40mm lens is it the perfect inbetweeny

A few years back, I was interested in stitching frames together to achieve a sort of poor man's Xpan vision of the world. My line of thought was that if a 43.2mm lens theoretically gives natural perspective for a 36x24mm format, a 40mm lens should be close to ideal for stitching frames together. That was obviously wrong, as you can see from the overhead cable on this stitched image. I don't know why it was wrong, though. Any thoughts?

Rollei 35 Tessar, Ilford Delta 100 in Tetenal Emofin


Incidentally, the resolution of that little Tessar lens is pretty darn' good.

As a rather simplistic explanation, if you rotate the camera and lens, objects toward the edge of the frame will not line up exactly. The effect will be more pronounced with shorter focal lengths than with longer, even if you keep the subject image size the same.

If you keep the film on the same plane in both photos, by shifting the camera or lens sideways, the objects will line up better.

grat said:

What does that make the fairly common 50mm f/1.7?

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Affordable good sense.

r_a_feldman said:

As a rather simplistic explanation, if you rotate the camera and lens, objects toward the edge of the frame will not line up exactly. The effect will be more pronounced with shorter focal lengths than with longer, even if you keep the subject image size the same.

If you keep the film on the same plane in both photos, by shifting the camera or lens sideways, the objects will line up better.

Click to expand...

Ah, OK, got it! Thanks. Shifting the film plane sideways accurately could be rather tricky in practice.

Wasn't there a special panoramic tripod head made by Rollei for their MF cameras, made to allow accurate location of adjacent frames? How did that work, and why did it not suffer from the problem described?

film_man said:

I like a 40. My main lens on the EOS 1N is a Voigtlander 40/2. Also have a 40/2.8 STM.

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The start of this thread coincided when I was thinking to assemble a light and compact modern SLR with AF for those ocasions where my Nikon FM2 is not a good option (i.e fast action in low light).

So I finished with this pretty inexpensive combo:


Canon 300X (Rebel T2 in US) with a 40mm f/2.8 STM.

The whole kit with batteries weights 530gr and it has a total depth of 9 cm, the integrated flash (GN 13) is also a welcome addition for the intended purpose. It seems a very capable camera in a cheap "suit", really looking foward to put some film on it...

[mods: sure this is long and off-topic, but I felt the need to correct some inaccurate statements]

snusmumriken​

My line of thought was that if a 43.2mm lens theoretically gives natural perspective for a 36x24mm format, a 40mm lens should be close to ideal for stitching frames together. That was obviously wrong, as you can see from the overhead cable on this stitched image. I don't know why it was wrong, though. Any thoughts?

Click to expand...

r_a_feldman​

As a rather simplistic explanation, if you rotate the camera and lens, objects toward the edge of the frame will not line up exactly. The effect will be more pronounced with shorter focal lengths than with longer, even if you keep the subject image size the same. If you keep the film on the same plane in both photos, by shifting the camera or lens sideways, the objects will line up better.

Click to expand...

Diagnosis correct. Remedy not.
Diagnosis is correct. A camera (a normal one, see below) projects the 3-d world onto a plane. If you rotate the camera, you change the plane, and the geometrical transformations do not match. Yet in all cases, straight lines in the world are mapped to straight lines on film. Won't go into more details, would require preparing figures, and even so... The laws of perspective are known since Alberti and a few other worked them out in the 15th century.
Remedy (move camera with film in same plane) is not. Demonstrated with a counter-example. Imagine there is a house on the right of the field of view of the first picture; far enough to the right that you see its left-side wall. Now move your camera to the right, keeping the film plane parallel, until the house is in left of the viewfinder. Now you don't any more see the left wall of the house. How could you possibly stitch these two images together?

snusmumriken​

Ah, OK, got it! Thanks. Shifting the film plane sideways accurately could be rather tricky in practice.

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Go back to the camera in a fixed place, "just rotating" between frames. Take overlapping pictures (1/3 of a frame overlap recommended). Feed them to a piece of software called a pano stitcher. The software will "undo" the projection from the (two or more) film planes onto a sphere (as above, don't ask for more details), and, from the overlap areas, figure out how the images should be positioned. It will also figure out more subtle things, like the distortion of the lens; I mean true distortion, as in pincushion of barrel, not the "distortion" of wideangle lenses. Once the images match on the sphere, the software will re-project them onto...

• A plane, effectively providing the picture that you would have obtained with a view camera. You can choose that plane, giving the equivalent of shifts/tilts. Or...
• A cylinder, effectively providing the picture that you could have taken with a Horizon or Noblex camera.
• Several other options.

And, what is meant by "just rotating" between frames? That the camera stays at the same place. But which part of the camera? If you rotate the tripod head, the front lens will rotate and move. So we have to a small degree the unwanted effect described above in the example of taking a pano of a house by parallel shift. Over the internet, so many experts state (parrot) that the nodal point of the lens is what must be kept fixed, while truly it is the entrance pupil. What is the entrance pupil? stare into the front of the lens, with the diaphragm partly closed; the entrance pupil is where the diaphragm appears to be, as seen through the front group(s) of lenses.
This issue of what part of the camera must remain at a fixed position is significant only if there are nearby foreground objects.

Pano software (just example that I have used): PTGUI (shareware), Hugin (freeware).
Example Piazza dell'Anfiteatro, Lucca, Italy

halfaman said:

The start of this thread coincided when I was thinking to assemble a light and compact modern SLR with AF for those ocasions where my Nikon FM2 is not a good option (i.e fast action in low light).

So I finished with this pretty inexpensive combo:

Canon 300X (Rebel T2 in US) with a 40mm f/2.8 STM.

The whole kit with batteries weights 530gr and it has a total depth of 9 cm, the integrated flash (GN 13) is also a welcome addition for the intended purpose. It seems a very capable camera in a cheap "suit", really looking foward to put some film on it...

Click to expand...

I have used the EOS 300V with the 40mm STM. It's an awesome walk around, light combination. A nice sharp lens with a very capable little camera.

bernard_L said:

Now move your camera to the right, keeping the film plane parallel, until the house is in left of the viewfinder. Now you don't any more see the left wall of the house. How could you possibly stitch these two images together?

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Great post, thanks, which deserves its own thread. I tried the above method of moving the camera in a parallel fashion a few years ago and the software stitching result was as bad as you would predict, even with significant overlap. The software couldn't figure out a reasonable solution, and even if it could the perspective would have been all wonky as you rightly point out.

bernard_L said:

[mods: sure this is long and off-topic, but I felt the need to correct some inaccurate statements]


Diagnosis correct. Remedy not.
Diagnosis is correct. A camera (a normal one, see below) projects the 3-d world onto a plane. If you rotate the camera, you change the plane, and the geometrical transformations do not match. Yet in all cases, straight lines in the world are mapped to straight lines on film. Won't go into more details, would require preparing figures, and even so... The laws of perspective are known since Alberti and a few other worked them out in the 15th century.
Remedy (move camera with film in same plane) is not. Demonstrated with a counter-example. Imagine there is a house on the right of the field of view of the first picture; far enough to the right that you see its left-side wall. Now move your camera to the right, keeping the film plane parallel, until the house is in left of the viewfinder. Now you don't any more see the left wall of the house. How could you possibly stitch these two images together?



Go back to the camera in a fixed place, "just rotating" between frames. Take overlapping pictures (1/3 of a frame overlap recommended). Feed them to a piece of software called a pano stitcher. The software will "undo" the projection from the (two or more) film planes onto a sphere (as above, don't ask for more details), and, from the overlap areas, figure out how the images should be positioned. It will also figure out more subtle things, like the distortion of the lens; I mean true distortion, as in pincushion of barrel, not the "distortion" of wideangle lenses. Once the images match on the sphere, the software will re-project them onto...

• A plane, effectively providing the picture that you would have obtained with a view camera. You can choose that plane, giving the equivalent of shifts/tilts. Or...
• A cylinder, effectively providing the picture that you could have taken with a Horizon or Noblex camera.
• Several other options.

And, what is meant by "just rotating" between frames? That the camera stays at the same place. But which part of the camera? If you rotate the tripod head, the front lens will rotate and move. So we have to a small degree the unwanted effect described above in the example of taking a pano of a house by parallel shift. Over the internet, so many experts state (parrot) that the nodal point of the lens is what must be kept fixed, while truly it is the entrance pupil. What is the entrance pupil? stare into the front of the lens, with the diaphragm partly closed; the entrance pupil is where the diaphragm appears to be, as seen through the front group(s) of lenses.
This issue of what part of the camera must remain at a fixed position is significant only if there are nearby foreground objects.

Pano software (just example that I have used): PTGUI (shareware), Hugin (freeware).
Example Piazza dell'Anfiteatro, Lucca, Italy
View attachment 327098

Click to expand...

Thanks very much for this, very helpful. Apologies for leading the discussion astray.

halfaman said:

The start of this thread coincided when I was thinking to assemble a light and compact modern SLR with AF for those ocasions where my Nikon FM2 is not a good option (i.e fast action in low light).

So I finished with this pretty inexpensive combo:

Canon 300X (Rebel T2 in US) with a 40mm f/2.8 STM.

The whole kit with batteries weights 530gr and it has a total depth of 9 cm, the integrated flash (GN 13) is also a welcome addition for the intended purpose. It seems a very capable camera in a cheap "suit", really looking foward to put some film on it...

Click to expand...

I've got the first gen 300 (Rebel 2000) and it does make a great little combo with the 40. Sometimes I look at the photos and wonder why I need any of the other big and heavy stuff.

awty said:

As long as they are sharp from f4 to f11, the other apertures are for indulgence.

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OR necessity.

r_a_feldman said:

As a rather simplistic explanation, if you rotate the camera and lens, objects toward the edge of the frame will not line up exactly. The effect will be more pronounced with shorter focal lengths than with longer, even if you keep the subject image size the same.

If you keep the film on the same plane in both photos, by shifting the camera or lens sideways, the objects will line up better.

Click to expand...

I wanted to photograph a dam spillway with a defaced mural on it last year (the Army Corp cleaned it at the end of last year). I brought my Mamiya C330f with a 55mm lens, and as a back-up I brought a Kiev 4a with a 21mm SC Skopar. I hoped the 55mm would get the shot, but could not get back far enough before the terrain started dropping off. I tried a center position and two rotated shots. I then took the same shot with the 21mm lens from about the same position and got the entire spillway. For the composite shot, I should have taken two straight on shots at 1/3 and 2/3 of the distance and at the same normal distance from the spillway (but I had no way to accurately measure the normal distance...). Both images used Delta 100 developed in ADOX FX-39 II.

Composite 6x6 image

Prado Dam by Mark Wyatt, on Flickr

35mm image with 21mm SC Skopar

Prado Dam whole by Mark Wyatt, on Flickr

I once owned the Minolta Rokkor 40mm/F2.0--the last version, for the CLE. I didn't own a CLE though, so I used it on my M6 or my M3.

It was a great lens optically and handling wise (except for something I'll detail in a moment). I really liked the photos I got from the lens, and it seemed like the perfect size, too, quite compact. And I did like the focal length, as well--I think a "normal" lens should be a little wider than 50mm, the 40 felt just about right. But eventually I got rid of it--traded it in on a Version 2 35mm Summicron from my favourite London second-hand dealer.

There were a few reasons for that--one, the Summicron was slightly but perceptibly better built...it was a Leica lens, after all. And it was just a little wider, and so a bit more different, from the 50mm lens I already had. Plus, I got it *reasonably* inexpensively, because (1) Leica lenses hadn't shot upward astronomically in price yet, (2) that is the least popular 35mm Summicron, and (3) my particular specimen has a very tiny coating flaw on the front element. Which of course the true Leicaman, as Ken Rockwell calls him, would sneer at it with "That lens is trashed!" (One of my dealer's regular customers, who was constitutionally and vocally very persnickety, actually did describe the lens that way. Of course, if he'd managed to drive the price down enough by disparaging it so, *he'd* have snatched it up, too.)

Aaaaand, there was the incident that was the last straw. To me, the 35mm framelines on the M6--which I used it on most often by far--suited the 40mm focal length much better than the 50mm framelines...which the 40mm lens brings up. I didn't want to do anything so drastic as the surgery involving grinding the tab on the back of the lens to alter it to bring up the 35mm framelines, and I had read of a trick for lodging the preview lever in the 35mm frame position: the poster recommended cutting a pie-shaped wedge out of a plastic Ilford film canister lid, and by slipping the tip of that under the preview lever, you could jam the framelines in the 35mm position. No irreversible alterations to the lens, no damage to the camera (as that's *why* the preview lever is there in the first place, to allow you to hold it on a different frameline to see what the composition would look like with that focal length). Great!

And indeed, it worked pretty well. But then came the day I was at London Bridge Station, around the time they were finishing the Shard. There were several workers abseiling up the side of it in echelon, apparently checking windows from the outside. I quickly pulled off the 40mm and popped on my old 90mm Elmarit, and snapped a few shots I thought would be quite dramatic, before the men reached all the way to the top. Afterward, when I went to put the 40mm lens back on, I couldn't find the little lever stop, and I assumed I'd dropped it.

The photos *would* have been just as nice as I suspected--but I discovered what had happened to the bit of plastic that had gone missing. When it fell out from under the preview lever, as I was fumbling to mount the 90mm, it went *into* the camera body (it apparently fell back out when I put the 40mm back on, as it wasn't inside the camera any longer). All four or five images I shot with the 90mm had a nice, triangular blank area on the film, where the tip of the plastic bit had blocked light from reaching the film.

For me, that was it--it just wasn't worth the trouble of potentially losing another shot like that, and faffing around with that kludge all the time just wasn't on, really. When the Summicron became available at the price my go-to guy offered it to me at, I made the switch.

I do miss that lens a lot though, and I keep telling myself I'll get another one some day. It *was* nice. If I do get one, I'll probably just put it on my M3, and use the whole viewfinder for framing--and, another kludge, if I put a bit of black tape over the frameline illuminating window, I won't be distracted by the always-visible 50mm framelines. That would probably be a great combo!

CV 40 2.8

CV 40 2.8, C200

CV 40 2.8, C200

Olympus Trip 35 (40mm 2.8 lens)

Huss said:

CV 40 2.8, C200

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What great color and composition. Forgive my ignorance but who makes that lens?

CV 40 1.2, C200

KerrKid said:

What great color and composition. Forgive my ignorance but who makes that lens?

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Sorry, CV = Cosina Voigtlander. i.e. the current Voigtlander lenses

Summicron 40 f2, C200

Rollei 40 2.8 Sonnar, Arista 100

Summicron 40, Arista 100

halfaman said:

The start of this thread coincided when I was thinking to assemble a light and compact modern SLR with AF for those ocasions where my Nikon FM2 is not a good option (i.e fast action in low light).

So I finished with this pretty inexpensive combo:

Canon 300X (Rebel T2 in US) with a 40mm f/2.8 STM.

The whole kit with batteries weights 530gr and it has a total depth of 9 cm, the integrated flash (GN 13) is also a welcome addition for the intended purpose. It seems a very capable camera in a cheap "suit", really looking foward to put some film on it...

Click to expand...

One of my exact setups.
Last film camera Canon made. Great meter and shutter. I purchased around 10 last 10 years for $10-15 each. Small and light and don't care if it breaks. I wish it had a spot meter like Minolta 5.
The canon 40mm is in my opinion the best "cheaper" lens. I have compared results with my Leica and Minolta 40mm and it holds very well. From those 3 the Leitz is the worst. "don't like flares".

MattKing said:

Actually it does.
And more significantly, an over-sized chin and overly prominent shoulder.
And both don't matter much at all, because the other strengths of the image make those concerns unimportant - at least to me.
You may find that the subject of the photo would be bothered by these things.
But possibly not - one of the the results of the explosion of cel phone photography - particularly selfies - is that many people seem much more comfortable with what I consider to be the perspective distortion that arises from a too-short camera-to-subject distance.

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Even those cameras on your monitor when using Zoom distort a lot unless you;re using something more professional. The best portrait lenses in my opinion are medium zooms and start at 85mm for a full frame camera. 105mm and 135mm work well too for closeups.