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Thread: DOF on 8x10 vs. 4x5?

  1. #11
    Drew Wiley
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    Re: DOF on 8x10 vs. 4x5?

    Relative to comparable ANGLE OF VIEW, lets say you do use a 240 lens at f/22 on 4x5. But to get the same angle of view on 8x10, you'd need a 480mm lens - twice the focal length. So to obtain the same depth of field, you'd need to stop down to f/45 instead, if you use the same shutter speed and same film ASA. That's my level of math - 2X this or that ! Actual compositional issues regarding depth of field is something I judge with my eyes and a loupe on the ground glass itself. Hyperfocal theory and "circle of confusion" is a bunch of nonsensical confusion for sure, as far as I'm concerned. By the time you finish fussing with the math, the lighting has changed! I do sometimes employ hyperfocal theory in Med Format usage. But composition with a view camera needs to become a lot more intuitive and second-nature unless you want to risk unnecessary hurdles. Desired degree of magnification in the end use is also a determining factor. It always amused me when someone fussed around all day long trying to nitpick this topic in some studio application, and then had their 4x5 chrome published even smaller in some magazine than their original 4x5 film!

  2. #12
    Vaughn's Avatar
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    Re: DOF on 8x10 vs. 4x5?

    Quote Originally Posted by Jody_S View Post
    It's pretty easy to understand that if you take an image with a 240mm lens at f22 on your 4x5, then mount the lens on your 8x10 and re-take the image still at f22, the resulting images will have the same depth of field...
    But in practice, to "re-take" the same 4x5 image with the same lens, one would have to move the 8x10 camera closer to frame it the same. This would give you less DoF even at the same f/stop...and a change in perspective.

    The young Thomas Joshua Cooper approached his Holiness, Saint Adams with this question. Should he continue to chase the light with his old trusty 5x7, or should he move up to an 11x14? St. Adams in his wisdom spoke for the 5x7, for DoF issues arise when using normal to long lenses on 11x14. So it has been recorded.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  3. #13

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    Re: DOF on 8x10 vs. 4x5?

    More than just Depth of Field _ Depth of Focus, larger the film format on table top or similar non-infinity images, the larger the problems will be.. To believe larger film format always yields better image quality is simply not true. The overall image making system is a LOT more complex than that.

    Bellows factor becomes an issue as image size on the GG or magnification increase. At life-size or 1 to 1, loss of two f-stops must be added to the taking lens aperture.

    Image circle of the lens increases with magnification or images made at less than infinity focus grows the lens image circle. This often adds stray flare light inside the camera bellows that often reduces image contrast and alters film exposure. Cure is to use a lens shade that can be adjusted to cut off the excessive lens image circle. This demands carefully setting of the adjustable lens shade to achieve good results.

    Highly recommend staying with 4x5 for table top work for a host of reasons from DOF, film cost, lighting needs, optics involved, camera movements needed and a whole lot more. Having done 5x7 and 8x10 table top stuff in the past, IMO 4x5 is a good format (specially color film, which is not the same as B&W film in many ways) if done properly. Know as the lens is stopped down to gain apparent focus, diffraction will negatively affect the image. Idea is to hold the taking aperture to no smaller than f22_ish if at all possible using camera movements and image size on film. If DOF become difficult to achieve, back up the camera-make the GG to film image smaller. Lenses achieve true focus at essentially a small flat plane to point, stopping down only provides the illusion of focus not actual focus. Other problems with sheet film sizes larger than 4x5, film flatness. Film flatness IMO is a very serious problem as film sizes grow. Problem is not as acute with contact prints from film formats 8x10 and lager. If the film is projection enlarged to make a print, that is when film flatness and more can become a very serious issue.. Don't think or believe scanning the big sheet of film then working with it in the digital domain will solve all image difficulties, it will not.


    Bernice

  4. #14

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    Re: DOF on 8x10 vs. 4x5?

    Hi Bernice, you make some very solid points and I appreciate you sharing your knowledge and experience.

    I absolutely will be staying with 4x5 for all tabletop work. I can't think of any possible reason to do anything else. I am very happy with my Linhof Technikardan and the reality is that I do this for my love of it. I will never be someone that generates an income from this and I am okay with that, but that doesn't mean I don't take this seriously. It is about me exploring, enjoying, learning, and creating images that I am proud of.

    It would be good to hear your thoughts about the pros and cons of E-6 vs. C-41 for tabletop work?

    I develop both at home in my Jobo, so either one is a non-issue from a development standpoint. I feel that I have a good post-production workflow for both as well. I know a lot of people struggle with getting colors right in post-production with color negative film, but I don't feel that I do.


    Thanks

    Larry



    Quote Originally Posted by Bernice Loui View Post
    More than just Depth of Field _ Depth of Focus, larger the film format on table top or similar non-infinity images, the larger the problems will be.. To believe larger film format always yields better image quality is simply not true. The overall image making system is a LOT more complex than that.

    Highly recommend staying with 4x5 for table top work for a host of reasons from DOF, film cost, lighting needs, optics involved, camera movements needed and a whole lot more. Having done 5x7 and 8x10 table top stuff in the past, IMO 4x5 is a good format (specially color film, which is not the same as B&W film in many ways) if done properly. Know as the lens is stopped down to gain apparent focus, diffraction will negatively affect the image. Idea is to hold the taking aperture to no smaller than f22_ish if at all possible using camera movements and image size on film. If DOF become difficult to achieve, back up the camera-make the GG to film image smaller. Lenses achieve true focus at essentially a small flat plane to point, stopping down only provides the illusion of focus not actual focus. Other problems with sheet film sizes larger than 4x5, film flatness. Film flatness IMO is a very serious problem as film sizes grow. Problem is not as acute with contact prints from film formats 8x10 and lager. If the film is projection enlarged to make a print, that is when film flatness and more can become a very serious issue.. Don't think or believe scanning the big sheet of film then working with it in the digital domain will solve all image difficulties, it will not.


    Bernice

  5. #15
    Drew Wiley
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    Re: DOF on 8x10 vs. 4x5?

    Film flatness is a non-issue if you use an adhesive or vacuum holder for 8x10 film. The film plane will be even more precise than using a conventional 4x5 sheet film holder. I really like the advantage of 8x10 film for prints 30x40 inch or larger. 4x5 will do the job; but 8x10 adds something special. Of course, very little commercial work demand this level of quality. But personal applications might deserve it. I only print optically, so there's no loss like in digital printing.
    But it is interesting just how different compositional logistics can be between 4x5 and 8x10 depth-of-field strategy. Maybe flip a coin with 5x7 on each side.

  6. #16

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    Re: DOF on 8x10 vs. 4x5?

    Drew, when my health gets better, I hope to return to doing landscapes in the field again with my 8x10. I never thought about using adhesive before. Are you talking about adhesive in the film holders? If so, can you elaborate and share what you use? I would be interested in knowing more. I also print my 8x10 optically in addition to contact printing too.


    Quote Originally Posted by Drew Wiley View Post
    Film flatness is a non-issue if you use an adhesive or vacuum holder for 8x10 film. The film plane will be even more precise than using a conventional 4x5 sheet film holder. I really like the advantage of 8x10 film for prints 30x40 inch or larger. 4x5 will do the job; but
    8x10 adds something special. Of course, very little commercial work demand this level of quality. But personal applications might deserve it. I only print optically, so there's no loss like in digital printing.

  7. #17
    Drew Wiley
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    Re: DOF on 8x10 vs. 4x5?

    The most easy kind of adhesive holder to make involves removing the film slide-in fins from a regular plastic Lisco or Fidelity holder, using a utility knife and straightedge, then carefully applying a sheet of reusable Post-It style adhesive film with permanent acrylic adhesive on one side, but low-tack repositionable adhesive on the front side. This is most commonly available as a particular 3M ATG tape. I can't remember the exact product number at the moment. I haven't tried European equivalent products. The thickness of the adhesive film itself is almost nil with respect to 8x10 focus. The amount of film bowing in a regular unmodified holder is a much greater factor. This type of adhesive seems to last many years if you don't get dirt or dust inside the holder. Mine are still working properly after 25 yrs of continuous use. Of course, you could eventually solvent-remove the old adhesive film and replace it if necessary. I reserve these holders mostly for color work, since I never enlarge black and white shots larger than 20x24, whereas I sometimes print color 8x10 shots larger. And having a history of Cibachrome printing, and now similar Fujiflex polyester medium, which holds extreme detail equally well, the precision of the adhesive holders has been a real advantage.

  8. #18

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    Re: DOF on 8x10 vs. 4x5?

    Or you can cheat as I do and use a Quick Disk by Philipp Salzgeber for exposure compensation seems to work pretty well. Though I haven't gotten around to figuring out how to extend the range to use it for head and shoulder shots on 11X14.
    For depth of field I look at the image and see what's there.

  9. #19

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    Re: DOF on 8x10 vs. 4x5?

    Quote Originally Posted by LFLarry View Post
    Do you think hyperfocal is useful or relevant when doing product/studio work?
    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.

    Click image for larger version. 

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    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.
    Attached Thumbnails Attached Thumbnails ___dof.jpg  

  10. #20
    ic-racer's Avatar
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    Re: DOF on 8x10 vs. 4x5?

    Quote Originally Posted by LFLarry View Post
    I am trying to better understand the reasons why there is less depth of field (DOF) with 8x10 vs. 4x5 at the same aperture.

    I think I understand the basic principles of light and that larger film at the same aperture as a smaller format like 4x5 has less DOF.

    Can someone help me better understand the "why" and the science behind this a little better?

    Thanks
    Magnification. This is important, because many DOF tables and equations leave OUT magnification!

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