Canon LTM Appropriate settings for a 28 mm lens?

[wrs1145]

I have a 28mm lens and would like to know the appropriate settings for it. For example: if you set a 25mm lens at f8 and 3.0m, then everything from 1.5m to infinity is in focus. What are the corresponding numbers for a 28mm?

Thank you very much,
Bill

 

[boojum]

I have a 28mm lens and would like to know the appropriate settings for it. For example: if you set a 25mm lens at f8 and 3.0m, then everything from 1.5m to infinity is in focus. What are the corresponding numbers for a 28mm?

Thank you very much,
Bill

I have never heard of a lens without that on it. You are talking of depth of field.

28mm depth of feld chart at DuckDuckGo

DuckDuckGo. Privacy, Simplified.

duckduckgo.com

 

[Coldkennels]

Going by the depth of field scale on my Voigtlander 28mm f/3.5 Color Skopar:

About 5m and f/5.6 gets you about 2.5m to infinity.
About 3.5/4m and f/8 gets you about 1.6m to infinity.
About 2.5m and f/11 gets you about 1.2m to infinity.

But:
a) depth of field scales aren't always accurate, so it's generally best to use the next stop along when it's critical (i.e. use f/8 and assume you'll get the results from the f/5.6 section of the DoF scale, and
b) not every lens of the same nominal focal length will have the same DoF or same DoF scale. For example, the 28mm f/6 Orion-15 claims a slightly tighter depth of field at all stops compared to the VC28. It's always best to test each lens you use instead of relying on generalisations.

 

[Coldkennels]

I have never heard of a lens without that on it. You are talking of depth of field.

Modern focus-by-wire lens typically don't have a focus scale. No first-party Fuji X lens does, for instance. It drives me insane.

 

[Darinwc]

"in focus" is dependant on how sharp you want it to be. Even at F-16, there is a difference between 3 meters and infinity.
And that will also depend on the aperture you select.
There are online calculators available.
Search for hyperfocal calculator.
For a 28mm lens at f8. Set the lens at 4.86 meters and everything from 2.5m to infinity will be in focus. -according to the first calculator I found, but it did not show what the circle of confusion was used.

 

[SWB]

I have a 28mm lens and would like to know the appropriate settings for it. For example: if you set a 25mm lens at f8 and 3.0m, then everything from 1.5m to infinity is in focus. What are the corresponding numbers for a 28mm?

Thank you very much,
Bill

There is only one place in focus, the thing you've focused on, but using the depth of field scale and a smaller aperture other things in front and behind that point (one third in front, two thirds behind as a rough guide) become 'acceptably sharp'. What 'acceptably sharp' is varies from person to person.

 

[Freakscene]

There is only one place in focus, the thing you've focused on, but using the depth of field scale and a smaller aperture other things in front and behind that point (one third in front, two thirds behind as a rough guide) become 'acceptably sharp'. What 'acceptably sharp' is varies from person to person.

There is no such thing as a point or place of focus; only blur circle.

 

[DownUnder]

A mentor I had a long time ago told me that when I was photographing landscapes, it was best to ignore any depth of field scale and leave the lens on infinity (= the '8' symbol). Which gave the image some depth of field in the medium ground but at the same time let the foreground look after itself. A little out of focus part in a landscape does give it 'character', tho' I suspect many will differ with this.

He did add that relying too much on the DOF at settings like f/5.6 or f/8 tended to put everything in the negative not quite sharp. To this day I've never found any confirmation or more importantly an explanation for this. And it may be more a factor with the roll films of yesteryear than today's more modern 35mm.

I suspect this old rule may have dated back to the days when films were infernally slow (does anyone here recall Kodachrome at ISO 10?) and getting it all sharp on a negative was more a random act of the universe than a technique.

Otherwise, with a 28, as with almost all wide angle lenses, the best rule of thumb I can think of is, "f/8 and be there"...

 

[JohnGellings]

Modern focus-by-wire lens typically don't have a focus scale. No first-party Fuji X lens does, for instance. It drives me insane.

But this is in the Canon LTM group …

 

[Coldkennels]

But this is in the Canon LTM group …

I was aware of that. I was merely pointing out that "I have never heard of a lens without [a depth of field scale] on it" isn't accurate nowadays.

With regards to DoF, there's something else that needs to be taken into consideration: diffraction. As much as Ken Rockwell drives me nuts, this shows the issue well: Nikon 50mm Lens Comparison

You might be getting more "depth of field" at f/8, f/11, or even f/32, but that doesn't necessarily mean you're getting the most sharpness out of any point of the image. (This might be what your guy was on about, @DownUnder.) Again, it's always best to test your own lenses and viewing the results in the format you prefer to see what works for you. Something might look okay at f/22 on a 5x7, but it probably won't at 12x16.

 

[stuart_115]

Going by the depth of field scale on my Voigtlander 28mm f/3.5 Color Skopar:

About 5m and f/5.6 gets you about 2.5m to infinity.
About 3.5/4m and f/8 gets you about 1.6m to infinity.
About 2.5m and f/11 gets you about 1.2m to infinity.

But:
a) depth of field scales aren't always accurate, so it's generally best to use the next stop along when it's critical (i.e. use f/8 and assume you'll get the results from the f/5.6 section of the DoF scale, and
b) not every lens of the same nominal focal length will have the same DoF or same DoF scale. For example, the 28mm f/6 Orion-15 claims a slightly tighter depth of field at all stops compared to the VC28. It's always best to test each lens you use instead of relying on generalisations.

I've checked a Senerar 28mm lens, and got the result in feet:

About 14ft and f/5.6 gets you about 7ftm to infinity.
About 9.5ft and f/8 gets you about ft to infinity.
About 7ft and f/11 gets you about 3.5ft to infinity.

Which is more or less the same as the Color Skopar.

 

[Rob-F]

There is no such thing as a point or place of focus; only blur circle.

I don't know why you said this. There is just one distance at which the subject is truly in focus. So the part of the subject which is at that distance, is the point that's in focus. OK, it's the part/area/place that's in best, or sharpest focus, if you prefer. Seems to me that's all that's needed for the OP's question. Why bring in blur circle into this?

 

[Coldkennels]

I've checked a Senerar 28mm lens, and got the result in feet:

About 14ft and f/5.6 gets you about 7ftm to infinity.
About 9.5ft and f/8 gets you about ft to infinity.
About 7ft and f/11 gets you about 3.5ft to infinity.

Which is more or less the same as the Color Skopar.

I'd say those measurements were much more lax and assume a slightly wider depth of field / larger CoC than the Color Skopar. The VC 28 is also marked in feet, and it is much tighter than those measurements (the hyperfocal distance at f/11 is given as 8ft and only gives a depth of field down to 4ft, for instance). That might be splitting hairs, but it does show that these things aren't completely consistent from lens to lens or manufacturer to manufacturer.

 

[Godfrey]

I have a 28mm lens and would like to know the appropriate settings for it. For example: if you set a 25mm lens at f8 and 3.0m, then everything from 1.5m to infinity is in focus. What are the corresponding numbers for a 28mm?

Thank you very much,
Bill

Focus and aperture settings on any lens control the distance to the optimum focus plane and the distance in-front-of and behind that focus plane that provides "satisfactory" sharpness. This is the notion of "Depth of Field" (DoF). Here's an online calculator:

Online Depth of Field Calculator

Depth of field and hyperfocal distance calculator

www.dofmaster.com

A simplistic rule of thumb is to consider that for any set aperture and focus distance, the total length of the zone of satisfactory sharpness (or "focus zone") is split by the plane of best sharpness about 1/3 of the way in the direction of the lens, and about 2/3 of the way in the direction away from the lens. Of course, if that distance away from the lens includes the infinity point, this approximation is even more approximate. 😉

Given the example you offered (25mm lens set to f/8 and 3m, presumably on 35mm FF format), a similar resulting focus zone for a 28mm lens requires either changing the focus setting to 3.3m or changing the aperture setting to about f/9. You can try plugging a variety of different settings into the DoFMaster calculator and seeing how things change.

How you use DoF is up to you as a photographer. What settings are "appropriate", "best", or "poor" depends on what your subject is and what you are trying to achieve in your photograph. For instance, if your subject is a broad, sweeping landscape and there's little of significant interest in the foreground, you probably want to bias the focus zone to render all that lovely distance view as nicely as possible. And if your subject is an incisive thinking moment on a person's expression and there is lots of miscellaneous stuff in the background, you can try to get the person's face as sharp as possible and limit the DoF with a wide aperture to soften distracting elements in the background.

The most important thing to learn when studying the use of different lens settings is to think about what you are trying to achieve with each photo you make, and to think about how the specific settings made to focus and aperture help you achieve that. And then go out and experiment, practice a bit, with different subjects and ideas until you find what combinations of settings do what you had in mind.

G

 

[JohnGellings]

I was aware of that. I was merely pointing out that "I have never heard of a lens without [a depth of field scale] on it" isn't accurate nowadays.

I think it still is for Canon LTM lenses though…

With regards to DoF, there's something else that needs to be taken into consideration: diffraction. As much as Ken Rockwell drives me nuts, this shows the issue well: Nikon 50mm Lens Comparison

You might be getting more "depth of field" at f/8, f/11, or even f/32, but that doesn't necessarily mean you're getting the most sharpness out of any point of the image. (This might be what your guy was on about, @DownUnder.) Again, it's always best to test your own lenses and viewing the results in the format you prefer to see what works for you. Something might look okay at f/22 on a 5x7, but it probably won't at 12x16.

 

[boojum]

It is interesting to see folks post numbers for 28mm depth of field. I posted a link to several 28mm depth of field charts in my post, the second IIRC, which have been pretty much ignored in preference for discussion of what it is and how it works. I was misguided in thinking that the request for DoF info was cut and dry. LOL

It seems the OP asked what time it is and has been told how to make a watch.

 

[Dralowid]

It is interesting to see folks post numbers for 28mm depth of field. I posted a link to several 28mm depth of field charts in my post, the second IIRC, which have been pretty much ignored in preference for discussion of what it is and how it works. I was misguided in thinking that the request for DoF info was cut and dry. LOL

It seems the OP asked what time it is and has been told how to make a watch.

Sadly this is the way of these things...I could go on but best I don't!

 

[Freakscene]

I don't know why you said this. There is just one distance at which the subject is truly in focus. So the part of the subject which is at that distance, is the point that's in focus. OK, it's the part/area/place that's in best, or sharpest focus, if you prefer. Seems to me that's all that's needed for the OP's question. Why bring in blur circle into this?

It’s true. ‘Focus’ is the point where the blur/circle of confusion is least. It’s one of the hardest basic concepts to teach optics students. There is no point of focus . . .

And if you want to figure the distance out and really have everything look in focus in a photo, use a calculator and make the circle of confusion smaller, so the photo doesn’t look ‘sort-of’ in focus, but in focus in practical terms to your eyes.

 

[Phil_F_NM]

42.
That is the setting.

Phil

 

[boojum]

42.
That is the setting.

Phil

No, no, 3 7/8.