Portra 400 Pushed 2 Stops

Does anybody out there have any experience with pushing Portra 400 2 stops during processing? Mainly interested in the granularity, color shifts and black density. I will be making some long exposure tracked astro photos and the Fujichrome Provia 1600 I used to use is no longer available. I'm shooting 4x5 format and this ASA 400 film is the fastest color stock I can find. Trying to decide between pushing 2 stops during processing, or going longer on the exposure and just pushing 1 stop. Then I'm fighting reciprocity failure which really extends exposure times. Thanks for any help.

Good question, I've only pushed Porta 400 one stop, it was ok, going 2 stops, just wonder if that's a bridge too far.

Best I can suggest is try it (with a partial roll of 35mm, perhaps, as opposed to a 4x5 sheet) and find out...

Two f/stops is still within the range of Portra 400 developed normally. Three stops would be a bit to much IMNOHO.

I have generally found that C-41 film can tolerate up to 4-5 stops of overexposure and still get a useable scanned image from the film. However, it will only tolerate about 1 stop of underexposure before the shadow detail and the blacks start to suffer. On the flip side E-6 film can absorb 4-5 or so stops of underexposure and still get a reasonable scan from the film. However, as we all know, it will tolerate maybe 1-2 stops overexposure and everything goes clear on the film.

I have also generally found that most times I make images in astrophotography, which I have been doing for some 35 years, overexposure is not really an issue. But underexposure definitely is. That is why I always shot E-6 Fujichrome Provia 1600 pushed 2 stops during processing. It handled the extra development like a champ and I always got good images. C-41 just can't deal with the underexposure problems encountered during dark sky imaging.

Now there are always exceptions. Hypersensitizing being one, pre-flashing the film another, but I always choose to get the best exposure in the camera that I can. My current project will require me to make exposures between 20-30 minutes long at f/2.5, tracking the stars as I image. There is no good option for high speed E-6 film anymore, particularly in 4x5 format. So I'm left with the Portra 400. I could push it 2 stops in the lab and I know I would come out with a reasonable image for exposure. I just have no experience with this particular film stock or its reaction to the extra development time. I could also push it 1 stop at the lab and extend the exposure time, probably a preferable choice, but I'm already fighting reciprocity failure at 30 minutes. If I need to compensate for 1 stop less processing time I will need to double the exposure, plus the reciprocity compensation value. In reality that could push the exposure out to 1 1/2 to 2 hours, plus looking through the eyepiece to keep the camera correctly tracking with the sky for that amount of time is tedious at best.

I appreciate all your comments and have decided to hedge my bets. I have 5 film holders which gives me 10 pieces of film to expose. Using 4x5 format also gives me the ability to make different exposures on 1 sheet of film. I can expose for 10 minutes and push the dark slide 1/3 of the way in (without moving the camera!), go another 10 minutes and push the dark slide another 1/3 of the way in, then continue for 10 more minutes. That way I get a 10, 20 and a 30 minute exposure on one sheet of film. I will do this twice, then process one sheet pushing 2 stops and the other pushing just 1 stop. This should give me enough information to go back out the next night or two and get the shot I am looking for. I will definitely post my findings here for you to all share.

Funny, I'm probably the last guy out there still shooting film like this. I never switched over to digital because there is just something about film that always draws me back. Maybe it is the anticipation of going to the lab the next day to see what I got. Whatever it is I am hooked forever, or at least until they make the last roll/sheet of film.

I have included one of my images from 1996 of Comet Hyakutake that I had made into a poster. If you look in the gap in the tail at the upper right you can see the spiral galaxy M-101 just visible. It was only there that one night.

Exposure: Taken with a Nikon F3 coupled to a Nikkor 180mm ED lens wide open at f/2.8. Shot on Fujichrome Provia 1600 film pushed 2 stops during processing. Exposure was 6 minutes on a GEM clock drive - dual axis drive, March 25, 1996. This was taken around 2am from the top of Figueroa Mountain just north of Santa Barbara, CA under glorious clear skies.

Matt Hall said:

I have included one of my images from 1996 of Comet Hyakutake that I had made into a poster. If you look in the gap in the tail at the upper right you can see the spiral galaxy M-101 just visible. It was only there that one night.

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That's a great image! I've never had the chance to do astrophotography, but like you, I've never switched to digital. From 35mm to 4" x 5" sheets, film will always have me "hooked."

Don’t have much to add, but that was interesting reading and thanks for the sample.

Sympathize with your predicament. Probably not that many that would have the experience to help, so yeah, looks like you’re gonna have to do your own testing. I do know that Portra 400 has a great reputation for underexposure (without pushing), but those are very different usage cases, because they’re usually more forgiving whereas you’ll be looking for the cleanest dark tones you can get. I think pushing (and probably pre-sensitizing or flashing) will be your best bet, since you’re likely not gonna need to worry about pushing your highlights too far.

Be very curious to hear the results. Hope you’ll update us.

You could use Portra 800 instead and then with normal development, the film would be only one f/stop off.

Sirius Glass said:

You could use Portra 800 instead and then with normal development, the film would be only one f/stop off.

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Oh if only I could! They do not make Portra 800 in 4x5 format, only the 400 speed. I know that one stop does not sound like much to most people, but when the subject you are shooting takes 30 minutes of exposure at ASA 1600, one stop is absolutely huge.

So I setup the perfect exposure of Kodak Portra 400 at 1/125 and underexposed by 4 stops and overexposed by 10 stops, processed at box speed and got these results.

Kodak Portra 400 exposure range by Les DMess, on Flickr

I can take the +10 overexposure and recover a workable image by applying simple white balance and levels. At -4 underexposure, I had to extend the exposure in scan and then apply some post work to get a reasonable image.

Regarding reciprocity failure, I have conducted extremely long exposures lasting hours many long using many films and the only "failure" I have found is managing various ambient lights in the frame.

This one on Fuji 100 with controlled white balanced light source . . .

Fuji 100 long exposure by Les DMess, on Flickr

This one on Kodak Gold 100 . . .

Gold 100 long exposures by Les DMess, on Flickr

After a few others of not getting any failures, I just didn't bother doing controlled exposures anymore but just used them in real shots.

This one on Kodak Portra 400 for about 10 seconds . . .

Kodak Portra 400-11-31 by Les DMess, on Flickr

This one on Kodak Portra 800 for about 15 minutes . . .

Kodak Portra 800-06_22B by Les DMess, on Flickr

This one on Kodak Ektar 100 about 30 minutes . . .

Kodak Ektar 100_37-31B by Les DMess, on Flickr

Since these long exposures look "normal", for reference, this is what that Kodak Ektar 100 scene looks like as taken by celphone . . .

IMG_20160703_223609044 by Les DMess, on Flickr

Les, I really do appreciate all the hard work you must have done to create this test. It does illustrate the ability of film to accurately, or inaccurately record exposures over varying lengths of time. However, I think you missed the point of my post. I was inquiring if anyone out there had any experience with pushing Portra 400 by 2 stops during processing. I am interested in how the film will react to the longer temps/times with regards to the blacks, granularity and color shifts.

When it comes to astrophotography one needs to remember that there is no over exposure to consider, ever. I will be under exposing my images by 2 stops (or more) and then push processing the film to compensate for that lack of exposure. At that point things that were 4 stops underexposed have become just 2 stops under and can now be recovered in printing, etc. Your test involved normal processing which will not help my situation. 4 stops under stays at 4 stops under and is really not usable in my situation.

As for the reciprocity failure, and that is the term Kodak uses as well, you have never noticed a failure because it is not something that jumps out at you as a problem. Here in a nutshell is what reciprocity failure involves. If you give film the same overall exposure, over longer periods of time the film will become increasingly underexposed. Another words, 5 minutes @ f/4, 10 minutes @ f/5.6 and 20 minutes @ f/8 will not yield the same exposure or density readings on the film. By the same token if I'm shooting at 30 minutes @ f/2.5 and I'm under exposed by one stop I cannot just double the exposure to 60 minutes at the same aperture to get the correct exposure. The film has a failure to accurately record all the photons striking the silver halide crystals as the time extends. You need to add in a reciprocity failure compensation value. That can push exposure times out to several hours which is why I want to employ the "push processing" method to help alleviate that extra time. A night time city scape might seem dark to some, but it is hundreds of times brighter than some of the scenes I'm trying to shoot through my scope/cameras.

I graduated from Brooks Institute of Photography with a degree in industrial/scientific photography and did a study as part of my Masters program on reciprocity failure and various methods to combat the problem. I employed pre-flashing the film so that the next photon that strikes a silver crystal will record an image. I also did extensive hypersensitizing film in a forming gas (hydrogen mix) to greatly improve the films ability to record every photon striking it (the only problem is you have to use the film immediately after hypering). I also experimented with temperature reduction to help offset the reciprocity issue. These all work, to varying degrees, to help reduce overall exposure times. Reciprocity failure is real, although it is not something the average photographer will ever have to deal with.

Actually, those of us who work with pinhole cameras deal with reciprocity failure regularly!
I'm not sure you are going to find an answer that you like.
Due to their nature, push processing does somewhat increase the sensitivity of transparency films, but does not increase (meaningfully) the sensitivity of negative films.
With negative films, it mostly increases contrast

MattKing said:

Actually, those of us who work with pinhole cameras deal with reciprocity failure regularly!
I'm not sure you are going to find an answer that you like.
Due to their nature, push processing does somewhat increase the sensitivity of transparency films, but does not increase (meaningfully) the sensitivity of negative films.
With negative films, it mostly increases contrast

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Yes, I never thought about pinhole cameras. The only time I ever used them was to record sunspots or solar eclipses. In that situation the light source is so bright that it is not an issue.

Thank you on the feedback regarding the C-41 film stock reaction to pushing. I only have experience with E-6 films so all this is new to me. I plan on making several exposures on each sheet of film, you know - 10min, push the dark slide in 1/4 of the way, 10 more min, another 1/4 of the way in. I should get 4 exposures per sheet. I have decided to make 3 of these test sheets and process one normally, push one 1 stop and push the other 2 stops. A comparison of these 3 films should yield the information I need.

Matt Hall said:

Les, I really do appreciate all the hard work you must have done to create this test. It does illustrate the ability of film to accurately, or inaccurately record exposures over varying lengths of time. However, I think you missed the point of my post. I was inquiring if anyone out there had any experience with pushing Portra 400 by 2 stops during processing. I am interested in how the film will react to the longer temps/times with regards to the blacks, granularity and color shifts.

When it comes to astrophotography one needs to remember that there is no over exposure to consider, ever. I will be under exposing my images by 2 stops (or more) and then push processing the film to compensate for that lack of exposure. At that point things that were 4 stops underexposed have become just 2 stops under and can now be recovered in printing, etc. Your test involved normal processing which will not help my situation. 4 stops under stays at 4 stops under and is really not usable in my situation.

As for the reciprocity failure, and that is the term Kodak uses as well, you have never noticed a failure because it is not something that jumps out at you as a problem. Here in a nutshell is what reciprocity failure involves. If you give film the same overall exposure, over longer periods of time the film will become increasingly underexposed. Another words, 5 minutes @ f/4, 10 minutes @ f/5.6 and 20 minutes @ f/8 will not yield the same exposure or density readings on the film. By the same token if I'm shooting at 30 minutes @ f/2.5 and I'm under exposed by one stop I cannot just double the exposure to 60 minutes at the same aperture to get the correct exposure. The film has a failure to accurately record all the photons striking the silver halide crystals as the time extends. You need to add in a reciprocity failure compensation value. That can push exposure times out to several hours which is why I want to employ the "push processing" method to help alleviate that extra time. A night time city scape might seem dark to some, but it is hundreds of times brighter than some of the scenes I'm trying to shoot through my scope/cameras.

I graduated from Brooks Institute of Photography with a degree in industrial/scientific photography and did a study as part of my Masters program on reciprocity failure and various methods to combat the problem. I employed pre-flashing the film so that the next photon that strikes a silver crystal will record an image. I also did extensive hypersensitizing film in a forming gas (hydrogen mix) to greatly improve the films ability to record every photon striking it (the only problem is you have to use the film immediately after hypering). I also experimented with temperature reduction to help offset the reciprocity issue. These all work, to varying degrees, to help reduce overall exposure times. Reciprocity failure is real, although it is not something the average photographer will ever have to deal with.

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Actually -2 stops underexposed developed at box speed is still very easy to work just by adding a little longer exposure in scan and/or post work and push processing. The Kodak Portra 400 docs is silent on push/pull processing and the typical statement regarding long exposures - test it yourself in the conditions you're shooting. I have done some push processing of Fuji 800 film to 3200 and the colors looked relatively normal given the gym lighting conditions although grain was definitely more pronounced. Although I have not done it myself, I would guess a two stop push with Kodak Portra 400 will be uneventful. I look forward to seeing your results if you care to share them.

I didn't take any technical classes on photography but I am a test engineer so I did plan out the testing. My reciprocity testing - the long exposures as opposed to the over and under exposure testing, were done with controlled lighting as determined by the meter to the extent possible. I was not over or underexposing them as I was extending the exposure time by limiting the light to the film. Nor did I dial in any compensation as those times are strictly based on the exposure reading of the meter. And it is by these results I concluded that I saw no reciprocity failure. BTW, the much longer exposures were conducted by the Pentax LX as it is the only camera I am aware of that will aperture priority autoexpose a scene for as long as it takes - hours long, and it does not have any built-in algorithms for reciprocity failure compensation nor do I dial in any.

Les, I have to admit that I was a bit perplexed by your results. They indeed do not show the reciprocity issues I would have anticipated. Perhaps it brings up a point that Kodak has found a workaround with their newer emulsions that greatly diminishes the problem. Your results would seem to bear that out. Thanks again for the testing and sharing your results. I will definitely use them when determining my test exposures. And yes, I will be happy to post all my results here for you to see. If we could figure this out together that would be great!

Matt Hall said:

Yes, I never thought about pinhole cameras. The only time I ever used them was to record sunspots or solar eclipses. In that situation the light source is so bright that it is not an issue.

Thank you on the feedback regarding the C-41 film stock reaction to pushing. I only have experience with E-6 films so all this is new to me. I plan on making several exposures on each sheet of film, you know - 10min, push the dark slide in 1/4 of the way, 10 more min, another 1/4 of the way in. I should get 4 exposures per sheet. I have decided to make 3 of these test sheets and process one normally, push one 1 stop and push the other 2 stops. A comparison of these 3 films should yield the information I need.

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Matt.
As I'm sure you know, reciprocity failure of the type we are discussing here - Low Light Intensity Reciprocity Failure ("LLIRF") is actually not related to the length of exposure at all. It is related to the intensity of the light that reaches the film. We tend to think of it in relation to exposure times because lengthening the exposure time is the tool we tend to apply when we are dealing with that low light intensity.
Les' test exposures don't get into reciprocity failure territory because, while they include under-exposed film, even that film is being exposed to fairly bright light - just for a bit less time than would result in correct exposure.
You are photographing the stars and other things up in the skies. By the time it gets to your film, that light is dim! So that is why you have to deal with LLIRF.
Push processing works with slide film because of a bunch of technical reasons that relate to the fact that what we see in a transparency is actually an image of the parts of the emulsion that were originally exposed in camera, but were not developed into an image. Essentially, you are seeing what is left over after the first development is finished, and then bleached away. The combination of the develop, bleach, redevelop process is what gives you a sensitivity boost from push processing of transparency film. Without those additional steps, C-41 film doesn't gain sensitivity.
IIRC, the early moon shot photos were on negative films, cross processed as slides, because of a number of factors, including that potential boost in sensitivity. I don't know whether that might be an approach that would help you.
FWIW, there is also High Light Intensity Reciprocity Failure ("HLIRF") - we most often see that with high power flashes, used at close distances.

MattKing said:

Matt.
As I'm sure you know, reciprocity failure of the type we are discussing here - Low Light Intensity Reciprocity Failure ("LLIRF") is actually not related to the length of exposure at all. It is related to the intensity of the light that reaches the film. We tend to think of it in relation to exposure times because lengthening the exposure time is the tool we tend to apply when we are dealing with that low light intensity.
Les' test exposures don't get into reciprocity failure territory because, while they include under-exposed film, even that film is being exposed to fairly bright light - just for a bit less time than would result in correct exposure.
You are photographing the stars and other things up in the skies. By the time it gets to your film, that light is dim! So that is why you have to deal with LLIRF.
Push processing works with slide film because of a bunch of technical reasons that relate to the fact that what we see in a transparency is actually an image of the parts of the emulsion that were originally exposed in camera, but were not developed into an image. Essentially, you are seeing what is left over after the first development is finished, and then bleached away. The combination of the develop, bleach, redevelop process is what gives you a sensitivity boost from push processing of transparency film. Without those additional steps, C-41 film doesn't gain sensitivity.
IIRC, the early moon shot photos were on negative films, cross processed as slides, because of a number of factors, including that potential boost in sensitivity. I don't know whether that might be an approach that would help you.
FWIW, there is also High Light Intensity Reciprocity Failure ("HLIRF") - we most often see that with high power flashes, used at close distances.

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How would the E-6 process deal with the built-in orange mask in C-41? I doubt it would remove it so you would get some very strange color, low contrast images, right?

The colour is different.
But these were made that way (with pre-C41 film and pre-E6 process): https://www.google.com/search?q=Moo...gJjQIHaIlAKYQ9QF6BAgCEAE#imgrc=gSQ891LTFVD7UM

The mask is, of course, created by the development process, not built into the film, so it is different in cross processed film.
Here are some examples: https://www.google.com/search?q=C41...E&biw=1920&bih=937&dpr=1#imgrc=zRrk6UVwIRpMmM

MattKing said:

Les' test exposures don't get into reciprocity failure territory because, while they include under-exposed film, even that film is being exposed to fairly bright light - just for a bit less time than would result in correct exposure.

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I provided the over and under exposure range to show that 2 stops underexposed may not need process compensation. The others are low light metered properly so that the camera uses the correct setting. I added the smartphone shot for the boat picture to show just how dark that setting was and the reason the film exposure was that long to make it look like a well lit exposure. The other long exposures - that look like well lit scenes, are the same - they were all extremely dark settings.
For instance this is what my smartphone saw compared to that coastal shot on Kodak Portra 800 that was more "properly exposed" . . .

IMG_20150118_202603725 by Les DMess, on Flickr

Matt Hall said:

Does anybody out there have any experience with pushing Portra 400 2 stops during processing? Mainly interested in the granularity, color shifts and black density. I will be making some long exposure tracked astro photos and the Fujichrome Provia 1600 I used to use is no longer available. I'm shooting 4x5 format and this ASA 400 film is the fastest color stock I can find. Trying to decide between pushing 2 stops during processing, or going longer on the exposure and just pushing 1 stop. Then I'm fighting reciprocity failure which really extends exposure times. Thanks for any help.

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Speaking from some experience, you probably won’t be happy with 400 pushed 2 stops for astrophotography.
You loose a lot of the fine detail in the dark areas that makes the celestial sky interesting to most, and the grain does increase noticeably.

You seem set on not trying preflashing.
But you might want to try it on a couple of frames at least. It does help give a real speed increase for modest pushing.

400 is an amazing film that keeps surprising me.

Helge said:

Speaking from some experience, you probably won’t be happy with 400 pushed 2 stops for astrophotography.
You loose a lot of the fine detail in the dark areas that makes the celestial sky interesting to most, and the grain does increase noticeably.

You seem set on not trying preflashing.
But you might want to try it on a couple of frames at least. It does help give a real speed increase for modest pushing.

400 is an amazing film that keeps surprising me.

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Per your, and others, suggestions I did a pre flash test last night with some Portra 400 35mm film. I used 35mm format because it is substantially cheaper to shoot than the sheets of 4x5 I will ultimately be using. Although the two films will be a difference batch, I am making the assumption that the emulsions will react similarly. I used a white balanced 2 watt LED bulb and set the film camera distance to 12 feet. Turned out all the lights and made exposures ranging from 1/125 sec all the way out to 4 minutes in 1 stop intervals. For this test I used my Nikon F3 body with the lens removed and locked the mirror in the up position. This yielded an overall even flashing for the frame. I used the camera shutter for the shorter exposures and the T setting for the longer ones (having just had the shutter speeds checked and they are accurate). I also made reference exposures between each test frame with the room lights on at 1/60 sec. This was done so I could see where the low end test frames were. The roll would have likely started out with just blank film and I would have never determined exactly where each test frame resided on the film. I did these same exposures for 2 rolls of film and had one processed at a 1 stop push and the other a 2 stop push. I pick up the film later today and will do densitometer readings to determine which exposure starts to create density on the film. I want to be at a place where the next photon striking the film will register an exposure (at least ideally).

By the way you mention Portra 400 will not be satisfactory for astrophotos. I have searched and cannot find another film to use. What color film do you recommend, and remember I am shooting 4x5 format (a lot less options than 35mm or 120)?

Exciting! Looking forward to seeing your results.
I’m actually currently using a very light global diffusion filter for flashing (kind of like the Tiffen ones). That will of course not work well for astro photography.

Flashing does work for Portra 160 and 400 but not with quite as drastic results as with HP5 or TMax 400.

I’m still working on a concurrent flasher to make flashing easier and more efficient.

The best long exposure colour film bar none (and possibly the greatest colour film ever), is Provia 100.
Just exceptional reciprocity characteristic, high resolution and natural colour.
You can push it to 400 without it getting too off.
Never tried flashing it, but it should in theory work.

You could build a barn door tracker to make the need for fast film a bit less. That would exclude getting any landscape in-camera though, of course.

I've pushed Portra 400 by 2 and 3 stops respectively and agree w/ Helge that it is unlikely to yield desirable astro results (I *do* like it for some portraiture), though I'm very keen to see the results of your testing. In my experience, the grain increase is noticeable and color skews browner.

Helge said:

Exciting! Looking forward to seeing your results.

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Well, I just picked up my film and there are a bunch of notes on the envelope from the lab. I didn't tell them I was doing a test strip exposed to straight white light. They got a little freaked out when most of my frames were either completely dark or clear. I think they assumed they had processed it wrong. Kinda funny actually!

So the results have surprised me a bit. I thought that the correct flash point of just reaching readable density would be around the 5 to 10 second area. I wasn't even close! I can clearly see density in the 1/30 sec. exposure for the 2 stop push and 1/15 sec. for the one stop push using a loop and the naked eye. I thought it would be easy to flash the 4x5 sheets since the time would be in seconds since I will have to do it manually using the dark slide. Now with the correct time at 1/30 - 1/15 sec. I am left with a problem. I do not have a lens/shutter that I can use to flash the sheets and I KNOW that I cannot be accurate to 1/30 sec using the dark slide. I will need to attenuate the light source by at least 7 stops to get the time out to 4 seconds where I can be accurate enough to even consider using the dark slide. At least I have a starting point.

Helge said:

You could build a barn door tracker to make the need for fast film a bit less. That would exclude getting any landscape in-camera though, of course.

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I guess I should have mentioned that I am using a German Equatorial Mount with dual axis drive for my exposures. You can see the camera I built for this in the following string here on Photrio:

https://www.photrio.com/forum/threads/aero-ektar-12-inch-f-2-5-4x5-astro-camera.189944/

I will also be using a 400mm f/5 guide scope with a 2-inch eyepiece for tracking using an illuminated reticle to help keep the entire system trained on one point in the sky with no errors. I'm trying to get some detail in the gaseous region around Orion, including some of the H-alpha emission areas (think Horsehead nebula) and such. That is the reason for the extended exposure times I need. Not too many photons from those distant objects reach us here on Earth. My favorite film for astrophotography was the Fujichrome Provia 1600 which was a 400 speed film made for pushing 2 stops in processing. Bright points like the heads of comets, etc. would get burned up, but for the most part it rendered some great images with surprising tonal ranges. Shadow detail was also excellent. But, as we all know, all these great films are gone. You can go back to my Feb. 16 post in this string to see one of my favorite shots.

Matt Hall said:

Well, I just picked up my film and there are a bunch of notes on the envelope from the lab. I didn't tell them I was doing a test strip exposed to straight white light. They got a little freaked out when most of my frames were either completely dark or clear. I think they assumed they had processed it wrong. Kinda funny actually!

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It is funny, but I assure you that they were cursing you when they struggled with your negatives!
As a former colour printer, I must emphasize that communication with your lab is important!