Weekly pinhole sharing

[kier]

As I do every week on ƒ/D, I've shared some of my favorite finds from the last week. Hope you enjoy them!

http://fslashd.com/2016/06/inspiration-week-of-66/

 

[MattKing]

I enjoy your posts and the links therein, but might suggest you use a single, regularly updated thread instead. Most of us here seem to track New Posts, so your updates will come to our attention. And if you reference the dates of your blog postings in the thread, it can serve as a rough index as well.

 

[kier]

Sure - makes sense - I can do that. My hope with the posts has been to drive interest in the pinhole forum in general. I don't make any money off of ƒ/D, just trying to broaden the community.

 

[ciniframe]

Thanks you for posting this pinhole photography and links. I notice that almost all pinhole cameras tend to go from very wide to ultra wide in the angle of view. I wonder if anyone works with a more nominal angle (45-55 degrees) or perhaps even narrower. I have a 4x5 home made pinhole camera that I selected 90mm for basically because the pinhole I was using came in the reward package of the Kickstarter Travelwide camera. I wanted to use the pinhole but didn't want to go through the hassle of unmounting the lens to do so. My design uses black foam core between a plywood front and rear standard to adjust focal length so it is easy to alter. I'm just not sure how long I can I go before the 0.3175mm hole diameter (is that figure really that precise?) will be too small. I've seen the pinhole calculators that have recommended diameters for various focal lengths but I wonder how much I can fudge on those numbers.

 

[kier]

Which figure are you asking is precise? The pinhole diameter spec'd for that pinhole? Or the recommended pinhole diameter? If it's recommended pinhole diameter, there is some fudging that you can do. All pinhole calculators are not equal in that a component of the math involved is picking the optimal light wavelength - many pinhole calculators pick different values for this, resulting in slightly different results. When observing the pinholes used by Zero Image, Reality So Subtle, and others, the trend seems to err on the smaller pinhole, not larger... hope that helps.

As for normal view, you can use the pinhole calculator angle of view design wizard. For 4x5 film, you need a 220mm focal length: http://www.mrpinhole.com/wiz.php?Func=AngleOfView

 

[ciniframe]

Kier, when I asked 'is that really that precise' I was commenting on the four digit accuracy supposed by the specification. In other words, when you have etched pinholes made up to a certain specification can they really work to ten thousands of a millimeter accuracy? Seems a bit dubious to me. I would think that hundredths of a millimeter would be sufficient.

After asking how much of a fudge factor there was in "ideal" pinhole sizes I got to thinking, why not just try it out and see what happens. If I push it out to 150mm it will give me the very slow f stop of f470 so exposures will be longer but beyond that the result will be what ever it is.

 

[kier]

Ah I see - yeah I've never seen 4 digit accuracy read like that in a pinhole. Usually it's .300mm - but of course that's 3 digit accuracy, if only to assure that the hole is exactly .3mm. More important that 4 digit accuracy is the thickness of the material the hole is in. The thicker that material, the more vignette and distortion you get off center axis from the hole - meaning that the portions of the image further from center will start to vignette and also the light beams become eclipsed somewhat.

the high f stop numbers is, in my view, a big reason why more people don't do longer focal length pinhole cameras. that and, I think people generally have more fun with the extreme wide angles. Looking forward to seeing your results!