In the last two articles, "Achieving critical focus with digital SLR cameras" and "depth of field test DSLR" I discussed the basic principles that determine the optical depth of field (DOF) and showed how remote camera of the subject, the focal length and f-stops are connected. I've also shown as evidence to demonstrate a series of field DOF tables, and how it all works. If you have not already done so, please read the previous two articles, to ensure that you are absolutely clearCooperation between the camera subject distance, focal length and aperture.
In this article I will discuss the situation, the condition of fire called Hyperfocal distance (HFD) and how you can use it to today's digital SLR cameras, where depth to reach the absolute maximum for each. hyperfocal focus allows you to create a depth of field within the next possible date covers the camera to produce through the infinite.
DSLR
maximum depth of field allowsThey are subject to relative scale as a creative element to be used in the compositions, all while still tack sharp. Since the relative sizes of objects projected onto a flat plate, namely, the "film" or "sensor" is based on their position relative to the camera, objects closer to the camera appear larger than the distance. If you focus on both might be able to produce an almost tactile objects near to them on a scale much larger than the distanceObjects. A good way to do that is you try to place the camera on a fence along, while everything in sight. Not only is a geometric convergence of parallel lines, but near objects with maximum texture and detail.
hyperfocal distance is that particular attention has been achieved in the clear focus of half the hyperfocal point of focus to infinity. In other words, I do not know if the HFD on the given focal length and aperture and focusE 'then all of half that distance to infinity.
Well, here's the crux: HFD calculates only three numbers, the focal length of lens used the f-stop and the circle of confusion. The circle of confusion is a number that can be obtained from a reference table and does not vary. Basically, if you want the DOF to expand from the nearest point to infinity in a small aperture you shoot anyway, so you do not mind the wider goalAperture. I table the HFD for a 50 mm lens, I often run in my brain is fired, the F-22 by 20 feet and that half of the HFD HFD's 10 '.
This is my rule of thumb for this purpose: to 50mm, if I focus on 20 'I know that everything from 10' to infinity died hard. According to the rules of perspective, I know that a 50mm lens when focusing on the HFD F-22, produced a strong image of 10 'to infinity. I also know that I did not get closer than 10 'andstill extend my focus to infinity, it becomes a bit 'less, but not infinite. I do not need any other tables or calculations for this goal when I'm with F-22, I used to work in the landscape. I fit all my other similar data for the first lenses and all on a laminated card that fits in your pocket!
To better understand the impact of the above, I recommend if you have not already done so, go to dofmaster.com and print a graph of depth for a Canon30D, 50mm lens. If you read the distance scale on the extreme left to 20 meters and then move right onto the page for the F-22 column shows that the focus of the 0.7 9'-9 "and the focus of much infinity is touched. You can also to extract from the consideration of one of the following table, that if I concentrated on 18 to say 'my point of focus is around 0.6 9'-3 ", but my focus is 276 away, 'but not far infinity! If I move to 20 'which is calculated by the HFD, I touch eternity. If I focus on more than 20 ', my next goalmoves away from the camera to infinity.
50mm lens @ f22
Focus Distance .................. Near the point of focus ............... Far Focus Point
18 ................................................. 9'-3, 6 "................................. 276 '
20 ................................................. 9'-9 0.7 "................................ Infinity
30 ................................................. 11'-8 ".................................. Infinity
To completeTheir understanding of HFD, http://www.dofmaster.com go to their computers and download free HFD. Enter all the values on the data screen is easy enough if you do not need at.019mm the circle of confusion, you should initially set for the most portable digital cameras. If you want to know the circle of confusion, it can be read on the site further. In any case, the screen of the program, and the graph HFD.
For my 50 mm lens, set the circle of confusion at.019mm:my table reads, and I can calculate the focus close to ½ ", the HFD as:
f-stop .................. HFD .........................½HFD
2.8 ....................... 150'........................ 75 '
4 ............................ 110'................... ... 55 '
5.6 .......................... 80'..................... .. 40 '
8 .............................. 55'................. ....... 28 '
11 ............................ 38'................... ... 19 '
16 ........................... 27'.................... .. 14 '
22 ............................ 20'................... ... 10 '
I hope the above has beenuseful to understand the mysteries of the fire is useful in applied optics. Now go out and shoot some (well focused) scenes.
Thanks again to Don Fleming on the installation and maintenance dofmaster.com a wonderful site that has all kinds of candy and free information and DOF and related topics.
DSLR and the hyperfocal distance
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