Re: Film Reciprocity failure and high/low shutter speeds
Probably all you have to do is cool the hell out of it. As was mentioned before, Thermal noise is probably what limits slow captures. rg Herb Chong wrote: not at the slow end. a good CCD sensor can accurately count individual photons. the *istD one isn't that good, but you get the idea. Herb... - Original Message - From: "Robert Gonzalez" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, March 02, 2004 3:42 PM Subject: Re: Film Reciprocity failure and high/low shutter speeds Does a CCD suffer from reciprocity failure also? If so, are the curves published anywhere?
Re: Film Reciprocity failure and high/low shutter speeds
not at the slow end. a good CCD sensor can accurately count individual photons. the *istD one isn't that good, but you get the idea. Herb... - Original Message - From: "Robert Gonzalez" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, March 02, 2004 3:42 PM Subject: Re: Film Reciprocity failure and high/low shutter speeds > Does a CCD suffer from reciprocity failure also? If so, are the curves > published anywhere?
Re: Film Reciprocity failure and high/low shutter speeds
what film have you been using? if slide film, then whatever you have been using hasn't had enough reciprocity failure to notice. Provia 100F is a good example of one that isn't affected by exposures as long as 30 seconds. if a print film, then you need to look at the density of the negatives. if all you have been looking at is the prints, the difference usually isn't enough to notice as you will compensate for a slightly thin negative with a slightly higher paper grade. no Pentax cameras make any such compensation. Herb - Original Message - From: "David Miers" <[EMAIL PROTECTED]> To: "[EMAIL PROTECTED] Net" <[EMAIL PROTECTED]> Sent: Tuesday, March 02, 2004 9:45 AM Subject: Film Reciprocity failure and high/low shutter speeds > My question in a > nutshell is are the onboard computers in the Pentax cameras smart enough to > be calculating for this failure ahead of time and is there any information > in the DX coding that helps the computer make such a calculation? I've done > exposures up to the 30 seconds suggested and supported by included shutter > speeds and nailed the exposure. Some of the charts indicate I should be > using up to 2 minutes here depending on the film.
Re: Film Reciprocity failure and high/low shutter speeds
Rob Studdert wrote: On 2 Mar 2004 at 14:42, Robert Gonzalez wrote: Does a CCD suffer from reciprocity failure also? If so, are the curves published anywhere? I believe that they are pretty linear from their minimum exposure time (determined by the matrix read speed) out to lengthy exposures. The main problem is self noise which will eventually saturate (fully expose) all pixels regardless of light hitting them or not. I agree that self noise is probably the limiting factor on the long exposures. I'm guessing that it makes sense that they are linear. But, the matrix read basically only limits how fast you can continually take pictures (added to other parts of the capture pipeline), I don't believe that it limits the minimum exposure time, if you can get the shutter speed to 1/2, I believe you can capture photons (in bright enough light!) that will represent the image. I think the matrix reading happens post-capture, and it has to undergo A-to-D transformation (after scaling for ISO), followed by memory write, and finally conversion if necessary to JPG or other formats and final write to card. rg
Re: Film Reciprocity failure and high/low shutter speeds
On Tue, 2004-03-02 at 17:11, William Robb wrote: > > No light meter in the world can take reciprocity into account. > DX encoding has the ability to give the camera latitude information, > but I have yet to see a camera that makes use of the data. The PZ-1(p) has the contacts for this latitude information, so I assume those cameras use it. > Failure of exposure reciprocity is one of lifes little mysteries, and > must be calculated by the photographer to be absolutely sure. > Film data sheets are a good starting point, and will generally give a > close enough guestimate to ensure usable exposures, though on slide > film, you probably will want to bracket a bit anyway. > The nice thing is, it's a repeatable thing. > > William Robb > -- Frits Wüthrich <[EMAIL PROTECTED]>
Re: Film Reciprocity failure and high/low shutter speeds
On 2 Mar 2004 at 14:42, Robert Gonzalez wrote: > Does a CCD suffer from reciprocity failure also? If so, are the curves > published anywhere? I believe that they are pretty linear from their minimum exposure time (determined by the matrix read speed) out to lengthy exposures. The main problem is self noise which will eventually saturate (fully expose) all pixels regardless of light hitting them or not. Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Film Reciprocity failure and high/low shutter speeds
Hi All It has been recently discussed about film reciprocity failure in my photography class at college. I have personally never considered this into my calculations of exposure times and simply accepted the speeds suggested by my Pentax (PZ-1 & PZ-1p) light meters and had good luck. The safe zone is only from about 1 second to 1/1000 second. As you all know our cameras exceed that greatly on both sides of the spectrum. My question in a nutshell is are the onboard computers in the Pentax cameras smart enough to be calculating for this failure ahead of time and is there any information in the DX coding that helps the computer make such a calculation? I've done exposures up to the 30 seconds suggested and supported by included shutter speeds and nailed the exposure. Some of the charts indicate I should be using up to 2 minutes here depending on the film. Dave
