Pentax 645Z firmware update includes turning off dark-frame subtraction

[buckshot]

Pentax 645Z Firmware Update

Amongst other things, long exposure noise reduction (aka slow shutter speed noise reduction) can now be switched off.

Sounds like Pentax listens to their customers.

[Bart_van_der_Wolf]

Pentax 645Z Firmware Update

Amongst other things, long exposure noise reduction (aka slow shutter speed noise reduction) can now be switched off.

Sounds like Pentax listen to their customers.

Hi,

That's very encouraging. Although I've heard that it does not activate that often when on automatic, it can be of great benefit for those who need to acquire larger numbers of long exposures, with predictable/short intervals between successive images in a sequence.

The Dark-frame subtraction will also be of higher quality if done with an (averaged) master dark-frame. Of course that does require (preferably) a Raw converter that can deal with such separate dark-frame subtractions, e.g. like RawTherapee.

This is very good news for MF long exposure aficionados, who apparently already were well served with the 645Z capabilities.

Cheers,
Bart

[michael]

This is great news for those of us doing astrophotography and who want to do our own dark frame subtraction.

Michael

[Jim Kasson]

The Dark-frame subtraction will also be of higher quality if done with an (averaged) master dark-frame.

Right you are, Bart. Dark frame subtraction with a single dark frame will reduce the read noise component that is invariant frame to frame, but will increase the read noise that changes from frame to frame by a factor of 1.414, since sqrt(n^2 + (-n)^2) = sqrt(2*n^2) = 1.414*n.

In some cameras,, like the D810, the frame to frame invariant read noise has almost all of the low-frequency (objectionable) content:

 http://blog.kasson.com/?p=7936

In other cameras, like the Sony a7S, that is unfortunately not true:

http://blog.kasson.com/?p=7971

I don't know which camp the 645Z falls into.

Jim

[ErikKaffehr]

Hi Michael,

Nice to hear you are happy and nice to hear about your newborn (or reborn) interest in astrophotography. And, thanks for sharing of course!

Best regards
Erik

This is great news for those of us doing astrophotography and who want to do our own dark frame subtraction.

Michael

[BernardLanguillier]

Hi Michael,

Nice to hear you are happy and nice to hear about your newborn (or reborn) interest in astrophotography. And, thanks for sharing of course!

Erik,

I sometimes wonder whether you are on a secret mission to add at least one answer to every single thread at LL?

Cheers,
Bernard

[ErikKaffehr]

No Bernard,

No secret mission. I just enjoy hearing from Michael Reichmann and I am interested in the kind of stuff he does.

Best regards
Erik

Erik,

I sometimes wonder whether you are on a secret mission to add at least one answer to every single thread at LL?

Cheers,
Bernard

[Ken R]

Erik,

I sometimes wonder whether you are on a secret mission to add at least one answer to every single thread at LL?

Cheers,
Bernard

Erik still has not reached 8000 posts while you are well over that mark. Just sayin' But its close enough. Not much difference between you two in regards to posting frequency. Although I see you registered well before Erik. Hummm.