You achieve the same DOF with short and long lenses with the same reproduction ratio, but once you are outside that sharp zone long lenses blur off more quickly. So there is an illusion of less depth of field.
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You'd have a different perspective even with a very fast 150, but it might work in a slightly different sense. Logistically, you might be uncomfortably close to the sitter.
John,
One important thing to add is OOF roll off nature !!!
To have the same framing than in 4x5/210mm if you shot with a 16x20" camera you would be using a 840mm lens.
You may set an aperture in the 840mm to have the same 40mm DOF you mention, in that range the image will be the same, considering format equivalent CoC (circle of confusion).
but the way the image gets more blurred as it goes beyond the dof range should be different.
Sometimes I used an smartphone app to learn how a lens/distance/aperture will roll off in the OOF, see here how it shows the CoC grows :
Attachment 175369
This is why you see a different OOF nature from what you see from a 4x5, if I'm not mistaken...
PD: as Totias also points...
https://play.google.com/store/apps/d...achs.dof&hl=es
you can add new custom cameras of any format, etc
"A compatible version of DoF is also available for Windows computers at:" www.dl-c.com/DoF
The image you're inquiring about is a wet plate collodion photo, either made on glass or metal. Lenses made for the process (dating to the early 1850s, when Wet Plate Collodion was invented) had very specific traits, especially evident in the portrait length lenses, and it was typical that they had very shallow depth of field, as they were meant to be used wide open (they had no apertures, and not until later years did they have slots for waterhouse stops). The lens designs of the 1850s (and for a period afterwards) were of the Petzval design, which did not have a flat focal plane, but was in fact curved. This Petzval curve enhanced the illusion of very limited DOF, and the closer you were to the subject, the more pronounced the effect becomes. This is what you are seeing in Quinn's photo. Its typical of the effect seen when using many (most?) of those early portrait lens designs.
This is one of the mid-1850s Petzval design lenses: a 15" f5 Lerebours et Secretan:
Attachment 175374
I'm friends with Quinn, shot with him at the Paris Foto Fair, and moderate his website Collodion.com. Why don't you ask him? He's a nice guy, and has several web sites and training youtube vids. But basically a fast lens with wetplate and natural lighting. Using a flash you won't get the deep blacks around the sitter, usually.
Or go to the Collodion website, or one of the facebook sites (he has one there called Wetplate Photographers), and read up on it. Lots of people doing wetplate today, compared to 10 years ago when I began (when there were about 1 in every state, max). Or if someone is interested, I occasionally do wetplate workshops in Tucson.
2010 wetplate demo booth:
https://c2.staticflickr.com/2/1289/4...73280db2_z.jpg
Hi guys! So much good information here!
I have to consider focal plane bending on Petzval lens and sharpness drop off with larger formats...
At this moment I only have a 4x5 camera for my wet plates, though with a few lenses.
Which one do you think will do the better job from this point of view?
- Schneider 5.6/240mm
- Industar 4.5/300mm
- An old brass f8/210mm
- Schneider xenotar f2.8/150mm
(I guess the first 5.6/240mm is out of this game...)