Pinhole photography with Leaf and Phase One backs

[rogerxnz]

I have hijacked the thread How does the Dalsa-based backs know the Copal shutter speed? into a discussion about how to turn a Hasselblad 5xx camera into a digital pinhole camera with an Aptus or Credo back and I reckon the new subject deserves more prominence. So, I have copied an edited version of the discussion on pinhole photography here but please see the other thread for the links and images.

My initial query:
I know it [pinhole photography] can be done with a Phase back because they are triggered by the metal "feeler" that comes out of the rear of the body when a shot is taken to ensure the film slide is absent and they have a button you can press to turn the sensor on and off. But a Leaf back is triggered from the flash synch and that won't be present with a pinhole lens attachment.
Roger

Reply from DOUG PETERSON (dep@digitaltransitions.com)


0. Set the back to "large format"
1. Unplug the sync cable from the lens.
2. Take a ballpoint pen and hold it against the contacts of the cable sync cable, while doing this uncover the lens.
3. Prior to releasing the ball point pen recover the lens so the sensor is in darkness when you release the ball point pen.

Alternatively you can use the "old style wakeup cable" from Phase One with the Leaf back. This is part #50300131 on our estore. Same end result, but much easier mechanics (just hold the button down for the length of the shot - the very slight camera shake will be hidden by the utter lack of sharpness of the pinhole camera).

See more medium format pinhole images. http://www.doug-peterson.com/?s=pinhole

Comment from Yair


See also Chris Ireland's article [see the article at http://www.directdigitalimaging.com/article/technical-articles/]

[rogerxnz]

Now, to continue the discussion, I would like to know how the photographers get away with the long exposures usually required for pinhole photography when the backs have a limit for exposures of one or two minutes?

Chris Ireland uses a Phase One back and mentions exposure times of 1 second up to 9 mins (at f180!).

How can he do that? Wouldn't the sensor have gone into meltdown before it got to 9mins?
Roger

[Doug Peterson]

Now, to continue the discussion, I would like to know how the photographers get away with the long exposures usually required for pinhole photography when the backs have a limit for exposures of one or two minutes?

Chris Ireland uses a Phase One back and mentions exposure times of 1 second up to 9 mins (at f180!).

How can he do that? Wouldn't the sensor have gone into meltdown before it got to 9mins?

Phase One IQ180 and Mamiya Leaf Credo are each spec'd for 2 minute max exposures.
Phase One P20+, P21+, P25+, P30+, P45+ are each spec'd for max one hour exposures. Of these the P45+ is generally acknowledged as the king of long exposure amongst all backs, especially at times over 30 minutes.

So 9 minutes is not even breaking a sweat for a P45+.

Given that there is not that much scene detail (cause it's a pinhole, not an uber sharp modern lens) you can safely apply fairly aggressive single-pixel noise reduction and exceed the stated specs by a bit.

My pinhole was a larger-than-normal pinhole and I hand held it at something like ISO800. Probably some camera shake, but I mean, it's a pinhole - I wasn't exactly obsessed with sharpness :-).

These times are:
- at lowest ISO
- at ambient temperatures around 68F (20C). Longer is possible at lower temperatures, less at higher temps.

[FredBGG]

Another option is to get an old large format shutter out of the middle of a large format lens.
That way you can just attach your sinc to the flash connector on the shutter.



Just make sure you get one with a b and t setting on the shutter speed. makes long exposures easier.

You can also mount a skink pinhole "lens" on the front.

[HarperPhotos]

Now that’s using the old grey matter Fred. Good idea.

Cheers

Simon

[rogerxnz]

If you attach a ground glass viewing adapter to the rear of your pinhole camera (similar to the viewfinder arrangement for the Flexbody), can you preview your pinhole shot or is there not enough light?

I'm thinking that turning a Flexbody into a pinhole camera could open up many possibilities but it only be worthwhile if you could preview the effects of the tilt/shift/bellows extension.
Roger

[Stefan.Steib]

With an HCam and our electronic timer you can do this 1 hour shots with a P45+ easily.
You caneven set it up  to wait 1 hour and a minute before the next eposure (because this is what you need for the dark calibration)

regards
Stefan

[Graham Welland]

Another option is to get an old large format shutter out of the middle of a large format lens.
That way you can just attach your sinc to the flash connector on the shutter.



Just make sure you get one with a b and t setting on the shutter speed. makes long exposures easier.

You can also mount a skink pinhole "lens" on the front.

This is what I did for my Alpa. Rather than buy a new Copal 0 shutter I was able to find and buy a damaged Nikon LF lens for $100 and took the as-new Copal 0 shutter from it. I got the pinhole from Lennox Laser: http://www.lenoxlaser.com/index.php?dispatch=products.view&product_id=122 and then mounted them on a lens board/helicoid for a 47mm lens that I found used on GetDPI.

I use the Copal shutter with my wake up cable to trigger the back with wake up pulse and then keep open using T or B mode. With the P25+ there is no problem with long expsoures. With my IQ160 you can shoot longer than the 'official' 1 min limit without problem although noise increases significantly and you'll need to clean up in post. I've shot 4 min+ with my IQ160 for long exposure B&W but it does need noise clean up. The P25+ just keeps on chugging and i specifically bought it for this purpose because the resolution difference is pretty immaterial when you start shooting these types of things.