# Thread: Sensor size and Hyperfocal range (with the same lens)

1. ## Sensor size and Hyperfocal range (with the same lens)

Hi all,

I've a question about Hyperfocal distance as I'm seeing all sorts of cross talk involving actual focus, perceived focus and so on.

If shooting a scene with a lens at say, 35mm focal length on a full frame sensor (could be medium format 6x7, 35mm FF or 6x4.5) at F8 would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?

The reason I ask is that I'm using a wide angle zoom and am considering a smaller sensor body so I can get more reach with the same setting and flash power without resorting to a longer lens with a narrower DOF and searching for a correct understandable answer is appearing problematic.

2. ## Re: Sensor size and Hyperfocal range (with the same lens)

I can't say in fully understand the maths but apparently yes sensor size makes a difference.

Punch some numbers into this and see what happens.

http://www.photopills.com/calculators/dof

3. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Chris Giles
Hi all,

I've a question about Hyperfocal distance as I'm seeing all sorts of cross talk involving actual focus, perceived focus and so on.

If shooting a scene with a lens at say, 35mm focal length on a full frame sensor (could be medium format 6x7, 35mm FF or 6x4.5) at F8 would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?

The reason I ask is that I'm using a wide angle zoom and am considering a smaller sensor body so I can get more reach with the same setting and flash power without resorting to a longer lens with a narrower DOF and searching for a correct understandable answer is appearing problematic.
I used these two website tools to show you the difference between what you get with a Nikon DX vs Nikon FX sensor and a Field of View Calculator
DOFMaster Depth of Field Calculator

You can use them to plug in your format and lens choices to see what you get.

Nikon FX FoV and DoF:

Nikon DX FoV and DoF:

This pair of calculations holds focal length, focus distance, and aperture setting constant, letting field of view change. Notice that the 35mm lens on the smaller format has significantly less FoV, thus greater magnification in the captured image, which reduces DoF at the same lens opening. If you switched to a 24mm lens on the Nikon DX, be holding FoV constant, not focal length: Then you'd see similar FoV and magnification, and more DoF at the same aperture setting.

Make sense? Play with the calculators and see how to get what you want.

G

4. ## Re: Sensor size and Hyperfocal range (with the same lens)

I'm not sure that's correct.

The two formats do not have a different magnification of the captured image.

The crop sensor is just that - a crop of what would be captured under identical settings with a larger sensor.

There is no difference in depth field of a captured image due to changing sensor size whilst maintaining focal length, aperture, and distance to subject.

Where there is a difference is in the depth of field of the print, assuming both images are printed to the same size and viewed from the same distance.

Kind regards,

Gerald.

5. ## Re: Sensor size and Hyperfocal range (with the same lens)

Hi,

My take is that if you used the same focal length/aperture combo the CoC for the same amount of defocus would be exactly the same, as it doesn't depend on the sensor.

But, with a smaller sensor you would need a higher magnification, so you would need a small CoC for perceived sharpness. So, a smaller sensor will give less DoF.

On the other hand, a smaller sensor needs a different focal length for the field of view, say you would use an 60 mm lens instead of 90 mm and that would give you a larger DoF.

Using a DoF calculator might be a good idea.

Best regards
Erik

Originally Posted by Chris Giles
Hi all,

I've a question about Hyperfocal distance as I'm seeing all sorts of cross talk involving actual focus, perceived focus and so on.

If shooting a scene with a lens at say, 35mm focal length on a full frame sensor (could be medium format 6x7, 35mm FF or 6x4.5) at F8 would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?

The reason I ask is that I'm using a wide angle zoom and am considering a smaller sensor body so I can get more reach with the same setting and flash power without resorting to a longer lens with a narrower DOF and searching for a correct understandable answer is appearing problematic.

6. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
I'm not sure that's correct.

The two formats do not have a different magnification of the captured image.

The crop sensor is just that - a crop of what would be captured under identical settings with a larger sensor.

There is no difference in depth field of a captured image due to changing sensor size whilst maintaining focal length, aperture, and distance to subject.

Where there is a difference is in the depth of field of the print, assuming both images are printed to the same size and viewed from the same distance.
(bolded) That is the point: DoF calculations, the CoC etc, are always made with respect to a reference image size (usually a print, usually 8x10 inches (or metric equivalent) in size). Creating an image to that size from an APS-C size format implies more magnification of the image than from FF format.

G

7. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
(bolded) That is the point: DoF calculations, the CoC etc, are always made with respect to a reference image size (usually a print, usually 8x10 inches (or metric equivalent) in size). Creating an image to that size from an APS-C size format implies more magnification of the image than from FF format.

G
Hi Godfrey -

Does that still hold true in the digital age though?

Would it be true to say that a 24 megapixel APS-C image would require more "magnification" (all other things being equal) to print at the same size as a 6 megapixel FF DSLR image?

Kind regards,

Gerald.

8. ## Re: Sensor size and Hyperfocal range (with the same lens)

Hi,

In CoC terms yes. A high pixel camera just puts more pixels in that unsharp area. The CoC of confusion is the same, just more exactly described.

To complicate the issue, it is possible to deconvolve the CoC and having more pixels may be helpful in that.

Best regards
Erik

Originally Posted by gerald.d
Hi Godfrey -

Does that still hold true in the digital age though?

Would it be true to say that a 24 megapixel APS-C image would require more "magnification" (all other things being equal) to print at the same size as a 6 megapixel FF DSLR image?

Kind regards,

Gerald.

9. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Chris Giles
Hi all,

I've a question about Hyperfocal distance as I'm seeing all sorts of cross talk involving actual focus, perceived focus and so on.

If shooting a scene with a lens at say, 35mm focal length on a full frame sensor (could be medium format 6x7, 35mm FF or 6x4.5) at F8 would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?

The reason I ask is that I'm using a wide angle zoom and am considering a smaller sensor body so I can get more reach with the same setting and flash power without resorting to a longer lens with a narrower DOF and searching for a correct understandable answer is appearing problematic.
Chris, the two areas of bolded text imply a few things:
1. You will not change the camera position.
2. You would crop the final output file in the FF case to get the "reach" you need.

I want to "focus" on your first assumption about longer lenses having less DOF. If you do not change the camera-to-subject distance, the longer lens will have the same DOF as the wider lens after cropping on that FF camera, assuming the same f-stop and a reasonable magnification (not macro). If the final output angle of view is going to be the same, and your camera-to-subject position is going to be the same, then all this falls out in the wash (aka the crop). Just use the FF camera and the lens that provides the view you want. There are some minor effects of pixel pitch on COC, but I think that only applies to pixels, i.e. viewing at 100%; not a scaled output.

If you are considering different final output views in your two circumstances, then the one that gets magnified the least will have the most DOF. Again, all this assumes the camera position doesn't change (focusing at the same distance).

Dave

10. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
Hi Godfrey -

Does that still hold true in the digital age though?

Would it be true to say that a 24 megapixel APS-C image would require more "magnification" (all other things being equal) to print at the same size as a 6 megapixel FF DSLR image?

Kind regards,

Gerald.
Hi Gerald,

It doesn't matter what the pixel count is. Magnification in imaging is with respect to the physical image size projected onto the sensor, not how that sensor is subdivided into pixels. People just aren't as aware of this in the digital age because they don't see the captured image in its native size anymore; it's not like looking at various sized pieces of film on a lightbox.

Ray

11. ## Re: Sensor size and Hyperfocal range (with the same lens)

Would the area of focus be greater?
In my experience, yes, as I could compare my 110mm f/2.8 lens on 6x7 to a 50mm f/1.4 lens on 35mm. When shot wide open, they offer about the same area of focus. The is highly distance based, as you know, with focus at nearer distances providing less of an area of focus.

The difference will be more noticeable if you are accustomed to a 50mm focal length on medium format and then use the same lens and aperture on 35mm (36x24mm) - f8 will give a greater area of focus on the smaller format. The effect would be less so on full frame 35mm compared to APS-C.

12. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
I used these two website tools to show you the difference between what you get with a Nikon DX vs Nikon FX sensor

This pair of calculations holds focal length, focus distance, and aperture setting constant, letting field of view change.
However it also lets the circle of confusion change, and that is the real reason why the calculated DOF changes.

If you enlarged both images by the same factor, clearly the DX print will be smaller than the FX print, but the DOF will be the same in both.

That calculator is not based on equal enlargements/magnifications, but on equal print sizes; and when you enlarge a smaller-sensor image by a larger factor to match the print sizes, you also enlarge the impression of blurriness in the areas just fore and aft of the plane of focus. The calculator adjusts for this by imposing a smaller limit to the circle of confusion in the original capture. You are now judging the same image projected by the same lens [in the areas where the sensors overlap] by a harsher criterion. But that is what the eye's tolerance for unsharpness demands from equal print sizes.

So, back to Chris' original question: "would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?"
Answer: No. It will be either the same, or smaller. The same, if you enlarge them by the same factor, and end up with a smaller print from the smaller sensor. Smaller, if you enlarge them to the same print size.

Ray

13. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by segedi
Would the area of focus be greater?
In my experience, yes, as I could compare my 110mm f/2.8 lens on 6x7 to a 50mm f/1.4 lens on 35mm. When shot wide open, they offer about the same area of focus. The is highly distance based, as you know, with focus at nearer distances providing less of an area of focus.
That's not a good example for this thread, as you are talking about a different scenario - two different focal lengths.

Originally Posted by segedi
The difference will be more noticeable if you are accustomed to a 50mm focal length on medium format and then use the same lens and aperture on 35mm (36x24mm) - f8 will give a greater area of focus on the smaller format. The effect would be less so on full frame 35mm compared to APS-C.
That is not physically possible. Please check my most recent post here.

Ray

14. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
Does that still hold true in the digital age though?

Would it be true to say that a 24 megapixel APS-C image would require more "magnification" (all other things being equal) to print at the same size as a 6 megapixel FF DSLR image?
You're still adjusting the size of the image from what the lens images on the sensor to where the ink is laid down on paper by the same amount. Don't think about the pixel count ... that affects resolution and dynamic range, not image geometry.

The evidence supports that it continues to work as the calculators suggest it ought to.

I tried it: I have both FF and Micro-FourThirds format cameras, 50mm and 25mm "normal" lenses respectively, and 35mm lenses for both.

I made the same photograph with my Leica M-P and my Olympus E-M1, using a 50mm lens at f/8 on the on Leica and 25mm lens at f/8 and f/4 on the Olympus. That's the "same FoV-same DoF comparison" ... printed full frame to 8x10s, the 50-f/8 and 25-f/4 images were identical, the 25-f/8 image had two stops more DoF.

I then made photos of the same target with 35-f/8 on the Leica and 35-f/8 on the Olympus: that's the "same focal length-same aperture comparison" ... printed full frame to 8x10s, the Leica image showed more FoV and more DoF, the Olympus image showed less FoV and less DoF.

I suggest you do some experimenting. It's the best way to get a feel for this kind of thing IMO, rather than trying to work it all out by numbers and debating the opinions of others who haven't done the experiments. You can replicate my experiment with a single camera, say a FF Nikon or Canon (whatever you have to hand):

1. Make a test exposure with a 50mm lens*at f/8, then a 25mm lens at f/8 and f/4 (or a 35mm if you want to compare to APS-C).
2. Print an 8x10 of the 50mm image.
3. Crop the 25mm image to the same number of pixels as either an APS-C or FourThirds format would have produced.
4. Print 8x10s of the 25mm images.
5. Make a test exposure with a 35mm lens at f/8.
6. Print an 8x10 of the 35mm image.
7. Crop the 35mm image to the same number of pixels as either an APS-C or FourThirds format would have produced.
8. Print an 8x10 of the cropped 35mm image.
9. Now compare them.

You don't have to do any calculation of COC or whatever to see the differences. :-)
G

15. ## Re: Sensor size and Hyperfocal range (with the same lens)

Hi Godfrey -

I appreciate you taking the time to go through this, and I think you're right - I'm going to have to test this out for myself.

The situation with regards different focal lengths, or moving the camera position to maintain the same FoV I totally get.

But I simply cannot get my head around why using the exact same lens from the exact same position on different sensor sizes would change the depth of field.

Kind regards,

Gerald.

16. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
I appreciate you taking the time to go through this, and I think you're right - I'm going to have to test this out for myself.

The situation with regards different focal lengths, or moving the camera position to maintain the same FoV I totally get.

But I simply cannot get my head around why using the exact same lens from the exact same position on different sensor sizes would change the depth of field.

That's why I don't read other people's theoretical articles. I test for myself. :-)

If it didn't make any difference, then why all these insane debates about why FourThirds format doesn't give you the ability to make shallow depth of field, why FF lets you get beautiful bokeh, why MFD gives you such shallow and controllable DoF, etc etc?

The debates have been going on for a decade and a half. I did my first experiments on this when I bought my Canon 10D in 2003: I did it comparing the DoF using its APS-C 1.6x crop vs simulating the Sony F707's 5/8" sensor format. I've repeated the exercise with other APS-C, FourThirds and FF cameras over and over again since. The results are always the same: the calculators work.

Try it. :-)

G

17. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
You're still adjusting the size of the image from what the lens images on the sensor to where the ink is laid down on paper by the same amount. Don't think about the pixel count ... that affects resolution and dynamic range, not image geometry.

I then made photos of the same target with 35-f/8 on the Leica and 35-f/8 on the Olympus: that's the "same focal length-same aperture comparison" ... printed full frame to 8x10s, the Leica image showed more FoV and more DoF, the Olympus image showed less FoV and less DoF.
Hi Godfrey,

Those are exactly the same points I made - glad to see we are in agreement.

Originally Posted by Godfrey
I suggest you do some experimenting. It's the best way to get a feel for this kind of thing IMO, rather than trying to work it all out by numbers and debating the opinions of others who haven't done the experiments.
While as a physicist and observational astronomer, I will never dismiss the process of experimental verification, this truth also holds: well-established physics (like geometrical optics) does not yield to "debate" or "opinions". One does not argue with gravity, for example!

Cheers,
Ray

18. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by ondebanks
Hi Godfrey,

Those are exactly the same points I made - glad to see we are in agreement.

...

While as a physicist and observational astronomer, I will never dismiss the process of experimental verification, this truth also holds: well-established physics (like geometrical optics) does not yield to "debate" or "opinions". One does not argue with gravity, for example!

Cheers,
Ray
I agree, Ray. However, the vast majority of photographers are neither physicists, astronomers, nor even mathematicians (my particular affliction ), so there is an absurd amount of debate on subjects like geometrical optics for the simple reason that they aren't really very aware of the math and physics, nor know how to recognize real information vs hokery when the discussion is theoretical.

That's why I urge photographers to do easy experiments that demonstrate what happens clearly and simply. The level of experimentation required to understand photographic behaviors isn't rocket science.

enjoy!
G

19. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by ondebanks
well-established physics (like geometrical optics) does not yield to "debate" or "opinions".
Oh, agreed! The problem is that people don't always ask the question to which they actually want the answer. "Equivalence" debates rage between formats even though the equations are VERY easy to solve.

People use words like Depth of Field, but there are many reasonable definitions, and it's hard to convince everybody to at least start from the accepted definition in the literature, and then, if they want something else, figure out how their something else relates to that definition.

I enjoy coming up with non-technical explanations of these results, but they're no help if the question itself isn't defined.

Oh, and +1 on experimentation. In the end, we're all after looks. Sharp, pleasing bokeh, weird bokeh, whatever, and measurements really just aren't the same thing.

Best,

Matt

20. ## Re: Sensor size and Hyperfocal range (with the same lens)

OMG - look into a pit and dive into it ...

Hyperfocal effectiveness is based on prints, not necessarily pixel peeping. If you pixel peep, use root(2) x pixel pitch for sharpness considerations. If you look at real photos printed on real paper, use the traditional calcs for viewing the prints and just relax. Heck even the DoF scale on your lens will work out just fine.

If you pixel peep, you'll just be disappointed and frustrated with your 1mm in focus region.

21. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
That's why I don't read other people's theoretical articles. I test for myself. :-)

If it didn't make any difference, then why all these insane debates about why FourThirds format doesn't give you the ability to make shallow depth of field, why FF lets you get beautiful bokeh, why MFD gives you such shallow and controllable DoF, etc etc?
Because the larger the sensor, the greater the field of view for a given focal length.

The only thing that has a bearing on perspective is absolute subject distance.

Therefore, for a given subject distance and desired framing, the larger format enables you to use a longer focal length lens.

Longer focal length, same subject distance, shallower depth of field.

At least, that's the way I've always looked at it.

Kind regards,

Gerald

22. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by GrahamWelland
OMG - look into a pit and dive into it ...

Hyperfocal effectiveness is based on prints, not necessarily pixel peeping. If you pixel peep, use root(2) x pixel pitch for sharpness considerations. If you look at real photos printed on real paper, use the traditional calcs for viewing the prints and just relax. Heck even the DoF scale on your lens will work out just fine.

If you pixel peep, you'll just be disappointed and frustrated with your 1mm in focus region.
I think it's a little condescending to dismiss anything that isn't printed. The vast, vast majority of photos taken nowadays (whether you consider them real or not) will never be printed. And why should we limit ourselves to viewing images at a proscribed distance?

Pixel peeping has its place, surely?

Kind regards,

Gerald.

23. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by GrahamWelland
...

​​"If you want to take more interesting photographs, stand in front of more interesting things!"
I really, REALLY, like that.

thx,
G

24. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
I think it's a little condescending to dismiss anything that isn't printed. The vast, vast majority of photos taken nowadays (whether you consider them real or not) will never be printed. And why should we limit ourselves to viewing images at a proscribed distance?

Pixel peeping has its place, surely?

Kind regards,

Gerald.
While I generally do my testing and evaluation of DoF with prints in mind, I don't eschew digital presentation at all. HOWEVER, the same principles apply ... and they're not 'pixel-peeping'. When I'm judging a photo for printing, I display it at a size similar to the print size on my display ... I usually print 6x8 or 8x8 on 8.5x11 paper, or 9x15 on 11x17 paper, or similar. So it's easy to simulate the actual DoF that the prints will have that way with a 27" display.

I do a similar thing when evaluating photos I'm going to put on my iPhone or iPad ... I check them at the display size. DoF varies and sometimes I need to soften the image for these small display spaces in order to achieve the look I want. And sometimes I need to reduce the photo in several small stages for these platforms because the 'all at once' interpolation down from a 24 Mpixel image to a iPhone display leaves a lot of ugly mess behind and looks terrible.

I didn't find Graham's comments condescending. Pixel-peeping (the act of excruciating inspection of photographs at 1:1 pixel magnification) is worthless to determine DoF and the overall look of either a printed image or of a well-presented digital image on a display. It's a great way to make specious arguments about the so-called "image quality" of lenses, however.

G

25. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
While I generally do my testing and evaluation of DoF with prints in mind, I don't eschew digital presentation at all. HOWEVER, the same principles apply ... and they're not 'pixel-peeping'. When I'm judging a photo for printing, I display it at a size similar to the print size on my display ... I usually print 6x8 or 8x8 on 8.5x11 paper, or 9x15 on 11x17 paper, or similar. So it's easy to simulate the actual DoF that the prints will have that way with a 27" display.

I do a similar thing when evaluating photos I'm going to put on my iPhone or iPad ... I check them at the display size. DoF varies and sometimes I need to soften the image for these small display spaces in order to achieve the look I want. And sometimes I need to reduce the photo in several small stages for these platforms because the 'all at once' interpolation down from a 24 Mpixel image to a iPhone display leaves a lot of ugly mess behind and looks terrible.

I didn't find Graham's comments condescending. Pixel-peeping (the act of excruciating inspection of photographs at 1:1 pixel magnification) is worthless to determine DoF and the overall look of either a printed image or of a well-presented digital image on a display. It's a great way to make specious arguments about the so-called "image quality" of lenses, however.

G
When I print, I typically print 60x40. And people examine those prints with their nose pretty much touching them. So it's kinda important - to me - to "pixel peep" to ensure that the things I want in focus, are in focus - and not just appear to be in focus from 6 feet away.

Here's a 100% crop from an 80MP image that will be printed.

Of course if you're 6 feet away you're never going to see that detail. But it is important to me that the detail is there should someone want to go looking for it.

For digital display, I routinely create multi-gigapixel images.

Here's an example.

http://dubai360.com/#!s=1313-burj-kh...igapixels&l=en

Pixel peeping is not "worthless" to determine either DoF or the overall look of an image, if you're prepared to take a leap of faith and accept the fact that not everyone is in the business of creating small prints that are only ever to be viewed from a proscribed distance.

Kind regards,

Gerald.

26. ## Re: Sensor size and Hyperfocal range (with the same lens)

Hi,

I would add that diffraction also sets a limit. No idea to stop down beyond Airy circle size being similar to CoC?

Best regards
Erik

Originally Posted by ondebanks
However it also lets the circle of confusion change, and that is the real reason why the calculated DOF changes.

If you enlarged both images by the same factor, clearly the DX print will be smaller than the FX print, but the DOF will be the same in both.

That calculator is not based on equal enlargements/magnifications, but on equal print sizes; and when you enlarge a smaller-sensor image by a larger factor to match the print sizes, you also enlarge the impression of blurriness in the areas just fore and aft of the plane of focus. The calculator adjusts for this by imposing a smaller limit to the circle of confusion in the original capture. You are now judging the same image projected by the same lens [in the areas where the sensors overlap] by a harsher criterion. But that is what the eye's tolerance for unsharpness demands from equal print sizes.

So, back to Chris' original question: "would the area of focus be greater if using the same lens on a smaller sensor and focusing at the same distance at F8?"
Answer: No. It will be either the same, or smaller. The same, if you enlarge them by the same factor, and end up with a smaller print from the smaller sensor. Smaller, if you enlarge them to the same print size.

Ray

27. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
When I print, I typically print 60x40. And people examine those prints with their nose pretty much touching them. So it's kinda important - to me - to "pixel peep" to ensure that the things I want in focus, are in focus - and not just appear to be in focus from 6 feet away.

Here's a 100% crop from an 80MP image that will be printed.

...
If you're going to print to 60x40 inches (really? or do you mean centimeters? 60x40cm == 23x15 inch) and you expect people to be examining the prints with a magnifying glass, none of the calculators or DoF scales are going to give you realistic DoF numbers since the scales and calculations are always based on something like an 8x10 inch print viewed at about 18 inches distance.

The only thing you can do in that instance is make a print and see if it suits your focus requirements.

Pixel peeping does little to help since looking at pixels on a display screen isn't anything like looking at an image printed by ink on paper. The sample clip you showed me tells me nothing about whether the photo is in or out of focus, or has the right focus zone, etc.

sorry,
G

28. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by Godfrey
If you're going to print to 60x40 inches (really? or do you mean centimeters? 60x40cm == 23x15 inch) and you expect people to be examining the prints with a magnifying glass, none of the calculators or DoF scales are going to give you realistic DoF numbers since the scales and calculations are always based on something like an 8x10 inch print viewed at about 18 inches distance.

The only thing you can do in that instance is make a print and see if it suits your focus requirements.

Pixel peeping does little to help since looking at pixels on a display screen isn't anything like looking at an image printed by ink on paper. The sample clip you showed me tells me nothing about whether the photo is in or out of focus, or has the right focus zone, etc.

sorry,
G
Yes. Inches. As a minimum.

But no - people do not use magnifying glasses.

The level of condescension is overwhelming.

I give up.

29. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
Yes. Inches. As a minimum.
But no - people do not use magnifying glasses.
The level of condescension is overwhelming.
I give up.
Sorry you feel that way. There's no condescension intended in my statements.

If you're printing that big, and expect people to look at the prints at close up distances, there are no calculations available that will give you a realistic assessment of the resulting overall DoF. Or rather, you're going to have to run your own calculations using a CoC adjusted for such extraordinary magnification and consider focus zone on a local scale, not across the entire image field (the standard use of the term DoF), ignoring the commonly used scales and calculators ... they're meaningless for such work.

And I simply don't believe there's any usefulness in examining such images at 1:1 pixel magnification for DoF at all. It doesn't net you any useful appreciation of the DoF, which has been the subject of this thread. Examining an 80 Mpixel image at 1:1 pixel magnification can tell you that this bit in front of you that you're looking at now is suitably sharp, or not, and that's about it. That's not an evaluation of DoF according to any standard definition of the term.

You're in a space of "special circumstances": the standard measures are not useful for those circumstances.

G

30. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by gerald.d
The level of condescension is overwhelming.

I give up.
Gerald

Definitely no condescension intended from this end.

For you it's obvious that CoC and viewing distance still come into play. In your case it's nose depth from the print so I would assume (without calculating it) that you're as near as damn it at pixel peep level for those prints. That in itself would make critical sharpness a challenge at MF and F stops that aren't subject to significant diffraction. The discussion of course is what is your acceptable depth of focus? As we know there is only one exact plane of focus and everything else in front or behind is just gradually getting softer and it's a question of whether that softness is visible or acceptably visible or not.

Like I mentioned though, this one is a rathole that always descends into strong opposing views and opinions about what is acceptable DoF. It never ends well ...

The best quote I ever heard on this was regarding the definition of "Circle of Confusion" - a bunch of photographers sitting around a table arguing over depth of focus/field calculations ...

31. ## Re: Sensor size and Hyperfocal range (with the same lens)

Hi,

I am aware of the CoC explanation you mention.

Two small reflections:

I was asked to do a presentation about the hyperfocal distance at our camera club. So I prepared two A2 size prints (16"x23") one with CoC based on lens markings on my Distagon 60/3.5 for the blad, the other with foreground in accurate focus. Close viewing there was a difference even a blind man could see, but just looking at normal viewing distance it was not obvious at all that the one print was better than the other.

The other observation is that I don't think we observe images at nose lengths distance. Human vision can normally focus to around 10", so that would be reasonable with full 20/20 vision and young eyes. Older persons cannot normally focus that close and corrective glasses are normally not made for close focusing distances. Personally, I am near sighted so I can view images quite close. What I see is that I tend to pixel peep A2 size images and larger at around 40 cm or 16", measured with a laser distance meter. Interestingly, it is often said that 180PPI is needed for an excellent print, that corresponds to 20/20 vision at 50cm/20".

Best regards
Erik

Originally Posted by GrahamWelland
Gerald

Definitely no condescension intended from this end.

For you it's obvious that CoC and viewing distance still come into play. In your case it's nose depth from the print so I would assume (without calculating it) that you're as near as damn it at pixel peep level for those prints. That in itself would make critical sharpness a challenge at MF and F stops that aren't subject to significant diffraction. The discussion of course is what is your acceptable depth of focus? As we know there is only one exact plane of focus and everything else in front or behind is just gradually getting softer and it's a question of whether that softness is visible or acceptably visible or not.

Like I mentioned though, this one is a rathole that always descends into strong opposing views and opinions about what is acceptable DoF. It never ends well ...

The best quote I ever heard on this was regarding the definition of "Circle of Confusion" - a bunch of photographers sitting around a table arguing over depth of focus/field calculations ...

32. ## Re: Sensor size and Hyperfocal range (with the same lens)

Eric,

I'm so happy to know that you and I both agree.

20/20 vision imposes certain limitations (for me they're severe now close up but perfect at 3ft onwards).

33. ## Re: Sensor size and Hyperfocal range (with the same lens)

Originally Posted by GrahamWelland
Eric,

I'm so happy to know that you and I both agree.

20/20 vision imposes certain limitations (for me they're severe now close up but perfect at 3ft onwards).
I've never had perfect vision, but can get to 20/20 in my right eye and 20/30 in my left with correction still. It's not been a problem.

To me, discussing DoF means discussing the "apparent sharpness of a photograph", a global phenomenon, which is by no means the same thing as "evaluating a photograph's resolution", which is a local phenomenon. If you're not looking at the photograph as a whole, discussion of DoF is way off the mark and no amount of CoC calculations or pixel peeping has any meaning.

I don't know about anyone else, but I can't look at the whole of even a 13x19" print at much less than 30 inch distances... !

G

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