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Forum: Pentax Medium Format
12-05-2010, 06:45 PM
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I did not see my post regarding diffraction in larger prints so I'll redo my post.
In talking with a highly regarded photographer who's very familiar with large (40 inches on the short side) prints, this photographer finds little difference, between an image exposed at f 8 or f 22, with proper sharpening. "WITH PROPER SHARPENING"! Without the right sharpening a big difference. With, hardly noticeable.
Now before I get slain with look at this or that examples on websites xyz (diglloyd, cambridge in colour, etc., etc., etc.), I'm familiar with these sites. But the diffraction examples at these sites beg the obvious question; what did one do to process the image out of the camera? The answer of course is nothing. Post process is another question that needs a separate answer. Yes f 8 looks terrible compared to f 22 out of the camera. But the sharpening software that's out there now is impressive and effective.
In my mind this is great news! The tools to hone and perfect a big print are only getting better. And for me at least, big prints are the reason to buy a medium format camera. Plus not being stuck at f 5.6 to f 11 is really good news!! Additional field options are a good thing in my book.
Also, I'm not saying that given the chance I won't do what I can in the camera and avoid work, or a disappointing result at the back end.
The diffraction issue also depends on the standard of individual photographers. There are some who want prints as sharp as they can be from a viewing distance of three inches. Others are okay with prints that look okay from twenty feet away but look worse than news print at three feet.
To each his own.
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
11-29-2010, 05:19 PM
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One is not correcting a building or anything else's convergence by shifting the front standard. This type of shift assumes that the camera back (the geometric perspective) is parallel to the subject. Shift allows top and bottom of a tall subject, like a building, to be included in the picture frame. It does not change geometric perspective. That's done at the film plane.
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Forum: Pentax Medium Format
11-29-2010, 05:06 PM
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First of all geometric perspective is controlled at the film plane i.e. the camera back, not at the lens.
Second you can't have the whole landscape in focus. What sheimpflug does is change the shape of the field of focus into a wedge, that's three dimensional of course. With the critical plane of focus running through the wedge. You still place the critical plane of focus as with a fixed body/lens, but it's not at hyperfocal anymore.
Third using scheimpfug allows one to not use f 64 to attain depth of field and use the aperture that yields the very noticeably sharper image and print. Something more like f 22 is more common as an optimal f stop. Not to mention the reduction in exposure time which can be critical in the wind, to stop water movement, etc. Wider angle lenses like a 90 have more depth of field and field of view and require even less tilt.
Claude Fiddler
Linhof 4 with Rodenstock 150mm. The only camera I owned or used for 30 years
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Forum: Pentax Medium Format
11-29-2010, 07:25 AM
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Dear All:
Given the tolerances of sensors it's easy to see the need for focus accuracy in terms of best image quality, especially when large prints are made. In my mind there is no pretty good when it comes to focus. It's either right or it's not.
Digitalis points out the difficulty getting a dslr into focus at times. Disconcerting news for the perfectionist.
From what I've read it seems that auto focus is a hit or miss proposition on mfdslr and manual focus is required. Since there's no penalty with multiple exposures and there's software available why doesn't focus blending or focus bracketing solve the focus problem? That's given that there isn't another fly in the ointment, as in lens performance, operator error, sensor mis- alignment....etc.
I've seen critical focus errors over and over again with medium format.
Oh well, tough love.
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
11-17-2010, 07:21 PM
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Nick
If the 75 was sharp in the corners....then the duck wasn't misalignment. Manual focus should have been a piece of cake. Trying to align the camera parallel to the wall is not an option a lot of the time in the real landscape world. As you know. I would have tried a focus bracket on a subject like this.
This is great info and a great pot stir.
Thanks
Claude
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Forum: Pentax Medium Format
11-16-2010, 08:55 PM
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2010 Mini Medium Format Shoot-out
For those of you who remember the argument that testing wasn't too important and 10K should buy perfect quality check out the phase and pentax problems. I agree the problem is misalignment of the sensor.
Nick did a great review using a...wall for his critical test subject.
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Forum: Pentax Medium Format
11-14-2010, 07:16 AM
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Nick
In the article you write that the 80 to 160 is good in the lower range. At what focal length is it not so good? The 80-160 manual focus version has an infinity stop and the precision of manual focus. Does anyone have any comments regarding image quality of this compared to the auto focus 80 to 160? I assume you could have switched your 80 to 160 to manual focus. Does it have an infinity stop.
And onto the rear control not working. That's a bummer but not unexpected. There are going to be problems with the 645D and its lenses regardless the cost and perception that 10K will buy perfect function. What will matter is how these problems get resolved.
Thanks again for the great review.
Claude Fiddler
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Forum: Pentax Medium Format
11-13-2010, 07:54 AM
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Nick
Just read your 645 article in the Luminous-Landscape forum. Excellent. Just what was needed.
Thanks
Claude Fiddler
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Forum: Pentax Medium Format
10-30-2010, 03:55 PM
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Check this sample out on the lu-la forum. Yes it's a jpeg and yes it's at 800 iso. But it's a 1248x672 pixel crop.
Pentax 645D and Leica S2 sensor size
The detail looks good. I won't nitpick the obvious noise.
Something to chew on.
Claude
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Forum: Pentax Medium Format
10-24-2010, 09:36 AM
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Etrigan
Good Luck!
I HIGHLY recommend you look at LLoyd Chambers S2 review and comparison with Nikon D3X. This review is based on fact, not opinion and covers everything from field use to extensive post process.
Hoping to see your report.
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
10-24-2010, 06:20 AM
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Digitalis
Are you sure about the hasselblad manufacturer? I know the camera is made by Fuji. But I beleive the lenses are Zeiss.
On a different note: DNScott548: I'm over the hill (pun intended) at Crowley Lake. It's not that long drive for me to Sacto. Could I come over to check the camera out?
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
10-23-2010, 06:18 AM
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I for one am looking forward to 645 test/reviews from members of this forum. DXO didn't reveal much. 11.5 stops of dynamic range I can really live with. What an improvement over chromes.
Can anyone comment on the 80 to 160 telephoto for 645. The 1.4 tele converter. Does the lens have an infinity stop? Is it sharp, specifically corner to corner. Quality build. Does the autofocus work? and work well or is a manual focus lens the way to go. How does it stand up to weather. Anything else... I'm completely unfamiliar with Pentax lenses. The one thing that I do know is that I'm interested in the medium/normal range telephoto.
On a different note note diglloyd.com just did an extensive Leica S2 review. This is a subscription based website. The review is excellent and in my opinion is a good benchmark for the type of comprehensive info that needs to be published on the 645D.
Thanks in advance.
Claude Fiddler
wildernesslight.com
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Forum: Pentax Medium Format
10-22-2010, 04:55 PM
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Surftogo
Could you post Getdpi link where folks are claiming 645D is a notch below...That's a curious statement in that it doesn't say anything. Notch below in sharpness, can't say anything about dynamic range unless both cameras are set up at the same time, on the same subject and shot the same way, notch below with focus accuracy.....notch below....what???
My guess is that the notch below is an elusive and subjective opinion as opposed to veifiable fact.
That being said the 645D is taking a beating where it matters most; image quality.
Thanks
Claude Fiddler
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Forum: Pentax Medium Format
10-21-2010, 07:56 PM
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I know David to be articulate, helpful and very knowledgeable about MFD and other digital capture camera systems. Obviously he's very familiar with and a fan of the the Leica S2.
If you read his blog you'll find out a lot about the Leica. I think he gushes too much about the S2 and glosses over what I feel are some problems with the camera. But as far as image quality the S2 has proven to be a stunning performer. Lenses that are absolutely sharp corner to corner, wide open. Probably the best glass in the world.
That said the 645D should be able to produce results of equal quality. As far as sensors go I believe they're the same. So the question becomes one of the glass and camera mechanics. If the 645D has a vibration problem, it's toast. Based on samples that would show up as consistent blur. As far glass goes, stopping down the lens, (Diffraction isn't going to matter in a print. I've seen Joe Holmes work at f 20 with his Phase/Mamiya and diffraction's not a problem in a print and the proof is in the print pudding in my book) is going to level the glass playing field as far as corner to corner sharpness is concerned.
And I've looked at TONS of prints from my good friend Robert Ketchum's 645 and Velvia. I don't know what Bob used for glass but the cibachromes at 32x40 were spectacular.
The 645D with 2 cards that can be used as back-up, the battery life, the ability to work in harsh conditions, the layout of the controls, the lens selection, the distortion correction, all point to a fantastic camera/lens system.
David isn't bashing the product, he's pointing out potential problems. Or call his comments throwing down the gauntlet if you will. The Leica S2 has proven itself with rigorous testing and samples. The 645D should be able to do the same. The ball is in the 645D's court to prove David wrong.
Claude Fiddler.
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Forum: Pentax Medium Format
10-18-2010, 03:41 PM
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Thanks Harklee
This is a jpeg, set to level 11 correct that has an n.d. filter sharpening and noise reduction applied.
With minimal photoshop processing? in addition. What is minimal?
Was the wind blowing. The tree top, left side, looks blurred. Other foliage appears not to be moving, maybe that was the case. Did you use a tripod? I'm sure you did with a 2 second exposure at ISO 100. Did you use AF or MF. If MF where's the plane of sharp focus.
Harklee, I don't mean to sound ungrateful for your efforts on getting us all some much anticipated info. It's good to see some results from the 645D. In my opinion though, it would be helpful, if you would shoot an image like this, use DNG, use a tripod, no N.D. as without gives a clue into the dynamic range the sensor can handle, manual focus on a particular point so the sharpness at the plane can be evaluated, and send 100% full rez crops from portions of the image so that the capabilities of the sensor/lens can be evaluated. Don't do any post process. This also gives valuable info on how the sensor renders an image. For example: the photo may look too sharp, or come up somewhat flat or vice versa, but that can't be determined if you post process. It also can help determine how much detail the sensor is able to deliver.
Thanks for you efforts,
Claude Fiddler
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Forum: Pentax Medium Format
10-13-2010, 07:27 PM
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Steve
Why did you get a view camera?
Claude
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Forum: Pentax Medium Format
10-10-2010, 07:50 AM
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Thank you Harklee.
I think the flare on the right side could be caused by the bright lights below the bridge casting light upward. The flare has a straight line on the right side. Probably caused by a part of the bridge directing the light. This bright light also seems, (I cant see this on my monitor for sure) to be blowing out the highlight on the bridge pylon. I'm glad you didn't try to save this highlight. I think its more valuable to see how many stops of range the camera can handle. Did you happen to figure out how many stops of range were in the scene?
By the way, you probably know this, with a long exposure you could have used your hand (moving it in front of the lens) to burn down the sky and the bridge highlight. I used to use the dark slide of a film holder with the 4x5 to burn down all sorts of highlights in the camera. Worked, for me at least much better than an ND as I didn't get the weird gradations that can happen with an ND. Like a tree in a sky region that's black in the ND area and obviously lighter below.
The GND filter makes it harder to evaluate dynamic range capability. Where did you place the GND. It looks like you did a great job as the bridge towers don't have an obvious lurch in tone scale.
Shadow detail looks okay but it's hard to tell how sharp it is.
Bridge tower detail looks to be there. But under the bridge, those dark shadows don't appear to have detail, except where they're lit by bridge lighting.
Distant lights of Sausalito appear to have detail but like the shadows hard to tell how much.
Thanks again,
Claude Fiddler
www. wildernesslight. com
p.s. Mom used to take me to Marshall's and Ocean Beach as a toddler.
p.p.s. The following spec page shows ISO 100. Is ISO 200 the lowest ISO setting? https://www.pentaxforums.com/forums/pentax-medium-format-slr-camera-reviews/9...ntax-645d.html Also, if you're interested LLoyd Chambers www.digglloyd.com does what are, in my opinion, excellent camera/lens tests. His tests cut to the chase in in terms of performance and allow one as Keith Richards puts it "get on with the show".
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Forum: Pentax Medium Format
10-09-2010, 07:15 AM
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Infinity focus is a subject that has no near or middle ground. For instance, the summit of a peak one quarter mile away. With the 4x5 in this for instance, one would focus on the peak and there would be little or no bellows draw.
Not being familiar with medium or 35 systems, this would mean turning the focus ring of the lens to the infinity marker, or in a preferred set-up to the infinity stop (the lens has no travel left) where one was assured that the summit of the distant peak or whatever was in focus. I'm guessing that this was/is a feature of older manual focus lenses. You're probably much more versed than I with these camera systems and could bring me up to speed on lens function.
For me at least this is an important issue as a lot of what I do is infinity focus. Infinity focus would also seem to be pretty important for stitching as one could maintain the same plane of focus during the stitching process. I've only experimented with stitching a few times and at the present don't intend to use it.
My intent with the 645D is to use a legacy telephoto with tele-converter. If the AF lenses don't have an infinity stop I may opt for a manual focus lens. Stick with MF you might say, but my eye-sight is not what it once was and I would prefer to rely on an AF system. The 4x5 got harder to focus with glasses on and off.
And like you Digitalis I prefer to work with a single set-up. I had a 150mm Rodenstock parked on my Linhof IV. I didn't use another camera or lens for two decades and had only one other lens, a Nikkor 300mm. I used the 300 twice in that twenty year period and finally sold it.
Hope this answers the question.
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
10-08-2010, 08:28 PM
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Dear Digitalis
Yes quality should be worth a damn at 10K. Unfortunately the fact is that it is untrustworthy at even higher prices. Joe Holmes saw almost 50% failure with sensor alignment and lens sharpness in the system he tested.
You can have a tack sharp lens but if you get images that are out of focus, as our original contributor did, how are we to know where the problem lies? Harklee's example points to an AF that might not focus where he intends or the need to stop down further and does not appear to be a sensor problem. But who knows without another.....test.
You yourself point to some need to make a confirmation about lens performance and film color.
Would you keep a faulty piece of equipment. There's no work around for a misaligned sensor or soft lens, or auto focus that does not work, or manual focus that's not accurate. Would you practice your craft with faulty equipment. Would a mountaineer head up Mount Everest with a broken ice axe?
The result is going to be bad photographs or worse on Everest. Who would abide an image that's not perfect from a new 645D. I assume Pentax wouldn't. I wouldn't. I'm guessing you wouldn't.
I saw a brand new Alpa, Phase, Rodenstock set up that would focus on 600 feet instead of infinity at the infinity setting. I had a Canon something point and shoot, I can't remember, out of the box, with a sensor misaligned so the left side of the image was out of focus. Bad quality control from the top to the bottom of digital equipment is what I've seen.
I never had a problem with film flatness with film holders or ready loads. Roll film is where that problem usually occurs.
I'm not talking about obsessing on tests. I would not have made six trips to the Brooks Range in Alaska, climbed to 27,500 feet on the West Ridge of Mount Everest, set the world speed climbing record on the Salathe Wall of El Capitan in Yosemite or had four books published if I was obsessing about testing. But I sure as hell knew my equipment would not fail and was tested over and over again.
You're right, this did happen through many years of use. What I'm advocating is a get off on the right foot approach.
I have had the harsh lesson of not testing, been on a long trip and gotten what I thought would be stellar photos, only to find the spot meter wasn't working right and I had worthless sheets of film.
I'm not into countless tests. It seems we'd both agree that there's way too much emphasis placed on the tech side of photography. I think what you're pointing to is how some people get totally hung up on analyzing, looking at or making tests to the point where they forget what it is they're supposed to be doing. That being taking pictures.
I for one am still waiting for a decent set of, you guessed it, tests from the 645D so I can evaluate it's performance. That probably will only happen when I get my hands on one.
And then I'll spend half a day testing and I sure am hoping that what's revealed is a superb camera and lens. I truly want this system to work out.
Re lens performance as it pertained to Ansel Adams and Edward Weston: Adams writing to Weston: "As for the lens trouble you write about....I think what you want for your best solution is the Zeiss Protar No.6, 19 in....This lens is quite light in weight. You could always add the second element to it (or have a set of elements to use singly or in combination). The Protar....cannot enlarge as many times as the Dagor but for contact and moderate enlargement it cannot be excelled....."
Edward Weston was unhappy if not obsessed with a particular a lens' performance. You can argue how they went about their testing but it's obvious ( otherwise why bother with the in-depth comparison by way of testing) Ansel Adams and Edward Weston very much considered lens performance important to their craft and art and I do too.
Lastly, I don't care if someone takes my words to heart. I 'm not writing a photo rule book or trying to be a photo process judge. To each his own. I should have made it more clear that what I'd like to see is, or what I would do is.....but it's Harklee's camera and lens to do with as he sees fit. What matters to me are superlative images, regardless of means.
I apologize for being pushy.
Claude Fiddler
Wilderness Light |
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Forum: Pentax Medium Format
10-08-2010, 05:58 AM
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Boards and Thistle for one from Ansel Adams. Devil's Postpile for two, Shards of Glass for three, White Post for four, Self portrait in Utah for five, Political Sign for six, Billboard for seven.... and on and on. You can't control a sensor that's not aligned. You have to return the camera for repair. The subject is not the issue, using a flat plane to make a test is.
You seem to be missing the point of doing a simple set of tests to prove quite easily, after spending multiple thousands of dollars for a set of equipment, that your equipment works correctly. Why would you want to discover on a photo trip that your equipment was defective? Do you think that Ansel Adams didn't know absolutely that every piece of his equipment worked perfectly before he went to Alaska for six weeks? What's wrong with doing a simple set of tests? Sure you can make tests by doing what you like.
Ansel Adams and Minor White and others from f64, applied stringent craft, (and that included testing of multiple parts of the photographic process), to their art. Both Adams and White were adamant that a "bohemian" approach to photographic craft was not to their liking.
As Ansel Adams said and I quote"Craft facility liberates expression".
If you're having a problem with my suggesstion go to Joseph Holmes Natural Light Photography Home Page and read his article on the problems with medium format cameras, lenses and sensors. By the way Ansel Adams called Joe's color work "a revelation".
And a note: I've only used a 4x5 since 1983. You can see my work in one of three monographs: Wilderness of Light, Chronicle Books, A Vast and Ancient Wilderness: IMages of the Great Basin, Chronicle Books, and Yosemite Once Removed: Portraits of the Backcountry, The Yosemite Association.
Claude Fiddler
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Forum: Pentax Medium Format
10-07-2010, 08:25 PM
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Dear Harklee
Your fore ground gravel etc. looks sharp. What looks out are the sea stacks and back ground. It appears that you're too front focused or that's what the AF did. I think that you would be better served, as would potential 645D purchasers, if you picked an easy, bland and boring subject that gave you hard data about the camera and lens performance. For instance, I live at Crowley Lake at 7,200 feet on the east side of the Sierra Nevada. The fall colors are going off against a foot of new snow. Diaphanous clouds are rolling across the mountains creating beautiful dappled light. But if I had just received the 645D and lens I'd be shooting pictures of the side of my house trying to know for certain that the sensor was aligned, that the camera focused repeatedly on the exact same spot at all focal lengths, that corner to corner sharpness was achieved at a certain f stop and I'd make damn sure that infinity focus indeed focused on infinity. I don't care what f stop I stopped down to. Diffraction doesn't matter in a big print. I've never seen it and I used f 32 and 45 plenty. If you need f22 you need f22. Who wants a blurry image. And you bought the 645D to make big prints, right? I only used a 4x5 because I wanted to print to 32"x 40". Otherwise I would have used a 35mm camera.
Do a sample, no jpegs, of a subject 4-6 feet away from the camera. Who cares about bokeh. When was the last time you saw an Ansel Adams image with bokeh. A bush of some sort will work well. You can look at how detail is rendered in a very difficult depth of field situation. Then do the side of a building at 30 foot distance, or a tree, or rock wall. Check corner to corner sharpness. Then check infinity focus. A mountaintop, the moon, distant buildings are good. Infinity focus is VERY important and it should not be assumed that when a lens is turned to infinity that that is where it is focused!! Lenses with infinity stops are REALLY useful.
The goal is to prove the camera and lens and sensor can do what you want them to. Craft first, and that includes equipment, then unfettered expression and creativity can follow.
I look forward to seeing meaningful tests that prove the 645D is what we hope it to be.
Claude Fiddler
Wilderness Light |
