Using a PC-Nikkor Discussion

[dan_brown4]

<p>My hope is to get a detailed discussion about using a PC-Nikkor going, by presenting an straight-forward example. The following pictures result from a rather repetitive trial and error process to converge on an acceptable image. This is rather tedious, and it would be most helpful to learn from other's experience in setting up and shooting, hopefully to converge on a good result more quickly.</p>

<p>The goal of this project was to photograph a relatively flat object that does not fit within the 3:2 aspect ration of the FX format when taken at a square angle. This is achieved by taking an acute (or obtuse) angle shot, thereby filling the FX frame. The further goal was to ensure the entire surface of the object (a guitar) was in sharp focus.</p>

<p>For this task, I use f4.0 on the lens to keep the DoF shallow, hopefully making the sharply focused guitar appear to float above the unfocused table surface.</p>

<p>The final image:<br>

<img src="http://www.dlaab.com/photo/pctest/guitar.med.jpg" alt="" /></p>

<p>The final set-up used:<br>

<img src="http://www.dlaab.com/photo/pctest/setup.jpg" alt="" width="700" height="331" /></p>

<p>Point of focus:<br>

<img src="http://www.dlaab.com/photo/pctest/fret.detail.jpg" alt="" /></p>

<p>Lower portion of frame (headstock):<br>

<img src="http://www.dlaab.com/photo/pctest/headstock.detail.jpg" alt="" width="444" height="266" /></p>

<p>Upper portion of frame (bridge):<br>

<img src="http://www.dlaab.com/photo/pctest/bridge.detail.jpg" alt="" /></p>

[blake_schwalbe]

<p>You mean tips on applying the Scheimpflug principle with the PC-Nikkor that isn't based on trial and error?</p>

[mike_halliwell]

<p>I seem to remember that you draw 3 imaginary planes from 1) the object axis, 2) the chip's axis and 3) the 'front-of-lens' axis. The aim is to make all 3 planes meet so that the depth of field/focus is at it's maximum. Not sure f4 is enough for a sharp image. Try f5.6-f8.</p><div></div>

[dan_brown4]

<blockquote>

<p>You mean tips on applying the Scheimpflug principle with the PC-Nikkor that isn't based on trial and error?</p>

 

</blockquote>

<p>Well, yes. Some process to approach the task that gets to the goal more quickly.</p>

[dan_brown4]

<p>Mike: In your diagram, the line 3 is the lens plane. It would be helpful if Nikon would imprint the lens plane on the lens body, like they do the film plane on the camera body. However, Nikon does not do that.</p>

[bjørn rørslett]

<p>The indicator is on my DSLR Nikons so should appear on yours as well? Left-hand side of the finder housing when you look into the camera from the rear.</p>

[dan_brown4]

<p>Thanks Bjorn. Yes the camera has a film plane indicator, but the lens does not have a lens plane indicator. I guess this is because the lens plane moves as the lens is focused.</p>

<p>BTW, I know you are a PC-Nikkor user. Do you start the tilt-focus process by focusing on the close object first, then trial en error tilt angle and focus to get the far object in focus? Or is there some other technique?</p>

[mike_halliwell]

<p>errr...you couldn't have a lens plane indicator...'cos it moves and <strong>TILTS</strong>!! You are changing the lens axis compared to the 'film' axis. Using shift alone they are parallel. When you introduce tilt they are <strong>NOT</strong> parallel. <br>

Use a straight edge across the front filter face. I used to have a 4ft balsawood rod from my ex-modelmaking days, very light and didn't scratch the lens if I was extra clumsy! I guess you could even glue it onto a cheap step-up ring. You'd have to ensure it always pointed 'down', ie perpendicular to the guitar-face axis. (vertical <em>plane</em> not pointing straight down!). Compositionally, it is abit trial and error. For product shots, you end up with a table with descrete marks as to the frame edges and place you object within the marks. Frame slightly loosely and crop later. However, I've never used a PC 'long' lens, only the 24, 28 and 35mm varieties, so it may be harder to do it that way. 5 x 4 inch mono-rail cameras make this so much easier!</p>

[blake_schwalbe]

<p>Was the guitar actually raised above the table? There's a shadow underneath it. What is the focal length of the lens you used?</p>

[dan_brown4]

<p>The guitar was raised about 3" above the table. The lens was an 85mm PC Nikkor shot at f4.0. I wanted to do this test at f2.8, but, the strobes were already at the lowest power setting and the D700 was at ISO 200.</p>

[mike_halliwell]

<p>IQ is bad enough at f4, I'm fairly certain this £1400 beast is not really supposed to give great results wide open. It's primarily a Macro lens for up to 1/2 scale reproduction of small stuff such as stationary small wildlife & jewellery etc. where the ability to manipulate the depth of field in a plane not parallel to the chip to get the most in focus at any one time. Shooting wide open is kinda the other way around!</p>

[dan_brown4]

<p>I know, I was trying to learn how to control the focus plane of the lens, not optimize image quality. BTW, the pictures was an in-camera jpg, and I had inadvertently left the white balance on cloudy day. Default sharpening, and nothing done to the images in PhotoShop other than crop and size.</p>

[bjørn rørslett]

<p>Front of the lens defines the plane you are looking for .... Whether one uses a yard stick or eyeballing is immaterial. From my close-up days, standing beside the camera to ascertain alignment of planes has become second nature and using a PC lens just continues along the same lines as it were.</p>

<p>I usually have the PC lenses set up to give tilt and shift in the same plane. Then, you apply tilt to arrange the plane of focus where it is most needed, and afterwards, use shift to touch up on the framing. Not really different from using my 4x5" camera in the older days, but LiveView (LV) is not always the better alternative to examining the groundglass with a powerful loupe (LV only gives you optical 1X, remember; no enlargement). In a studio setting, you could run the camera in a tethered setup and use your computer monitor to evaluate peak sharpness.</p>

[steven_p]

<p>Interesting discussion.<br>

I use the 85 for close-ups of flowers and the like. I'm still learning it's quirks and looking forward to springtime. The main purpose for me is controlling/increasing depth of field without stopping down as much.</p>

<p>Mike,<br>

It's pretty darn sharp, wide open.</p>

<p>Dan,<br>

Beautiful twang box, and a bit of a distraction. I have a 72' custom.</p>

[mike_halliwell]

<p>I'm not near my Depth of Field Calculator but what do you get at 1/2 scale at f2.8? Sounds perfect for picking out a diamond in a ring setting but, up to a point, you can do that with a 50mm 1.4 with a tube or two....and save £1200. Tilt and Shift with the opposite use of the Scheimpflug principle is<strong> THE </strong>way of minimising depth of field/focus. <br />I guess I'm biased, but I prefer the whole flower in depth, not just a stamen....! Unless I'm being arty.....! or in your case the 'tightening keys' sharp with the 'string holders' soft.... (sorry for the terms!)</p>

[Andrew Garrard]

<blockquote>(LV only gives you optical 1X, remember; no enlargement)</blockquote>

 

<p>Huh? You can zoom in on live view to the pixel level, and scroll around the image (although you need the camera mounted solidly if you don't want to move it while scrolling). Use with a T/S lens is the entire reason I waited for a full-frame camera with live view (D700) to come out rather than having got an original 5D a year earlier. Before that, since I could always crop afterwards, I tended to get set roughly the tilt I wanted and then wave the camera around to get the focal plane in the right place. Not very exact, but fast!<br />

<br />

I still hope (and suggested to Nikon a while ago) that Nikon might consider letting the Live View be split into quadrants which can be zoomed and positioned independently. If you could put three of the quadrants at points on the plane you want in focus and keep the last for a framing overview, it would make setting up a T/S lens much easier.<br />

<br />

That said, my T/S is a cheap Arsat (on my Canon I had a Hartblei, which had much better ergonomics) and I've not yet made much use of it, so this isn't an expert opinion.</p>

[dan_brown4]

<p>Andrew, I love the LiveView quadrant idea. Or even just split screen to pick two locations and twiddle with the lens looking for focus.</p>

<p>Also, Bjorn, great description of how to use tilt and shift together (i.e. tilt to get focus then shift to align image in frame). That was one of my frustrations, getting the focus and then moving the ball head to align, which caused focus to go off Aurrggghhhh!!!!!</p>

[dan_brown4]

<p>Here is another round, more carefully focuses (Liveview), shot more "square" and stopped down to f8.</p>

<p>Yamaha guitar<br>

:<img src="http://www.dlaab.com/photo/yamaha.jpg" alt="" width="525" height="700" /></p>

<p>Headstock area:<br /> <img src="http://www.dlaab.com/photo/peg.jpg" alt="" /></p>

<p>Central area (binding):<br /> <img src="http://www.dlaab.com/photo/binding.jpg" alt="" /></p>

<p>Upper area (bridge):<br /> <img src="http://www.dlaab.com/photo/bridge.jpg" alt="" /></p>

<p>All in all, I am quite happy with this performance (again, these are camera JPEG).</p>

[dan_south]

<p>If the near and far area in the frame are not as sharp as the center (where you focused), then there are only two possibilities. Either you have tilted too much or you have not tilted enough. You need to adjust the tilt and refocus. </p>

<p>Focus first on the center of the frame. Now take a look at details in the near area (the head at the end of the guitar's neck). To get the near area in sharp focus, are you rotating the focus ring TOWARD infinity or AWAY from it. If you are turning the focus ring toward infinity to get the near objects in focus, you have tilted TOO MUCH. Try less tilt and begin the focusing process again from the middle point.</p>

<p>If you are rotating the focus ring AWAY FROM infinity to get the near objects in focus, you have not tilted enough. Tilt a little more and start the focusing process again from the middle point.</p>

[andreas_weber]

<blockquote>

<p>IQ is bad enough at f4, I'm fairly certain this £1400 beast is not really supposed to give great results wide open.</p>

</blockquote>

<p>Limited depth of field wide open isn't really a lens flaw ...</p>

<blockquote>

<p>Front of the lens defines the plane you are looking for</p>

</blockquote>

<p>Front <em>focal plane</em> of the lens, actually ...</p>

<blockquote>

<p>LV only gives you optical 1X, remember; no enlargement</p>

</blockquote>

<p>Enlargement <em>compared to what</em>? At max. zoom the view on the back of my D3 approximately equals that of a projected 6x9" image. And as Andrew stated, you can judge sharpness at pixel level; the camera <em>doesn't resolve more</em> than you could see at that magnification ...</p>

<p>Dan Souths explanation is the most helpful so far. A more elaborate version can be found at http://www.largeformatphotography.info/articles/bond-checklist.html; and with Nikon's PC-E 85 I'd start focussing on a line about halfway between center and edge of the frame (with a portrait oriented frame). That's about where focussing distance doesn't change with tilt for that lens (It's funny, I wrote a blog entry about that topic just two days before you asked this question -> http://blog.zauber-allenthalben.de/tilt-effect-on-nikon-pc-e-lenses-24-85-mm).<br /> More useful for practical application than the Scheimplug rule is the lesser known "hinge rule", termed by Harold Merklinger. Read his materials about focussing the view camera (<a href="http://www.trenholm.org/hmmerk/index.html#FVC">http://www.trenholm.org/hmmerk/index.html#FVC</a>)! The hinge rule allows you to prepare a "cheat sheet" for your lens to preset tilt. If your preset was decent one iteration of focussing/tilt adjustment usually is enough to get the plane of focus exactly where you want it.<br /> <a href="http://blog.zauber-allenthalben.de/tilt-effect-on-nikon-pc-e-lenses-24-85-mm"><img src="http://posterous.com/getfile/files.posterous.com/temp-2011-01-15/kktuymjvpytikErurDhEBsoABviJpuneuzGhAceIoqsHbhBxgJwjIpyfprzu/Cheat_Sheet.jpg" alt="" /></a></p>

[andreas_weber]

<blockquote>

<p>Front <em>focal plane</em> of the lens, actually ...</p>

</blockquote>

<p>Arrrgh, stupid place to make a translation/copy mistake. Should have been "front <em>principal</em> plane", of course ...</p>

[dan_brown4]

<p>Dan South; thank you for taking the time to share your experience on running the PC Nikkor. I'll get in the studio later and work through your procedure a few times.</p>

 

<blockquote>

 

<p>If the near and far area in the frame are not as sharp as the center (where you focused), then there are only two possibilities. Either you have tilted too much or you have not tilted enough. You need to adjust the tilt and refocus.<br>

Focus first on the center of the frame. Now take a look at details in the near area (the head at the end of the guitar's neck). To get the near area in sharp focus, are you rotating the focus ring TOWARD infinity or AWAY from it. If you are turning the focus ring toward infinity to get the near objects in focus, you have tilted TOO MUCH. Try less tilt and begin the focusing process again from the middle point.<br>

If you are rotating the focus ring AWAY FROM infinity to get the near objects in focus, you have not tilted enough. Tilt a little more and start the focusing process again from the middle point.</p>

 

 

</blockquote>

[andreas_weber]

<p>Aaand, I have to correct my numbers for the maximum "size" of the live view image, as well (it's quite a bit bigger actually):</p>

<blockquote>

<p>At max. zoom the view on the back of my D3 approximately equals that of a projected 6x9" image.</p>

</blockquote>

<p>From a quick "live view" look at a ruler the maximum zoom gives you about 13.5x magnification compared to the view without zoom. The displayed image is pretty exactly 60 mm wide; enlarged 13.5x the entire image would be about 810 mm wide and 540 mm tall. You see the live view image slightly bigger than a 4x5" view screen with a 5x loupe ...</p>

[bjørn rørslett]

<p>I used 12X-16X loupes on the ground glass of 6x9 or 4x5". Much better than anything LiveView can offer. Yes, resolving beyond 1 pixel is not easy :) With film systems you actually focused on the aerial image and could apply a lot of secondary magnification without running the risk of empty magnification.</p>

<p>For exacting close-up work, with the earlier F-series, I used clear-glass screen with etched mm scale and cross-hairs, plus 6X finder loupe. That gave a precision of focus not attainable by any of today's digital systems.</p>

<p>To the current thread: using Liveview (and a tripod-mounted camera) is a must of you should get a good utilisation of the Scheimpflug principle with the 85 (or other PC lenses). Finder magnification is so small you cannot ascertain critical focus, and the danger of over- or undercorrecting tilt is a real issue. Shift is easier to handle ...</p>

<p> </p>

[dan_south]

<p>Good luck, Dan! You're going to nail it!</p>

<p>One more note: As others have mentioned, ideally you might want to shoot at a smaller aperture than wide open. f/8 would probably be a good choice, but you might want to test 5.6, 11, and 16 to see which one works best in this case.</p>

<p>Edge sharpness can be a problem for any lens when it's wide open. PC lenses have a larger image circle than other lenses. This larger circle extends and intensifies the soft edge effect. As with any other lens, a smaller aperture will help to minimize the soft edges.</p>