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Black Reference with Rodenstock Aperture Unit
- Thread starter eisbaer
- Start date
Turn off the lights.:grin:
Being more constructive; my understanding is that Rodenstock's aperture unit, unlike a Copal shutter, cannot be completely closed.
Copal shutters have a lever that does this.
(I never precisely understood the purpose of that feature, since cocking the shutter does automatically close the shutter. Certainly wasn't designed in view of P1 black frame requirement.)
Last edited:
Christopher
Active member
Lens cap.
Isn’t the lever on copal shutters more to open the shutter, rather than close it? I always think of it as the ground glass “preview” lever. At least with LF film you basically want your shutter completely closed at all times unless you’re composing or exposing.
Yes, muscle memory is very powerful and hard to fight! I recently demoed an IQ4 which required a black frame after many (but not all) exposures, and I used the lever to close the copal shutter when prompted to do so. Other than this moment, however, it needed to remain open for live view and exposing (using the electronic shutter).
It was quite difficult for me to wrap me brain around this new sequence on the shutter and I often got things “backwards” and exposed the “dark” frame with the shutter open and tried to expose my frame with the shutter closed... I got the hang of it eventually but it was tough!
dougpeterson
Workshop Member
Thanks Doug! I thought there was something along those lines but my dealer seemed to be either unaware of it (doubtful as he is quite technical and is the primary Phase One specialist at my dealer and a regular user of the backs, but certainly possible), or preferred the "old-school" method. There was a lot to go over with the back so I didn't want to dwell too much on dark frame capture.
Does the little "moon logo" button on the shooting screen toggle this function? Or is that there to manually capture a dark frame?
dougpeterson
Workshop Member
Presuming it was Walter and the team at B3K, they are really good, so if he didn't mention it that's probably more owed to the fact there are so many cool features to go over on an IQ4 for first time users.
Two options to switch to Pre-recorded Darkframes:
1) Swipe up to access the Menu. Navigate to Menu > File Settings > Black Ref. > in this menu, select “Prerecorded”
2) Tap the moon icon on the digital back screen. If there is a line through the moon icon, then the digital back will use Prerecorded Black Reference frames.
(2) is faster but I sometimes forget exactly what each moon icon-state means (they have changed over the last few years and iterations of IQ3/IQ4 firmware) so I typically do (1) since it is unambiguous in exact meaning.
It was indeed Walter. Now that I think about it he may have mentioned "pre-recorded dark frames" while going over the back, but since I was expecting to hear "no more need for dark frames" then I perhaps missed it.
Anyway, it's nice to know that there is an option for a workflow that doesn't involve the back promoting you to open and close the shutter after any change to the shutter speed (which if you are shooting LCCs along with e-shutter, is most of them!).
Thanks
No dark frame and no CCC shoot required.
Two substantial workflow advantages of the IQ4 over the IQ3.
dougpeterson
Workshop Member
For completeness it's probably best to say "LCC dramatically less important/frequent".
That is, there might still be some use cases where you still want to do an LCC with an IQ4 150mp. For example, if you're doing high-accuracy art reproduction or scientific work you'd want to do an LCC. But most of our users are not doing LCCs for most lens/movement combinations. That's a stark contrast to the IQ3 where nearly everyone did an LCC for nearly all lens/movement combinations, and indeed a big advantage of the IQ4 over the IQ3.
dougpeterson
Workshop Member
He's a good and knowledgable guy.
You can definitely be forgiven for having missed/forgotten that part of the walkthrough; the IQ4 interface is intuitive and generally easy to learn (the dark frame being an example of one of the less intuitive), but there are just SO many features on an IQ4 that don't exist on previous backs or on any other camera.
When using pre-recorded dark frames, is it normal to have some hot pixels present in the image? I thought I had a bum sensor, but then tied the flaming hot pixels I was seeing to be present only when using pre-recorded dark frames.
eisbaer
Member
That’s the reason why I asked. As the prerecorded black reference works fine wit normal lit shots up to one second. But if you have night or dark shots or exposures longer then 1/2 second you get exactly this.. hot pixels. In the manual as I remember they advise to use prerecorded black references only up to a 1/10th of a second. I ruined some shots with longer exposures as the hot pixels are difficult to fix in some areas
Thank you for this! Unfortunately I have some stuck/hot pixels visible at fast shutter speeds when using prerecorded dark frames. I haven’t tested ALL shutter speeds, but they are certainly visible in the 1/60-1/250 range. Sounds like this is not normal...
I’ve already been corresponding with my dealer so hopefully this can be dealt with expediently.