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10-28-2015, 08:11 AM   #16
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QuoteOriginally posted by mikeSF Quote
i like the thought of a wide zoom as you described with tilt-shift, but for my purposes, I would be perfectly happy with a 21mm f/5.6 manual focus prime.
When pentax spoke of exploring medium format mirroless the Idea I outlined would be by far the most spectacular way pentax could do it. A weather sealed medium format camera with integral tilt shift and a fixed wide angle zoom lens has never been done before. It would catch the attention of many professional photographers like myself who have been looking for such a camera. It would also exploit many of the technological developments of the past few years regarding medium format sensors.

10-28-2015, 12:25 PM   #17
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A mirrorless MF camera as such has never been done before. So may be start simple, a body with three prime lenses would be great.
10-28-2015, 05:23 PM   #18
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QuoteOriginally posted by sculptormic Quote
A mirrorless MF camera as such has never been done before. So may be start simple, a body with three prime lenses would be great.
Anyone can do that, low hanging fruit : so low that there are plausible rumors of Sony doing exactly that. No, pentax needs to aim higher and do something profoundly weird to catch the attention of jaded professionals these days.
10-28-2015, 05:58 PM   #19
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Yes, but first they need to make an actual complement of DFA lenses for the existing body…………..

10-28-2015, 10:39 PM   #20
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QuoteOriginally posted by Digitalis Quote
On a mirrorless MF camera a 15-24mm lens with a constant aperture of f/4 wouldn't be as big as you think. Though to be fair, to create a lens with an image circle large enough to allow for extended movements, speed may be sacrificed in the name of increased coverage. A lens with the coverage of a 67 lens would just about do the trick.
But not as small as you think either, I am afraid It would be a pretty big lens on a not-so-big camera, creating potential balance problems; but, even if they can make it small enough, it would be very expensive; what is more important, for the intended target f/4 would be unnecessary, and as we all know the fastest the lens the more difficult it is to get it to perform great on the whole frame. What is most important, such a lens would introduce potential image quality and ergonomic problems (see below). I'd rather have f/5.6 sharp corner to corner than f/4 with mushy corners. The HUGE 25mm wasn't as good there, if you remember...

QuoteQuote:
Though as you mentioned, filters could be potentially problematic as the front element of such a lens would most likely have pronounced curvature. However there are specialized filter holders made by the filter maker: Lee, that are designed for lenses with this characteristic: like the Sigma 8-16mm f/4.5-5.6 and the Nikkor 14-24mm f/2.8G
I had the Lee system for my 14-24 and Sigma 8-16, and the Lucroit as well, and this is exactly why I want a lens with a normal filter thread: these solutions to filter stupidly-hooded lenses are huge, cumbersome, difficult to store in a bag, very expensive, and I'd rather do without. This is also why I'd prefer f/5.6 to f/4: with a smaller front element, curvature can be kept into a regular filter ring, say about 82mm.

QuoteQuote:
(Incidentally, the lens on that Hasselblad Arc body is none other than the Rodenstock APO-Grandagon 45mm f/4.5. Rodenstock currently still make wide angle digital medium format lenses, the widest of which is the HR Diagron-S 23mm f/5.6 with a 72mm filters and a 70mm image circle, weighing in at 780g - about the same weight as the DA*200mm f/2.8)
Yes, I know, I used a digital view camera with Schneider (who still produces wide angle digital medium format lenses too) and Rodenstock lenses for a couple of years with a Phase back on a Silvestri camera first and on a Linhof camera afterwards; great glass, but not perfect either (see below).

One problem you fail to consider (or to mention) is that with a mirrorless camera and a short flange distance as you suggest you would incur in the "digital Leica M problem"; ray of light would fall on the sensor's edges and corners at a very acute angle, creating vignetting (not a huge problem) and color casts (a much worse problem) in the corner of your images. You'd have to create profiles to get rid of these casts, which are normally of different colours in opposite corners and profiles only go so far and introduce various degrees of image degradation, from mild to very strong depending on how much cast you need to correct (believe me, I fought with this for a couple of years!); change aperture and you'll need a different profile, change incidence of the sun and you'll need a different profile, and so on (and not everyone can or is willing to work this way). This is one of the most important reasons why I decided to get rid of the view cameras in the end. This is also the reason why both the Pentax 25 (with all its problems) and the Pentax 28-45mm, huge and with straighter incidence of the light on the sensor, do not suffer of colour casts in the corners.

It is because all of this, finally, that I'd rather have a more tele-centric lens design, which makes for a bigger lens, which in turn calls for a slower lens to keep size and weight at bay without compromising image quality and introducing unnecessary pains like colour casts, profiles, cumbersome filtering systems, and so on.
10-29-2015, 01:26 AM   #21
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QuoteOriginally posted by The Madshutter Quote
This is also why I'd prefer f/5.6 to f/4: with a smaller front element, curvature can be kept into a regular filter ring, say about 82mm.
I think that is a bit unrealistic to expect a stop difference in aperture is going to reduce the filter thread by that much.


QuoteOriginally posted by The Madshutter Quote
One problem you fail to consider (or to mention) is that with a mirrorless camera and a short flange distance as you suggest you would incur in the "digital Leica M problem"; ray of light would fall on the sensor's edges and corners at a very acute angle, creating vignetting (not a huge problem) and color casts (a much worse problem) in the corner of your images. You'd have to create profiles to get rid of these casts, which are normally of different colours in opposite corners and profiles only go so far and introduce various degrees of image degradation, from mild to very strong depending on how much cast you need to correct (believe me, I fought with this for a couple of years!); change aperture and you'll need a different profile, change incidence of the sun and you'll need a different profile, and so on (and not everyone can or is willing to work this way). This is one of the most important reasons why I decided to get rid of the view cameras in the end.
You are correct, but these issues are by no means insurmountable. Capture one and Lightroom both have abilities that can correct for this. though i'm prepared to admit sometimes the colour shift from lens casts can be so catastrophic that correction is nigh on impossible. I never said my concept was perfect, however with a fixed lens approach and keeping the focal range of the lens to a modest level would hopefully allow the sensor design to take some of these issues into account, or allow for decent profiles to be designed to suit most applications. The reason I'd prefer a faster lens is that inevitably we all have to stop the damn things down, camera movements allow one to extend DOF beyond what a fixed focal plane camera can achieve. I own a D-FA25mm f/4 - i'm well aware of its optical shortcomings, and like most lenses it performs best when stopped down. this is an extreme example but who really expects a 50mm f/1.2 to perform at f/1.2 as well as it does at f/2.8, or f/5.6? I'm aware that with live view, EVFs lens aperture doesn't mean as much as it used to in therms of viewfinder brightness - it is a known fact that a slightly faster lens when stopped down a bit is nearly always superior to using a slow lens wide open.

QuoteOriginally posted by The Madshutter Quote
I'd rather have a more tele-centric lens design, which makes for a bigger lens, which in turn calls for a slower lens to keep size and weight at bay without compromising image quality and introducing unnecessary pains like colour casts, profiles, cumbersome filtering systems, and so on.
That is a tall order, but it is technologically within reach.
10-29-2015, 03:20 AM   #22
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QuoteOriginally posted by Digitalis Quote
Anyone can do that, low hanging fruit : so low that there are plausible rumors of Sony doing exactly that. No, pentax needs to aim higher and do something profoundly weird to catch the attention of jaded professionals these days.
But nobody is doing it!
As long they do it first, the fruit will be quiet tasty. They will be king. To start with such a complicated design, a tele with rise, shift and tilt, is asking for trouble. I am with Vieri on this.
If they design a good body with the right flange distance to stay out of trouble they can always add a TS lens.
11-06-2015, 11:31 AM   #23
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QuoteOriginally posted by Digitalis Quote
I think that is a bit unrealistic to expect a stop difference in aperture is going to reduce the filter thread by that much.
We need precise calculations for this, but I am pretty sure that a stop on a MF-sized sensor would make for a pretty sizeable difference in filter diameter - I don't know if that would be enough to bring it down to 82mm, which would be my preference, but I'd definitely like something under 100mm

QuoteQuote:
You are correct, but these issues are by no means insurmountable. Capture one and Lightroom both have abilities that can correct for this. though i'm prepared to admit sometimes the colour shift from lens casts can be so catastrophic that correction is nigh on impossible. I never said my concept was perfect, however with a fixed lens approach and keeping the focal range of the lens to a modest level would hopefully allow the sensor design to take some of these issues into account, or allow for decent profiles to be designed to suit most applications. The reason I'd prefer a faster lens is that inevitably we all have to stop the damn things down, camera movements allow one to extend DOF beyond what a fixed focal plane camera can achieve. I own a D-FA25mm f/4 - i'm well aware of its optical shortcomings, and like most lenses it performs best when stopped down. this is an extreme example but who really expects a 50mm f/1.2 to perform at f/1.2 as well as it does at f/2.8, or f/5.6? I'm aware that with live view, EVFs lens aperture doesn't mean as much as it used to in therms of viewfinder brightness - it is a known fact that a slightly faster lens when stopped down a bit is nearly always superior to using a slow lens wide open.
As you said, colour shifts sometimes are such a pain to correct - even when you manage to end up with a clean result, which is far from 100% of the times... I am afraid that a fixed ZOOM lens wouldn't help much on this matter, even with a short range and in-camera profiles (too many variables & combinations), but I am with you that choosing to go for a fixed SINGLE FOCAL lens would make the thing decently correctable for colour shifts with in-camera profiles, or - even better - with angled micro-lenses on the sensor (which would rise the costs dramatically, though). About your Tilt-Shift idea, while I would LOVE it I am afraid that a TS ZOOM lens is never going to happen; a TS SINGLE FOCAL, on the other hand, would be doable and great: would you say no to a single focal fixed TS lens in the 21-23mm range, even at f5.6? I'd love to get one immediately...

QuoteQuote:
That is a tall order, but it is technologically within reach.
Well, in the end I'd be happy enough with a single focal lens in the 22-24mm range for my 645z, f/4.5 or f/5.6, with a filter thread, no TS and no stupid pseudo-hoods... so you see, anything out of our dream cameras we have been talking above would make me ecstatic!

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