rayazwinski@watmath.UUCP (Rick Yazwinski) (11/28/85)
Recently, there was an article in this news listing talking about high speed films, and pushing them to high ASA's (i.e. 3600+). I was wondering how can you do this without your film coming out super-grainy or not at all. (Do you have to inform your processor or what?) Rick...
howard@sfmag.UUCP (H.M.Moskovitz) (12/02/85)
> > Recently, there was an article in this news listing talking about high speed > films, and pushing them to high ASA's (i.e. 3600+). > > I was wondering how can you do this without your film coming out super-grainy > or not at all. (Do you have to inform your processor or what?) > > Rick... Pushing film speed depends on the type of film you're shooting. In black&white, grain and sharpness can be controlled by your developer. Tri-x or HP-5 can be shot at 800 asa with very little loss in sharpness. These films can be shot equally at 1600 or 3200 if developed in Acufine or Diafine developers. With Diafine, a two step developer, HP-5 at 1600 is a little sharper than at 400 with D-76. It is remarkably sharp at 3200 as well. Color slide film can usually take a one-stop push with only a small loss in sharpness and color saturation. A two stop push suffers a little more. This is due to there being only one chemistry available and the push is an over-development compensation to under-exposure. However Kodak and Fuji have released chrome films that have an standard index of 800 and 1600, respectively and can be pushed easily to 1600 and 3200. The grain is abpout the same as Ektachrome 400 shot at 800 (which is very good). Color print film does not handle push processing well and many labs will not even offer it. However Kodak has the vr-1000 film (1000 asa), and Fuji has their HR-1600 print film which is very nice. So the conclusion to this is: for black and white choose a developer to suit your needs, for color choose the film that does. -- --------------------------------------------------------------------- Howard Moskovitz AT&T Info. Systems attunix!howard
herbie@polaris.UUCP (Herb Chong) (12/05/85)
>> I understand that Kodak does produce a faster film, but it is only >> available to me if I buy a minimum of 43 - 150 foot rolls. High Speed >> Recording film RE2485 is this faster film pushable to 8000 ASA. >I have used 2485, buying it in 36-exposure rolls from a Kodak dealer. >You might check to see if it is still available in this form. Kodak 2485 High Speed Recording Film is technically offered only by Instrumentation Dealers (i.e. people who sell things like microfilm recorders and other such recording equipment). there was a feature article in either Modern or Popular Photography many years ago that i have lost by now. back then, only the 150 ft rolls were available. >> I have used the RE2485 ... pushed it to 12,000 and had no problems. >* Using what developer? Daylight conditions or CRT screens as Kodak suggests. under very flat lighting conditions, you can push any film to very high EI's. i have pushed Plus-X to 8000. of course, the fog was horrible and using #5 and #6 paper still had too low a contrast for pictorial purposes and grain was huge, but i got a picture i never would have gotten any other way in the time that i had to take it. with this amount of drastic underexposure, the image fades away in a few days so the film has to be developed immediately or frozen. BTW, this was with D-76, so adding an antifog would have helped. >> When you get any faster than that, you really need very sensitive >> stuff ... does the technology even exist? there are many techniques for increasing the EI of film. some work, others don't. the best book i've ever seen on this was put out as one of the Peterson Photographic Handbooks. i think it was called High Speed Photography or something like that. anyone with a Peterson book handy can look it up on the inside covers somewhere. they describe how to get an honest 3200 EI out of Tri-X (normal density range and able to resolve all 10 steps of the Kodak Grey Scale). with 2485, you can get up to the usable (not true) EI of over 20,000 with some of the techniques. >* I have heard that in the magazine ASTRONOMY, there are articles on using > chemicals (nitrogen?) on film before it is used to take shots of celestial > nature at "very" high speeds. mercury vapor and acetic acid are well known (and dangerous) ways of doing it. very cold (like -150 C) film is also more sensitive. pre-flashing of film with a very short exposure to a white evenly lit surface will also provide about 1 stop of real speed increase. > The developer that Kodak claims is best according to their >technical sheet on 2485 (P-94, 1981) is developer 587. I know no >more than that (ie. where it is available, etc). the developer is 957. again available only from Instrumentation Dealers. for EI 8000, they recommend something like 2 minutes (!) at 100 F. unfortunately, a rather grainy developer, but it serves it design, getting a recognizable and printable negative in the shortest possible time with no regard for picture quality (unless you are into grain). another developer that is useful on other film (like Tri-X) is a modified D-50 developer (i think). it provides a true EI increase of about 4 stops. unfortunately, the grain is so huge that you can see them individually at arms length on the negative. > Could those of you out there who can readily obtain 2485 >please either mail me directly or send to the net, the address of >your own distributor? According to photo stores in my area (including >Milwaukee), Kodak will not deal directly with consumers, and will only >sell 2485 to those stores with a certain kind of license/agreement to >carry products including this film. they have to be Instrumentation Dealers. find out where someone buys microfilm and you might get 2485 that way. be prepared to PAY though. 2475 and 2485 are very red sensitive compared to most B&W films. don't expect to get "normal" tonal rendition of you subjects. for really exotic high speed film work, you can use Ektachrome 400 or 1600 and get usable speeds up into the EI 20,000 to 30,000 range. you expose for it and push process it as if it were a colour NEGATIVE film. first, use a good high speed B&W developer, then bleach and fix as if it were a color negative film in C-41 chemicals. much experimentation needs to be done to establish the development time, but try 30 to 40 minutes at 68F in acufine as a starting point. the exact procedure is documented in the Peterson book i mentioned. you get a very strange color negative and you need an orange mask sandwiched with the negative to print on color paper. i haven't tried B&W paper though. i have experimented with very high speed films and stuff like that off and on for nearly as long as i have owned a camera. i don't mind grain that much and i usally shoot with it in mind. i usually use HP-5 at 400, although i also use it at 1600 nearly as much. i get quite good results with Plus-X at 1000 and certainly 2000 in flat lighting. grain is finer than Tri-X or HP-5 at 1600 but contrast is way up. Herb Chong... I'm still user-friendly -- I don't byte, I nybble.... VNET,BITNET,NETNORTH,EARN: HERBIE AT YKTVMH UUCP: {allegra|cbosgd|cmcl2|decvax|ihnp4|seismo}!philabs!polaris!herbie CSNET: herbie.yktvmh@ibm-sj.csnet ARPA: herbie.yktvmh.ibm-sj.csnet@csnet-relay.arpa ======================================================================== DISCLAIMER: what you just read was produced by pouring lukewarm tea for 42 seconds onto 9 people chained to 6 Ouiji boards.
rdp@teddy.UUCP (12/06/85)
In article <318@polaris.UUCP> herbie@polaris.UUCP (Herb Chong) writes: > >>* I have heard that in the magazine ASTRONOMY, there are articles on using >> chemicals (nitrogen?) on film before it is used to take shots of celestial >> nature at "very" high speeds. > >mercury vapor and acetic acid are well known (and dangerous) ways of >doing it. very cold (like -150 C) film is also more sensitive. >pre-flashing of film with a very short exposure to a white evenly lit >surface will also provide about 1 stop of real speed increase. > There are several different things happening here, in fact. First, chilling the emulsion duringh exposure DOES NOT increase it's base sensitivity at all, it simply reduces or eliminates the reciprocity failure. Tri-x, with a supposed ASA of 400 still hass that sensitivity at very low light levels when chilled, not more. Some gases (hydrogen) can truly increase sensitivity. Dick Pierce