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Thread: IQ180 and 8x10 assessment

  1. #11

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    Re: IQ180 and 8x10 assessment

    Awesome.

    <<getting popcorn>>

  2. #12

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    Re: IQ180 and 8x10 assessment

    Great! Will follow with anticipation.

    But do you have the best lenses? How did you make your choice for the 8x10?

    Asher

  3. #13

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    Re: IQ180 and 8x10 assessment

    I'd be inclined to place a resolution target in the center of the field of view for all the images. This would provide a target from which analytical data can be gathered directly from the final print. The black and white EV values can be measured with the densities recorded on film for an assessment of processing consistency for the film and - well I'm not sure how you would assess the digital exposure consistency - have to think about that a bit.

    Simply print out a copy of the US Air Force 1951 target at the appropriate size. Seems if you're shooting at 100 meters or so and using a 240 mm lens the demagnification factor is about 40X so to produce a 10 um line on film would require a 400 um line on paper at 100 meters. All very doable. For consistency using different focal lengths you would scale the size of the target to end up with about a 10 um line at the image plane. Hopefully you would cover at least the 5 um to say 200 um linewidth sizes at the film and sensor plane using the USAF or equivalent resolution target .

    Indeed, stability of the setup is quite crucial. Think about the laser pointer being reflected off part of the white target at 100 meters for a critical assessment of vibration.

    Nate Potter, Austin TX.

  4. #14

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    Re: IQ180 and 8x10 assessment

    Tim,

    If you have access to roll film holders for the Alpa and the Techno, you might consider shooting those as well. And if you can get hold of an Arca RM3DL, you could shoot 4x5 film and the IQ180 on the same camera with the same lenses. While the film will be smaller, it will eliminate differences due to camera and lens combinations.

    Or if the test is solely for 8x10 film, how about using a 4x5 reducing adapter, and then an adapter for the IQ180?

    Thanks for taking the time and effort.

    Kumar

  5. #15

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    Re: IQ180 and 8x10 assessment

    I'd shoot a newspaper and a grey step wedge taped to a brick wall indoors at 25 feet. Infinity outdoors just introduces atmosphere and haze as larger variables. If a lens is any good at 25 feet then it will be good at infinity.

    I'd set all the cameras as low as their tripods practically allow. Or no tripod. Whatever is going to be the most rock solid. How about ditching the ball head and just mounting to the tripod itself?

    I'd get some better 8x10 lenses that match the modernity of those fancy digital lenses. At least the Sironar-S and not the 20-year old Fuji Nikkor field cameras lens. Glass haze alone could affect the results.

    And I'd bracket the focus by actually racking the front in and out a mm each way. It's only three sheets.

    I don't see the point of adding all these other cameras into the mix, which only confuses the issue. Let your friends run those on the side and compare those results later or as a sidebar. Otherwise you'll just have too much information and not interpret it as clearly. Rather, do the very best IQ180 and 8x10 shots, do a bracket, pick the best and follow best workflow practices through out.

    Civilians won't be good judges, they'll focus on some aspect that might be irrelevant. Pick photographers who are unaware of this project. Only show them abstract crops so biases about the subject don't come into it.

    The probable flaws in the LuLu contest were that the 8x10 was not optimal - flimsy tripod, poorly focused, poorly scanned. Also it was a funky target, changing light, etc. Address those and keep it really basic and simple.

    OK one more variable. You're shooting the digi at f/5.6 and f/22 for 8x10. Given the same ISO between film and digital, the digi is only shooting at, say, 1/125th second versus the poor 8x10 having to shoot at 1/8th.

    Make a few shots at the same shutter speed, throw a ND over the digital. Not that it proves anything practical, since the digital will always have that advantage of working at a wider aperture and shorter shutter speed... but it would be a reference as to how much the slower shutter speed degrades the image.

    Finally, if you projected a laser level beam from on top of the cameras, a spotter could tell when they stop shaking.

    Sorry to be so terse and bossy. Thank you for doing this and good luck!

  6. #16

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    Re: IQ180 and 8x10 assessment

    I second Frank's advice on just mounting the cameras (or just the 8x10) directly on the tripod legs/base.

    I have a Gitzo G1500 5 series. I also have an RRS BH55 that I use with my DSLR.

    The BH55 is a great ballhead, but when I use my Horseman 8x10 or 4x5, a camera that is probably heavier (and sexier ) than any camera you're using in this test, I do NOT use the ballhead. The giant, heavy camera goes directly on the legs.

    It's probably the next best thing to a studio camera stand.

  7. #17

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    Re: IQ180 and 8x10 assessment

    Tim - If you incur substantial expenses, I don't think it would be inappropriate if some of us could help out.

    If you are set up for PayPal or its equivalent, I'm sure that some of us would probably be very happy to contribute $5. Not a lot of money, but if 20 or more people do it, it can help cover the cost of processing. Fortunately, you'll be doing the scanning, but all those 8x10 chromes gotta cost something to purchase and process.

    If you send us a link, we can contribute anonymously. Just be sure to take down the link when your expenses have been met

  8. #18
    joseph
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    Re: IQ180 and 8x10 assessment

    Good luck with the comparison-
    It looks like a lot of work, and you won't like my suggestion-

    If diffraction is deemed to be a major constraint to the maximum print size for any given format, then your choice of aperture will have a major role to play. Different scene types require different depth of field, this is a real world consideration. A landscape with close up foreground stretching as far as the horizon will need to be stopped down more than a portrait, maybe, for example.

    It should be possible to make the largest prints using a sharp lens around optimal to wide aperture, diffraction limitation suggests this. But this is not how most people use their cameras-

    It might be good if the test could cover three different scene types- to cover the more common aperture ranges- on 8x10, perhaps an example at wide open, like around f/8, another stopped down to around optimal for the format, say f/22 or so- and another set for maximum depth of field- say, f/45 or f/64. Something measurable near the centre and edge can provide the line pairs for counting...

    A lot more work, perhaps three separately run tests really- but it might serve to show up the differences in resolution provided by the same sensor, but on different scene types- determined by aperture size- in addition to the test between formats and technologies.

    A single test at a single aperture might provide data that could accidentally favour one system over another when using one set of chosen parameters, and so I think it might be seen to be a valuable, if slightly inconclusive and potentially biased test-*

    Sorry, just being difficult...

  9. #19
    mortensen's Avatar
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    Re: IQ180 and 8x10 assessment

    Thanks, Tim, for taking the time and thoughts to do this. Your film comparisons and articles in general has provided me a lot of information and thoughts!

  10. #20
    Still Developing
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    Re: IQ180 and 8x10 assessment

    Hi Folks - I've just come back from a walk (which I was actually getting paid to photograph! Bonus part of doing National Parks commissions). I'll make sure I get back to these questions in the next few hours but in the meantime, thank you very much for you suggestions. Keep them coming and I'll do my best to accomodate - Tim
    Still Developing at http://www.timparkin.co.uk and scanning at http://cheapdrumscanning.com

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