D70 and high speed sync

[Patrice]

I did a test to see just how well a D70 would sync with old speedlights above the 1/500 second default maximum sync speed.

I connected an old Metz 45CT-5 to my d70 and procceded to take exposures all the way to 1/8000 seconds. Everything worked just fine until 1/8000 where I seemed to get a one stop underexposure. I think that at that speed the flash duration is longer that the shutter duration, hence the underexposure. The flash has a 'winder' mode which has a very short flash duration but the power is about 5 to 6 stops less than a full burst. That old flash does not have manually set power settings other than full and winder.

The same phenomenon happened with a newer Metz 45CL-4 (non digital) but the underexposure started happening at 1/4000 seconds. That flash does have 1/2 and 1/4 power settings as well as winder modes which shorten the flash duration.

A Vivitar 285 HV synced without difficulties to 1/4000 and had a 1 stop underexposure at 1/8000.

Here are some photos from the experiment - nothing fancy, just a test. Exif is still attached.

1/500 sec

1/1000 sec

1/2000 sec

1/4000 sec

1/8000 sec

Flash and camera

 

[Ken Rockwell Fan]

I wish all cameras were built as good as the D70 was.

 

[Restomage]

The D70 is a god. Love this camera and it was my first DSLR.

 

[epp_b]

This is a known, unpublished and unintended "feature" of the D70 (and variants), D50 and D40.

The reason this works is because they actually have two shutter systems: one, a physical shutter that has a maximum speed of 1/90th. Faster shutter speeds are handled by electronically shuttering the CCD sensor. A CCD sensor can electronically shutter the entire frame, unlike a CMOS sensor, which shutters sequentially by horizontal row.

This removes the limitation of flash sync, which is why you can still expose for flash at 1/8000th.

 

[el_shorty]

^^^ And that is the reason why I still have and use my D70s, but it will soon be converted to infrared.

 

[Garbz]

A CCD sensor can electronically shutter the entire frame, unlike a CMOS sensor, which shutters sequentially by horizontal row.

This isn't quite true. You can buy CMOS sensors with a global shutter as opposed to a rolling shutter. The implementation changes quite a bit though and introduces noise sources. Likewise very many CCD sensors still physically shutter despite being capable of globally shuttering in the electronics due to very horrible blooming and smearing effects that result form reading out incredibly light sources in anything but pure darkness. This is why cameras such as the D200 and D2x can't to the D70/D40 trick despite also having CCDs and why a lot of high end consumer CCDs would look horrible in live view, but perfectly fine when the picture gets taken.