mtk
Member
I'm relatively new to film, and I've read several times about "pushing" iso to higher band.. what does that mean? and how is it possible?
spyder2000
Dim Bulb
'Push' infers exposing film to an exposure index greater than that indicated on the box and then compensating for it in processing. That compensation can be either a more active developer, or longer development times in lesser active solutions.
Tri-X for instance, in Diafine developer, is often rated between 1200 and 1600 EI. Sometimes we 'push' because we made an error in camera or meter settings.
In any case, this speed 'increase' is accomplished by extending development time or using a more active developer. One stop and you probably need do nothing. Two stops requires an extension of 15 - 20% over your standard solution and time. Fixer time does not change.
Tri-X for instance, in Diafine developer, is often rated between 1200 and 1600 EI. Sometimes we 'push' because we made an error in camera or meter settings.
In any case, this speed 'increase' is accomplished by extending development time or using a more active developer. One stop and you probably need do nothing. Two stops requires an extension of 15 - 20% over your standard solution and time. Fixer time does not change.
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Ronald M
Veteran
Test before commiting. Some developers get a little more shadow detail. Extending time in most leaves empty shadows and increaed contrast in the rest so you don`t have to print on #5.
Since speed is based on shadow density, which does not normally increase, pushing is a myth.
With low contrast subjects, it will work better as the shadows are normally exposed more. For high contrast where you need the shadows to have detail, it just is not there.
Try Diafine, Microfine to get the most speed.
Since speed is based on shadow density, which does not normally increase, pushing is a myth.
With low contrast subjects, it will work better as the shadows are normally exposed more. For high contrast where you need the shadows to have detail, it just is not there.
Try Diafine, Microfine to get the most speed.
sepiareverb
genius and moron
Generally pushing (underexposing and over developing) increases contrast, and pulling (overexposing and underdeveloping) reduces contrast. I've been shooting in the woods a lot and pulling HP5+ to ISO 50 to keep detail in the branches without having the skies so blasted out.
Roger Hicks
Veteran
ISO speeds are developer dependent: take a look at
http://www.rogerandfrances.com/photoschool/ps iso speeds.html
If you give extra development time in any developer, you will get more shadow detail but you will also get more contrast. This is the normal definition of 'pushed', i.e. Ilford HP5 at Plus at EI 500 is a one-stop push in Perceptol (true ISO about 250) or slightly overexposed in Microphen (true ISO 650+)
Few if any developers give a true ISO speed increase of 1 stop (e.g. HP5 at 800) so anything beyond this is a push, i.e. it does not give ISO shadow detail or ISO contrast (again, these are explained in the link).
Push far enough and you will start to lose detail in the shadows though the main subject may still be of acceptable contrast, especially if the overall subject brightness is low or if you don't care about detail in the darkest parts of the image.
Hope this helps,
Cheers,
R.
http://www.rogerandfrances.com/photoschool/ps iso speeds.html
If you give extra development time in any developer, you will get more shadow detail but you will also get more contrast. This is the normal definition of 'pushed', i.e. Ilford HP5 at Plus at EI 500 is a one-stop push in Perceptol (true ISO about 250) or slightly overexposed in Microphen (true ISO 650+)
Few if any developers give a true ISO speed increase of 1 stop (e.g. HP5 at 800) so anything beyond this is a push, i.e. it does not give ISO shadow detail or ISO contrast (again, these are explained in the link).
Push far enough and you will start to lose detail in the shadows though the main subject may still be of acceptable contrast, especially if the overall subject brightness is low or if you don't care about detail in the darkest parts of the image.
Hope this helps,
Cheers,
R.
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Chris101
summicronia
While it is true that pushing (and pulling) affect the sensitivity of the film, I do it as much to control the contrast on a roll to roll basis. Since I don't shoot many different films or developers, I can just change the time - add a minute or so to get more contrast and grain, or shave it off the time for a flatter and smoother negative.
To control speed, I find it better to use a faster film.
To control speed, I find it better to use a faster film.
charjohncarter
Veteran
When I read my Mother-in-laws table top book about the life of her relative the Spanish painter Jose' Guerrero, I was stunned at what a great artist he was when he was in his teens and twenties. Later, he became a 'Modern Artist' which I never really appreciated. But that was because I just couldn't appreciate his recent work.
The same with film. Become good at developing film that produces all the tones, shades, and dynamic range, then go into pushing, etc: very much like Jose' did.
The same with film. Become good at developing film that produces all the tones, shades, and dynamic range, then go into pushing, etc: very much like Jose' did.
Joe
Established
I recently mistakenly underexposed a roll of tri-x by two stops (i.e. I shot it at 1600). I made no adjustments in processing and the images are fine, they just need a contrast boost in printing. On the other hand, I once shot a roll of tri-x at 800 and paid a lab to push it one stop. It was fine for most of the negs, but some of the highlights were too dense, making them hard to print.
40oz
...
IMHO, pushing for one stop is a waste of good film. Pushing for two stops can give very good results. The biggest consideration when pushing is the type of lighting.
To define "pushing": exposing as if your film is faster than it is, and developing longer than normal to compensate. For example, shooting Tri-X 400 as if it was a 1600 ISO film. It's not, so you lose some ability to capture the brightest lights and darkest shadows. But at 1600, what you lose is minimal in most scenes. The reason you do it varies. Most commonly, it's because you can't otherwise get an aperture and shutter combination that eliminates camera shake and/or subject movement blurring, or you want the "look" - you [/i]don't want[/i] to capture every tone the film is capable of capturing.
Bar scenes are very often quite contrasty, and any push becomes obvious as lighting turns to white-out bursts and shadows disappear into inky black. The effect can be quite dramatic and pleasing. Snow-covered streets and fields work very well, with a full range of tones on the negative as the reflected light from the snow illuminates more evenly. The negative isn't showing the full range it is capable of, but it doesn't need to look like a block print.
Exposure is important - know that a light bulb is going to appear as a globe of white when pushing, and the greater the push, the more pronounced the effect. If you don't expose for the shadow details specifically, they will be lost in blackness in most cases because the film simply didn't get enough light from them. It doesn't matter how long you let it sit in the developer, unexposed film is unexposed film. And things like streetlights lose all shape and detail because everything above a certain point becomes blank white on the print.
That said, pushing is a very useful tool. It lets you capture scenes that would otherwise not be possible. It also lets you capture a scene as *you* want it to look, rather than as someone else might have taken it. It's a creative tool.
To define "pushing": exposing as if your film is faster than it is, and developing longer than normal to compensate. For example, shooting Tri-X 400 as if it was a 1600 ISO film. It's not, so you lose some ability to capture the brightest lights and darkest shadows. But at 1600, what you lose is minimal in most scenes. The reason you do it varies. Most commonly, it's because you can't otherwise get an aperture and shutter combination that eliminates camera shake and/or subject movement blurring, or you want the "look" - you [/i]don't want[/i] to capture every tone the film is capable of capturing.
Bar scenes are very often quite contrasty, and any push becomes obvious as lighting turns to white-out bursts and shadows disappear into inky black. The effect can be quite dramatic and pleasing. Snow-covered streets and fields work very well, with a full range of tones on the negative as the reflected light from the snow illuminates more evenly. The negative isn't showing the full range it is capable of, but it doesn't need to look like a block print.
Exposure is important - know that a light bulb is going to appear as a globe of white when pushing, and the greater the push, the more pronounced the effect. If you don't expose for the shadow details specifically, they will be lost in blackness in most cases because the film simply didn't get enough light from them. It doesn't matter how long you let it sit in the developer, unexposed film is unexposed film. And things like streetlights lose all shape and detail because everything above a certain point becomes blank white on the print.
That said, pushing is a very useful tool. It lets you capture scenes that would otherwise not be possible. It also lets you capture a scene as *you* want it to look, rather than as someone else might have taken it. It's a creative tool.
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kaiyen
local man of mystery
one note - pushing does not affect the sensitivity of the film.
mtk
Member
Thank you all..
ClaremontPhoto
Jon Claremont
We generally push B&W, underexpose and develop longer.
Color film does not need pushing as it is much more tolerant.
Color film does not need pushing as it is much more tolerant.