Expanding on the idea of using a spreadsheet to calc the coverage of a particular lens ahead of time....
If subject is 5' tall and 10' away, and you're shooting with a 100 mm lens on 35mm film:
60"/120" gives a height / distance ratio of .5
So, the lens used will also give a height /distance ratio of .5. In the calcs below I'll stick in a 100mm lens:
image height / focal length = .5
image height / 100mm = .5
50mm / 100mm = .5
Image height of 50mm is too high, since you've only got 24mm film height. So you can change the distance of the group, change the focal length of the lens, or both.
I actually made up an Excel spreadsheet to take the drudgery out of it, and make the calc very fast, so I know ahead of time what the image size will be, and can then concentrate more on composition instead of fretting quite so much about the technical details.
By doing a spreadsheet, assuming you're going to split the group into two rows, tallest person is 6', use a 90mm lens, 4x5 film, and a distance from subject-to-camera of 20', I get an image *height* of 27mm. Assuming the subject width to be about 19.5', I get an image width of about 88mm.
So, will your flash cover 20' distance? Well, more like 22' distance, so the back row is lit, too.
Also bear in mind photography basics, ie, the lens may have unflattering aberrations at the edges, so you may want to leave some space around the subjects.
While you're on the phone Doug, I have a swing lens question for you--
I just got a Noblex 6/150F. If I want to do a group shot and have the group appear as a straight line, do I arrange them in a circle like you do with the Cirkut? The Cirkut must also have a curved film plane like the Noblex, I'm guessing, but I suppose it works differently with the rotating camera mount.
An arc. A 120-degree arc. Shoot me your email addy and I can share a family reunion pic where I did exactly that with the Widelux. Dunno about the Noblex, but the viewfinder isn't real accurate on the Widelux, and so drafting the geometry on the ground was a much better deal than blindly trusting the viewfinder.
I had people on a radius of 11', because that's where the fixed focus is on the Widelux (I don't know the number for the Noblex). My son and I drove a stake into the ground under the Widelux tripod, then used a surveyor tape to measure out the R11' arc. Ahead of time, I trigged out what the chord would be across that arc, for 120d. I put rope on the ground where we needed people to be. Did all the above ahead of time. Then posing them along the arc was really fast, telling them what I was doing as I went. You've gotta talk with them as you go, so everybody is coached on exactly what to expect, and when, and aren't surprised when you trip the shutter.
Test the above ahead of time. Get your numbers, lay it all out at home, and take some shots with maybe your kids are neighbors at the far ends of the 120d arc, so you *know* it works. But it will.
Conceptually, the Widelux and Cirkuts work the same, both exposing film through a vertical slit. Except the Cirkut the film stays still (relative to the ground) while the camera rotates around, exposing the film through a vertical slit (which is moving in synch with the camera). The Widelux, the film and camera are stationary, and the lens turret with the vertical slit is moving.
So, same results, and Widelux pics and Cirkut pics have a very similar look - esp. if you use the 10" lens and 10" film on the Cirkut, and only rotate 120d. Widelux is 26mm lens and about 24mm height film, so pretty proportional.
Did I answer it, or just blather on way too much?
Oh, and the Cirkut doesn't have a curved film plane. But the slit where the exposure is happening describes a circle in 3D space as it rotates, so it *emulates* a curved film plane.
I'm thankful that my day job is mechanical design, or a buncha the concepts on Cirkut and swing-lens stuff would just dumbfound me. Instead I can think my way through, after a bit of reading and thought.
David, here's the example I offered. The people are in an arc, confirmed by the curvature of the *straight* fence behind them. I won't leave this pic up real long, just until you get a look at it:
One tip if you use my advice about laying out the trig / arcs to fill your frame..... You may want to tilt the camera down slightl, so you don't get the feet at the absolute lowest limit of the film frame. If the people dominate the frame as they should, nobody will notice a slight upward bow to the horizon beyond the subjects. I'd suggest putting the subjects bellies at midpoint in the frame, height-wise.
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Thanks, Doug. I thought that was how the Cirkut works, but I wasn't quite sure how to describe it.
The Noblex has a rotating cylinder with the film slit on the back and a wider slit that the lens looks out in front, and the lens is rotating in the middle. The film plane is curved, and the 5x12 cm versions have a 135 degree angle of view across the horizontal (and 146 degrees across the diagonal). Mine has focus settings at nominally infinity, 5m, and 1m, but the actual focus distances are 17.2m, 6.5m, and 2.8m, and I printed out a DOF chart in feet that's taped to the back of the camera. Newer models have an engraved DOF chart.
I think what I'll do is make up a couple of measuring strings for group photos, not that I do them that often, but I like the look of the group shots with the swing lens cameras, so I want to be prepared when the opportunity arises.
The camera arrived today, and I shot a couple of test rolls, which I'll process tonight to make sure everything is working properly. It does seem like a fun camera. I think I'll be using it often. It's more practical for me than the 6x17 back, which I sold to offset the cost, because the negs will fit my 4x5" enlarger, and it should work well as a wide option with either my 4x5" or medium format cameras.
David, that camera sounds very very cool. I'd love to be able to focus my 35mm Widelux, but the bits and pieces are pretty tiny, you'd need tweezers. I'm jealous of that big negative - that should really rock.
About the only suggestions I'd make to you then would be to pose your group along an arc that's one of the focus distances, to have subjects as clear as can be. And you have shift on that model Noblex too, correct? If so, you can keep the camera level and just shift the lens down a little to keep the feet up a bit from the bottom of the frame.
Have fun, post up when you have something neat to show for your efforts. It won't be long, is my bet.
I've got two rolls of way-past-date Tri-X drying on the line (figured I'd experiment with cheap film), so maybe I'll have something to post in the next couple of days.
My camera doesn't have shift, but some of the later versions do. That would be a nice feature.
The camera does have a few odd quirks that I have to sort out, like making sure I push the shutter button all the way. I got one double exposure, I think because I didn't quite press the button to the end, which releases the wind knob. I also got a blank on one vertical exposure, but I could feel that it wasn't working right when I took it, so I've got to figure that out. I've also got to experiment a bit to find the practical close focus distance, since I got too close on one, and it's out of focus. They sell two closeup lenses, so I may look into those, because I'd like to be able to do environmental portraits at a subject distance of about three feet. The closeup lenses and filters actually do require tweezers to fit through the front slit, and they attach magnetically to a ring that surrounds the lens.
Here is one taken on 3-1/4 x 4-1/4, f/16 1/50th sec on Efke PL-100 processed D-76 1:1. The lens is the standard Graflex Ektar original and is not the best, especially at the edges, but the group picture came out ok. Considering that it was made with a 70-year-old Speedgraphic I can cut some slack to the image. For larger groups I think 4x5 is preferable, but I didn't want to haul the larger camera to this reunion. There are better emulsions too, but not in 3x4 size. The standard lens is ok for such pictures but you will have to be farther back from the group and you will no doubt be using the image edges as well.
Last edited by mts; 12-06-2009 at 12:24 AM. Click to view previous post history.
Reason: forgot to add the photo
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