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01-18-2011, 08:12 AM   #76
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QuoteOriginally posted by kuau Quote
Eddie,
This is where I totally disagree with you.
To get the most out of the 645d, maybe besides there current /old discontinued 120mm macro lens, pentax needs to update there fa line of lens that will be digital ready.
And not just re release old film lenses that did not need the same tolerances as do digital lenses demand..

"Digital ready" is marketing gimmick. The only diference is the coating on the rear elements. It is myth that digital sets stronger demands on lenses; what's different from film is pixel peeping. Much of what is described as optical defects under magnification equal to a piece of film under a microscope, is simply the laws of optics...

01-18-2011, 08:30 AM   #77
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Fully disagree - there is quite a difference in how analog and digital lenses present the focal plane to the sensor (in terms of incidence angle). Especially on sensors that have microlenses. Google "telecentric lens" for a good start. Then have a look at Schneider's documentation on their Digitar line. Its the laws of optics + the nature of CCD/CMOS sensor design.

QuoteOriginally posted by Pål Jensen Quote
"Digital ready" is marketing gimmick. The only diference is the coating on the rear elements. It is myth that digital sets stronger demands on lenses; what's different from film is pixel peeping. Much of what is described as optical defects under magnification equal to a piece of film under a microscope, is simply the laws of optics...
01-18-2011, 10:41 AM   #78
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QuoteOriginally posted by VoltMan Quote
Fully disagree - there is quite a difference in how analog and digital lenses present the focal plane to the sensor (in terms of incidence angle). Especially on sensors that have microlenses. Google "telecentric lens" for a good start. Then have a look at Schneider's documentation on their Digitar line. Its the laws of optics + the nature of CCD/CMOS sensor design.


Disagree. One thing is theory - reality is something else. We heard exactly the same thing about 35mm digital. I found out that it isn't true. Older lenses are in general just as good if not better. The dissapointment is due to pixel peeping but if you pixelpeep a piece of film you'll see that eg. the A 24/2.8 show just as much purple fringing on film. So does the FA645 33-55/4.5.
It is no easier today to make "perfect" lenses than it was 20 years ago. It is the user expectation that has increased due to pixelpeeping.
01-18-2011, 10:54 AM   #79
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QuoteOriginally posted by Pål Jensen Quote
Disagree. One thing is theory - reality is something else. We heard exactly the same thing about 35mm digital. I found out that it isn't true. Older lenses are in general just as good if not better. The dissapointment is due to pixel peeping but if you pixelpeep a piece of film you'll see that eg. the A 24/2.8 show just as much purple fringing on film. So does the FA645 33-55/4.5.
It is no easier today to make "perfect" lenses than it was 20 years ago. It is the user expectation that has increased due to pixelpeeping.
which is why i judge a photo truly by a print. it's my main frame of reference having started in film 37 years ago and spent a lot of time as a youth in the darkroom pursuing a good print. i never understand the obsession with pixel peeping, it's not how you will look at the photo if you print it (you'll be standing back taking in the whole thing not combing it with a loupe looking for minor imperfections) it's the whole that counts not the minutiae

01-18-2011, 11:04 AM   #80
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On film, when one silver halide particle is activiated, the whole "grain" developes. The size of them are somewhat random and the location is random compared to the pixels on the strictly regular grid.

Part of the reason of "film looking" and even the best software trying doing "simulated film grain", which try to modulate the pixels (additive or multiplicative noise), had only limited success is they do not actually move pixels around (upsample to 200% and introduce the random shift element).

So the way photons interact with light sensitive element is somewhat different but the question is for the same size circle of confusion would the results (extent of blur) different.
01-18-2011, 05:34 PM   #81
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I posted my view in another post which you might find supports some of your views as well : https://www.pentaxforums.com/forums/pentax-medium-format-645-6x7-645d/128403-...ml#post1341563

I also believe there is too much pixel peeping and brick wall comparisons going on - not to say they don't have a place though - the results of these tests are sometimes disappointing but pretty much the reality we live in. But to say that "digital" designs are just marketing is incorrect and ill-informed. There are fundamental issues with using analog lenses on digital sensors. Just because most of our lens kit is still analog doesn't mean that a newer lens designed around the parameters and constraints of digital imaging isn't required. Mamiya was forced to realize this with the takeover by Phase, and moved on to introduce the "D" series Sekors which by far are much sharper and contrasty than their predecessors.

That doesn't mean that we can't do good things with the lenses we have now - I've just traded in a full line of Mamiya 645 kit (including both analog and later "D" series lenses) for a Pentax 645D. As part of that I accepted a compromise in the lens quality and performance to gain some benefits from the 645D I couldn't get with Mamiya/Phase 645DF.

For me this is all deja-vu, the arguments presented by long time Mamiya users were much the same until the Schneider and D series were introduced and eventually they realized how bad their analog lenses were and moved on.

Last edited by VoltMan; 01-18-2011 at 05:59 PM.
01-19-2011, 07:47 AM   #82
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QuoteOriginally posted by VoltMan Quote
But to say that "digital" designs are just marketing is incorrect and ill-informed. There are fundamental issues with using analog lenses on digital sensors. Just because most of our lens kit is still analog doesn't mean that a newer lens designed around the parameters and constraints of digital imaging isn't required.

But this is blown out of proportions. While it is true that lenses designed for digital may see different design priorities than older lenses for film, the result is rarely visible in real life - not to mention prints. Is there any reason to regard the only digital 645 lens, the 55mm, as better than older 645 lenses?
01-19-2011, 10:57 AM   #83
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QuoteOriginally posted by Pål Jensen Quote
"Digital ready" is marketing gimmick. The only diference is the coating on the rear elements. It is myth that digital sets stronger demands on lenses; what's different from film is pixel peeping. Much of what is described as optical defects under magnification equal to a piece of film under a microscope, is simply the laws of optics...
Based on my limited observations, I agree that many of the old lenses are fine with the 645D, with issues appearing only at the pixel peeping level, but becoming moot in a print. But the sensor does not respond the same way film does. Here is a series I did with a 67II (45mm), 645N (35mm A) and 645D (35mm A). Same camera position. The crops are from an area receiving considerably more light than the rest of the scene. Look at the bird's neck and beak. The film was scanned with a Nikon 9000. Order of images: full, 67II, 645N, 654D. Some CA in the 67 and 645 scans. Much more pronounced in the 645D, particularly the edge of the lamp. There may some effects from blooming here as well, but there is a clear difference. Perhaps focus issues have an impact, I don't know. No color corrections applied (obviously ).

.




01-19-2011, 12:52 PM   #84
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Interesting that the 645D has less noise, but more CA on the high contrast edges...
01-19-2011, 12:54 PM   #85
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Lens prices

I have a question for you knowledgeable 645 people. I'm looking at eventually upgrading to a 645d (probably a couple years out). In the meantime I'm looking to pick up some 645 lens (manual focus for now due to budget). What is a current fair price for a 75mm 2.8 A and a 150mm f3.5 a series lens? I have found them in excellent condition, and just want to know what is fair current market value. I assume the current prices listed in the review section are underestimates now.

Cheers,
01-19-2011, 01:18 PM   #86
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QuoteOriginally posted by kenyee Quote
Interesting that the 645D has less noise, but more CA on the high contrast edges...
I’m not very experienced with digital, but I suspect some of the increased CA may be the result of blooming. I don’t see such a big difference in other regions and in this example the highlight areas are completely blown, so exactly where blooming would occur. The lenses have some CA, as can be seen in the film scans, but blooming is causing spilling into neighboring pixels increasing the apparent CA for the 645D. Someone more knowledgeable than I may have a better explanation.
01-19-2011, 01:20 PM   #87
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QuoteOriginally posted by moray-eel-bite Quote
I have a question for you knowledgeable 645 people. I'm looking at eventually upgrading to a 645d (probably a couple years out). In the meantime I'm looking to pick up some 645 lens (manual focus for now due to budget). What is a current fair price for a 75mm 2.8 A and a 150mm f3.5 a series lens? I have found them in excellent condition, and just want to know what is fair current market value. I assume the current prices listed in the review section are underestimates now.

Cheers,
If you subscribe to Lloyd's DAP he lists KEH used lens prices, which is usually set according to Blue Book values. The price for "EX" condition ("Like New" everywhere else) used 75mm/2.8 A is $149 and 150mm/3.5 A is $165. Samples with caps and hood (the 150mm has a built-in hood) can cost little bit more.

The only problem is, of course, they don't have them. In case anything shows up at all the life time is usually about few minutes.

Last edited by leping; 01-19-2011 at 01:35 PM.
01-19-2011, 01:31 PM   #88
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I find it difficult to compare scans to digital because there is always an alternate scan method that could eliminate the issue. An Imacon for example may well have produced a better scan where the primary noise would be grain due to film chosen.
not to know the example because i find it interesting
of course since the idea is to produce high quality large prints the fairest comparison is not pixel peeping but producing comparative large format prints. this of course is a bloody expensive method of doing a comparison and why people pixel peep i imagine.
01-19-2011, 03:51 PM   #89
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(Sorry for the long post but I've a lot of "Pent" up thoughts and conjecture from a few months of pondering the 645D...)

QuoteOriginally posted by Pål Jensen Quote
But this is blown out of proportions. While it is true that lenses designed for digital may see different design priorities than older lenses for film, the result is rarely visible in real life - not to mention prints. Is there any reason to regard the only digital 645 lens, the 55mm, as better than older 645 lenses?
Perhaps in the context of the current (initial) Pentax 645D offering it can be construed as blown out of proportions when comparing the new 55mm against other FA/A series lenses - but that's not due to "digital design" in general, but more (from what I can observe) as a result of Pentax's inconsistent quality control and perhaps inexperienced initial efforts at a "digital" lens design. That doesn't give reason to indict digital lenses in general though - if you look at a more mature system from let's say a reputable lens maker like Schneider you can make definite comparisons between current, production digital and analog lenses and see clear differences if each are used against their intended and un-intended usage (e.g. 120/5.6 APO-Digitar vs. 120/5.6 APO-Symar-L on both digital and film).

As for myths and gimmicks - if you look at the pricing on both of these lenses (both still in production):

a digital lens - Schneider 120mm f/5.6 Apo Digitar N Lens w/ Copal #0 03-019696

and its analog counterpart - Schneider 120mm f/5.6 Apo-Symmar L Lens 01-029328 B&H Photo

you'll find the prices are darn near the same. I seriously doubt someone like Schneider would do parallel production of both analog and digital lens lines just to scrape an extra $100 from someone using a digital back. I have both of these lenses above, and for all practical purposes the Symmar is a paper weight as I don't shoot film on my technical camera and it's performance on my digital back is clearly lacking compared to the Digitar.

As I see it the real problem we have with Pentax (and the 645D) is that the FA lenses were designed for analog film, in later times by probably not the most skilled or motivated optical engineers available (let's keep in mind where they were a few years ago until Hoya threw them a lifeline), and were last built in a consumer grade plant that obviously lacks quality control and proper assembly infrastructure to produce lenses of the quality now required to get all of the performance out of the 645D. Now we're bagged with the legacy output of a company that neared bankruptcy and their relative inexperience in the form of their current lens offerings for the digital age. I hope that will change for the better in the near term, but I bought into this system eyes wide open at least and accept the shortcomings.

As for the 55mm - from living in Japan for the last 12 years I can tell you what most likely happened - at the last moment when they sensed 645D would really be a live product management and marketing told the optical engineering section "we need a new lens!". The crusty engineers who were left in the medium format sub-section (because after all those years couldn't find new jobs), accustomed to long days of sipping green tea and staring out a window worrying about their severance pay (none in these times), got excited, dusted off the dormant 55mm FA design, threw in an SDM motor and coatings borrowed from the other guys in consumer SLR goods, and most importantly stamped "D" in front of its designator. In keeping with marketing's desires they then added a few "O" rings and pronounced it "all weather" just to up the anty. The CAD drawing got shipped off to Vietnam, who bungled around trying to produce it on machinery intended to make point and shoot and consumer SLR grade lenses, and VOILA!, we now have the "optimized" D FA 55mm 2.8 AL(IF) SDM super-duper digital lens. Along then came the pixel peeping, brick wall shooting, and comparisons with the likes of traditionally superior (Leica and Zeiss) or more modern (Canon and Nikon) lenses and a pronouncement (rightfully so) that the new digital 55mm from Pentax doesn't measure up. And now we're supposed to be disappointed? From that story line I guess you could surmise its a marketing ploy/gimmick, but I suspect its more incompetence and desperation at play while they try to re-boot a long dormant and neglected product line in the medium format sector.

Even with all that negativity - in the end the 645D & it's existing FA lens line offers to me much the same the original Pentax 645 did 26 years ago - an entry level medium format camera at a price I could afford, packed with features I could only have found in a smaller format 35mm SLR. If you compared the original 645 in 1984 to the likes of Leica, Rollei, Hassleblad, or even Bronica, you'd find it lacking in optical quality. But then I couldn't afford those systems, so compromise had to be made on my part. Same is true today - if people can afford a 40 megapixel Phase or Hassy system for their primary camera they probably wouldn't be here in these forums without specific requirements (like autofocus). Want to compare the existing 645D & FA lenses with your Canon/Nikon/Leica? Go ahead, it'll be a very long wait to get to 40MP with EF/F/M mount and your existing lens designs.

ON ANOTHER NOTE: - has anyone made comparisons of their autofocus experience of the 645D with other medium format cameras ? I have. After having the camera for one day (with 55 and 45-85) I can tell you this camera's AF f**king blows away any other (Phase/Hasselblad/Contax/Rollei/Leica S2) I've owned, used, or tried. Its fast, accurate, and flexible!! Man do I love the AF on this system - and isn't that why I bought into 645D w/FA lenses? I have a ton of medium format gear and lenses, from the likes of Zeiss to Schneider to new Phase/Mamiya, yet --none-- of it (despite that kit costing me 4X the price of the Pentax) can do autofocus anywhere close to the 645D. It's LIGHT YEARS AHEAD in that regard, as well as many other features. So in my mind, the 645D's ugly duckling FA lenses are the best AF medium format lenses money can buy - simply because --they work--. In a single day of learning the camera, I can say I've more than well validated the decision to move from a Phase/Mamiya645DF to the Pentax platform for my application (mostly street shooting).

I predict in 2 months time you'll see the pricing on Phase/Mamiya/Leaf and later Hassy/Leica drop significantly (like 20-30%) in an attempt to make up the ground lost to Pentax, and in the end they won't due to their suck AF
01-19-2011, 04:21 PM   #90
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QuoteOriginally posted by VoltMan Quote
(As I see it the real problem we have with Pentax (and the 645D) is that the FA lenses were designed for analog film, in later times by probably not the most skilled or motivated optical engineers available (let's keep in mind where they were a few years ago until Hoya threw them a lifeline), and were last built in a consumer grade plant that obviously lacks quality control and proper assembly infrastructure to produce lenses of the quality now required to get all of the performance out of the 645D. Now we're bagged with the legacy output of a company that neared bankruptcy and their relative inexperience in the form of their current lens offerings for the digital age. I hope that will change for the better in the near term, but I bought into this system eyes wide open at least and accept the shortcomings.

With all respect, the above is plainly absurd. Pentax have been making MF cameras and lenses for more than 40 years. They have been the number one MF outfit for tough outdoor use. Their lenses are widely regarded as of being of high quality - in fact, this what Pentax is known for far more than for their bodies. Many of the older 645 lenses are regarded as among the best MF lenses money can buy. Pentax is probably the only company that has lens designers that are minor celebrities among those in the know.

As for the 55mm; it is after all a commercial enterprise and is the standard or kit lens if you like. I suspect its qualities are due to compromises for making the lens affordable. Those compromises seem natural to me: most people will stop the lens down for landscape and anything demanding DOF. Wider apertures is usually reserved for three dimentional subjects with the subject far from the edges of the frame.
Canon and Nikon lenses are no better. Maybe they too lack experience and faculties for making high-grade optics?

Last edited by Pål Jensen; 01-19-2011 at 04:28 PM.
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