effects of swing/tilt apparent on GG ?

[BigSteveG]

Should the effects of swing/tilt be apparent on the GG during the composition phase?

[CTSELLAS]

yeah. i see them.

[Matt Miller]

Absolutely. What you see on the GG is what you get on film.

[Daniel_Buck]

for subtle movements (swings and tilts can often be subtle for focusing) a loupe may be needed to see the subtle focusing changes.

[Leonard Evens]

As already noted, the effects can be subtle, particularly for wide angle lenses. The region in focus is a wedge which swivels on the so-called hinge line which is in line with the lens on a line parallel to the film plane. How wide it opens depends on the aperture, but it is always much narrower closer to the lens than far from the lens. So the changes should be most evident for subject points close to the lens.

Note that the hinge line is below the lens if you tilt down, to the same side that you swing if you just swing, and somewhere intermediate if you both tilt and swing. Its distance from the lens depends on the tilt/swing angle, the larger the angle the smaller that distance. It can never be smaller than the focal length, but you would have to have an enormous tilt/swing for it to approach the focal length, which will never happen in practice. For a small tilt angle, the hinge distance is approximately 60 times the focal length divided by the tilt/swing angle. So if you used a 5 degree tilt with a 150 mm lens, the tilt distance would be approximately 60 x 150/5 = 1800 mm = 1.8 meters. This rule breaks down for large angles. The exact rule is that the hinge distance is equal to the focal length divided by the sine of the tilt/swing angle.

[Bill_1856]

Not a dumb question at all. The answer is "yes," but it sort of depends on what you mean by "apparent." You'll probably have to use a magnifier on the GG, especially after stopping down

[steve simmons]

I usually recommend getting one of the gg brighteners to make the image easier to see. These usually brighten the image about 2 stops.

steve simmons
www.viewcamera.com

[Tomaas]

Good day Steve,

What do you mean by a "gg brightener?"

Do you mean a fresnel gg such as the ones produced by the specialty gg maker?

Tomaas

[steve simmons]

yes, Bromwell Marketing has them, Beattie, Linhof, etc. If you can find Bill Maxwell in Georgia he supposedly makes a good one as well. As far as I know, all of these will replace the stock gg on your camera.

steve simmons

[timparkin]

You could try starting with a normal lens (150 or thereabouts on 4x5) and setting up your camera so that it is close to the ground.. if you are about a meter away from the ground you'll need between 5 and 10 degrees of tilt to get the focus 'hinging' about the ground at your feet. You should then see the ground at the far distance come in and out of focus as you move your focus backwards and forwards but the ground in the foreground should stay in focus all of the time (or if you've got the tilt wrong, it will stay out of focus most of the time)..

Working close up focus and close to the ground is a good way to learn though..

Tim

[John Powers]

A faster lens can help as well. An example Sandy King has mentioned is an f5.6 360mm Symmar convertible is going to present a much brighter focusing image than an F9 355mm G Claron. Of course the down side is you will have more weight to carry. If you are not trying to back pack the trade off favors the brighter image.

John

[Leonard Evens]

You could try starting with a normal lens (150 or thereabouts on 4x5) and setting up your camera so that it is close to the ground.. if you are about a meter away from the ground you'll need between 5 and 10 degrees of tilt to get the focus 'hinging' about the ground at your feet. You should then see the ground at the far distance come in and out of focus as you move your focus backwards and forwards but the ground in the foreground should stay in focus all of the time (or if you've got the tilt wrong, it will stay out of focus most of the time)..

Working close up focus and close to the ground is a good way to learn though..

Tim


This advice is more or less correct, but let me quibble a bit.

When the hinge line is on the ground, this is what happens. As you focus by moving the standard, the DOF wedge will swivel on the hinge. If you start with the the standards close together, then nothing you can see on the gg will be in focus. As you move the standards apart, the ground will begin to come into focus. In principle the entire ground plane will be equally in focus or out of focus. The ground near the camera won't be in any better focus than the ground far away, but it may appear to be just because objects near the camera are larger and your eye doesn't expect as much in order to register them as sharp. But if you compare images of the same size on the gg glass, i.e. increasingly larger subjects the greater the subject distance, they should appear equally sharp. As you proceed to move the standards apart, subject points above the ground will start to come into focus. The vertical extent close to the lens will be much smaller than that far from the lens, but if there is little of interest close to the lens in a vertical plane, you may not notice it. On the other hand if there is some extensive vertical structure close to the lens, such as a tree, it will become clear that you can't get it all in focus by moving the standard. As you continue to separate the standards, more and more above the ground will come into focus, but if you go too far, the ground will start to go out of focus.

[Gordon Moat]

I think this image might be an extreme case of what Leonard mentions:

http://www.gordonmoat.com/swops/GM_swop_06.jpg

The shoes near the camera are in focus, the people are in focus, and the building is in focus. While there are several other movements in this camera set-up for this shot, I think it is possible to see this wedge Leonard mentions. I don't have his technical explanation skills, though I can clearly see this on the ground glass. It became simpler after installing a Satin Snow ground glass, though I could probably pick this up with a loupe on the stock ground glass. Set-up is somewhat slow and laborious for me to do these types of shots. Usually these are as near wide open shutter as the shutter speeds will allow, often f5.6 or f8.0.

Ciao!

Gordon Moat Photography (http://www.gordonmoat.com)

[trink408]

Good reading, I've struggled to tell the focus changes when using swing/tilt. I will have to try the suggestion on practicing close to the ground...

[Leonard Evens]

When you use a swing, as in Gordon's example, the wedge should be apparent. But when using tilt, since much of the DOF region is in empty space or under ground level, it may be harder to see. If there is a vertical wall which extends from close up to the far distance, you may see the trace of the wedge on the wall, but still much of it may be underground.

[john borrelli]

One of the challenges in "seeing the wedge" during composition is that we often compose our images at the lens' widest f stop, typically F5.6 or F8. At those stops, the wedge is at its thinnest(if you will). The problem arises with shots that have a three dimensional quality but can still be captured sharply enough at a smaller f stop (for example F32) with this type of shot it is a challenge to see, or estimate, the complete effects of the movements while composing.

[Leonard Evens]

One of the challenges in "seeing the wedge" during composition is that we often compose our images at the lens' widest f stop, typically F5.6 or F8. At those stops, the wedge is at its thinnest(if you will). The problem arises with shots that have a three dimensional quality but can still be captured sharply enough at a smaller f stop (for example F32) with this type of shot it is a challenge to see, or estimate, the complete effects of the movements while composing.

John is right. You can of course observe how the wedge increases in size as you stop down, but often, if you stop down to the taking aperture, you won't be able to see much of anything on the gg. If you have a bright screen---I have a Maxwell screen----that helps quite a bit. You can also use a loupe, which should help. If, for 4 x 5 format, you use more than about 2 X magnification (or equivalently viewing the gg closer than 6 inches), you in effect reduce the acceptable coc. That will make less appear in focus than with the larger cc, which means that if something is still in focus with the loupe at a given aperture, it is likely to remain in focus in a print at even smaller apertures (larger f-numbers). The ratio of the f-numbers is the same as the ratio of the magnification to the enlargement necessary to produce an 8 x 10 print from the negative. In other words, for 4 x 5 format, if something is in focus at f/16 with a 4 X loupe, it is likely to remain in focus in an 8 x 10 print if shot at f/32.