PDA

View Full Version : moderate wide angle on 4x5?



mircea nicolae
11-Sep-2012, 03:00
Hi,

So far I have been using a 150 mm Rodenstock Apo-Sironar S in urban settings. It handles great when I take shots of objects that are closer to the camera (8 to 10 meters away). However, as one would expect, when faced with a cityscape, you have to stop down quite a lot to get a decent DOF, use front tilt, and choose your plane of focus carefully.

The color negatives are printed on 1 m x 80 cm format, so a good overall definition of details is quite important.

This is why I was thinking that a moderate wide angle lens might solve these problems. Maybe some of you have had some experience with this and are willing to share some knowledge.

Basically, I am looking for a moderate wide angle lens on 4x5. My interest for it is the large depth of field. At the same time, I am also a bit put off by the possibility of barrel distortions on the edges of the shot, which usually come with wide-angle lenses.

I already saw what a 90mm wide angle does to an urban setting. The edges of the shot are very elongated and all circles in the image turn into ovals if they are close to the edge. My guess is that if one increases the focal length, these distortions tend to become smaller. Is this so?


If it is, it would seem that lenses in the 120 mm / 150 mm range might be what I am looking for.
After some research, I found two sets of options:

1. schneider 120mm / nikkor sw 120mm
2. schneider xl 150mm / nikkor sw 150mm


Which of these lenses, when used on 4x5, offer reduced, possibly no barrel distortion on 4x5?

How wide are they actually, compared, let's say with a 135mm Rodenstock Apo-Sironar on 4x5?

Can I use the nikkor sw 150mm on my shen hao hzx 4x5 IIA?

I know that the opening of the camera is about 80 mm, and the rear element is about 100 mm. I was wondering if it would be possible to unscrew the back element, mount the front and the lens board on the camera, and then screw the back lens on.


To conclude, my main interest in a moderate wide-angle lens on 4x5 is the increased DOF, but I am also looking not to have too much barrel distortion if possible.

If you have some pictures to back up your statements, they would be highly appreciated.



Thanks

rdenney
11-Sep-2012, 07:27
Some of your wording suggests misconceptions that might be getting in your way.

For example, a wide-angle lens does not produce barrel distortion. I cannot think of a single large-format lens of any focal length or coverage that produces visible barrel distortion. It's the lack of barrel distortion that distorts round objects in the corners of the frame. We would more accurately call that rectilinear distortion.

But it's not an outcome of the the lens, it's an outcome of being very close to a round subject that is framed at the edge of the picture. The lens is looking at the object from an oblique angle, but the viewer is looking at the photo straight-on. That's what makes it look distorted.

There are two solutions to this problem: 1.) don't frame the image with round objects near the edges, or 2.) don't get close to round objects in the first place.

I'm not sure you'll find it easier to achieve the depth of field you desire even with a shorter lens. I routinely use a 90mm and even a 65mm lens with 4x5, and I still almost always have to tilt the lens to manage the focal plane when I have near and far objects that must both be in focus. There is less tilt required to achieve the same effect, but that actually makes it more fiddly rather than less fiddly.

For example, here's an image I made with a 121mm f/8 Super Angulon on 6x12:

http://www.rickdenney.com/images/japns_maple_scan0015_lr.jpg
Japanese Maple, 2009

I used both tilt and swing to focus the trunk of the tree and the leaves at the left, and still maintain some sense of the shape of the leaves at the top (but not behind the trunk, where I wanted more selective focus). Even at f/45, I could not have achieved that effect, but at that small aperture, I'd have been stuck with a shutter speed that would have prevented the photo altogether because of the slight breeze that day.

When I get down to a focal length of two inches, it becomes possible to get real depth of field using aperture alone, perhaps. But not at 120mm, especially at the print sizes you desire. Here is another 6x12 example that I've shown before, made with a 47mm Super Angulon at f/22:

http://www.rickdenney.com/images/Niagra_cannon_scan19-20_lr.jpg
Fort Niagara, 2009

In this image, I did not use tilts or swings, because the lens lacked the coverage to do so.

For example, a little consultation with DOFMaster, using a circle of confusion of 0.025mm (reasonable considering your print size), I get depth of field from 6.5 feet to infinity using a 47mm lens at f/22. But f/22 only gets me depth of field from 43 feet to infinity using the 121mm lens. Even f/45 only provides depth of field from 21 feet to infinity using that 121mm lens, and f/45 will degrade the image a little because of diffraction (in addition to demanding a long shutter time).

It seems to me that tilts and swings are part of the package with large-format photography, if you want to include close objects rendered sharply in addition to a sharp horizon.

If you want to exaggerate the near-far relationships, including round objects in the corner of the frame, and gets loads of depth of field, considering using a fisheye lens on medium format. But the problem we often run into is that we want rectilinear projection for straight things like buildings while wanting to avoid rectilinear distortion of round things like faces, and that defies an optical solution. But it can be managed with composition.

By the way, a wide-field lens like the Sironar and an ultra-wide-field lens like a Super Angulon XL will both produce exactly the same image if they are the same focal length and are used with the same format. The wider field of the Super Angulon merely permits more extreme movements. If you want a wider view in the picture and greater depth of field, you must reduce the focal length. The lenses you mentioned (as well as all the lenses made by Schneider, Rodenstock, Fuji, and Nikon) are excellent and more than good enough for your intended print size.

Rick "who uses fisheye lenses in medium format a lot to manage this issue" Denney

mircea nicolae
11-Sep-2012, 08:58
Thanks a lot for this.

Gary Beasley
11-Sep-2012, 18:41
The only camera/lens combination I've ever seen that will not produce these distortions is a swing lens panoramic camera. Since the film to lens distance is the same across from one side of the frame to the other due to the curved film plane you don't get the distortions you mention. This will only get you the correction in the direction of the swing of the lens, the other direction will still have the distortions. This is mitigated by being a much smaller dimension than the swing dimension.