the immediate foreground but let's say they were. I'm thinking that he would need to use a wide angle lens to focus so close into the scene and use a short focal length? (to manage the same sharpness) Would the choice of aperture matter?

His second image with the log in the immediate foreground also follows my thought process

[Mike Buckley]

Actually there are four variables that influence DOF: Focal Length, Distance Focused on, f/stop AND CIRCLE OF CONFUSION for the format you are shooting.

I have never understood the circle of confusion and gave up long ago on trying to understand it. While the circle of confusion may impact depth of field, it has so little impact that I am never concerned about it. Using your first example, which is rather extreme, there is a difference of less than 1/2" using the two sensors.

That's especially true in this modern era of using digital cameras when we can use magnified Live View in advance of releasing the shutter or use a magnified view of the captured image on the LCD to determine our actual depth of field. My advice to Christina for all practical purposes is that she ignore the circle of confusion.

[Mike Buckley]

Christina,

I have an idea for you. Use your wide angle lens every day for a week shooting nothing but landscapes. Set the lens to f/11 and don't change it. Focus on something that is about 1/3 to 1/2 of the distance in the scene. Let us know what if anything is not in focus. You might learn tremendously from that exercise.

As an example, the image shown below was shot at f/11 and a focal length of 17mm.

[Brownbear]

Hi Mike,

I will give it a try. It will likely take me more than a week as the forecast is for pouring rain every day for week or more. But will do.

Thank you for including an image shot at a wide angle with something close in.

I have to ask where you placed your focus point? There seems to be nothing to focus on a third or even 1/2 of the way in, ie; just snow... It looks like you focused on the house not the snow. Or was it a foot print?

I suppose if I took this shot at this moment at F11 I would focus on a foot print in the snow, (but I would want to focus on the fence in foreground) and hope that it was indeed true that the DOF extended 1/3 of the way back to the fence and 2/3 of the way to include the house...

PS is not F11 a who cares aperture?

Christina,

I have an idea for you. Use your wide angle lens every day for a week shooting nothing but landscapes. Set the lens to f/11 and don't change it. Focus on something that is about 1/3 to 1/2 of the distance in the scene. Let us know what if anything is not in focus. You might learn tremendously from that exercise.

As an example, the image shown below was shot at f/11 and a focal length of 17mm.

[Polar01]

Christina during your use of the wide angle just try focusing on something close or near the lower thirds' line. The above image from Mike focus was I would think at 17mm and f11 it would have been on the up-right rail pointing at the tree and barrel just above where the three rails cross. That would have be the place I would have used. Could be wrong only one that knows for sure is Mike.

Cheers: Allan

[Digital]

Christina, in Mike's photo example where would you place your focus if there was no footprint in the snow between the fence, and the red building?


Bruce

[Mike Buckley]

I made that photo five years ago using a tripod and have no idea how or where I focused. My software indicates the focus point for Nikon lenses if I use auto focus and if I don't focus and recompose, but I used a Tokina lens. I only know that if I did it today I would use manual focus and magnified Live View before releasing the shutter to ensure that everything is in focus. The camera that I used for that photo has no Live View.

is not F11 a who cares aperture?

That's the point of the exercise that I suggested. When using a focal length of 10mm to 18mm in a typical scene, you're going to have to try hard to get something out of focus using f/11. Not that that can't happen but f/11 would be my go-to aperture at those focal lengths with my Tokina 12-24 zoom if I had only one chance to get the shot and couldn't preview the depth of field in advance using Live View.

[Stagecoach]

Hi Christina,

Just in case you cant get out because of the weather here's a practical example of the theory and figures we find in DoF charts and calculators. Comments regarding where to focus and focus point indication in ViewNX prompted this from my balcony and I also know exact distances to to all points in the scene.

Shots taken at f11 and handheld, NEF sreenshots downsized in PSE and output sharpened 0.3 100%

No 1 - Focused on palm which the far right frond is 3 mtrs from camera


No 2 - Focused on horizon line which is 5000 mtrs (5 kilometers) from the camera


From the DoF Calculator;

No 1 : Subject Distance - 3 mtr
Focal Length - 18mm
Aperture - f11
Near focus distance - 1.26 mtr
Far focus distance - inf

No 2 : Subject Distance - 5000 mtr
Focal Length - 18mm
Aperture - f11
Near focus distance - 1.54 mtr
Far focus distance - inf

For further info if the shots had been taken at f7 near focus distances would have been, 1.34 and 2.43 mtrs for 3 and 5000 mtr subject distances respectively.

This is also a good example of a scene where it's not easy to judge 1/3rd distance into it for focusing and also when you do there's a good chance that the focus box area contains subject that is both nearer and farther. The focus box area in No 2 is perhaps questionable as to exactly what the AF focused on but I did do a further example later where I positioned it perfectly and results were identical to No 3.

Grahame

[Glenn NK]

Christina:

Have you tried using the DOF preview of your camera? Manually stopping down to the aperture the image will be taken at and see what's in focus and what's not in focus?

Have you tried using live view (LV) to check what parts of the image are in focus?

With a 10 mm lens at f/8 it's very difficult to NOT GET everything in focus. At f/11 it's pretty much impossible.

Try this: http://www.dofmaster.com/dofjs.html

With a 12 mm lens on a crop body at f/8, I had to work to not get everything from a couple of feet to infinity in focus; pretty much the same result with a FF body. It didn't matter if you focus at two feet or five hundred feet.

Could you be worrying this one too hard?

Glenn

[Mike Buckley]

Great demonstration, Grahame.

Great reminders, Glenn, though I personally stopped using DOF preview because the image becomes so dark that it's difficult to see. In the film days, I wouldn't buy a camera that didn't have it (not many consumer-grade cameras had it) but with better alternatives on digital cameras I no longer have a need for it.

[Brownbear]

Thank you to all.

Allan

Thank you. I will try just that in my exercise which will be a variation of Mike's suggestion

Bruce

Where to place the focus point in a landscape is why I asked this question. I would want to focus on the red house but I would focus on the fence post closest in. Until most recently I wouldn't have photographed this scene unless there was wildlife in the scene. ie; if there were a horse behind the fence I would focus on the horses eye/head and simply select a small enough aperture to allow for the horse and the entire scene to be in focus and/or choose a larger aperture if I wanted more DOF (if there was a line of trees in the scene instead of the the house). And if it were a bird I would focus on the bird and likely choose a large aperture, use a long lens and position myself differently to blur away the background.

ie; all of a sudden I'm placing my focus on something in the scene which is not the point of interest - very different and new to me

Mike

Thank you for sharing. I am quickly learning just how handy live view can be. We have a sad looking tree just outside our home that I can photograph through a window when it's raining and just outside our door when it stops raining. I will try out my wide angle lens on that tree using different apertures and focal points, and I will also try F11 on various landscape scenes.

Grahame

Thank you for taking the time to demonstrate the choice of focal point and share the images. I can see that the difference is insignificant. Truly appreciated. I will try this exercise on the tree.

Glenn

Thank you for advising. Good to know. The wide angle lens is new to me, and I've only tried it a few times. I am aware of the DOF button on my camera but I have yet to try it, but will do. Most recently due to Mike's encouragement and help I have started using live view and I like using it. Yes, I am beginning to see that I am worrying about the placement of the focal point too much but that is simply because I was not comprehending why I would place my focus point 1/3 of the way into the scene instead of on the subject.

In Summary

I feel like I am gaining a better understanding of the chosen focal point, field of view and why it is different with my wide angle lens and even my 28-200 mm lens (also not used very often except for the occasional snap shot of a landscape scene or a person)

The lens I use most often are a 300 mm fixed lens and a 105 mm fixed macro lens mostly for photographing birds and bugs. With the 300 mm lens I'm usually just concerned with blurring the background away by being close and but also selecting a small enough aperture to allow the bird to be in focus. And with bugs by choosing placing myself at an appropriate distance and selecting a large enough aperture to provide sufficient DOF.

Therefore while trying to learn to photograph landscapes, trying to understand why F22 seems to be the chosen story telling aperture of F22 and placing the focus point at a specific point in the scene instead of the subject of interest, in combination with using different lens is quite foreign to me. But the good news is that I'm beginning to see the relationships and gain a better understanding of my choice of lens and focal point.

Thank you to all!

[Mike Buckley]

trying to understand why F22 seems to be the chosen story telling aperture

Depending on the quality of the lens, f/22 wouldn't be my go-to aperture because the image may not be as sharp as it could be. As an example, f/22 is the smallest aperture on my Tokina 12-24 and the sharpness is not as good at that aperture as at f/8 or f/11. This is a matter of lens quality, not diffraction. As this thread has discussed, that fact poses no practical limitations except perhaps in the very rarest situation because so much is so sharp at any focal length of the lens when shooting at f/11.

[Mike Buckley]

You brought up a really important point, Christina, so important that it will be very helpful for you to wrap your arms around a different way of thinking about what needs to be sharp: Completely change your mindset from making the subject sharp to making everything sharp that needs to be sharp.

Sometimes only the subject should be sharp, as in the case of a bird filling almost all of the frame. Sometimes everything in the image has to be sharp even when the subject is no more than 15% of the image, such as the situation that you mentioned when you are making environmental portraits of wildlife.

[Brownbear]

Mike... Thank you for the additional pointers. You know so many books say F22 so it is a helpful reminder, and yes I need to learn to wrap my arms around in a different way, and now, thanks to everyone, I understand why.

[jcuknz]

I recently got to play with a 7.5mm lens on my E-PL1 and on looking at the lens it has infinity marked and 0.25metre ... so I have placed the focus point about half-way between them and just press the trigger [ adjusting the aperture down, smaller, from f/8 when the camera protests ]. Makes life much simpler
Here I am sitting in the Railcar seat next to the man and the cruiseboat seems fairly sharp. One day I may just consult the tables to work it all out.

I will leave it to the experts to work out what the lens is equivalent to in an APS or FF camera
Even my palm seems fairly sharp as that hand holds the camera and presses the trigger.

[ajohnw]

Mike... Thank you for the additional pointers. You know so many books say F22 so it is a helpful reminder, and yes I need to learn to wrap my arms around in a different way, and now, thanks to everyone, I understand why.

There is need for some caution at F22. I wont go into diffraction but it is a real effect. Colin for instance has nice big pixels on a full frame sensor. When people wrote the books and suggested F22 there is a fair chance that there sensors also had big pixels. Even bigger actually as they tend to get smaller year by year.

Does it matter is a bit more difficult. Sharpening and size reductions can mask effects. Easiest thing to do is take some shots of something or the other with detail in it and try various apertures. The effects are likely to be most noticeable in low contrast detail. Say conifer tree lines for instance but you can test for it in the house.

I've probably suggested this before but for landscape type work it's a good idea to spend a bit of time here but don't go over the top on it.

http://www.dofmaster.com/dofjs.html

I did one for you

As it's the most extreme I chose 10mm. I selected Nikin D7000 etc as pixel count doesn't matter and F8. It then comes up with the dreaded hyperfocal distance. In the case 2.08ft. When the lens is focused to 2.08 ft everything will be in focus from 1.04ft to infinity- read a long way away- any horizon distance that happens to be there. Then I did something else to show why there is no need to go over the top on this. Another box allows a focal distance to be entered so I put 200ft in it. Now the near limit is 2.03ft and the distant one still infinity. Lost 1ft of near. Then I stuck 500ft in the box. The near limit is now 2.04ft. Then 2000ft. The near limit is now 2.05ft. 50,000 ft doesn't make much difference either.

At the other end of the scale 300mm things get tighter but your likely to find F8,F11 and maybe F16 give the sort of depths of field that you are likely to need with a lens like that.

At 18mm for instance things tighten up. The F8 hyperfocal distance is 6.7 ft, near limit 3,35 ft, distant infinity. Set the focus distance to 1000ft and the near limit goes up to 6.7ft. Things at 6.7ft probably wont be in the frame so again there is a huge range of possible focus distances for sharp results.

The other landscape type focal length is 50mm on your camera. Hyperfocal distance is 51ft at F8 covering from 25ft up. Things are a lot trickier now. I'll leave you to play with the numbers but you will find F11, F16 may start being needed and shots need more thought.

Why F8. Most lenses will be on song at that point. A rough rule of thumb is 1 to 1 1/2 stops down from max aperture. Very fast lenses may benefit from 2 down.

I'm not saying shoot everything at F8 just pointing out what you need to be aware of especially on landscapes. The what needs to be sharp is important as well.

Lots of people say try to focus 1/3 of the way into the subject. From the above you can see why this can work in landscape type situations. As the focal length goes up the lens sets just how far away the nearest part of the scene is. I would say most people who shoot in that sort of fashion then make a conservative guess about the aperture that is needed to meet their needs. There may not be anything at that distance to focus on but there may be something around some way into the subject that can be used or focus directly on it realising that slower stops may be needed to keep the foreground in.

John
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[Brownbear]

PhotoNut - Thank you for sharing an interesting pic and a simple demonstration.


John - Thank you. Your detailed but easy to comprehend explanation is truly appreciated. I've been trying different shots with my wide angle lens and I can see that I can use the small apertures with no worries. I will play with my 300 mm lens, and my 28-200 mm lens to get a feel for using these in landscape images, too, and I will try that calculator just to get a sense of the numbers.

Thank you.