First 4x5 Exposure - Movement Question

[yardboy]

I recenty recieved my first 4x5 camera, a shen hao field camera. I

bought it with a Fujinon NW 125 5.6 and a Commercial Ektark 8 1/2"

6.3. I went to the beach yesterday to use if for the first time

after some dry runs in the past week, learning how to open, close,

etc. The shot I'm including is was the last exposure of the

afternoon, and the only one that had any artistic merit, imo. It

was a challenging shot, and my goal was to render the entire scene

within the DOF with my 210 lens.<br><br>

 

I tilted the front aggressively, and the rear was titled back a

bit. The top of the concrete, uh, thingy, is tack sharp most of the

way out, and definitely in the lower left corner, however the sand

at the base of it, in the foreground is out of focus. Any

suggestions on how to get such a shot in focus from edge to edge,

side to side? Thanks.<br><br>

 

<a href="http://www.binarydesigninc.com/image.php?

image_id=1136930168">http://www.binarydesigninc.com/image.php?

image_id=1136930168</a>

[amund_aaeng]

Did you check front to back focus on the groundglass?

For a scene like this, here`s what I would do. First you focus on the far, then tilt the front(just a little) until you have the foreground in focus, and then check the far again, continue to do this until you have the back and front in focus, doesn`t take long before you get the hang of it. With a 210mm I` d probably stop down to f/32 for this.

[wilbur_wong]

It may or may not be possible. You have learned your lesson about using Scheimflug well and you are doing exactly what needs to be done. On thing to possibly understand is that without using view camera movements, the camera is resticted to a flat depth of field which deepens as you stop down, however that depth is irrevocably forever locked to be parallel to your film with some distance in front and some distance behind the focal point.

 

When you use Scheimflug to change the plane of focus, (I refer to it in this instance as "laying it down") The plane of center of focus, the lens and film all pass through a common "hinge" point. In addition to these central planes, the front depth of field as well as the behind depth of field also will pass through the hinge point. In other words, the portion nearest you has a much smaller thickness of depth of field as that which is further away.

[leonard_evens]

When you say you tilted the front aggressively, just what do you mean? Normally it isn't necessary to tilt very far for a scene like this. For example, if your lens were 1 meter over the subject plane, with a 210 mm lens, and the back plumb, you would tilt about 12 degrees.

 

Usually there is no need to tilt the back unless you want to change the shape of the image.

 

Normally, it is difficult, if not impossible, to get a considerable vertical extent in focus near the camera. That is because the region of adequate focus is a wedge bounded above and below by two (half) planes. It hinges on a line below the camera as you focus. The vertical extent in focus increases with distance from the lens, but it can be quite small near the lens.

 

If the standards are parallel before you tilt, there should be no significant variation in focus from side to side at the same distance from the lens. It looks to me as if there may be a slight swing present in addition to the tilt, but it is hard to be sure.

 

It looks to me as if your plane of exact focus goes up at an angle and that results in the distant objects being out of focus. This may be the result of your trying to get as much in adquate focus near the lens as possbile. You didn't manage to do that to your satisfaction, for the reason I gave, and in the process you sacrificed the distant objects.

 

Let me reenforce the recommendations already given. Choose a far point and a near point. Make a first guess at a tilt. Then focus on the far point and refocus on the near point. If you have to increase the distance between the standards to do that, increase the tilt. If you have to decrease the distance between the standards to do that, decrease the tilt. You should now be able to refocus so that the exact plane of focus passes through both the near point and far point. But, as noted above, the wedge shaped region of adequate focus will extend vertically above and below that plane, and the whole region will roate about the hinge line as you focus. The angular width of the wedge will depend on the f-stop, the smaller the aperture, the larger the angle. By appropriate choice of aperture and focusing, you may be able to get evertyhing of interest within the wedge region, but you can't violate the laws of optics. So any extensive vertical extent close to the lens may be impossible to encompass while still keeping distant points in focus.

[yardboy]

Thank you for your comments. I think that shot simply may not be possible at the exact angle I used with the lens I used and at the exact camera point. Or perhaps the vertical distance between the sand and the top of the concrete tube is simply too much. Or I need to modify my plane of focus, from the top of the concrete to a plane that disects the concrete tube about halfway up from the sand. I did use f32 in fact. Well, I plan on going back this evening for another shot at it. I'll try the focusing methods suggested, and probably slightly change my camera location. Everything about the wedge shaped DOF based off the angle of the focal plane makes sense to me, and did as soon as i developed the negative.

 

The good news..8 negs exposed, only 1 ruined (forgot to close lens before yanking out the darkslide), one i didn't bother developing, and the rest turned out reasonable well, in that a halfway decent exposure was recorded and developed in the emulsion. It was a first time for any of that with 4x5 so I'm pleased.

[yardboy]

A question I should probably ask: should i apply base tilt or tilt from the center of the lensboard in this situation? Does it really matter?

[pico_digoliardi]

Keep it simple at first: learn what just rear tilt can do for you.

[sladez]

Jason--a shot like this should be easily taken care of with any lens using a LF camera. It looks like to me you laid the focus plane down correctly but your focus point is too high. You still need to consider the amount of focus above and below your point of focus. If you focus on the cement "thingy" you are waisting a lot of dof above. even though your plane of focus is at the correct angle (from what I can see) the 210mm doesn't have enough dof up close to cover all the way to the sand. If you had place your focus point midway between the top of the cement and the sand you should have gotten everthing sharp without having to stop down too much.

 

There are A LOT of methods used--some very technical/exact--I have tried them all but continue to go back to what Amund was describing. It always works and becomes the least complicated and easiest method of them all once you get the hang of it. The only time this method gets tough is in low light or wide angle lenses where it is hard to see. having a camera with base tilt rather than axis tilt makes it tougher as well--just need to refocus more often. I use the Shen Hao as well--it has both but the axis tilt is a pain to use so I just refocus more often using base tilt.

 

You will find over time it takes a lot less tilt than you think to bring this type of scene into focus. With that said and reading your message--you may have had too much forward tilt and maybe your angle of focus wasn't running parrallel with the cement "thingy"--hard to tell on this monitor at work.

 

Good luck.

[geert_de_keyser1]

Hey Slade,

 

I was looking at the very beautiful pictures on your site (especially like the general mills pic) and I was wondering about something. I've noticed that you sometimes use and EI of 64 and sometimes an EI of 50 for your Kodak T-Max 100. Why the difference in EI? And can you actually see this different setting in the results?

[leonard_evens]

To answer your question about base versus axial tilt, it doesn't matter as far as the end result is concerned. But axial tilt can sometimes make it easier to see what is happening because some of the image stays in focus, if it was originally, when you tilt. I don't think that is your problem.

 

About rear vs front tilt, my opinion is that one should start off keeping the back vertical and use only front tilts. Rear tilt does two things: it changes the shape of the subject and it also changes the plane of exact focus. Front tilt only changes the plane of exact focus.

 

Here is one further bit of information you might find useful. You can estimate the effect of different apertures as follows. First find the hyperfocal distance for your focal length and aperture. This is available in various charts and calculators. With the back vertical, estimate the distance below the lens where the exact subject plane will go, i.e., the hinge distance. Then at the hyperfocal distance from the lens, the vertical extent above and below the plane of exact focus which falls within the DOF will be the same as the hinge distance. The vertical extent at other distances will be increased or decreased proportionately.

 

For example, using a coc of 0.1 mm, the hyper focal distance for a 210 mm lens at f/32 is about 13.8 meters. If the hinge line is 1 meter below the lens, then at 13.8 meters, 1 meter will be in adequate focus above and below the exact subject plane. One meter from the lens, this will be reduced by the factor 1/13.8, which yields about .0725 meters or 7.25 mm. So you see how little is in focus that close to the lens. If the hinge distance were doubled by raising the camera to 2 meters above the exact subject plane, you would still only have 14.5 mm in focus that close to the lens. If you double the f-number to f/64, you reduce the hyperfocal distance by a factor of two, and that will also double the amount in focus 1 meter from the lens, but it will still be pretty small.

 

You would have greater luck by decreasing the focal length. For example, using lens of half the focal length, or 105 mm, would reduce the hyperfocal distance by a factor of four. At f/32, this would be about 4.5 meters. Hence, with a hinge distance of 1 meter, at 1 meter from the lens, the wedge would extend about 1/4.5 ~ .3 meters above and below the exact subject plane. Unfortunately, short focal lengths make distant objects look smaller and "distort" the perspective when the final print is viewed from further than the center of perspective, which is normally the case.

[sladez]

I appreciate your comment about my site. You bring up a point that sort of goes with this

discussion. When I first started LF I was VERY exact--thought I needed to be. I had my EI

worked for each lens, different developers, my N+.25 time worked out, what EI I needed if

I were to develop at N+.5....etc. I was nuts! The more I do LF the more I find it isn't

necessary to be like that. I totally believe in consistancy and I am be no means out there

shooting and developing on a whim but I get better images now that I have calmed down

and decided it was ok to have one developer and one paper and not need a N-.37

development time.

 

Most of what you see shot at an EI 64 instead of my usual EI 50 either had an N+2

development (compensating for the increase in film speed during a longer development

time) or, more than likely it was an older lens I had and a different developer I was using.

EI 64 use to be my normal number for most of my lenses--I did own a really crappy 90mm

that required an EI of 32 and could only be used at 1" or bulb--hated that lens!

 

To answer a simple question in this agonizing reply--yes, you can see some difference but

no--not enough to worry about. I would favor the EI 50 and if you find yourself having to

burn down your darker zones more than you think you should.....move it to an EI 64 or

80--not going to kill an image--keep sneeking up on it and you will know when it is just

right.

[yardboy]

Leonard - Thanks for you in-depth assessment. Before you even got to your last paragraph, I knew what I probably needed to do, which was use my 125mm fujinon instead of the 8 1/2" commercial ektar. I'm going to head back the next overcast day we have and try again. That is some great info you gave me though, and did answer many many questions I was thinking but didn't ask. Thanks!

[yardboy]

Leonard - Thanks for you in-depth assessment. Before you even got to your last paragraph, I knew what I probably needed to do, which was use my 125mm fujinon instead of the 8 1/2" commercial ektar. I'm going to head back the next overcast day we have and try again. That is some great info you gave me though, and did answer many many questions I was thinking but didn't ask. Thanks!

[doc_w]

...and not even taking into account that it was your first day, it's a pretty nice photograph. Please show us your next attempts at the same subject.