120 Ilford HP5+ 400 at EI 12800

  2016 April 16    Film   Developing


If you like to shoot film at night without a tripod, pushing film is essential.

Set your camera at a higher ISO (technically, EI number) than the box speed. 

Kodak HC-110 might not be the only developer you'll ever need, but it could be the only developer I'd ever need.  For pushing film, it's top notch.  Question is, just how far could it push Ilford HP5+ 400?

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In This Article

Basic Idea


Developing Times For E.I. 6400 And Up


Basic Idea

If you want to push Ilford HP5+, pick some EI value higher than 400.  Pushing the film to 800 would be a one-stop push; 1600 would be two stops, and so on.

Many cameras have auto modes (Aperture Priority, etc), which means the light metering is tied to the ASA/ISO setting.  In other words, it's not manual;  adjusting the ASA/ISO dial will have a direct effect on what settings the camera uses.  The dial doesn't usually say "E.I.";  it says "ISO" or sometimes "ASA".  If you were going to push the film to 3200, you'd set the dial to ISO 3200.  On the later Nikon film SLR's, you have to move the setting off "DX" and onto the ISO that you want.  You have to do this because you're not using the box speed of the film, so the DX coding would be useless here.

If you want to shoot the film as 6400, that's four stops under-exposed, compared to the box speed of 400.  To complete the equation, you would then process the film as if it were 6400: four stops past the box speed.

In other words:  shoot the film as if it were that ISO, then develop as if it were that ISO. 

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As with Tri-X or any film, pushing has some potential drawbacks.

Good lighting and proper metering should still yield usable pictures.  Very dim lighting, or incorrect metering, can have more drastic effects with pushed film. 

Highly-pushed films are not picking up true speed increases.  Neither are pushed digital cameras;  you can't increase the native sensitivity of the photosensors. 

The setting you choose on the ISO dial is not the real ISO of the film;  it's actually the E.I. (exposure index).  A 400 film pushed to 6400 is not going to have the full range of shadow detail.  It might produce a very worthwhile image, though. In fact, if you do it right, the result might have almost the tonality of box speed.  If the film is not picking up a speed increase, it's only a technical point that doesn't matter that much.

I have noticed that highly-pushed Ilford HP5+ doesn't lose much shadow detail, provided you use good lighting and develop it right.  If the dynamic range is still mostly there, it becomes closer to being a true film speed.  And actually, some developers really do increase the effective film speed, though no one seems to want to allow a true film speed of more than 1000.

120 Ilford HP5+ 400 at EI 6400
HC-110Dilution B
68-70 Fahrenheit, 43.5 minutes

Look again at that image.  It has almost the full range of shadow detail.  Can you believe this was shot hand-held, f/8 at a 125th?  With film, that's almost what you'd be using outdoors in full sunlight.  Originally I had this figured as EV 6, but I believe this scene is EV 7, so conservatively I'm calling this EI 6400.  No matter; you're not even supposed to be able to push the film this far.  It's a 400 film!

Film is truly incredible.  It is still one of the greatest technologies of our time. 

By the way, the TLR camera has a leaf shutter, so there's no mirror slap.  However, the longer focal length (80mm) means you have to hold the camera really still at 1/60th.  (1/60th on this camera is like a 30th on your film SLR with its 50mm lens.)  A shutter speed of 1/125th is the recommended minimum without a tripod.  What makes it tricky is that the apparent depth of field also shortens with a medium-format camera.  What you get in return, though, is less visible grain because of the larger film.

Next up, some data for pushing Ilford HP5 Plus.


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Developing Times For EI 6400 And Up

How long should you develop 400-speed B&W film shot at EI 12800?  How about EI 25600?  Searching around for published data, there wasn't much for speeds above 3200.

I graphed out some known times for HC-110 Dilution B and obtained a best-fit equation.  The result was a power equation of the form y = b * x ^ a, where a and b are some real-number constants.  This is a common type for chemical reactions.

After thinking some more about this, I think this curve may be incorrect.  For highly-pushed films, we should be seeing either linear, or increasing at an increasing rate.  See Pushing Tri-X for more details.  Probably I will update this page as well, when I work out better times for pushed Ilford HP5+.

So here are the tentative dev times for Dilution B, rounded to the nearest minute:

6400:  28 minutes @ 68-70 F
12800:  44 minutes @ 68-70 F
25600:  67 minutes @ 68-70 F

Ilford HP5+ does seem to have a speed advantage over Tri-X in HC-110, but I'm still thinking these dev times are much too short.  For 6400, I'd be wanting to try at least forty minutes, and at 12800 I'd go with at least 70 to 90 minutes for starters.  You probably couldn't go too far wrong by just trying the Mk.II dev times for Tri-X.  (For 12800, figure on 2 hours or perhaps a bit more.)

If you do try these times, be sure you have enough total HC-110 in the solution that it doesn't deplete halfway through the process.  For a roll of 135-36 you'd want about 6 ml of concentrate in the solution.  If you're using enough Dilution B to cover one roll in a Paterson tank, you'd have 10 or 11 ml of HC-110 there anyway.  For a roll of 120 film you'd have even more.

Don't forget to use de-gassed distilled water for your developer and fixer.

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This has been a look at pushing Ilford HP5 Plus 400 to 6400 and beyond.  Data were lacking in that range, so I made a graph and obtained a power equation.  I'm starting to think that a cubic polynomial equation might be a better fit, though.  When I re-do the graph for HP5+ as I did for Tri-X, I'll update this page.

f/8 @ 125 was correct for that second photo if it were EV 6, but it might not have been.  What I'm thinking is that it was EV 7, which seems about right for that lighting situation.  f/8 and 125th would be EV 7 for 6400, so what I think we're really seeing there is EI 6400. 

Density looks right to me when the negative is held up to the light.  It scanned easily;  very little adjustment required.  The first photo was about half- to one stop under, but as a pure guesstimation it sure worked out better than using my in-camera meter.

The film manufacturers did a lot of work so that we can enjoy the films at their recommended speeds;  realize that extreme pushes are well outside that range.  Even so, the results can sometimes be quite amazing. 

I'm really impressed with how well Ilford HP5 Plus did here.  I actually tried it because I didn't have any Tri-X in 120 size.  There was a lone roll of HP5 Plus sitting in the fridge (not two rolls as I'd thought).  So I figured "why not?"  Great film!

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