Medium Format Family

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Why use medium format film cameras

najobskalf

Member
There seems to be some concern that the film Hasselblad may disappear one day, replaced by a purely digital H version. This would be unfortunate for quite unsentimental reasons, one of which is the fact that digital backs are smaller than 6x6. It was recognized back in the 1970s that the area of the film (or other image-forming medium) limited the amount of information that the image could hold. Thus a smaller format had to have more highly corrected lenses just to try to compensate for this. Hence, in practice a Hasselblad has used for the highest quality, rather than a Leica. (This reasoning does not lead to large formats being preferred, as it becomes much more difficult to correct lens aberrations for these.) My point is that sticking a well-corrected Zeiss medium format lens in front of a small(ish) CCD is defeating much of the work that went into designing the lens in the first place - even if the CCD has 32 MPs. If we have to go digital, at least let us have backs with 6x6 CCDs. Canon has recognized the value of "full-frame" CCDs in its latest digital SLRs - let us hope that the current owners of the Hasselblad marque come to understand it too.

(I do not despise digital photography as such - I use a Nikon Coolpix 7600 for all my casual snapshots.)
 

fotografz

Active Member
Bojan, due to the build quality of mechanical Hasselblads, their longevity in manufacture, and the abundance of decent repair facilities, I doubt one would ever be without the option of shooting a film Hasselblad in our lifetime ... as long as there is film to put in it.

I also hope a 6X6 digital sensor becomes available eventually. But it is doubtful. 645 seems destined to be the MF of the future because of digital.

I recall reading somewhere that the someone at Hasselblad (their President?), said that 45 megapixels was the theoretical limit the MF lenses could resolve. Imacon's new 39 meg back is approaching that number. Further improvements will most likely be in ISO speeds and wireless transfer, bigger/brighter LCD screens, and so on.

Concerning format size, the current 645 sized sensors are just a hair under being a full 645 size. So the lenses are used just about out to the usable edge of the 6X6 image circle. And, in fact, the current configuration is a more practical ratio for making normal prints like 8X10, 11X14 and 16X20.

Do not confuse smaller digital sensor cameras with these Imacon backs. While not the same as film, they are quite capable
of stunning renditions of light, smooth tonal transitions and resolving detail. Most catalogs of products, all the way up to those for automobiles, are now shot using digital backs.
 

najobskalf

Member
Marc, I find some reassurance in your comments about Hasselblad longevity, and I recognize that the digital backs for MF are very good indeed.

However, I do wonder about the Zeiss lenses being unable to resolve more than 45 MP (if my maths are not completely wrong, this implies a linear limit of something like 120 dots per mm). Also, the total number of pixels is distributed between gree, red and blue sensors. So, the actual number of image-forming elements is much lower than the headline figure.

If one looks at a simple ratio (which may be very naive, I admit) the 39 MP for MF, compared with
12 MP for 35mm is about 17.2 MP per sq.mm, as opposed to about 13.9 MP per sq.mm for the miniature format. It isn't that big a difference.

Then again, I believe that the final resolution in an image (on film) is a fuction of both lens resolution and film resolution, neither of which is by itself a limiting factor. I cannot recall the equation. In the mid-1970s even the great Zeiss (Oberkochen) went through a phase of stating that there was no point in designing microscope objective lenses with ever greater resolving power, as the available films would limit the final resolution. This was actually wrong as it was based on a misunderstanding (probably by their marketing people) of the relationship of both film and lens to the final result.

Maybe I am nitpicking, but a lot of post-processing can be carried out on a digitized image - and probably is - to obtain a superb end result.

I suppose some of my concerns arose from the transfer of Hasselblad into Japanese hands. While Japanese optics are very good, they never reached the heights of Zeiss or Leitz. At least if it remains possible to use existing Zeiss lenses on the H series ....

Finally, (I am droning on now) what about the issue that someone raised on this forum about the problem of storage of huge digital images?
 

afranklin

New Member
Hi Bojan,

> Maybe I am nitpicking, but a lot of post-processing can be carried out > on a digitized image - and probably is - to obtain a superb end > result.

...and when you "process" an image, in most cases you decrease it's fidelity. Why do you want to do that? You could use a computer paint program to generate digital images, if more "representative" images are what you are looking for.

There is little processing that should be needed to any image to get a "superb" result IMO (digital or film), if using equipment that provides sufficient fidelity for your needs, and you get all your settings right (exposure for ex&le, development for film).

Now, that's just me...I don't do any post processing...I believe in getting it "right" (as much as I can) on the imaging medium (film or digital file), instead of spending time in an imaging program (or in the darkroom) trying to "make" an image.

Regards,

Austin
 

qnu

Banned
Bojan,

Must have been something else, not microscope lenses.

Microscopy has hit against the unassailable limit of what is resolveable using visible light a long time ago already.
UV-microscopy has pushed the limit a bit, but even then there's only so much you can expect.

And all the time, lenses were quite capable, not the limiting factor. Light itself was, and is (hence the phenomenon of electron microscopy).


With either type of microscopy, film isn't even a factor. It's easy enough to have any old film record every last detail produced by the microscope.

Anyway, lenses are quite capable of delivering anything digital sensors can resolve. They are not the problem.
 

fotografz

Active Member
Bojan, Hassleblad did indeed produce a CF adapter to allow use of all CF,CFi and CFE series Zeiss lenses on the H camera. It works quite well, and has an added bonus that the AF sensors in the H1 and H2 provide focus confirmation in the viewfinder when manually focussing.

Quite a nice feature actually, especially when using a wide angle in lower light.
 

najobskalf

Member
Q.G., I used an electron microscope for tissue research for many years. For this, one processes the tissue so that it is optimally preserved and embedded in plastic (an epoxy resin on my case). The E.M. allows you to see inly a very small area at a time. So, as a routine procedure we used to cut 0,25 micro sections from the plastic embedded tissue and examine it in the microscope. We used an 80x oil immersion N.A. 1.6 Zeiss apochromat and the differential interference contrast method. We could reliably resolve detail like the endoplasmic reticulum in liver cells. Most microscope lenses were the limiting factor at the time - this was an exceptional lens (it cost about GBP 1,600.00 in the mid 1970s). In our experience, as you say, the film was not critical but I imagine the images would have been crap if we had used, say, Tri-X! We actually always used a fine-grained 5x4 monochrome film. Believe me, both optics and film mattered a great deal.

Your statement that lenses can deliver anything that digital cameras can resolve is worrying if true. With respect, however, I think you may be making the common error of assuming that the end-product is determined by a particular limiting factore, rather than being the product of at least two.
 

najobskalf

Member
Robert, I know it was a slow film but I cannot be sure at this time.

Incidentally, I should have said that, using the light microscopy method I desacribed, the resolution was limited not by the wavelength of light but by a quarter of the wavelength.
 

rcyoung

New Member
> Tech Pan was used a LOT by anyone needing very high resolution > from the late 1960s ( in Photomicrography, Photographing > electrophoretic gels, Microfilming, etc) until the film was > discontinued by Kodak about 2 yrs ago. Some old stock is still > being sold, although the amateur astronomy types have gobbled it up > whenever it surfaces. It has a red sensitivity out to 690nm > ( beyond where hydrogen in gas clouds emit) and can be hypered > with hydrogen gas to increase its response for long time exposures.
 

olenberger

New Member
> Austin, How do you feel about applying unsharp mask to scanned film? This relates to something I've often wondered about: If you have to apply a bit of unsharp mask (either during the scan or after) to get a superb digital image, has the sharpness of the Zeiss lens gone to waste? Is the appearent sharpness of the final image due primarly to the digital manipulation (unsharp mask) rather than the quality of the lens?
 

simonpg

New Member
Fritz, that is a very interesting question.

The other day I got back my slides taken with my XPan II and the superb 45mm and 90mm lenses - sensational sharpness and other attributes. Then I looked at the scans (competently made) and felt so disappointed that scanning just DOES NOT do full justice to superb optics and film qualities.

So, I too wondered if even the Fuji optics are wasted and also wondered if the same applies to my arsenal of Zeiss / Hassy optics.

After much soul searching, I decided that these optics are indeed not wasted - my digital images from scanning are only for computer and TV viewing and on-line sharing type stuff.

For real quality and large prints I either have them drum scanned (I'm sure that level of scanning brings through the qualities of the film and optics and their image capture) or optically printed giving me all the benefits of the optics and film used.

I'm sure from what I hear and read that those who use high end digital Imacon/Hassy backs feel they get the benefits of their Zeiss (V series and H series with the adapter) and Fuji (H series) optics from those backs. But they will have to tell you for sure.

But as you say, scans other than the very high end machines produce, really don't do full justice to optics or the best films for that matter. But I keep in mind that what is not captured by great film and lenses can't appear on a scan file if it's not there in the first place.
 

rcyoung

New Member
> What you are saying is in essence the old adage "only as strong as > the weakest link",,,,I would rather have the "weak link" in the > photo process be somewhere else rather than the start so that there > is at lest some chance of improvement as time (and technology or > technique or equipment) progresses.
 

qnu

Banned
Robert,

You used a TEM?
Nowadays, you can do really amazing things with "environmental" SEMs. Great fun!
I know where to find a TEM, if i need one. SEMs on the other hand, let alone "environmental" ones are "beyond my reach"

But that aside.

Optics used in microscopy really aren't a factor. Of course, differential contrast and other tricks require special 'optics'. But in whatever type of light-microscopy, it's no problem making lenses that are capable of going to what light is limiting resolution to. Lenses are not the limiting factor.

It's no problem "blowing up" the image produced by a microscope. Though it will not increase resolution, it will make it possible to record the detail in the image using even coarse grained film.

And while i'm niggling: whether you say one whole wavelength, or a quarter wave is the resolution limit in light-microscopy, wavelength is still limiting resolution, right?


Lenses are so good, that they put resolution limiting filters ("softeners") between lens and sensor...
Sensors like high contrast resolution, but only up to a point. What our lenses are capable of is artificially reduced to something even not-so-good lenses have little trouble producing.

So in this case, the "system resolution" is not a factor of lens + sensor, but of sensor + "softener".
Lenses are the "too-strong" link in the digital imaging chain.
 

najobskalf

Member
Q.G. With respect, optics in microscopy are a very real factor! A second rate objective will give you a poor image. Or are you suggesting that we have all wasted our hard-won grant money when we could have done just as well with cheap mass-produced optics? Dream on!

What you imply about digital being so poor does depress me, however. Does this mean that I can sell my existing Hasselblad lenses, use the money to get a digital H body, and find an adaptor to fit some cheap Eastern bloc lenses to it? It's a thought.
 

qnu

Banned
Yes, using a coke bottle bottom instead of a good lens will make (!) optics a factor.

The point is that it is not difficult to make perfectly good lenses, that will allow you to get everything there is to get. So they indeed do make very many perfectly fine lenses that do.
So no, optics are not a factor.
Now, i do not know how you spent your grant money, but getting proper lenses for your microscope will not have dented the budget very much.

And yes, it's a thought indeed... Anything above about 40 lp/mm is wasted on digital sensors.
With these larger sensors in MF backs, larger pixels, spaced out more, even considerably less than that.
 

simonpg

New Member
Bojan and Marc, I think it was I who posted recently the comments of the Hasselblad CEO about expected sensor MP size - likely to be limited to 45MP in the foreseeable future. I recall the comment was in the context of the medium term focus being on quality of the pixels rather than quantity and the fact that file sizes beyond 45MP sensors would become impractical - lead to size/time/handling issues.

But, I think the future remains as hard as ever to predict as one never knows what technologies could be around the corner that could eliminate limiting factors.

Remember years ago it was predicted by industry moguls that PC clock speeds would soon not increase for a range of reasons; but, it continued to increase at (I think) an average of 150% per annum! There is still no real sign of that slowing down.

But I for one would like to see 6x6 sensors become full frame - It's just a comfort factor so that I don't have to worry or think about lens issues arising from a cropped sensor. But then again I can't afford what's available now, so what the heck - I'll just enjoy film and watch with interest.

I'm with Robert when he commented that he'd prefer the weak links in the digital imaging chain to be post capture where he has some better control over the remedy.
 

olenberger

New Member
> Simon, in addition to using an Epson 2450 for smaller prints (up to 13x19 > inches) and posting to the web, I too have drum scans made for larger > exhibition-type prints (30"x30"). These have higher resolution and > greater dynamic range than a flat bed scan, but my service bureau told me > that they do apply unsharp mask in the scanning process. You might want > to ask the people doing your drum scans. I should say that I find the > resulting prints beautiful and tack sharp, but I have to wonder if that > apparent sharpness comes from the lens or the USM process.
 
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