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What do you want to understand better about photography?

Discussion in 'Photography' started by JohnRice, Sep 24, 2017.

  1. JohnRice

    JohnRice Executive Producer

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    Here's a topic that just drives me crazy, because so many "experts" have no idea what it is and how it works. That's distortion.

    I'm at work and don't have any examples to post, but I can if anyone requests it. What so many writers and other so-called experts tend to refer to as "distortion", particularly regarding portraits, is actually just perspective, and not distortion at all. Distortion is an intrinsic characteristic of a lens. It's always there. You can obscure it or correct for it in post, but it is always there. When a lens takes a straight line and curves it, that's distortion. When you use a wide angle lens to get close to a subject, so that it's nose is a lot bigger than it's head, that's perspective, not distortion. This annoys me because I read so many lens reviews where people are taking portraits and talking about perspective and calling it "distortion" like it's some kind of mystery.

    I recently was reading a review of the Lensbaby Velvet 50mm lens, where this expert took a 3/4 length portrait and marveled at how it didn't have "distortion". That has nothing to do with the lens. It has everything to do with the camera to subject distance. On a full frame camera, a 50mm lens isn't desirable for a full face portrait, but it's fine for a 3/4 length portrait. Why? It has nothing to do with the lens and everything to do with the camera to subject distance. If you are shooting a full face portrait, you use a longer lens to move the camera further from the subject, which compresses the facial features. You could also use a 50mm lens, step back to the same spot where you would have taken the portrait with a 100mm and crop the image, and the result will be exactly the same, just at lower resolution. A 3/4 length portrait with a 50mm lens would be taken from even further from the subject than a full face with a 100mm. That's why it wouldn't produce exaggerated perspective.

    I got thinking about this because I'm planning to re-photograph all the teas at work for our web site. I want to do them in a completely different way, with tea spilling out of an amuse bouche spoon, and some exaggerated perspective to make it pop. I have this 15mm macro lens that will be perfect for it, but even shooting with a crop camera, the focal length will be shorter than I really want. Since the camera has far higher resolution than I need, I'm just going to put the camera on a macro rail to precisely adjust the camera to subject distance, and then crop the image to get exactly the perspective I want. By changing the camera to subject distance and then cropping the image, I am basically fine tuning the effective focal length to get exactly the result I want.
     
  2. Scott Merryfield

    Scott Merryfield Executive Producer

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    John,

    Isn't the idea behind a tilt/shift lens to correct for this perspective, or "distortion" as some people refer to it? Tilt/shift lenses are popular for architecture photography for that purpose. From what I understand about Lensbaby lenses, some of them perform a similar function. Also, some lenses do show more of a bowed look at their wide end than other lenses at the same focal lenght if you look at the lens tests.

    I have never used a titl/shift lens. They are expensive, and look complicated to use. I have used the "transform" function within Lightroom to correct for odd perspectives on buildings quite often, though. Sometimes you need a wide angle lens to fit in a building based on where you can position yourself, but that results in an odd perspective. Lightroom can correct for this, up to a point. Below is a lighthouse I shot in Acadia National Park this summer. I had no working distance, so could barely fit things in at the wide end of my 24-105mm lens (on a full frame camera). I could correct for some of the odd perspective in LR, but not all of it.

    [​IMG]
     
  3. JohnRice

    JohnRice Executive Producer

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    Scott, the LensBaby Velvet is a completely different lens from their other ones. There's no tilt. It produces a variable soft effect determined by the aperture used, but otherwise it's a fairly traditional lens. It's just also completely manual.

    This does get to one aspect of my point, though. Converging lines are not distortion. They are another aspect of perspective. If straight lines are still straight, it's not distortion, and no matter how many "experts" call it that doesn't make it so. You get converging lines when the film (sensor) plane in the camera isn't vertical while shooting a building. Like you said, it can easily be corrected digitall, but with some image degradation. There are also ways to avoid it, like using a shift lens. Tilt alters the focal plane, which different.

    Distortion is an intrinsic aspect of a lens. It's always there, not matter what you do. It can sometimes be camouflaged, but it's still there unless it's corrected later. Perspective is entirely due to how a photo is taken. Wider lenses will amplify perspective, but ultimately it is a result of how the camera is handled and how a photo is taken. There's a critical difference between those two, which is why it's important to know the difference between them and not call them the same thing.
     
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  4. JohnRice

    JohnRice Executive Producer

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    I'm starting on a project at work and thought some of you might be interested in seeing the setup and the result. I own a company that sells premium loose leaf tea, and I want to update the pictures of all our teas. I'd been thinking about how to make them more eye-catching, while still showing the difference in the appearance of different teas. I need to figure that out first, because I'll have to do this about 200 times and I want them to be consistent, plus be able to replicate it well enough when I have new ones.

    I've pretty much settled on this.

    [​IMG]

    I wanted the tea to really jump out at you, so I need to shoot very close with a nice, short lens. That makes it perfect for the Opteka 15mm macro I got a while back. Without that lens, it simply wouldn't have been possible to get this look. I ordered some porcelain amuse bouche spoons to put the tea in.

    The working distance is crazy. The front of the spoon is 2 1/2" from the front of the lens. The camera (Nikon D500) is on a tripod, attached with a long macro rail, so I can move it as far forward as needed and adjust it precisely. That Opteka is a neat lens, but it's completely primitive. It's not only manual focus and non-cpu, but it have no communication with the camera at all. There are no links, physical or electronic, between it and the camera. The aperture is what we used to call "pre-set", which means the aperture physically closes down as you adjust it. Fortunately, the D500 is one of the few cameras that's designed to completely function with that type of lens.

    [​IMG]

    It's a pretty simple lighting setup, using two Calumet (Bowens) 750 w/s monolights. One in a deep reflector and the other in a medium (2'x3') softbox. The reflector is elevated, at about 10 o'clock, and the soft box is on a boom, directly overhead, about three feet above the tabletop. I wanted the crisp, point source characteristics of the reflector, but an overall soft photo, so I have both lights at equal levels at the subject, metering and adjusting using a Minolta Flash Meter. That way, I get the detail in the tea from the reflector, but a nice, smooth fill with mild shadows from the soft box, which is effectively very large at this close working distance and small subject size.

    [​IMG]

    Live view is awesome for this kind of shot. I set the exposure in manual, then open the lens all the way up and use live view in AE to set the focus and check the overall photo. Then stop down the lens, flip it to manual exposure, and take the shot.

    Here's a view of the setup in the corner of the warehouse.

    [​IMG]
     
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  5. Mike Frezon

    Mike Frezon Moderator
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    Well you got THAT PART right, John.

    That is a very helpful post for me as I am looking to set up a similar type set-up so I can shoot some products on my wife's behalf.
     
  6. JohnRice

    JohnRice Executive Producer

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    Mike, it's rarely a good idea to use a short lens for product photos. It tends to look amateur and gimmicky. This is an uncommon exception. In most cases, products are kind of like portraits. You want a slightly long lens to compress the product. Of course, if there's this exception, there must be others. What do you need to shoot?
     
  7. Mike Frezon

    Mike Frezon Moderator
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    I was referring mostly to the mini-studio set-up with the lightbox and how a small temporary studio can be so effective.

    I am often tasked with shooting dog products and such that my wife receives that she then blogs about. Often, though, she likes to have the dogs in the pictures with (or using) the products.

    I have some backdrops and supports...but still need to purchase a lighting kit. I know something (but not a lot) about lighting from working in TV for a long time. But lighting for still photography seems more precise (and just plain different).
     
  8. JohnRice

    JohnRice Executive Producer

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    There are plenty of options these days, and several of them are very affordable. I see CFL light kits that are extremely reasonable, and LEDs that are getting there. They might not take any abuse, but they'll get you where you need to go. That approach is a lot easier, since you can evaluate the light just looking at it. For speedlights, Yongnuo has a really slick, remotely controllable system that's about $70 per light and $50 for the controller. Then you can add softboxes, umbrellas and reflectors, but metering is a lot more complicated. I got those monolights 20 years ago, and they cost a fraction of what they do now. I think Bowens 750s run $1K each these days, but I see other brands for a lot less. You don't need that much power for small products. 200-250 w/s would be plenty for small products. I'd be checking into CFL or LED kits if I were you.
     
  9. JohnRice

    JohnRice Executive Producer

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    Anyway, with products, you always want your key light behind the subject. The smaller, primary (key) light should be at least somewhat behind the subject, with a shadow casting forward. Then, you use a large softbox as fill from toward the opposite side of the product. There are infinite variations, but that's product lighting 101 in two sentences. The most amateur mistake that's commonly made lighting products is to light them only from the front. You NEED two lights. You rarely need more. If you need to bump some more light in somewhere, you can usually do it with a folded piece of blank paper set up as a reflector. I do that all the time.
     
  10. Mike Frezon

    Mike Frezon Moderator
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    I had a guy come to my house once to shoot the cover for Peg's first book...(I didn't feel I could accept that responsibility).

    He had a remote gizmo which fired remote flashes which were set up in the obvious places (as you describe above) which fired when he pressed the shutter button. I hadn't seen that before. It was pretty cool. But I think I'd do better just using constant lighting and investing in a softbox or two. Or maybe a softbox and two small key lights (CFL or LED as you suggest).

    We just started using LED light panels for our video cameras at work and having nice success with those. We do a lot of news-type stand-up interviews with those (straight-on camera mounts). They give a much wider throw than the old single bulb lights and give much better coverage on the subject and reduce the harshness of the lighting in that type of situation.

    I think my dogs would react better to constant lighting than to the suddenness of the flash...although they haven't ever really reacted badly whenever I've used my camera-mounted speedlight flash.
     
  11. JohnRice

    JohnRice Executive Producer

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    You see that gadget on the shoe of my camera? Same thing. An RF trigger for the strobes. Yeah, they’re slick.
     
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  12. Sam Posten

    Sam Posten Moderator
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  13. JohnRice

    JohnRice Executive Producer

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    I'm at work, so I haven't watched that video yet. Some friends are selling their house and a couple weeks ago I went out to take pics of it. I haven't done architecture in a long time, but I immediately realized how great the touch focus is for this type of stuff. I've shot for so long that I have a feel for where to focus, but setting up the camera on a tripod, turning on live view, then just tapping on where I wanted the camera to focus was really slick. Of course, live view focus on Nikons, even the D500, still sucks, so you need to find a spot with good contrast.
     
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  14. JohnRice

    JohnRice Executive Producer

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    Just for grins, here are a couple of the shots I mentioned above. I didn't spend a lot of time on them. Used the focusing method I mentioned, three exposure, 2 stop increment HDR using the Optimizer mode in Photomatix to combine them, and a single, bare, warm white 100 watt equivalent LED bulb to ease up the dynamic range. Then corrected the little bit of barrel distortion from the lens, and parallax in Photoshop. It's all a LOT easier than it used to be. Both shots are using the D500 and Sigma 8-16mm. The living room is 14mm f/11 and the bathroom is 8mm f/16.

    Questions?

    [​IMG]

    [​IMG]
     
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  15. Scott Merryfield

    Scott Merryfield Executive Producer

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    Those shots turned out very well, John. That's a perfect application for HDR shooting, and your results look very natural. The barrel distortion from the ultra wide lens cleaned up very nicely, too -- especially on the first shot. I really need to give Photomatix a try sometime. I rarely shoot for HDR, but it's something I need to do more -- it could help some of my landscape photography.

    We just swapped out all our old incandescent light bulbs for LED ones. The light seems much whiter, so I am interested in seeing how it changes my need for white balance correction of interior shots at our house. Even using a flash, everything was too orange under incandescent lighting. Shooting RAW makes it easy to correct in post processing, but it would be nice to get something clean right out of the camera using the auto white balance setting.
     
  16. Sam Posten

    Sam Posten Moderator
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    Before shots?
     
  17. JohnRice

    JohnRice Executive Producer

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    Are you asking for an example of a single exposure without any lens corrections?
     
  18. Sam Posten

    Sam Posten Moderator
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    Yes
     
  19. Message #39 of 168 Apr 2, 2018
    Last edited: Apr 2, 2018
    JohnRice

    JohnRice Executive Producer

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    OK. I said I did three, 2 stop increment shots for the composite, but that's not quite the entire story. I feel it's the outrageous detail in shadows that are a big part of what make so many HDR shots look artificial. Usually it's the highlights I want to capture, more than the shadows. So, the three shots are usually at a bit of a minus EV. Typically -0.7 or -1.0. So, here's a completely uncorrected conversion from the RAW file of the most exposed shot, which would actually be +1.0 EV (The +2.0 EV exposure at -1.0 EV overall).

    The barrel distortion in this shot is pretty minimal, but you can see it on the wall edge on the right. There was a decent amount of parallax to correct, though.

    Remember, there's a 100 watt equiv warm white LED bulb over the camera to bump up the shadows a bit.

    [​IMG]
     
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  20. JohnRice

    JohnRice Executive Producer

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    Keep in mind that LED bulbs are available in both daylight and soft white, which is meant to more closely match incandescent bulbs, but they're almost always a higher color temp than incandescents. They also shouldn't drop nearly as much as they age. I wouldn't use daylight bulbs for general use, except maybe in a work area, where you might want daylight color.

    If you're shooting under incandescents or soft white LEDs with a fill flash, I'd use a warming filter over the flash to get it to more closely match the color temp of the interior light. If you don't do that, you'll really never color balance the entire shot. When you're outdoors, take off the filter. Most better flashed come with the filters you need, but you can buy generic sets very cheap.
     
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