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Thread: Pentax 645D, Mamiya DM22 / DM28

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    Pentax 645D, Mamiya DM22 / DM28

    Hello all... I'm new around here, and mainly joined because this seems like a good place to gather information about medium format digital backs and newer medium format systems. I've been shooting mf for the last couple of years, after a friend of mine got me into 120 / 220 film, and I discovered that a lot of the cameras on the used market can be had for pennies on the original dollar. I process all my film at home in a Jobo processor, and especially love watching the final product come out of the tank (particularly slides).

    I'm not a pro like many here, mainly a serious amateur who has had a few paying gigs over the years, but nothing major. (I took some head shots for a hairstylist's client once, and did a wedding for a friend's daughter). I have a day job that pays the bills to fund my little addic... er... "hobby", and these days I've become interested in seeing what's out there in terms of digital capabilities for all of these great medium format cameras. I've shot digital since the late 90s, and currently have one digital camera - a Canon 5DM2.

    I've kind of narrowed my search down a bit to two camera systems in particular - the new Pentax 645D, and the Mamiya DM series of camera kits (which I know is comprised of Leaf backs married to AFD-III cameras). What is the general opinion of folks out there regarding these two systems? It seems to me that Pentax have hit a home run after many years of R&D with their offering, especially considering the quality of the LCD screen on the back, as well as the 40MP resolution of the sensor. Can the Mamiya DM28, for instance, hope to compete against that once the camera starts to show up in larger numbers in the U.S.?

    I started this whole process a few weeks back when I started looking at the Rollei lineup of autofocus medium format cameras. I really had my heart set on either a 6008AF or HY6, because they are the only 6x6 AF systems that even exist (to my knowledge), and I really wanted a camera larger than the 6x4.5 format to help me get shots of my little ones running around. I get good ones these days with my RZ67 ProII & Hasselblad 501CM, but figured AF would be a really big help. However, after reading some more, I've learned that DHW, the company running the show for Rollei now, really aren't doing a good job, and investing the thousands of $$ into one of those systems would be a very risky venture if I ever needed support for the camera / lenses down the road.

    Right now I'm kind of leaning toward the Mamiya system, just because you can take the digital back off and put a nice film back on whenever you want, whereas with Pentax, even though it's cheaper, you are stuck with digital full time. I'm probably going to wait a while too to see if prices come down at all once the Pentax starts showing up in larger numbers here in the U.S. I figure they both have a good lineup of lenses, so it won't be too hard to find some good used glass for either one.

    Thanks for reading and I appreciate any insights the community here has!

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    Senior Member David Schneider's Avatar
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Make sure you see http://forum.getdpi.com/forum/showthread.php?t=24174 . It might give you a chance to get some questions answered.

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Quote Originally Posted by DeckardTrinity View Post
    Right now I'm kind of leaning toward the Mamiya system, just because you can take the digital back off and put a nice film back on whenever you want
    You might check with Mamiya to be sure, but I believe that the DM series kits are now shipping with the DF body, which does not accept film backs. Of course, you could always buy a used one with an AFDIII or a P1/645.

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Hi Deckard,

    Since you consider Mamiya DM22/DM28 I would suggest you to look at the Leaf corresponding backs through a Leaf agent/dealer. The benefit would be that you may be able to buy a used with low exposures under warranty, but also that they may offer you an upgrade a few years later. My dealer here in Hong Kong is stellar in support and service, and support and service is important. It has been nil problem with the quality of my back, but it is good to have someone reply quick when I have questions or need accessories .

    If you go with the Pentax, there will be no upgrade program. I use Leaf Aptus 65 myself but suggest you to compare also Phase One and Hasselblad backs to see what you prefer. Personally I prefer the files from backs with Dalsa sensors, which all Leaf backs and newer Phase One Backs have. I think some of newer Hasselblad have Dalsa also, not sure. The other backs had Kodak sensors and also the Pentax have such. Regarding the DM22/DM28 the DM28 has same identic sensor as my Aptus 65 and which is a newer generation sensor than in the DM22.

    One critical item is what do you shoot? If you prefer low ISO that should leave out the Pentax, which has a base ISO of 200.

    Regards
    Anders

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Thanks for the information! In response to Anders_HK's question regarding what I shoot, mainly I stick to the lower ISO speed films, and when I have to shoot indoors, I put a Canon 580EX-II flash on a bracket. I've discovered it's very hard to get rid of the yellow / orange cast of tungsten lighting with color film (neg or slide), even in Photoshop, so I just try my best to overpower that with the whiter light of a good bright flash when inside. I also do like Ilford Delta 3200 a bunch, grain and all, since it lets me shoot sans flash (got some great pics of a friend inside a darkly lit club / stage in Alphabet City in NYC last year pushing the Delta one stop to 6400). So I'm sure whatever mf digital solution I get, I'll be pushing it to its limits experimenting with lots of different shooting situations.

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    Re: Pentax 645D, Mamiya DM22 / DM28

    upgrading a leaf may well cost more than a new pentax though ...

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    Re: Pentax 645D, Mamiya DM22 / DM28

    I started on this slippery slope with an AFD-II body/ZD back coming from a Nikon D300, I have found that the ergonomics of MFDB are very different than dSLR bodies.

    The thread that was referenced above is a very good read.

    Even with the lowly ZD, when I take care with my technique and focusing, the results are simply stunning.

    My personal experience matches pretty well with the lens review on this site, the 45/80/150 are all really nice lenses, and the most expensive in the bunch is a $400 lens! I'm less happy with the 55-110. This made the Mamiya system the most affordable one for me.

    All that said, I have abandoned hope, and am in the process of trying to get my hands on a P30+ without either divorce or bankruptcy.

    Seriously, if you can at all afford it, I would look at at least a 30mp back as you will always be dithering about dSLR as in IQ almost as good. In my quest with the same question, I decided that IMAGE CHARACTER was the deciding factor where as IQ could be debated all day.

    YMMV

    Dave

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    Re: Pentax 645D, Mamiya DM22 / DM28

    There are some real differences you need to consider. First, the Mamiya is a real system. You can buy a camera and any lens you need right now and you can use the back on a 645, RZ or tech camera. The Pentax is not -- they are hard to come by and there really is only one lens. Second, the Pentax is billed as weather sealed, the Mamiya is not. I've always loved Pentax ergonomics, Mamiya I can deal with if I have to. Also, I would add that while the Pentax is a lower price for a new camera, I think the Mamiya might be a better value. I have seen a number of images from the Pentax and they are nice, but don't quite seem to be in the same league as other MFD systems and seemed like a really, really nice DSLR. Of course Pentax cameras have always handled like a nice SLR.

    My thought is if you need the camera now and are not 100% clear on why you need it, buy the Mamiya. If you are just kicking the tires, looking for the future, or need what it likely the most durable MFD camera around, get in line for a Pentax.

    Personally, I own neither and am a bit torn. I have a couple projects coming up that really beg for MFD, but also demand durability and reliability.

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    Subscriber and Workshop Member MGrayson's Avatar
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Slightly
    Back when the 645D samples were first showing up, and LL was "reviewing" it, I was sure it would be my next camera. I accumulated 5 older lenses, but then decided to hold off and stick with 35mm for a bit (thanks, Jono!).

    I'm wondering what to do with the lenses: hang on to glass for a system I may never get into? Or put it back into circulation. Glass hoarding - it's more common than you think!

    Just muttering,

    Matt

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Quote Originally Posted by Paul Spinnler View Post
    upgrading a leaf may well cost more than a new pentax though ...
    Not necessarily at all, please check. Plus how much will the future Pentax 60 MP or 80MP cost?????

    ---

    In regards to durability and weather seal, PhaseOne has been frozen, cooked, parked on and more per their youtube videos... I decided I did not need that. Who honest needs weather seal when take care of gear? I travelled worldwide with my Leaf, no issue. It is solid. My Leaf back fell on hardwood floor one time, bounced and rolled mutiple times like a ball... horrible scary experience. It worked flawless since. Do not try it, but... I wonder how Pentax will stand such test??? Do take note that PhaseOne and Leaf are built for professional abuse. As an amateur I do take careful care of my gear, but that said I also shoot in not perfect sunny weather! I dare say that apart from letting it sit outside in rain, weather seal is cosmetic. The Pentax seem aimed at amateurs while the digital backs are aimed at professionals... somehow that can be used to figure out which one is likely most solid build... but who knows the Pentax may be built well also. Any history on that? Search for Leaf and Phase One and there is history of how durable they are.

    Regards
    Anders

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Yeah, I've been reading some threads here and on LL, as well as some blogs, and it seems like there might be a real issue with the older glass on the 645D. Some of the lenses may work out, but my impression right now is that things are very much hit or miss. Certainly if one cannot rely on the price structure of the relatively cheap older glass, then you'll have to factor in the much higher prices of the new glass, not to mention the wait for it to all arrive.

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    Senior Member MaxKißler's Avatar
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Quote Originally Posted by djonesii View Post
    I started on this slippery slope with an AFD-II body/ZD back coming from a Nikon D300, I have found that the ergonomics of MFDB are very different than dSLR bodies.

    The thread that was referenced above is a very good read.

    Even with the lowly ZD, when I take care with my technique and focusing, the results are simply stunning.

    My personal experience matches pretty well with the lens review on this site, the 45/80/150 are all really nice lenses, and the most expensive in the bunch is a $400 lens! I'm less happy with the 55-110. This made the Mamiya system the most affordable one for me.

    All that said, I have abandoned hope, and am in the process of trying to get my hands on a P30+ without either divorce or bankruptcy.

    Seriously, if you can at all afford it, I would look at at least a 30mp back as you will always be dithering about dSLR as in IQ almost as good. In my quest with the same question, I decided that IMAGE CHARACTER was the deciding factor where as IQ could be debated all day.

    YMMV

    Dave

    Dave,

    you expressed what I feel about this topic and I agree with all you've said. Looks like we almost got an identical set up. I too hope to get a P30+ next (I'm already saving)... Apart from that, I'm happy to know that I seem to have made the right choice regarding lenses. Today I received my 150mm AF and it costed me 260$. Simply incredible for a good as new lens with a B+W filter. It is much bigger than I expected...

    Deckard,

    used Mamiya gear seems really inexpensive these days. Being an amateur myself this is a fact to consider. Whatever system you might choose, they are all great and the files you get from them are just not comparable to the output of any dslr. For me, it's much more fulfilling to work with MFD.

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Hi Deckard & All,

    I can only speak for the Pentax 645D system as I have intensively been putting it through its paces with a very wide variety of Pentax FA AF lenses...generally multiple samples of each that I've had access to, from a wide variety of photographic acquaintances. I haven't finished with my initial conclusions and I don't want to make statements that don't have sufficient backing without observing a consistency of a given type of lens, unless multiple samples of a given lens has exhibited "close to" identical results with one another. In a nutshell, that's sort of the problem. Different samples of some of the same type lens has quite divergent results (performance). Some of this can be compensated to a degree via the AF fine tune feature of the 645D body...but not always. It also seems that it's not as simple as adjusting AF fine tune at close distances with a test chart or device (as one generally does with a 35mm full frame DSLR) and then allow the larger depth of field take care of longer distances that might exhibit slight front or back focus. It appears one generally has to pick a distance they use most often as their starting point and then test out other distances (from min to infinity) and find a AF setting that is a good compromise. *** Please keep in mind I am examining files at 100% (pixel peeping) since output to large format prints is my ultimate output. Those that don't pixel peep might find the whole process easier.

    I also would like to stress that upon talking to others using different MFD systems (and my previous limited experience with a Hassy MFD system), that often different samples of lenses can vary quite a bit in performance. The weak end for the Pentax is at the wider focal lengths and here is an area which they need to address. They soon will be releasing a $5000.00 25mm lens which will give an angle of view of approx. 19.5mm on the 645D...so the economics of reasonably priced Pentax lenses will change, since other future releases are expected to be expensive, compared to those lenses that have been around for years and can still be found.

    Some are beginning to try other manufacturer MF lenses, such as Hassy lenses, on the 645D, such as

    The acuity of many of the Pentax telephotos lenses (above 75mm) are quite good, with reasonable resolution that gives justification to the 645D, resulting in larger quality MF files, compared to say a D3x. Then there are some lens that hold their own against most others manufacturers in similar focal lengths.

    Steven, who posted his lovely Yosemite 645D images in another thread here on Getdpi, and I have discussed many of our 645D/lens experiences and observations and have come to somewhat similar conclusions, although what we shoot and the subject distances to our subjects do vary. One thing most agree upon is the body itself, its feature set and the sensor are all of very high quality. Pentax has acknowledged the lens issues and is aware of the current situation. With careful selection, a very nice reasonably priced MFD kit can be assembled. There is nothing technically wrong with lenses that are purchased and then turn out to be ho-hum on the 645D body...its just that they individually weren't fine tuned (so to speak) nor tested on a 645D body when they were produced, to make sure they performed optimally on a digital body where finer tolerances are required. Pentax USA only has a 3rd party repair/adjustemnt facilities here in the States, who appear to have limited experience with the 645 system and although they (Pentax) has said a given lens can be sent back to Japan, there is no guarantee of any change or success from having them look it over.

    The term I've often used, is that the lens situation at the moment is a crap shoot. For some though it hasn't been, all depending on their expectations and what they hope to use the files for. For others, certain focal length lenses have been a headache and it has driven them to seek other alternatives. For me, so far, I'm of both camps...good lenses can be found and stopping down with many is sort of essential, but on the other hand, not all expectations can be met, no matter how many lenses one tries. It's a trade-off and whether one is willing to accept this will all depend on their personal/professional needs and expectations.

    Matt, you mentioned purchasing approx. 5 Pentax 645 lenses/ May I inquire what older Pentax lenses do you have so far (for this system)? Thanks!

    Dave (D&A)
    Last edited by D&A; 3rd March 2011 at 20:13.

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    Subscriber and Workshop Member MGrayson's Avatar
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Dave,

    I have the 35 and 80-160 in FA, and 45, 75leaf, and 120 macro in manual focus. I've checked them on a FF Canon, but can't say anything about their corners. I bet they'd look great on an M9

    Best,

    Matt

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    Re: Pentax 645D, FA 35mm f3.5 & Mamiya DM22 / DM28

    Hi Matt & All,

    Thanks for the response. The 120mm f4 macro (in either MF or FA versions) is consistently an excellent performer and the 1st lens I'd recommend if acquiring a 645D...not because it's a macro nor it's particular focal length...most every sample is consistently excellent at all distances and most f-stops, so one has a lens by which they can compare to most others and also feel confident that their 645D is generally performing as expected. The 45mm in general is often the opposite of the 120mm f4 macro and is not considered to be a stella performer. The 75mm leaf is the one single focal length lens I haven't tested yet. The 80-160mm zoom greatly depends on individual samples (although variation is not extreme) but often this lens does some erratic things focusing (AF) wise at 160 and sharpness also drops off just before this focal length is reached. Performance of this lens therefore can vary, although for the time being I've been primarily testing out the primes.

    Now we come to maybe the most interesting but controversial lens currently in the Pentax 645 line-up, the FA 35mm f3.5 645. I guess one can write a dissertation on it and certainly it's been the one lens I've purposely have tested many samples of and have documented all it's unusual optical properties.... but I'll keep my comments short. Ask 20 people for their opinion on this lens and you'll get 20 different responses. It depends on so many factors including what they shoot, whether it's on 645 film, 645D, a Canon DSLR system with adapter for tilt/shift etc. Curvature of field with this lens seems to vary considerably depending on camera to subject distance. How one sets the Af fine tune when used on a 645D body can have a most profound effect on its performance....again this setting depends greatly on camera to subject distance...even though we are talking about a wide angle lens which supposedly has considerable depth of field.

    My comments (below) reflect it's performance on a 645D and of course examanation of the crops of the files at 100%. Although the ultimate output is for large scale prints, how much of what I describe will have an impact on your prints, at a given size, is of course up to indiviual interpretation.

    Think of the field curvature in this len's case as a upside down letter "U" (Can't type an upside down "U" on the keyboard...LOL!). The Inner most center of this upside down "U" represents the center of the lens axis and center of the image field. At close and mid-distances, this upside down "U" is flattened out, something between a gentle arching rainbow and straight line..... so that field curvature and it's effect on focus is minimized, especially when stopped down. Excellent edge to edge sharpness of relatively flat field objects can be achieved and this is where the lens shines. It also is extremely impressive with angled street shots and images where various subject matter at different distandces are within the image. As subject distance increases towards infinity and depth of field becomes larger...it appears the curvature of this upside down "U" becomes "great" and imagine the "typed" upside down letter "U". The transition is dramatic and I don't have a precise distance where it occurs, but it's more sudden rather than gradual. If the center of the frame is focused on a relatively flat field subject at infinity (say a landscape)...the center is very sharp and as you head towards the sides/edges of the frame, resolution and sharpness is lost. Yet if one looks at the very left and right hand edges and corners for items in the extreme foreground (can be 100-300 feet closer or more), they are rendered very sharp. These foreground objects represent the sides and points of the upside down letter "U". It's quite uncanny and is consistent...and can't be completely compensated for by stopping down to say f11-f13.

    One way to moderately compensate, is to set the 645D Af fine tune to back focus the center of the frame to a degree...where it can still be rendered reasonably sharp at f11-f13 due to depth of field and thus cause a dramatic back focus shift of the sides/edges/corners of the frame to backfocus, causing them to appear in the same focus plane as the center of the frame. In order to be able to do this, the individual sample of the lens must have the latitude to focus past infinity so that the 645D AF fine tune can introduce slight backfocus for the center focus of the lens (at infinity). Not all samples have this latitude to start with...like many of today's 35mm lenses which can focus past infinity. Lens designed years ago were collimated to come into infinity focus just at the "stop" of the barrel at "infinity".

    All in all for many, they will find this a excellent performing lens, in fact a reasonably priced (relative) bargain in the MF world as long as they take note of its optical properties as described and work around them as much as possible. For subjects at close to medium range, it's a excellent lens all around as long as the AF fine tune is set properly. If shooting far distance landscapes where excellent (and greater) side and edge sharpness at the infinity distance is required, this lens may disappoint unless the adjustment I described is employed...which helps considerably but is definitely not perfect. Trail and error is definitely involved.

    Interesting how an older lens test report on the Web illustrating lpmm values for this lens and the Hassy and Mamiya Equivalents..showed by f5.6, the Pentax was the preferred lens in terms of edge to edge performance..and this lens I believed received a lot of noteriety from this lens test. This report though at the time predicted the demise of the Pentax 645 system...with a "RIP Pentax 645" (LOL). This report was in the MF digital era, but certainly prior to the 645D body.

    Alternatives to the FA 35mm f3.5 are the FA 45mm, which isn't particulary strong resolution wise across the frame. The FA 45-85mm zoom is strong from 45-65mm including sides/edge compared to a "unadjusted" FA 35mm f3.5... but the zoom does weaken considerably at longer focal lengths beyond the approx. 65mm zoom setting.

    Dave (D&A)
    Last edited by D&A; 4th March 2011 at 07:59.

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    Re: Pentax 645D, Mamiya DM22 / DM28

    That's quite an analysis Dave, thanks. I've read that the field curvature you describe is also a property the 33-55mm zoom. BTW, my copy of the 45-85 is quite good at 75-80mm, most reports I've seen indicate weakness after 65mm as you do, luck-of-the-draw I guess. I recently acquired the 400mm FA, it appears to be excellent on the 645D, on par with the 67 300mm ED.
    Did you ever locate a 200mm that was satisfactory?

    Matt: If you decide to sell the 35mm FA please pm

    Tom

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Hi Tom,

    Haven't shot with the 33-55 but from all accounts one can do better. Again this sample variation thing makes it difficult to come to a definitive conclusion about gievn lenses, thats why the multiple sample testing, so a consencious can be built. Interesting about the performance above 65mm with your 45-85 zoom...as most copies are soft above 65mm. Yes, the FA 400 is actaully quite good (very good) and I've been most impresed. It doesn't have the acuity of say a Nikon 300 f2.8 or 400 f2.8, but it surprised me, especially if one stops down a bit. Hopefully when things let up here (work wise), I'm going to have the chance to test two aquantences FA 200's...then I can make heads or tales of that particular lens. Also sent you a PM/e-mail Tom.

    Dave (D&A)

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    Re: Pentax 645D, Mamiya DM22 / DM28

    I have the 645d with 13 lenses, including 3 Leica Visoflex lenses (elmar 65/3,5 tele Elmar 134/4 and Telyt 200/4) and I am very satisfied of the results.
    I accurately test every lens before using it for jobs (I do aerials, and performance at infinity corner to corner is critical)
    My procedure is a first test with resolution charts at short distance, than a brick test at 30/50 meters, and finally a long distance check in various locations.
    This is a summary of my results:

    FA35- my copy is simply outstanding, probably the best lens I ever tested. Absolutely no field curvature at any distance,or any aperture stop.
    Full open it outresolves the sensor at center, and is a match with the sensor on corners. Stopping down, at 5,6 the microcontrast at corners increases a little,
    and than the lens outresolves the sensor till 11. Than diffraction rapidly prevails.

    FA45-a not so good lens, acceptable only on center. Sold it

    67 55/4- a very good lens for my work. from 5,6 to 11 it outresolves the sensor on full field in a very balanced manner, but still generating moirè on roofs at critical distances.

    FA75 and manual focus 75- both good, with slightly soft corners till 5,6. At 8-11 outreselve the sensor on full field

    67 105/2,4 similar to 75, but never reaches total sharpness on corners.

    FA120- very good full open on full field, with slight increase of performance stopping down. My copy required a full -10 AF calibration.

    FA150-even slightly better than the 120 at same aperture stops, and more contrasty, but
    full open CA is present

    Manual focus 200- good lens also full open, very usable, but to long to perform resolution tests with my charts set up.

    FA*300/4 perfect at all apertures, a very sturdy tripod is required in the range 1-1/60 speed.Required a -3 AF calibration

    FA45-85- I have 2, both more or less with the same defect, asymmetry on lower left corner that is visible till 11. Outresolves the sensor from full open on center, and optimum field increases stopping down.

    Than there are the Leica lenses, but this is a completely different story.

    All in all, I think I have been very lucky with my Pentax lenses. No one of them approaches the monstrous MTF performance of Leica S2 lenses, but for me this is an advantage, as I have substantially less problems with moirè and artifacts.
    Critically focused images with S2 lenses produce, IMO, in contrasty light environments,
    a sensation of iper-reality.

    Sergio

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    Re: Pentax 645D, Mamiya DM22 / DM28

    Hi Sergio,

    Nice findings and I concur with most all your wrote in my own testing (except those few lenses which I haven't tested yet). Keep in mind the Af calibration a given sample of lens might require on a 645D, may be completely different with another sample of the same lens. I've seen this time and again. For example one sample of a FA 150mm f2.8 required -3, another +2 and a third +5.

    Regarding testing distances, I do the same thing...close to min. subject distance, mid-range and then infinity.

    The field curvature that I refer to with the FA 35mm is not where you shoot a flat field (like a brick wall) and see curvature of the wall like barrel or pincushion distortion. It is where at infinity distances, you can see the field of focus is different between the center and the edges/sides. I've tested maybe now upwards of 9 samples of this lens..from early production to the most recent, and they were all virtually the same in this regard. If one shoots a infinity subject at a angle, like a 45 degree angle, the asymmetry seen with this curvature is difficult to make out exactly what is happening and not always is it noticeable, especially if the lens is set to slightly backfocus in the center of the frame, as one GETdpi member did with his lens. If one though shoots a infinity subject parallel to the sensor and equi-distant on both the right and left side, this curvature of focus can be readily seen. Two other 645D FA 35mm shooter here on Getdpi, also readily noticed this in the sample he shot with too. It's in the design of the lens and doesn't vary much from sample to sample. At mid range and closer, this phenomenon decreases to a degree and it isn't as noticeable (as I described in a previous post above)..since the curvature becomes more like a gently curved "arc".

    As you explained, its very important to calibrate AF with the 645D and its lenses to get anywheres near what the body/lenses are capable of.

    Dave (D&A)
    Last edited by D&A; 5th March 2011 at 22:12.

  20. #20
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Dave,
    thanks for your explanation. I to was referring to field curvature, and not distortion that is correctable with lens profile in ACR.
    I would be very gratefull if you have the patience to download the full size
    jpg of the test images that I post below (available on the "view all sizes" page
    on Flickr). Note that results with the Norman Koren charts are essentally the same from 5,6 to 11 and show a constant slight (approx.10%)reduction of microcontrast and resolution on corner-extreme side.How to these compare with your experience?
    Thanks.
    Sergio


    _IGP0395 by sergio lovisolo, on Flickr



    _IGP0136 by sergio lovisolo, on Flickr



    IMGP0448 by sergio lovisolo, on Flickr



    _IGP0439 by sergio lovisolo, on Flickr

  21. #21
    Super Duper
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Hi Sergio,

    Thanks ever so much for posting these images. At this very moment I'm on my way to a shoot, but will look forward to downloading the full rez files later and have a closer look. Except for shot #3, none of the others were taken at very long distances, which would constitute "infinity" and be able to show the "field curvature" focusing phenominon I refered to in my postings above. With shot #3, I'm not sure how far that treeline in distance is from the camea and there isn't too much detailed forground (and whats there is in deep shadow with little detail) to illustrate the point. A perfect illustration is one of the images another forum member took of a landscape at great distance whereby center at infinity was sharp, corners/sides less so yet, along the edges/corners in the extreme forground had items that were extreme sharp. I've seen and tested for this phenominon many times and its pretty consistant. It not only depends on how the lens is set up (AF fine tune wise) with a given 645D (whether to slightly backfocus in the center or not) but how perpendicular the subject is to the camera and how great a distance it is away from the camera. The other contributing factor is where in the frame the camera is focused on...such as the front of say a treeline or the furthest tree. In theory they are all at infinity with a wide angle lens, but often just a slight difference in the lens settling on focus point, seems to have a significant and profound effect on this side/edge sharpness.

    Your second and forth images most certainly illustrate what a great lens optically the FA 35mm f3.5 is, under most shooting circumstances...and what I described about certain types of very long distance landscape shots (and how critical it is to set up this lens properly for other distances) is only because it has come back to bite a few who have tried it and were surprised at their findings. Thanks again!

    Dave (D&A)

  22. #22
    Hikari
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Why would you want to set your lens to infinity for a landscape? The furthest anything could be away is about 20 miles or so, not that it is really important as the atmosphere is going to prevent a sharp image anyhow. And you are going to have foreground as well, so you would want to optimize the focus for that. Infinity marks/stop tend not to be accurate for a couple of reasons, one being the expansion and contraction on the lens barrel itself in different temperatures.

  23. #23
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    Re: Pentax 645D, Mamiya DM22 / DM28

    Quote Originally Posted by Hikari View Post
    Why would you want to set your lens to infinity for a landscape? The furthest anything could be away is about 20 miles or so, not that it is really important as the atmosphere is going to prevent a sharp image anyhow. And you are going to have foreground as well, so you would want to optimize the focus for that. Infinity marks/stop tend not to be accurate for a couple of reasons, one being the expansion and contraction on the lens barrel itself in different temperatures.
    Hi,

    While I have a second here....the true infinity focus of the lens is first checked and determined prior to taking a shot and takes into account the example you sighted. That's not what at play here with the superb but unusual optics of this lens. in fact Leicas 35mm lux asph often shows a similar outer zone file of curvature where the edges sides come into focus in a different plane than the center of the frame, when shot both wide open a and at moderately close distances. it's been well described too.

    Dave (D&A)

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