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05-30-2011, 08:07 PM   #1
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using distance markers (focus ring) in the lens

Can somebody tell me what the distance markers indicate and how it can be used in our photography workflow.
Does these numbers indicate that it is the starting from where we get things into focus or that is the exact point where we have the subject that can be in focus? What does the infinite marker signify that when i place the ring there that i get everything in focus?

05-30-2011, 08:19 PM   #2
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Think your question can be answered here but if you need more information somebody here will help.A lot can be learned by playing with the depth of field calculator on the site.
Jake
Understanding Depth of Field in Photography

Last edited by bjake; 05-30-2011 at 08:24 PM. Reason: addition
05-31-2011, 01:20 AM   #3
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The distance markers are in a sense a left-over from the "good old manual days": If your subject is at 5 meters distance, you set the distance marker at 5 meters too. (And, in fact, we could have separate distance meters at that time). The infinity setting is no different: That is just the setting for things very far away.

But then, as bjake indicates above, there is also the question: How much of the scene in front of and behind my focus plane (say the 5 meters mentioned above) will be reasonably in focus. That depends upon the aperture, the more you stop down your lens, the deeper will be the field where you have decent focus - we talk about Depth of Field (DOF).

On old, manual focus lenses there are additional marks to show just that. On modern (autofocus) lenses where everything is automatic, you will rarely have that, but you should still learn about DOF and consult the link shown by bjake above.
06-03-2011, 03:33 PM   #4
hcc
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Distance markers on the focus ring can be very useful in some situations. All would apply to MF and/or MF lenses. Let me illustrate two examples where I was very glad to have the focus ring

*Example 1
I was taking some shots of droplets and splashing in some (kind of) fountain. I had to place the camera in a 'tricky spot' and I could not view either the VF nor the LCD. Simply I was 'blind' and could not see ay camera indicator. Using the distance marker, I set the distance from lens to place where I wanted to photograph the spashing. After a few tries, I was able to get some nice shots that I would never have been able to take with AF nor with a focus ring without distance.

An example is in my gallery: look at the droplet stretching...



*Example 2
I shot volleyball players in a poorly lighted hall a fortnight ago. The only option was a MF fast prime to have a decent shutter speed. Since I knew the VB court dimensions (9m by 9m), I set the focus ring at the distance between the player (I aimed) and myself. Then I would do only minor focus ring adjustement to get some good shots.

More generally, I find the distance markers very useful in low light/poor light when working in MF. I set the lens focus ring to an approximate distance and do only minor adjustements around a mean position.


Hope that the comment will help.

06-04-2011, 02:43 AM   #5
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Yes hcc, that example was indeed very useful and makes things clear further!
06-04-2011, 05:11 AM   #6
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I use the marks to preset the focus when shooting manual lenses so it is close to what is needed. That way you don't waste time on focus acquisition with a long focus throw. I also use it for manual flash calculations when shooting old lenses on bodies that only support p-ttl
06-04-2011, 08:17 AM   #7
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Distance marks are much more usable on 1) wide lenses, and/or 2) long-focus-throw lenses, which tend to be old MFL's. And the marks are most UN-usable on short-throw teles. You can judge the usability of the markings for any lens for the focal range you intend to use: If the marks are jammed together, good f*cking luck. You might as well stop-down for thicker DOF.

Good lens: I often set the aperture on my Tokina 21/3.8 to f/11 and prefocus to 2m, for sharp DOF from 1m to infinity. Good for P&S action on bright streets, eh? Bad lens: When I zoom-out an old push-pull Kiron 80-200/4.5, all the distance marks are just about useless. Point'n'pray, eh?
06-04-2011, 08:29 AM   #8
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How relevant are the distance markers with lenses meant for older 35 mm cameras? Isn't there about 1 FStop difference in effective aperture - not sure which way?

06-04-2011, 10:55 AM   #9
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QuoteOriginally posted by Bill_R Quote
How relevant are the distance markers with lenses meant for older 35 mm cameras? Isn't there about 1 FStop difference in effective aperture - not sure which way?
The relationship between DOF and format is difficult at best. Native DOF of a lens does not change but you reframe images with the change in FOV for different formats and changes in print enlargement

But the focusing distance itself is independent of format
06-04-2011, 07:59 PM   #10
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As Lowell said, it's tricky. I generally use a 1+ f-stop factor. So if I set the aperture to f/11, I read the distance scales a bit below the f/8 marks, say around f/7, especially if I want DOF to infinity.
06-04-2011, 08:24 PM   #11
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QuoteOriginally posted by RioRico Quote
As Lowell said, it's tricky. I generally use a 1+ f-stop factor. So if I set the aperture to f/11, I read the distance scales a bit below the f/8 marks, say around f/7, especially if I want DOF to infinity.
So, it's narrower than indicated - I had forgotten which and was too lazy to look it up.
I reckon it would be an excellent learning tool to still include the markers on lenses - one plus of Pentax and using older lenses, you can get the indicator and then the "feel" without going to DOF preview or reviewing an image. I wonder of they have DOF charts for newer lenses.
06-05-2011, 05:11 AM   #12
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Bill I think there are dof charts and calculators you can download or access on the net. There might even be an iPhone app
06-05-2011, 01:23 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
Bill I think there are dof charts and calculators you can download or access on the net. There might even be an iPhone app
Thanks Lowell. Don't use an iphone. I can find one for Android but my Android Tablet is a bit too big to lug around. Will look for charts to print.
06-06-2011, 05:43 AM   #14
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QuoteOriginally posted by Bill_R Quote
Thanks Lowell. Don't use an iphone. I can find one for Android but my Android Tablet is a bit too big to lug around. Will look for charts to print.
I have an I-Pod, which has, among other things all my camera manuals, birding guides, ald a ton of other data. but I agree a tablet is too big for going out in the field. I am looking to do some charts for flash as well. DOF charts would be interesting but the question is, if you print enough of this data you have a book the size of the tablet. The tablet in the end is more useful than the book, once you get to that size of print out
06-06-2011, 04:35 PM   #15
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QuoteOriginally posted by RioRico Quote
As Lowell said, it's tricky. I generally use a 1+ f-stop factor. So if I set the aperture to f/11, I read the distance scales a bit below the f/8 marks, say around f/7, especially if I want DOF to infinity.
I do the same thing. I think digital has raised the bar on "acceptable sharpness", so if I am on f/11 aperture, I'll be reading the DOF on the lens as it I was using f/8.

The 2 situations I use the lens markings to preset my focus is for landscape and for street photography where in both cases AF is more a hinderance than a help. I agree it is a lot more usful for wide lenses.
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