Depth of field

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I fully aknowledge that I am on the amateur end of the scale when it comes to photography but it is something I enjoy and I have just recently been able to afford to buy some new equipment.

I am switching from a Canon A1 to a Rebel 2000 system and have some questions about depth of field. I realize that many of you may feel I should have gained a little more experience with the A1 before switching so please don't overload my inbox with such replies. ;-)

My question is....

How are you supposed to know what is going to be in focus??? On my old lenses the depth of field was printed on the barrel. I could tell how far the object I was focussing on was and then the scale would tell me (roughly) what would be in focus on either end (far/near) The new lenses don't have this information. I can download calculators and the like but they are pretty useless without actually using a tape measure. Am I missing something or is this a really big omission for the new lenses? Seems like it wouldn't have been that difficult or expensive to include.

P.S. I realize some of the lenses still do have these scales but I can't afford to buy L series lenses!!! I haven't seen it on any of the other ones I have looked at.

-- Scott Culp (dsculp@sympatico.ca), February 06, 2002

Answers

Scott,

Welcome to the world of EOS, where there are numerous choices to be made. Yes, I agree with your frustration. Canon kit lenses are very difficult to use; they lack DOF and distance scales, the manual focus rings are tiny if not non-existent and they feel pretty awkward. But do not despair, there are non-L lenses that have distance and DOF scales. Take a look at the canon page at these lenses. They are all zooms, so they will lack clearly defined DOF markings, but they will give you distance information. The 28-105 USM is a nice lens that can be found used for around $200US.

Roger

-- Roger S. (rashrader@hotmail.com), February 07, 2002.


http://www.usa.canon.com/eflenses/lineup/standard/index.html

Sorry

-- Roger S. (rashrader@hotmail.com), February 07, 2002.


I've heard that it's difficult to put DOF indicators on zooms that are not push-pull designs. I don't really know. I do have a Sigma 17-35 HSM with good distance marks and a decent DOF scale for both the wide and long ends of the zoom. I also have a Canon 35 f/2 with good distance and DOF scales. The Canon 85 /1.8 has a distance scale but only has a pair of f/22 marks for the DOF scale. It's problem is the focus rotation is too short to put many marks on it. A decent compromise in order to get faster AF.

The Rebel, and other Canon EOS cameras all have a DEP mode that does determine the distances of two separte objects and then sets the aperture and focus so that they will both stay in focus. By using it, you can determine what aperture and focus distance to use manually or let the camera do it for you.

The problem is with how DEP is implemented on the Rebel. With the older ones you had to get two AF points to line up on your near and far objects at the same time. I can only assume it's still the same way for the Rebel 2000. With the more upscale Canon's you use any or just one of the AF points to set the dear & far distances one at a time. Considerably easier.

I guess Canon figures that since they give you DEP mode, you don't really need a good distance and DOF scale. I wonder what Minolta, Nikon, Pentax's excuses are?

-- Jim Strutz (j.strutz@gci.net), February 07, 2002.


hi there scott...

the canon eos300/Rebel-2000 has something called a "Depth of Field Preview" button. when u click on that button, the lens closes down to the aperture u have set and u can see what is in focus and what is not. understandably the viewfinder gets pretty dark at very small apertures and at wide apertures the difference is barely discernible. i think u should be able to see some effect when u keep moving from f4-f8 or something provided u have enuff light.

well..thats the way its supposed to work anyways... :-) i particularly have not found it very useful. its pretty useless in low light conditions as the view finder gets really dark.

ciao

-- Venkat (venkat_p_iyer@yahoo.com), February 07, 2002.


hi there...

i wonder how much that DOF scale is useful. since i have never used it i don't have much idea about it. but i have used the DEP mode as well as DOF preview button to set the apperture. that gives me good estimate of how much of my picture would be focussed, though it may not be very accurate. i also wonder where you can use that DOF scale. i mean, may be in macro or close-up photography where you know approximately how much DOF you need.

hey venkat... what does that "ciao" you write at the end of every comment means.

-- sajeev (chack74@yahoo.co.in), February 07, 2002.



The best way to figure depth of field, I'm afraid, is to learn how to estimate it visually. You can get a feeling for it using those online calculators, then practice with sample shots until you know what f/8 looks like vs. f/5.6.

Your learning curve will be steeper, as you have discovered, if you do this with your A1 that has DOF markings on the lens barrel.

Those markings also assist zone focusing: pre-focusing the lens manually before shooting, like a street photographer with a Leica.

Canon obviously thought that auto-focus and other computer-assisted stuff would eliminate the need for the guesswork inherent in those old techniques.

Ciao and Namaste!

-- Preston Merchant (merchant@speakeasy.org), February 07, 2002.


i still didn't understood whats CIAO. is it BYE or NAMASTE ????

-- sajeev (chack74@yahoo.co.in), February 08, 2002.

Ciao, like namaste, is a universal hello/goodbye. It's Italian, deriving from "schiavo" meaning "(I am your) slave."

"At your service" might be a more modern translation, though really it's just hello or goodbye.

Linguistics in the global village!

Cheers!

-- Preston Merchant (merchant@speakeasy.org), February 08, 2002.


A DOF scale on the lens barrel is extremely useful and convenient. Unfortunately, Canon does not provide one on their zoom lenses (and on the 50mm 1.8 II).

I ended up carrying a hyperfocal distance scale (converted to feet): http://bobatkins.com/photography/technical/doftable.html

The scale is pretty useless without at least a distance scale on the lens, and Canon in its infinite wisdom decided that people who buy inexpensive lenses don't need a distance scale. Fortunately, most of canon's non "L" primes and mid-level consumer grade zooms do have distance scales. 28-105USM, 24-85USM, 28-135USM, 20-35USM, and 100- 300USM all have distance scales. These are all much better lenses than the cheapo 28-80 or 28-90 kit lenses, and will feel more like "real" equipment. Will not feel quite as solid as your FD metel barrel lenses. I would hold on to the A1 (its a real nice camera).

-- Kenneth Katz (socks@bestweb.net), February 08, 2002.


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