Hasselblad 500c and Phase One P45 Back - long exposure not working?

[kristyansen]

What position should the lenses be in?
a) for „normal“ exposures and
b) for „B“ exposure?

The lenses that work well are in X mode. No issue.

 

[FloatingLens]

Ah sorry, I meant M mode on the compur shutter because that one will NOT have the required sync timing.

 

[itsdoable]

The P45 is ready when it gets the wakeup call, and starts integrating light when it gets the sync signal, which is when the contacts close, and stops when the contacts open. If the contacts in the lens do not stay closed, or are noisy, the back may assume the exposure is over.

Note that the flash contacts are tricky to aligne when reassembling a C lens.

The back should work in both X and M mode. M will pretrigger the back, same as using the body sync. X will allow the back to cycle faster, and record the estimated shutter speed on the exif metadata, it's usually pretty close. M will record a much longer shutter speed.

 

[kristyansen]

A wake-up cable allows Phase One digital backs to be used on cameras with mechanical shutters. It has a button that, when pushed, wakes up the digital back.
Here is a graphic from my site of the type I use (there are less expensive cables available):

--

It sounds like a timing (latency) issue.
You may need to use a wake-up cable in long latency mode.
I know what the manual says about short latency, but that is not working!

Try this, as this is how I do long exposures with my tech cameras and the P45:

1. Attach wake-up cable to the P45 back
2. PC flash sync to the lens
3. Put the camera in B mode
4. Press the wake-up cable,
5. Then do your long exposure in B mode with the mirror locked up

Let us know how it goes.
Best of luck!

While thinking of options regarding some of my lenses being CLAed, I am still intrigued about this special wake-up cable.
@darr if you have some seconds I would be grateful for some more details on Step 5:

• When does the exposure on the body actually start and end, and how?
• When should the mirror locked-up - after waking up the body or before?
• Do I lock the mirror up from the special 500C button below the winding knob or by pressing the shutter button of the camera and holding it pressed and eventually depressing it?
• When is the shutter knob of the body being pressed, when is it depressed? (thus activating the lens PC sync...) - if at all?
• Do I need to press the wake-up knob of the cable again at the end of the photo?

Apologies for the many questions but I am really interested in this technique which seems less dependent on some not so reliable lens contacts...

 

[darr]

The only thing 'special' about the ALPA cable is it is made to attach to ALPA camera bodies (with the proper attachment).

The steps I went through are the ones I go through when performing a long exposure on my Hasselblad bodies.
Nothing special there, either. You said you were doing long exposures with a Hasselblad 500.

My P45 is an M645, not a Hasselblad V. My V digital backs have Live View, which is much easier to use with my Hasselblad bodies.

 

[darr]

• When does the exposure on the body actually start and end, and how?
• When should the mirror locked-up - after waking up the body or before?
• Do I lock the mirror up from the special 500C button below the winding knob or by pressing the shutter button of the camera and holding it pressed and eventually depressing it?
• When is the shutter knob of the body being pressed, when is it depressed? (thus activating the lens PC sync...) - if at all?
• Do I need to press the wake-up knob of the cable again at the end of the photo?

1) exposure happens when you open the lens after mirror lock-up
2) prepare your camera body before wake-up
3) mirror lock-up first with the lever below the winding knob
4) after mirror lock-up, press wake-up cable, then quickly press the shutter release cable
5) There is no need to wake-up the back again after the exposure

 

[darr]

You are operating a film camera first, then a digital back.

It can be overwhelming if you are not an experienced Hasselblad film shooter, as shooting older medium-format film cameras has distinct shooting checklists and is nothing like shooting a digital camera. Practice, practice, practice, as I said when I taught.

 

[kristyansen]

Thank you, Darr, yes, I am getting better at it.

Regarding the wake-up cable, I understand that the lens must still send the signal correctly to the digital back to end the exposure, so if my lens does send the signal too early while the exposure is still ongoing (the release button is still pressed), the wake-up cable will not solve the issue I am having and cannot send the end exposure signal to the digital back.

Thanks again!

 

[darr]

The P45 back functions within a sleeping architecture. It requires two signals: one to awaken and another to initiate exposure. This design ensures the CCD remains as cool as possible, eliminating the need for external cooling.

I have used wake-up cables with a push button to wake up the back and a shutter release cable to take the picture after the back awakes.
If you see a timeout error, the back gets your first signal and never gets the second one.

I do not think the statement "the lens must still send the signal correctly to the digital back to end the exposure" is correct. The second signal opens the lens shutter, and then the shutter closes as it would normally, and the back no longer receives any light, thus ending the exposure. I would like someone to clarify this.

So, are you saying your lens shutter is not operating correctly?
Did you try another lens and have success?

The Hasselblad 'C' lenses are old, some from the 1950s. I used them at the start of my career in the 1980s, and at least one 'C' lens was in the shop monthly, having the flash sync replaced. Sometimes, they even had burn marks on the metal from all the pop flashes I fired from them at special events, weddings, etc. The flash sync stub sticking out of the lenses caused problems with new assistants pulling the cords off haphazardly.

I never want to discourage a photographer from using Hasselblad gear, but old Hasselblad gear with digital backs might be challenging unless you have a good repair person.

Then, there is a possible shutter-in-body issue. Did you have a technician look at the body as well?