RE: [pinhole-discussion] Coverage
Well put... I'm STILL getting use to getting closer than close to my subjects. andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Michael Healy Sent: Sunday, January 12, 2003 3:24 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] Coverage snip One thing I especially like about the super short focal length pinhole is that it kicks me in the rear with lousy images every time I stand more than 18 from my subject. Using 50mm on a 4x5 means that you run the risk of having your subject poke you in the eye while you're trying to maneuver close enough. It also FEELS weird and overbearing to place a 4x5 studio camera mere inches from something. The whole experience makes for a very strange, enchanting, but also humbling encounter with reality. Mike ...
Re: [pinhole-discussion] Coverage
Thanks. About the x3.5, I hadn't really considered it as a malleable factor until Guillermo discussed it this AM. And he is right, my 50mm on a 4x5 isn't even 3.5, it's about 3.25. I've gotten falloff (especially along one side, which I suspect is the result of careless centering of the pinhole), but no vignetting. So I think I will apply the same factor of 3.25 or so on 7x17. Mike - Original Message - From: erick...@hickorytech.net To: pinhole-discussion@p at ??? Sent: Sunday, January 12, 2003 10:52 AM Subject: Re: [pinhole-discussion] Coverage Logic's fine. Eric is, I think, being a bit conservative at his 3.5 FL. It all depends on the brightness of the image at the edges of the range. If you stick within 3fl you'll never notice any vignetting. - Original Message - From: Michael Healy mjhe...@kcnet.com To: pinhole-discussion@p at ??? Sent: Sunday, January 12, 2003 8:39 AM Subject: [pinhole-discussion] Coverage I am building a 7x17 camera, which I intend to use w/ a pinhole. This will be a wooden folding camera, so it will have a fixed focal length. Therefore I need to be sure I arrive at a good camera length from the start. I wonder whether Guillermo and/or others could review my logic below, and confirm that I am doing this correctly. My concern has two dimensions: (1) I want the camera to be as short as possible w/o vignetting. I am having loads of fun shooting 4x5 w/ 50mm of bellows. This is sort of what I would like to continue in using a 7x17. (2) On the other hand, if I built it too short, then I risk inadequate coverage, and will have vignetting on every last image I shoot with it. This is a creative tool which does not interest me a great deal. According to Renner (p. 126), the diameter of the image circle is approximately 3.5x focal length. This seems to be about right, as I found last week when I followed Andy Schmitt's GREAT sugggestion to shoot inside a 4x5 film box. On 4x5, inside a box that is about 18-19mm deep, these images received about 5cm's of coverage. If the logic and my experience are correct, then for full coverage, one needs a focal length slightly greater than 1/3.5 of the film's diagonal, isn't this correct? (I am ignoring the issue of fall-off, which will be quite severe in the event that the image circle just barely exceeds the film's diagonal.) By this logic, my 7x17 camera will require a focal length -- a bellows length, technically -- that exceeds the film diagonal of 18.4 divided by 3.5, or approximatley 4.85. In other words, if I build this camera with a body length of 6 inches, then I ought to receive adequate coverage on a 7x17 sheet of film. That's my logic. But is it sound? Are there other factors I have not accounted for? Thanks! Mike ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/ ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] Coverage
HA! It is a folding camera that will be 18 wide and about 9 high. The body will follow the plan for a 10x12 that Alan Greene features in his book Primitive Photography. Much modification, though, because his wants a 22 body, and I intend to keep mine to 6. As far as I can tell, it simply will collapse and fold flat after the lensboard and film holder have been removed. The body itself is made of wood slats hinged together. Like shooting out the side of a shoebox. But it should be very sturdy. The most elaborate part will be (I think) the assemblage of the film holders. What I hope to do is shoot film. Berger makes 14x17 sheets of ASA 200, so these would be perfect if cut in half lengthwise. I want to use film because I'm doing argyrotypes right now (and soon will be doing albumen and POP salt). But paper isn't a bad idea, either. I've never actually done it. You might be right about making a box from scratch. I started out wanting this to be used with a lens, but decided that my first attempt will be with pinhole. It's the way I like to work anyhow. You've got me thinking, though. I'm still assembling the wood, etc., so there's time to change my mind and modify this the right way for a lens, and meanwhile make that box you mentioned. The idea worked fine when it was a 4x5 film box, so there isn't any reason it couldn't go larger. I will keep you informed. Mike - Original Message - From: andy schmitt aschm...@warwick.net To: pinhole-discussion@p at ??? Sent: Sunday, January 12, 2003 9:24 AM Subject: RE: [pinhole-discussion] Coverage -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Michael Healy Sent: Sunday, January 12, 2003 9:39 AM I am building a 7x17 camera, which I intend to use w/ a pinhole. This will be a wooden folding camera, so it will have a fixed focal length. ... snip Are you going to use a fold down with a bellows or a pull out? With the other dimensions being what they are and a 3 or 4 focal length, it might be just as functional ( a heck of a lot easier..) to make a fixed box. snip when I followed Andy Schmitt's GREAT sugggestion to shoot inside a 4x5 film box. Thanks... 8*) of course...what are you going to do about holding film/paper sheets? Will this be a one shot? so many questions...sounds like fun... I want to see it when you are done. andy
[pinhole-discussion] Coverage
I am building a 7x17 camera, which I intend to use w/ a pinhole. This will be a wooden folding camera, so it will have a fixed focal length. Therefore I need to be sure I arrive at a good camera length from the start. I wonder whether Guillermo and/or others could review my logic below, and confirm that I am doing this correctly. My concern has two dimensions: (1) I want the camera to be as short as possible w/o vignetting. I am having loads of fun shooting 4x5 w/ 50mm of bellows. This is sort of what I would like to continue in using a 7x17. (2) On the other hand, if I built it too short, then I risk inadequate coverage, and will have vignetting on every last image I shoot with it. This is a creative tool which does not interest me a great deal. According to Renner (p. 126), the diameter of the image circle is approximately 3.5x focal length. This seems to be about right, as I found last week when I followed Andy Schmitt's GREAT sugggestion to shoot inside a 4x5 film box. On 4x5, inside a box that is about 18-19mm deep, these images received about 5cm's of coverage. If the logic and my experience are correct, then for full coverage, one needs a focal length slightly greater than 1/3.5 of the film's diagonal, isn't this correct? (I am ignoring the issue of fall-off, which will be quite severe in the event that the image circle just barely exceeds the film's diagonal.) By this logic, my 7x17 camera will require a focal length -- a bellows length, technically -- that exceeds the film diagonal of 18.4 divided by 3.5, or approximatley 4.85. In other words, if I build this camera with a body length of 6 inches, then I ought to receive adequate coverage on a 7x17 sheet of film. That's my logic. But is it sound? Are there other factors I have not accounted for? Thanks! Mike
