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How much bigger can the sensor be for the Hasselblad H system

Here's something interesting I just discovered in a Hasselblad Worksheet published in Feb. 2007.

This Lens Multiplication factor sheet indicates a 1.7X factor for 16 meg backs on a 6X6 camera? This is in conflict with other published reports by them placing it at 1.5X.

Also, the 645 factor is stated as being 1.2X rather than the 1.1X.

Hmmm, I wonder which is correct?

26694.jpg
 
Isn't the factor 1.5 on a 16MP back? The film area is 56x56mm (at best) and the 16MP chip is 37x37mm. My calculations get me to 1.5.
 
Larry

The crop factor is 1.5 .
That is what it says in the CFV documentation on the HASSELBLAD webpage .
And that is also correct to the 37x37 sensor .
MF usually refers to (4,5x6) 6x6 , which is not really correct , because it is , as you say , only 56x56mm . But 6x6 is in our heads since the first ROLLEIFLEX , and will never go away any more . Never .
 
Hi Marc,

> This was from a shot processed at 8 bit ...16 bit might have > produced a tad better detail.

I am curious, why do you believe more bit depth gives you more detail?

Regards,

Austin
 
Perhaps because detail is not just to be found in spatial resolution, but may also hide in 'tonal' resolution?
 
Marc,

Perhaps that is because not all 16 MP backs have the same size sensor.
The CFV's 1.5 fits neatly in the 1 to 1.7 bracket, though it is a mystery which 16 MP thingy produces a crop factor of just 1x.
 
Hi Q.G.,

> Perhaps because detail is not just to be found in spatial resolution, > but may also hide in 'tonal' resolution?

Of course that *can* be true, but I wanted to see what he was talking about first before commenting.

Regards,

Austin
 
Hi Q.G.,

> Still hoping to catch someone with their pants down, are you?

No, sounds like your "projecting" ;-)

There is a lot of misperception, misconception and misinformation about bit depth, even from the most knowledgeable people.

Regards,

Austin
 
Yes...

So, Austin, why don't you tell us how it really is with bit-depth right away?
'Even if' very knowledgeable Marc does know what he is talking about, many will not, and will benefit.
Or does "there is a lot" mean it is to be found in very few people, but there to a great extent?
But i know you just love setting a trap and lying in ambush...
wink.gif
 
Hi Q.G.,

> So, Austin, why don't you tell us how it really is with bit-depth > right away? > 'Even if' very knowledgeable Marc does know what he is talking about, > many will not, and will benefit.

Perhaps, but I would like to clarify what Marc is talking about. If you wish to do a tutorial on the subject, by all means.

> Or does "there is a lot" mean it is to be found in very few people, > but there to a great extent?

In my experience, there are a lot of people who partake in digital imaging, and have a misunderstanding... of bit depth and it's effects/significance.

Regards,

Austin
 
Hi Austin,

As for more detail at higher bit depth: why would that be the case? I tend to read detail as in: higher resolution. Resolution is not dictated by bit depth or?

More gradual tonal transitions: I would say yes to that. Assuming that is within the limitations of the human optical sensors (aka EyeBall Mk I).

Wilko
 
Well. I have no shame!!!
So I don't mind giving my current understanding on what is bit depth and its usefulness.
Please enlighten me if I am wrong.

An 8 bit Image - 256 levels of grey for each colour channel.
An 16 bit Image - 65,536 levels of grey for each colour channel.

Our lovely photos shown on our expensive monitors are viewed in 8 bit.
Where the benefit of capturing in 16 bit comes in is when we wish to edit the levels of the image, there is more latitude for greater adustments to be made without posterisation occuring.
If we brighten/darken an 8 bit image we will be losing some information so that we end up with less than 256 levels of grey.
If we brighten/darken an 16 bit image we can still end up with 256 levels of grey (or more).
Therefor gradients in an image will not look stepped (or less chance of it anyway), Shadows can be adjusted/brightened to appear not filled in, and highlights can be darkened to not be 'blown-out'.
In this way a 16 bit image can have better detail.

That's all from me now... time for dinner
happy.gif
 
Hi Wilko,

You are correct, there are two types or "resolution" with respect to an image. One spatial, and one tonal.

> More gradual tonal transitions: I would say yes to that. Assuming that > is within the limitations of the human optical sensors (aka EyeBall Mk > I).

You are correct, but it also has to do with a couple of other things. If you are doing tonal changes...you want to do your tonal changes using higher bit depths. This reduces the chance of getting large gaps between values (also known as "combing" or "posterization"), especially when doing grayscale files, and images that have an even field, such as images with sky in them. Also, it has to do with the output medium/media. If what you are outputting to can only discern so many colors, then having more bits/colors does not necessarily lead to more in the output.

Most color images will not have any better discernable difference in tonal "resolution" using more than 8 bits/color, except as noted above with images that have even fields, like images with sky in them.

Regards,

Austin
 
Hi Austin,

Good to know I was not off into the woods.. ;)

My logic was (very) roughly following the reasoning of Shannon's Theorem: ensure you have enough s&le information available in your digital data. Like you wrote: make sure you have an excess of bit depth to "play with".

Wilko
 
And hiding in all that is the fact that detail in the subject may appear as tiny diferences in tone.
Having a higher tonal resolution is not just about avoiding 'combing' and making an image appear more natural, but may also make the difference between not being able and being able to record it.
 
Hi Q.G.,

> And hiding in all that is the fact that detail in the subject may > appear as tiny diferences in tone.

It was hardly hiding. That understanding is the basis for even limited understanding of the subject.

> Having a higher tonal resolution is not just about avoiding 'combing' > and making an image appear more natural, but may also make the > difference between not being able and being able to record it.

Again, this is part of a basic understanding of bit depth. Of course having higher bit depth allows for recording of higher tonal resolution. How useful/usable depends on to what extent the lower bits are at all "good". Having more bits does not assure more tonal resolution, it just means you have the space to store it *IF* the data is available/good. Simply claiming a particular bit depth gives no indication of the actual performance.

Regards,

Austin
 
It was hardly hiding.

Yet, Austin, all talk so far is about how smooth your tonal transitions are.
Stuck in the 'Data Side' of things.
 
Q.G.,

> It was hardly hiding. > > Yet, Austin, all talk so far is about how smooth your tonal > transitions are. > Stuck in the 'Data Side' of things.

I have no idea what the point you're trying to make is. I was simply asking Marc to give more information about one of his statements, so I could see where he was coming from. Simple as that.

If you are actually trying to have a discussion on this topic, which I am more than happy to do, then I suggest you be more clear as to what you are trying to get at.

Austin
 
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