DOF on 8x10 vs. 4x5?

[LFLarry]

hi. What app are you using in your phone that is pictured below?

Thanks

No...

Hyperfocal is for distant subjets in the scene, example, you want the mountains in the background in focus... then hyperfocal tells at what close distance other objects will be in also focus with the right settings. Using hyperfocal in the studio may lead to suboptimal results.

_____

Be aware that DOF formulas and calculators are only aproximate, specially in close distances and, depending on lens design, focus roll-off in the front and in the rear from the focused plane have their own nature and particular progressions.

In fact, there is a chart that plots that for a lens, "Through Focus MTF". This chart is often evaluated by Pro cinematographers, but amazingly it is pretty unknown in still photography.

Attachment 197433
http://cinematechnic.com/optics/super-baltar


In cinematography a production may cost $200 million, so they have resources

The "Deep Focus" nature, for example, is a particular behaviour of a lens that is not explained by general DOF calculators, because those calculations are based in an ideal simple lens, while a real commercial lens is a complex artifact, compared.


So DOF calculators are very useful, but one also needs to understand how owned glasses work.

Sent from my iPhone using Tapatalk

[Pere Casals]

hi. What app are you using in your phone that is pictured below?

http://www.dl-c.com/DoF/

By Jonathan Sachs, for android (google play) and for windows

[Bernice Loui]

No amount of Depth of Field _ Depth of Focus calculations can equal direct viewing of the ground glass image with the camera set up, lighting set up and the lens stopped down to the taking aperture. While the mental masterbation of trying to calculate what Depth of Field _ Depth of Focus will appear like on the film image could be Academically curious and in ways secure and satisfying, the actual results on film might be quite different from what was intellectually expected.

Lesson is, learn to view the ground glass image with the lens stopped down to the taking aperture, there is NO substitute for this skill. No set of numbers can ever equal visual acuity coupled with experience based on what the finished print needs to look like.


Berice

[Drew Wiley]

There's the science of this, which might be fun to study and pontificate about in an armchair style, and devise all kinds of fancy charts, formulas, and programs about, and then there's the actual DOING of it, which requires intuitive knowledge devoid of all the complicated cobwebs.

[LFLarry]

Well said Bernice, and I particularly like the line "mental masturbation"... totally made my day.

I am heeding your advice and going to try to stay in the f/16 to f/22 range with my next round of photos. I went to the deli this morning and picked up some treats to photograph and then of course enjoy this weekend...

No amount of Depth of Field _ Depth of Focus calculations can equal direct viewing of the ground glass image with the camera set up, lighting set up and the lens stopped down to the taking aperture. While the mental masterbation of trying to calculate what Depth of Field _ Depth of Focus will appear like on the film image could be Academically curious and in ways secure and satisfying, the actual results on film might be quite different from what was intellectually expected.

Lesson is, learn to view the ground glass image with the lens stopped down to the taking aperture, there is NO substitute for this skill. No set of numbers can ever equal visual acuity coupled with experience based on what the finished print needs to look like.


Berice

[LFLarry]

I agree with that Drew. For me, I need to "understand it" so I can then make an intuitive process. If I have no basis for understanding then I struggle. Thanks for sharing your knowledge.

There's the science of this, which might be fun to study and pontificate about in an armchair style, and devise all kinds of fancy charts, formulas, and programs about, and then there's the actual DOING of it, which requires intuitive knowledge devoid of all the complicated cobwebs.

[Doremus Scudder]

I think this is fun.

We've got statements that range from, "format has nothing to do with depth of field," and, "the larger the film, the less depth-of-field for a given angle of view."

The interesting thing is, both are correct. The real players here are aperture and magnification.

I like to think about it this way: If we take a lens, say a 240mm lens with lots of image circle and make a photo from a given position on an 8x10 camera at, say, f/45, the depth-of-field will be X. If we swap out the 8x10 camera for a 4x5 camera, but keep the same lens, camera position, aperture and subject, and make another photograph, the depth-of-field will also be X. It's just that we now have a photograph with different borders; i.e., cropped in comparison to the larger photo. If we took our scissors and snipped out the 4x5 piece from the 8x10 film that corresponds to the image on the 4x5 film, we would have two identical images with exactly the same depth of field.

However, let's say we want to make a photograph with the same angle of view, i.e., the same borders, as the one we made on 8x10 film with a 240mm lens. Well, then we'll need a 120mm lens. The resulting image will have the same content as the larger one, but it'll be smaller. If we use the same aperture as the larger photo was made with, we'll have a lot more depth-of-field, however. Less magnification = greater depth-of-field. Or, we can duplicate the depth-of-field in the larger photograph by using a larger aperture; f/22 in this case. Turning this around, one can see that a smaller format often makes it easier to obtain more depth-of-field for a given image. It's simply that the image on the smaller format is smaller, i.e., less magnified and the depth-of-field is, therefore, larger. If depth-of-field is what you're after, a good guideline is to use the smallest format that will give you the image quality you need at the enlargement factor you desire. Going larger just makes getting the desired depth-of-field harder.

And, conversely, more magnification = less depth-of-field. Racking your bellows out for close-up work is similar to moving a projector farther from the screen: the image gets larger (more magnification). It follows then, that depth-of-field for any given lens/aperture combination decreases with bellows extension. Or, looking at it another way, the closer the subject is to the lens, the less depth-of-field we get from a given lens/aperture combination. That's why smaller apertures get used a lot for close-up-work and why arranging your subject so you can judiciously use camera movements to get the plane of sharp focus exactly where you want it is so important.

Best,

Doremus

[LFLarry]

This has to be the single best explanation for large format DOF that I have ever read. This one is getting printed out and put in my journal...

Thanks Doremus!

I think this is fun.

We've got statements that range from, "format has nothing to do with depth of field," and, "the larger the film, the less depth-of-field for a given angle of view."

The interesting thing is, both are correct. The real players here are aperture and magnification.

I like to think about it this way: If we take a lens, say a 240mm lens with lots of image circle and make a photo from a given position on an 8x10 camera at, say, f/45, the depth-of-field will be X. If we swap out the 8x10 camera for a 4x5 camera, but keep the same lens, camera position, aperture and subject, and make another photograph, the depth-of-field will also be X. It's just that we now have a photograph with different borders; i.e., cropped in comparison to the larger photo. If we took our scissors and snipped out the 4x5 piece from the 8x10 film that corresponds to the image on the 4x5 film, we would have two identical images with exactly the same depth of field.

However, let's say we want to make a photograph with the same angle of view, i.e., the same borders, as the one we made on 8x10 film with a 240mm lens. Well, then we'll need a 120mm lens. The resulting image will have the same content as the larger one, but it'll be smaller. If we use the same aperture as the larger photo was made with, we'll have a lot more depth-of-field, however. Less magnification = greater depth-of-field. Or, we can duplicate the depth-of-field in the larger photograph by using a larger aperture; f/22 in this case. Turning this around, one can see that a smaller format often makes it easier to obtain more depth-of-field for a given image. It's simply that the image on the smaller format is smaller, i.e., less magnified and the depth-of-field is, therefore, larger. If depth-of-field is what you're after, a good guideline is to use the smallest format that will give you the image quality you need at the enlargement factor you desire. Going larger just makes getting the desired depth-of-field harder.

And, conversely, more magnification = less depth-of-field. Racking your bellows out for close-up work is similar to moving a projector farther from the screen: the image gets larger (more magnification). It follows then, that depth-of-field for any given lens/aperture combination decreases with bellows extension. Or, looking at it another way, the closer the subject is to the lens, the less depth-of-field we get from a given lens/aperture combination. That's why smaller apertures get used a lot for close-up-work and why arranging your subject so you can judiciously use camera movements to get the plane of sharp focus exactly where you want it is so important.

Best,

Doremus

[Bob Salomon]

This has to be the single best explanation for large format DOF that I have ever read. This one is getting printed out and put in my journal...

Thanks Doremus!

Except the CofC is also a major factor of DOF!

[Drew Wiley]

The first two things I learned to ignore, and never have regretted ignoring, are "circle of confusion" and "normal viewing distance". The latter might be relevant to a book printer, where there is a sort of standardized viewing distance; but for display print applications it's utter bunk unless the viewer simply can't get physically close to the print. But "circle of confusion" is just one of those hypothetical niceties that seldom applies to real world photography. A ULF shooter might have all kinds lens diffraction issues under a magnifier, but is apt to stop way down and contact print anyway. In such cases, what is meant to be deliberately out of focus, and what is not, is really an esthetic choice related to compositional strategy and not held captive to the rules of optics. You aren't working for the NSA at fixed infinity focus from a spy plane! The same largely applies to 8x10 photography with long perspective lenses, which might get enlarged, but how much? Not generally that much, magnification wise. Soft focus types want everything turned in a circle of confusion for their own esthetic reasons. Simply inspecting your groundglass image at different potential f-stops, then homing in on details with a loupe, will tell your far more in mere seconds about image sharpness than hours and hours of nitpicking hyperfocal and circle of confusion hypotheses. The instant you apply view camera plane of focus tilts and shifts, all that gets a lot more complicated to figure out anyway in a pre- sense. Sinar cameras have yaw-free depth of field calibration features that might come in handy for studio tabletop photography, but are rarely of any real benefit for field photography where nature has designed the shape of topography rather than a billiard table company.