Sharp Focus (Front to Back)
elvisfridge
Registered Users Posts: 13 Big grins
Sorry, New, Probably wrong place.
New, using 11-16mm DSLR, pictures of medium sized rooms (interiors), no central focus point, focussing on back wall, need better front/sides/back focus e.g. sharper.
Using small apertures / fast shutter / tripod + hand held.
Should I create a focus point, mid room, remove it and take shot to get better focus sides close and far.
Herlp really appreciated as am novice.
Thanks,
Fridge
New, using 11-16mm DSLR, pictures of medium sized rooms (interiors), no central focus point, focussing on back wall, need better front/sides/back focus e.g. sharper.
Using small apertures / fast shutter / tripod + hand held.
Should I create a focus point, mid room, remove it and take shot to get better focus sides close and far.
Herlp really appreciated as am novice.
Thanks,
Fridge
0
Comments
Shots taken with EOS 1000D / Tokina 11-16mm / ISO 100 / Shutter on auto / Focussed manually at infinity / zoom at 11mm end. Space shot is about 20 meters deep by 10 meters wide. Chairs with magazines on were placed front L+R (about 1 1/2 metres away from camera in front corners of viewfinder) Mid L+R and a chair at the back of space, my garden, with a book stood up on it.
Focussed at infinity (Tokina at 11mm) at f2.8 gave blurred front corners, about 1 1/2 metres away from camera. As the aperture went up the corners and front to mid focus improved as you would expect.
Sharpness middle to back seemed to stay roughly the same from f5.6 onwards.
The lens seemed to have a sweet spot between f8 and f12.
The chair at the back (and a piece of wooden fence in the corner) seemed to decrease in sharpness and legibility from f16 - f22. Those f stops didnt seem to do much anyway.
My conclusions are that to get best front to back sharpness (with my set-up) for this kind of space is to focus manually to infinity, at 11mm end of lens, use a tripod with shutter on auto (camera on AV Mode aperture priority) ISO 100, and use an f stop of around f10. forget about the meter and a half in front of the camera.
It did raise some questions ( I am learning fast but am a novice in reality ) that I would appreciate advice on e.g.
Does all this look feaseable to the experienced photographer?
Should the chair and fence at the back of the space become less sharp around f16-f22?
Should the lens exhibit a sweet spot as suggested earlier?
Do the larger f stops come into play when shooting large distant scenes.
Please let me know any thoughts you may have or advice. As stated I have pics to back these thoughts up, what is best way to post them, many thanks. Fridge.
you're asking questions, but I see no pictures you're admittedly referring to..
See, with a film camera all this is easy as there are numbered dials on the lens barrel.
Think of DOF like your eye - it's a sphere (like a lens), so light hits it with more focus in the center, like shining a flashlight on a basketball. Brightest in center. You can experiment with your eye: put the forefinger and thumb tips of both hand together so there's a little peek-hole. Look through it with one eye very close. Look at something normally blurred. Squeeze the finger and thumb tips together slightly; it will look sharper. That's because you're focusing all the light on the sharpest area of the eye.
That's depth of field, the aperture (f-stops) being the finger-tips, and the lens of the camera your eye. So set the aperture as high as you can and find a shutter speed that corresponds for proper exposure within the focal range you have to keep in focus - which depends on size of the room and where you're shooting from. If you have a tripod, shutter-speeds won't be a real problem.
Since you don't have rings around the lens barrel, use a DOF chart for the focal range you want. AND: Use a chart for the size of the lens (i.e., 50mm, 28mm etc) you're using....think you said 16mm.
If all this sounds too complicated, experiment! Start with a mid-aperture, like f8. See what you get. You have a digital camera, you can shoot 500 shots and see what's the best; (DON'T shoot 500 shots, - I have a feeling you will and it's a joke. Shoot 5 to start with)
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Interesting. I have an old folder camera, no nothing: everything manual, no coupled rangefinder so distance is estimated, no light meter, no film advance (except your fingers winding).. BUT, a lens that's great: Zeiss.
Anyway, it has a red-dot at the "sweet spot", where aperture and focus are lined up to give and ideal DOF for the lens for most outdoor shooting needs. On a normal sunny day you also use a well-known (back then) 125 for shutter speed. And shoot all day without re-focusing (long as it's beyond 15' or so)
And, it is a sweet, that spot! Think many folders of that type had that red indicator.
You may have stumbled on the same thing. I do know that opening a lens all the way can tend to give some distortion. So, maybe, avoid the extremes if possible and try to stick to mid-range apertures. (?)
(here's a shot with the folder: early 50's Zeiss Ercona, Zeiss Tessar Lens, 6x9 format (2 1/4" x 3 1/4")
This is per original post at f2.8
f5.6
f8
f16
and f22
Also Front Lefts (crops) @ f2.8
f5.6
f10
f16
f22
Front right crops f2.6
f5.6
f10
f16
f22
and finally and most interestingly (IMO?) The chair at the back
f2.8
f5.6
f10
f16
f22
that chair is seemed to be doing strange things between f14-22. (yes I took shots at all apertures and repeated the tests 3 times before adding the chairs, magazines and bits of wood in the middle. I appreciate its all a bit heath robinson but your feedback is welcome
Thanks,
fridge.
Thanks,
elvisfridge.
elvisfridge.
elvisfridge.
Well, like I said, it's easier for me because I shoot film a lot and often with 50mm in 35mm camera or equivalent (80mm) in medium format cameras. So the rings on the lens barrel give you an actual measure of DOF depending on what aperture you use. And the 50 mm lens (or 80mm in medium format), are common lenses so you can also find a DOF table pretty easily - even if the rings weren't there and you needed one..
Far as the critique of DOF you mentioned: DOF exists, like I said, that's how you see, (squinting to see something? focuses light on central area of eye-sphere.)
Anyway, I'm not sure your lack of sharpness throughout is DOF because it's not clear in the number of whole-area shots posted what you're focusing on. I'd do the chair so it's really sharp, and do an f10 or near and see what the sides of the area look like. Good DOF field should make at least 2/3 rds of the sides pretty sharp. And at least from the shots, looks like the distance is going to be before infinity. Say the chair and back hedge/wall are around 20' away. So, you want a DOF from 20' at the farthest distance, to as close to possible to the nearest object you want in focus. I guess you could skip the distance to the chair, and figure you'll likely get a far distance of Infinity at f16 or f22. If everything is focused to infinity, and the nearest object you want in focus 4', then the chair will be focused at 20' since everything from 4' to infinity is in focus anyway. Doing the shot with the charts, calculators, would likely give you the hyperfocal distance to use in that case- and that is where you would focus.
But before all that stuff try the easier way: focus on chair and use an aperture of around f16 and f22. See what that looks like, say two shots f16, f22. Maybe do f10 also.
Then you could try two of those exactly the same but with the old "1/3 in" suggestion. We'll say with an aperture of f16 or f22 there's a good chance the DOF runs to infinity - an educated guess without using calculators. But now instead of focusing on the chair, shoot one pix at f16 and another at f22 with the camera focused one third of the way out from the nearest focused object (which from an educated guess is maybe 10'. So, from 10', go out by 1/3 of the distance in front of you towards the rear of the area). This technique will sometimes give you more focus close to you than you would have had, while keeping the far focal point at infinity because infinity doesn't come closer to you (but the near-focal point will). You're really shifting the DOF near-distance point in towards you by one-third and thus making the near-focused area reach further in towards you. It helps in some situations. Worth the experiment.
If none of these 4 or 5 shots look good, then hit the charts and calculators. I bet some will do the trick though.
-universal calculator with some directions for converting digital zoom lens to the DOF criteria for the chart.
[url]hcttp://www.dofmaster.com/dofjs.html[/url]
And another based on camera name and that gives you a chart of values to work with:
http://www.dofmaster.com/doftable.html
It's a tough job trying to keep all of a relatively small area in focus, a room, or a yard etc. I sympathize.
PS:
I had it posted already on my Smugmug site (www.finnegan.smugmug.com) and pasted a link from there. Above the photo, there's a view of the web pages of your site after you loggin that includes a choice for "Share", and you can choose under that: "get a link".
Get the link for "large" view of the photo you want, on the forum message-template is a yellow icon for "insert image" on top. That's where you can paste the photo link, and the it will go in the message. Click "OK" on Insert Image. When you post the message, a photo will show up where the link was placed. (Place the cursor in the message box where you want your photo first. Then do the paste of the link into "Insert Image")
Again, thanks for the comments. I was focussing at infinity, using a tripod, and going through all the apertures. Is there a lack of focus throughout? the reason I ask this is that I only have the stock canon 18-55mm and Tokina 11-16mm to compare against. And I can't honestly say one demonstrates better sharpness than the other In similar tests. That said the Tokina is a much more expensive lens, and I need to ensure it is up to scratch (e.g. not a poor example). It was a windy day, and the light was constantly changing, but it gave me the seeds of understanding regarding DOF. NB these are some of the first pictures I have taken with the Tokina. I have to photograph an showroom with items hanging on the wall all around, about the same space as my back garden, hence the dry runs. I think I will start again and come up with a more decisive, simple test/s e.g. focussing at infinity V,s focussing at suggested hyperfocal distance etc, oh and take and post much better shots. Thanks again.
Sure. But why not try a few like i suggested: focusing on the chair at f16 and another f22.
Then do another two shots at f16 and f22 while focusing 1/3 rd of the way "in" towards the "rear" of the shot, in the case of your shot: 1/3 of the way in towards the chair (like if the chair was 30' away from you as you look at it, the focus would be 10' away from you. Just focus on the grass at that point, lock the focus and raise the camera back up level to the framing you want).
Here's an article about this "one-third" method http://digital-photography-school.com/where-to-focus-in-landscape-photography (note what it says about a shot - like yours - with a specific object that should be in focus at the farthest point away from you; i.e., this method may not work in such a case. But even so, give it a try as an experiment.)
My suggestion would give you four shots: f16 and focusing sharply on the chair; f22 and focusing sharply on the chair;
f16 and focusing 1/3 of the total distance in; f22 and focusing 1/3 of the total distance in. You could also do the same with two shots at f10 if you want.
I will be photographing a room roughly 20M deep and 10M wide. It has artifacts (different colors) hung on the walls all the way round, a bit of natural daylight coming through a window behind where I intend to take the shot (end of the room) 3 to 4 tungsten spots highlighting a few areas in the room and some office type strip lamps. I can't really change position of the shot (for many reasons) and at best turn the spots of (but not move them). I will be using the above camera with a Tokina 11-16mm lense (brief is to get as much room as possible in the shot) and a tripod. And for what its worth probably (after much help and advice from the forum) an hyperfocal distance between 1.2M-0.61M f11-f22 and will also give the one third rule a bash.
Question: Which Metering mode should I use e.g. Evaluative, Partial or Center Weighted Average?
So far in my limited career I have used evaluative, but this room is probably the most technically demanding picture I will have taken. Any input regarding this would be most welcome, also any hints and tips. Thanks
Fridge:ian
And finally are the hyperfocal distances given at the bottom of the f stop columns on the chart for all the
distances above them e.g. one hyperfocal distance covers all above?
Please help if you know that table as it is integral to what I am currently doing (re previous posts)
Thanks,
Fridge.:cool
Don't know your camera so what metering mode is a ?. What looks best under similar lighting you may have shot in the past?
The difference in DOF, hyperfocal and all that are minimal whether it's 16mm, 18mm or 11mm. Shoot with an average if you're using different ones, or if one use that - but you should have plenty of focused area in any of those with a high f-stop, the lens is so wide.
You shouldn't just use hyperfocal distance or the "1/3 rule", but shoot some shots focused on the farthest object, and some focused on an object say 3/4's of the way in. At those distances the hyperfocal stuff may not give you what you want, nor the "1/3 rule" (the latter i've only used in certain situations outside for landscapes.) So, don't depend on either as the things may be focused but nor really sharp.
Long as you're using a high f-stop, f10 or beyond, likely around 16, and you have a tripod, it should be OK.
Take a look though at whatever shutter-speed you need with those apertures. If it's really long, like beyond a few seconds, which is unlikely in a brightly lit store, then use some f-stop that'll give you a faster shutter speed while still keeping a higher depth of field. Long sutter speeds and your camera I take it is an unknown.
If you can go to the place ahead of time, least a day or so, and to some sample shots, or a few in a similar area, it'll help. Even just to look at it carefully if you can't use a camera.
Also depends on what objects are in the store and what you focus on. A huge print on a far wall would obviously be what would pull the eye in, so in that case, focus on that. Again, go to the place first- even without a tripod and shooting a few hand-held, experimenting on shutter speed, focus-point etc. Makes it a lot easier.
Hi,
Metering mode A is (re manual) all around metering mode suited for portraits and even backlit subjects.
I have done a reckie and took some hand helds. I didnt know about depth of field and wide angle lenses then (previous posts) etc.
Problem with focussing at different places is Canon method of locking focus requires keeping shutter button half pressed down.I will have to move the camera+tripod to allow focus at suggested points and then re position to take the shot whilst keeping shutter button half pressed down (I do intend to go over this again to make sure I read it right). just to clarify the room is semi partitioned with stock and am shooting down the middle to get as much of L+R sides as possible. This is why a manual focus point shot at f8 / f11 / f16 seemed promising (but if you read my previous post not even sure if I am entering the correct data in the dof chart). Thanks for your help.
The physical size (** pixels X ** pixels) of the photos need to be larger to be able to evaluate them properly.
If photoshop all you need to do is when you go into file and down to save for the web and that will give you options for saving at different sizes and quality...........
Focus manually.
Don't get so hung-up about all this hyperfocal, depth of field stuff. Just use a higher aperture and focus manually at the back if he wants you facing down the center isle of the store. If you want to try a couple with the "one-third" and at the hyperfocal, sure then try 'em. The rest is just your own eye, have fun with it! By the way, in your shot, for all practical purposed the hyperfocal distance is about half way between you and the back of the store. Back of the store we think is ininity.
My process would be:
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Did the shoot by the numbers (charts etc) bad move. I was shooting in a 30meter X 20meter box. Neon lamps, halogen spots, shiny surfaces around the walls. I am an amateur. With a big wide lens. It was like on the buss's, Open all hours, Benny Hill. Looking at the pictures, I realized how little I know.
I will learn more.
Fridge. (And try Harder).
Best thing to do to learn: take a lot of photos, anywhere, anything that interests you. Use the bits of broad principles you know - but then learn by doing it, or you get all hung-up with 10 dollar words, rules, settings etc. and don't enjoy it. I'd just put the camera on manual and experiment around. After a bit of that, read a little about technique, or find out specific answer to a situation you had shooting; then dump that all, go back and shoot more and apply a few other technique hints. Remember, modern day cameras are complicated, but you can go back to the simplicity of earlier days, just play with finding nice exposures, focusing, a little playing around with depth of field.
After awhile, if you want you can go thru some of the 1000 pages of instructions modern cameras have. But shoot for now like it was 1955.
Regarding the shoot, I wanted to do it as a favor for a friend, just because I wanted to learn. I have decided to go back (minus tripod and DOF numbers) and shoot it real rock n roll style. I am also going to change the exposure metering mode to spot, so the camera's focus is not getting pulled all over the place. I think the stock lens will force more creative shots due to its limitations, and the Tokina is going back to the manufacturers if I am still not happy with it. I have kept the cheap Canon 18-55mm lens that came with the EOS1000D I have traded in (The camera wasn't at fault, but it was too light) The 50D just looks and feels rock n roll, and its a bit better quality, thats important for me. Again, great words and on the money. I will nail this,
Thanks all,
Fridge
Another good thing is to go to a good fine arts library or that section in a good comprehensive library, internet is OK too but prints in a fine photography book are much better. Look at work of the great photographers of the last century. Often they were using very simple cameras (very GOOD cameras but simple) and using basic principles of composition, light, space, depth etc in conjunction with the lens to produce monumental shots. The camera is the eye, so train the eye.