| We hope you enjoy your visit. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free. Remember to visit our welcome thread here: Member Welcome Thread Join our community! *Flashing News*Email trigger on Alphadslr forum is now working. To setup the email trigger for your account: Just go to preference, select "Email & Subscription Settings" and Topic/Forum subscription alert type as "Alerts by email".. For thread tracking, you need to manually enable it for each thread. Once you're viewing a thread, scroll down to the bottom of the page. Locate the option "Track Topic" which appears to the left of the Board Time. From the page that loads you can select the notification type you want. |
| Landscape Photography; Getting the right Focus | |
|---|---|
| Tweet Topic Started: Apr 27 2009, 11:01 AM (1,397 Views) | |
| lenrek | Apr 27 2009, 10:03 PM Post #11 |
![]()
--9-6-1-8-9-5-5-6--
|
Awesome link! Hmm... This mean, whenever I select a particular F, I need to adjust the focus distant proper. I think I begin to understand the explanation given in the CS thread. |
![]() Lenrek's Blog, Facebook, Flickr | |
![]() |
|
| lenrek | Apr 27 2009, 10:04 PM Post #12 |
![]()
--9-6-1-8-9-5-5-6--
|
Me this sat not free. Need to go back hometown. Mother's Day... |
![]() Lenrek's Blog, Facebook, Flickr | |
![]() |
|
| FrederickYKFoo | Apr 27 2009, 10:15 PM Post #13 |
![]()
Alpha Carl Zeiss Member
|
It is okay. Just PM me when you can. I am not great in Landscape Photography or an expert. It is not my specially. But I can help to explain practically on DOF & Hyperfocal for Landscape Photography. But not in writing. Edited by FrederickYKFoo, Apr 27 2009, 10:18 PM.
|
|
It is okay to be slow, as long you never stop. Start and teach Photography since 1982 | |
![]() |
|
| Clem | Apr 27 2009, 10:20 PM Post #14 |
![]() ![]()
|
Well, let’s start from the beginning. I’m sure you guys are pretty familiar with DOF (Depth of field) by now. We all know that when the aperture gets smaller, the DOF widen. Also, for wide angle lens, the DOF is always wider than the tele lenses at the same aperture. Now the basic principle is illustrated in Diagram 1. Simple and straight forward. No sweat. ![]() The second diagram show how the majority of us will focus when we shoot landscape. We usually focus to infinity and step down the aperture as small as possible and hope that the DOF will be wide enough to cover the foreground. Now, of cause most of us will probably use a wide angle for such occasion and indeed the DOF can be pretty wide. ![]() But what if we decide that we would also like to include trees number two and three to be in focus? Can it be done? Well, we're in luck. It’s called (well you should now it by now) “Hyperfocus”. Pretty intimidating word huh? What it really means is that at a particular hyperfocus distance, anything from one half of that to infinity will be in focus. The distance is again dependent on the focal length and achievable aperture. If you have the old type of lenses where you have the marking, you’re in luck. But you’ll still need to learn how to read it of cause. But if you’re using the modern lenses, then you are out of luck. You’ll need to make a table using computer programs that are available in the internet, print it out and carry it with you all the time. Please also note that for the same lens, the hyperfocus length is different when you use APS-C size or FF camera. If you have both, then good luck. This is how it works. ![]() Instead of focusing to infinity, you now focus on the third tree and make use of the “extra” front focusing reach of the hyperfocus length. Lo and behold, the second tree is also in focus. Isn’t that amazing? For live demo, our bro Frederick is so kind to volunteer his service. Please do contact him and have a good time over a cup of coffee or Tea.
Edited by Clem, Apr 27 2009, 10:32 PM.
|
![]() |
|
| lenrek | Apr 27 2009, 10:45 PM Post #15 |
![]()
--9-6-1-8-9-5-5-6--
|
Thanks bro Clem for the explanation. For APS-C, does this mean, I need to multiply the crop factor into focal length? So a 50mm would be cal as roughly 75mm?? EDIT: I always thought the calculator in my phone is useless, now, it has a new purpose.
Edited by lenrek, Apr 27 2009, 10:46 PM.
|
![]() Lenrek's Blog, Facebook, Flickr | |
![]() |
|
| Mino | Apr 27 2009, 11:26 PM Post #16 |
|
Alpha Elite Member
|
There is on-line DOF (Depth of Field) Calculator and also available in PPC version which very useful outdoor. Things to input: 1a. Camera, film format, or circle of confusion: -----Use the actual focal length of the lens for depth of field calculations. -----The calculator will automatically adjust for any "focal length multiplier" or "field of view crop" for the selected camera. 1b. Focal length (mm) 1c. Selected f-stop 1d. Subject distance (m) Calculate: Will give Depth of field 2a) Near limit 2b) Subject distance [Reference or your focus point] 2c) Far limit 3a) Hyperfocal distance The concept of hyperfocal distance is easy to understand: focus a lens at the hyperfocal distance and everything in the photograph from some near distance to infinity will be sharp. Landscape photographs are often taken with the lens focused at the hyperfocal distance; near and distant objects are sharp in the photos. When the lens is focused on the hyperfocal distance, the depth of field extends from half the hyperfocal distance to infinity. Photography, Phil Davis, 1972. The hyperfocal distance is the point of focus where everything from half that distance to infinity falls within the depth of field. John Shaw's Landscape Photography, John Shaw, 1994. Circle of confusion 0.02 mm |
![]() |
|
| Clem | Apr 27 2009, 11:31 PM Post #17 |
![]() ![]()
|
Not so simple bro. Do a search on the internet, if you want the full story, it's kind of complex. But basically, if you can find the DOF calculator, just tabulate the data accordingly. The Calculator will definitely ask for the camera format. There's one hyperfocus length that I can remember clearly and is very handy when it comes to indoor shoots. Set your 17mm at f4, and focus at 3m, the hyperfocus length is from 1.5m to infinity. That's for APS-C size. Great for dinner table shots. No need to focus...
|
![]() |
|
| Mysilentkaopei | Apr 27 2009, 11:36 PM Post #18 |
|
Resident Kaopei Kia
|
whoa i think this one really need outing liao... shall i? bro frederick, you're free all saturday mornings right? |
|
MyFlickr MySilentKaopei WTS: Commemorative Coin Set "Macau Returns to China" ![]() | |
![]() |
|
| lenrek | Apr 28 2009, 12:35 AM Post #19 |
![]()
--9-6-1-8-9-5-5-6--
|
Wow... Not simple ah... I found a few links that cal DOF. Maybe will print the table based on my current lenses, and try it on my next landscape shoot. |
![]() Lenrek's Blog, Facebook, Flickr | |
![]() |
|
| lenrek | Apr 28 2009, 01:29 AM Post #20 |
![]()
--9-6-1-8-9-5-5-6--
|
Just a side note from this discussion, there was another discussion @ CS regarding the new 50mm DT from Sony. Someone in the thread complained that the new 50mm DT is still 75mm on APS-C which is not a "real" 50mm lens. He expressed his "frustration" that such design is not proper for APS-C camera body. Can read about here: http://www.clubsnap.com/forums/showthread.php?t=491098 At the time, I also don't understand why a lens that is design for APS-C still maintain the crop factor. I think I understand now. By looking at the DOF calculators I found from the net, if this new DT lens is indeed a "real" 50mm lens, I think it will screw-up the established calculation of DOF. Anyway, I did a little search from the net, and found this DOF table generator the best: http://www.dofmaster.com/doftable.html Edited by lenrek, Apr 28 2009, 01:31 AM.
|
![]() Lenrek's Blog, Facebook, Flickr | |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| Go to Next Page | |
| « Previous Topic · Newbie corner & website links · Next Topic » |















8:32 AM Jul 11