Comments for Silverbased http://silverbased.org Projects and ponderings for film photographers Mon, 13 Oct 2008 00:48:43 +0000 http://wordpress.org/?v=2.5 Comment on Why Can’t Digital Be Normal? by Vox http://silverbased.org/digital-normal/#comment-817 Vox Thu, 09 Oct 2008 17:11:13 +0000 http://silverbased.org/?p=263#comment-817 In an email, RobW asked, "Your article answered some of my questions, but I'm still not sure why the sensor cannot be the same distance from the flange (by which I assume you mean lens mount?) as on a 35mm camera? Is it a design choice that everyone has gone for, or a necessity? " A basic problem with digital cameras is the cost of the sensor chip gets MUCH higher as the area increases. It's not just a linear factor that a chip of 4x the size costs 4x as much--it's actually worse than that. There are a certain number of unavoidable defects scattered randomly across a silicon wafer; and if you are only getting 6 chips out of the wafer rather than 60, the odds of any particular one being spoiled and unusable shoot way up. So that's where the economic pressure comes from for cameramakers to use the smallest sensor they can get away with. The rule of thumb is that a normal lens is one whose focal length roughly equals the diagonal of the image format; so the smaller the image sensor, the shorter the focal length needed to yield the "normal" angle of view. Canon, Nikon, and Minolta wanted to keep their lens mounts compatible with their earlier film cameras; but even Olympus who were starting with a blank slate with the Four-Thirds system kept a longer flange-to-sensor distance than the "normal" lens focal length for the format. One reason is that the early generations of digital sensors didn't perform very well when light struck them at oblique angles. So it was preferable to hold the rear element of the lens a bit further away from the sensor, so light would reach it at more of a perpendicular angle. Otherwise it ought to have been possible for the camera to be extremely compact--as Olympus themselves proved with their "Pen" series of SLRs which shot a half-frame 35mm format. In an email, RobW asked,

“Your article answered some of my questions, but I’m still
not sure why the sensor cannot be the same distance from
the flange (by which I assume you mean lens mount?) as on a
35mm camera?

Is it a design choice that everyone has gone for, or a
necessity? ”

A basic problem with digital cameras is the cost of the sensor chip gets MUCH higher as the area increases. It’s not just a linear factor that a chip of 4x the size costs 4x as much–it’s actually worse than that. There are a certain number of unavoidable defects scattered randomly across a silicon wafer; and if you are only getting 6 chips out of the wafer rather than 60, the odds of any particular one being spoiled and unusable shoot way up. So that’s where the economic pressure comes from for cameramakers to use the smallest sensor they can get away with.

The rule of thumb is that a normal lens is one whose focal length roughly equals the diagonal of the image format; so the smaller the image sensor, the shorter the focal length needed to yield the “normal” angle of view.

Canon, Nikon, and Minolta wanted to keep their lens mounts compatible with their earlier film cameras; but even Olympus who were starting with a blank slate with the Four-Thirds system kept a longer flange-to-sensor distance than the “normal” lens focal length for the format. One reason is that the early generations of digital sensors didn’t perform very well when light struck them at oblique angles. So it was preferable to hold the rear element of the lens a bit further away from the sensor, so light would reach it at more of a perpendicular angle.

Otherwise it ought to have been possible for the camera to be extremely compact–as Olympus themselves proved with their “Pen” series of SLRs which shot a half-frame 35mm format.

]]> Comment on DIY: Plasticam Pinhole, Part One by Thrift Store Panoramic Pinhole « Lo-fi Photography–the low down http://silverbased.org/plasti-pinhole-pt1/#comment-815 Thrift Store Panoramic Pinhole « Lo-fi Photography–the low down Sat, 20 Sep 2008 21:00:48 +0000 http://silverbased.org/plasti-pinhole-pt1/#comment-815 [...] I soon found out it was much harder than I anticipated. Rather than re-invent the wheel go to silverbased.org for fantastic directions that even I could follow. In theory, you have a camera in which your [...] […] I soon found out it was much harder than I anticipated. Rather than re-invent the wheel go to silverbased.org for fantastic directions that even I could follow. In theory, you have a camera in which your […]

]]> Comment on Depth of Field: When Format Matters by Silverbased | Bokeh: What it is and isn’t http://silverbased.org/dof-vs-format/#comment-811 Silverbased | Bokeh: What it is and isn’t Wed, 17 Sep 2008 17:23:57 +0000 http://silverbased.org/dof-vs-format/#comment-811 [...] effect, and have written about how to get it. And because many of today’s digital cameras limit your ability to achieve this look, a photo with shallow focus and a creamy blurred background will often attract many admiring [...] […] effect, and have written about how to get it. And because many of today’s digital cameras limit your ability to achieve this look, a photo with shallow focus and a creamy blurred background will often attract many admiring […]

]]> Comment on Shallower Depth of Field? by Silverbased | Bokeh: What it is and isn’t http://silverbased.org/shallowest-dof/#comment-810 Silverbased | Bokeh: What it is and isn’t Wed, 17 Sep 2008 16:58:46 +0000 http://silverbased.org/shallowest-dof/#comment-810 [...] focus to give nicely blurred backgrounds can be very pleasing. I like this effect, and have written about how to get it. And because many of today’s digital cameras limit your ability to achieve this look, a photo [...] […] focus to give nicely blurred backgrounds can be very pleasing. I like this effect, and have written about how to get it. And because many of today’s digital cameras limit your ability to achieve this look, a photo […]

]]> Comment on Pimp My Polaroid, Part II: SX-70 by First Polaroids | Document One http://silverbased.org/sx70with600film/#comment-808 First Polaroids | Document One Thu, 11 Sep 2008 16:00:41 +0000 http://silverbased.org/?p=205#comment-808 [...] this past weekend (plus there’s a shot of Geneviève from this morning here in DC).  I used the technique described here to get around the fact that they don’t make the SX-70 specific film anymore (”Time [...] […] this past weekend (plus there’s a shot of Geneviève from this morning here in DC).  I used the technique described here to get around the fact that they don’t make the SX-70 specific film anymore (”Time […]

]]> Comment on Mercury Battery Replacements? by Bill Rogers http://silverbased.org/zinc-mercury-replacement/#comment-471 Bill Rogers Sun, 24 Aug 2008 19:47:00 +0000 http://silverbased.org/zinc-mercury-replacement/#comment-471 Vox - thanks for the assessment. Here's how I solved the problem with an external circuit and two holes drilled through the battery cap. http://home.comcast.net/~wjrogers76/mercury.html Vox - thanks for the assessment. Here’s how I solved the problem with an external circuit and two holes drilled through the battery cap.

http://home.comcast.net/~wjrogers76/mercury.html

]]> Comment on 101: What Do I Need to Develop Film? by John LeBlanc http://silverbased.org/101-bw-dev/#comment-421 John LeBlanc Fri, 22 Aug 2008 14:27:27 +0000 http://silverbased.org/101-bw-dev/#comment-421 I transferred my HC110 to a catheter bag immediately upon opening it to prevent oxidization instead of storing it in a bottle. This means that I can do all the one- shot developing I want and air never gets to the developer which is what limits its shelf life. If you can cold store it, all the better. It's a very versatile developer. I transferred my HC110 to a catheter bag immediately upon opening it to prevent oxidization instead of storing it in a bottle. This means that I can do all the one- shot developing I want and air never gets to the developer which is what limits its shelf life. If you can cold store it, all the better. It’s a very versatile developer.

]]> Comment on Pimp My Polaroid, Part 3: Double-Exposures by Vox http://silverbased.org/pola600double-mod/#comment-381 Vox Tue, 12 Aug 2008 12:44:41 +0000 http://silverbased.org/?p=219#comment-381 The mirror is underneath the angled back side of the camera shell--it's what reflects the image onto the film pack at the bottom of the camera. People who have e.g. an old TLR where the original mirror has been damaged often hack open an unwanted Polaroid, because it's an affordable way to get an optically flat, front-silvered mirror that can be re-cut to size. The mirror is underneath the angled back side of the camera shell–it’s what reflects the image onto the film pack at the bottom of the camera.

People who have e.g. an old TLR where the original mirror has been damaged often hack open an unwanted Polaroid, because it’s an affordable way to get an optically flat, front-silvered mirror that can be re-cut to size.

]]> Comment on Pimp my Polaroid, Vol. 4: Packfilm Mongrel by dan eccles http://silverbased.org/anguloid/#comment-380 dan eccles Tue, 12 Aug 2008 04:30:24 +0000 http://silverbased.org/?p=237#comment-380 I saw your site with your amazing camera. I've thought that building my own camera would be the only way to get all the things i want out of one, i'm gonna try to build something home made myself! Thanks! dan I saw your site with your amazing camera. I’ve thought that building my own camera would be the only way to get all the things i want out of one, i’m gonna try to build something home made myself! Thanks! dan

]]> Comment on Pimp My Polaroid, Part 3: Double-Exposures by Chuck http://silverbased.org/pola600double-mod/#comment-379 Chuck Mon, 11 Aug 2008 21:04:24 +0000 http://silverbased.org/?p=219#comment-379 Hi, I was looking to cannabalize a one-step. I was told I could find relatively large "mirror"! After examing your photos, I don' see amy mirror. Can you confirm or deny the presence of a mirror in the Polaroid one-step? Thanks Hi,

I was looking to cannabalize a one-step. I was told I could find relatively large “mirror”! After examing your photos, I don’ see amy mirror. Can you
confirm or deny the presence of a mirror in the Polaroid one-step?

Thanks

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