[ShawnH]

Dear Ricoh,

Now that you are about to introduce a new camera sometime this year, I have the following suggestion.

Please include a Dynamic Range Mode (DR) for those of us who prefer using our digital camera as an ISO less device to achieve maximum dynamic range - the way god intended digital sensors should be used. In this mode ISO is locked at 100 or the value that yields the maximum DR. Shutter speed and / or aperture can be designated to independently bracket the exposure as designated by the photographer.

The picture taking sequence will be as follows. 1) The camera/photographer will set aperture and shutter speed to suit the scene while avoiding over exposure - under exposure can be compensated in post processing. 2) Exposure meter will indicates under exposure stops if any 3) Photographer will set Bracketing so expose a number of frames varying f stop and/ or Shutter speed to compensate for the indicated under exposure.

There are many ways to achieve the same thing. I just want to put this out for general consideration. In my opinion it would really set Pentax apart from the pack.

[stevebrot]

There are many ways to achieve the same thing. I just want to put this out for general consideration. In my opinion it would really set Pentax apart from the pack.

Unfortunately, it would be an "empty" feature, if indeed the sensor is actually ISO-less. (The concept is inferred by observation, but not confirmed by any design or specification documentation, regardless of brand.) Pentax may simply state (and quite truthfully) that dynamic range is 14 stops, the bit-depth of the capture.


Steve

[ShawnH]

The point is to have mode that can take full advantage of the 14 f-stops.

[WorksAsIntended]

Unfortunately, it would be an "empty" feature, if indeed the sensor is actually ISO-less. (The concept is inferred by observation, but not confirmed by any design or specification documentation, regardless of brand.) Pentax may simply state (and quite truthfully) that dynamic range is 14 stops, the bit-depth of the capture.


Steve

The bit depth does not correspond to a specific dynamic range, not at all.
14bit simply means it can store 2^14^3 different colors, this can cover .5ev or 1000000ev.

[stevebrot]

The bit depth does not correspond to a specific dynamic range, not at all.
14bit simply means it can store 2^14^3 different colors, this can cover .5ev or 1000000ev.

It appears we have a difference of opinion based on inadequate knowledge. I won't tutor you on the basics.


Steve

[StiffLegged]

The bit depth does not correspond to a specific dynamic range, not at all.
14bit simply means it can store 2^14^3 different colors, this can cover .5ev or 1000000ev.

That is theoretically true. You could have a 14-bit sensor which has a working dynamic range of 2 stops, but can resolve very subtle tonal changes within those two stops. Or you could have a 14-bit sensor with a 48-stop dynamic range, but has difficulty avoiding banding in its images. Neither would be viable in the general photographic market.


Back to reality: a 14-stop dynamic range from a 14-bit sensor (at best) is how Pentax and the rest describe their sensors' sensitivity. Third-party measurements broadly confirm that.

[MrB1]

If you are going to do Step 1, I'm not sure I understand why you need Steps 2 and 3.

Philip

[stevebrot]

Or you could have a 14-bit sensor with a 48-stop dynamic range

That would be sort of hard to do without evaluating ranges to bits. While it is possible to do that in the A/D conversion, there might be downstream hazards in doing so.

Back to reality: a 14-stop dynamic range from a 14-bit sensor (at best) is how Pentax and the rest describe their sensors' sensitivity. Third-party measurements broadly confirm that.

Yep...creation of a linear TIFF using dcraw or evaluation in RawDigger seem to indicate that a linear response is the intent.


Steve

[WorksAsIntended]

Back to reality: a 14-stop dynamic range from a 14-bit sensor (at best) is how Pentax and the rest describe their sensors' sensitivity. Third-party measurements broadly confirm that.

And this is more or less a coincidence, not forced by 14bit by any means. The numbers look very similar and the dynamic increase was pretty linear to bit increase in the past decade, but there is absolutely no proportionality or linearity between those two quantities, unlike some people keep telling in forums until it is considered common sense.

---------- Post added 03-16-20 at 01:58 PM ----------

That would be sort of hard to do without evaluating ranges to bits.


Steve

Do you understand how a bit bandwidth works? Because it does not make any sense at all to conclude the bit per ev from that.
The conversion works perfectly fine as long as you go for more than 4bit. Digital processing in this high resolution has no missalignment issues as there were 30 years ago with digital circuits.

[StiffLegged]

And this is more or less a coincidence...

It's rather an academic point, don't you think? We don't agonise over the alternative when a delightful composition presents itself, the finished image is more important to us than that. Get the exposure right, focus accurately, frame the composition appropriately and hold the camera still!

Done.

[ShawnH]

"If you are going to do Step 1, I'm not sure I understand why you need Steps 2 and 3."

Often times light levels are too low (night photography) and the shutter speed required for a Sharp image is too short causing up to -5 stops of under exposure. However if you bracket shutter speed you have chance of getting a sharp image that is better exposed.

---------- Post added 03-16-20 at 09:02 PM ----------

If you are going to do Step 1, I'm not sure I understand why you need Steps 2 and 3.

Philip

Often times light levels are too low (night photography) and the shutter speed required for a Sharp image is too short causing up to -5 stops of under exposure. However if you bracket shutter speed you have chance of getting a sharp image that is better exposed.

Read more at: Dynamic Range Mode: Message to Ricoh - PentaxForums.com

[MrB1]

Often times light levels are too low (night photography) and the shutter speed required for a Sharp image is too short causing up to -5 stops of under exposure. However if you bracket shutter speed you have chance of getting a sharp image that is better exposed.

What you are describing looks like Av Mode with bracketing. Your range of desired shutter speeds would be selected by setting the number of bracketed shots, setting the Exposure Value between the bracketed shots, and adjusting Exposure Compensation. You could save a typical set-up as one of the User Modes and adjust from that for each new scene.

Philip

[ShawnH]

What you are describing looks like Av Mode with bracketing. Your range of desired shutter speeds would be selected by setting the number of bracketed shots, setting the Exposure Value between the bracketed shots, and adjusting Exposure Compensation. You could save a typical set-up as one of the User Modes and adjust from that for each new scene.

Philip

The problem with the AV mode is that shutter speeds can drop too low. That's why I am asking Ricoh top do something about it rather that we trying to put together a work around. I have set up a user mode now for night photography. It goes like this: Mode: ATV > Shutter 1/160 > Fstop: 2.0> ISO 100~3200> Bracketing +/- 2 stops 0 > Exposure Compensation -2 stops. This is a setup so that ISO is bracketed from 3200 through 100. The ISO 3200 is used for preview and ISO 100 is used for actual processing. However, I would like a mode that brackets the shutter speed from my predefined value down say 1/30 & 1/15. If those images turn out sharp enough then I would gain in lower noise and better image quality.

[Serkevan]

The problem with the AV mode is that shutter speeds can drop too low. That's why I am asking Ricoh top do something about it rather that we trying to put together a work around. I have set up a user mode now for night photography. It goes like this: Mode: ATV > Shutter 1/160 > Fstop: 2.0> ISO 100~3200> Bracketing +/- 2 stops 0 > Exposure Compensation -2 stops. This is a setup so that ISO is bracketed from 3200 through 100. The ISO 3200 is used for preview and ISO 100 is used for actual processing. However, I would like a mode that brackets the shutter speed from my predefined value down say 1/30 & 1/15. If those images turn out sharp enough then I would gain in lower noise and better image quality.

If I need a low shutter speed I brace myself, breathe in and shoot a burst. Normally one out of the 3 or 4 images comes out a treat, problem fixed.

[MrB1]

I would like a mode that brackets the shutter speed from my predefined value down say 1/30 & 1/15. If those images turn out sharp enough then I would gain in lower noise and better image quality.

That is what Av Mode with bracketing allows you to do. In the Menu (C2 on a KP) the Bracketing Order 2 or 3 are probably the better options - the displayed shutter speed is the one that's flashing on the EV scale on the rear screen. You can then select the range of shutter speeds you want by moving the set (of e.g. 5 shots) along the scale using the EC control.

Philip