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Thread: Using an IQ back with Live View on a tech cam

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    Sr. Administrator Jack's Avatar
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    Using an IQ back with Live View on a tech cam

    I wrote this post in the tech cam image thread and thought it warranted further discussion on its own. Here is the original post for reference:


    Quote Originally Posted by Jack View Post
    A comment about live view and a crop from the second image above...

    I've started using live view to focus in the field with tilts and I can tell you it works amazingly well. The hardest thing to get used to is the 2 or 3 frame per second refresh. So you go to 100% view, make a small adjustment then pause to let the frame refresh and see if it's better or worse, repeating as necessary until everything is right. Another tip: you can white balance the live view image by droppering it while it is playing and this helps the preview significantly. Note that this WB does NOT affect the image, only the live preview color balance. Anyway, it was live view that let me nail the precise focus and tilt for this image, which required a few very slight iterative tilt and focus tweaks to get the foreground and background rocks in optimal focus -- if you've ever worked a view camera under the hood with a loupe on the GG, then you've done these these tilt and focus tweak iterations. It works the same way here, just with the slight pauses.

    This is a crop from the lower center part of the larger foreground rock. Keep in mind this is a 30 second exposure and I am on a small bridge that vibrates along with 4 other shooters, and a breeze is blowing, AND this is nearer the outer edge of the lens' IC. Granted it's not perfect, a few of the leaves are obviously being moved by the slight breeze and there are a few hot pixels, and I'm into an area of the IC where I'm getting some resolution falloff -- but considering all of that, it's still a pretty impressive result IMHO:

    Here is the original image again for reference that the above crop was taken from:



    ~~~

    Here are some more examples and info (hopefully) explaining the value LV played with my tech cam.

    The first was the "ah-ha" image that brought it home. It's not a great image, but I was wanting to try closer focus technique with my 40 and see how it performed. 1/4 sec at f11:



    I seriously shot about a dozen images tweaking focus trying to get the rim of frost on this cattail in focus. Doug told me to try live view, so I did. "Wow" was the first expression out of my mouth -- the reason I could not get the frost perfect is the DoF of even the R40 HR at f11 was so shallow that a fractional turn of the focus helical on my Arca, meaning about half a full number, went in front or behind the frost rim almost immediately. With live view, I could tweak half a hash-mark and register the sharpest plane right where I wanted it. (On the Arca, 1/10th a whole number is just slightly over 1 degree or 1/360th of a full turn on the focus helical.) Keep in mind these are still relatively longish morning light exposures and cattails move with a breeze. Here's the crop of the cattail I working with in live view, imagine my surprise when I could see the FM light up on the frost and the actual structure of the frost crystals in 100% review:





    Next example. I was at a stream later in the day, and wanted specifically to "practice" using LV to focus with large degrees of tilt. So I set this shot up. It is another long exposure, 2sec at f11 with the R70mm HR lens. My goal was to get the close rock moss and the far stream bank both in focus. The difference here is there was no infinity, and focus distances were much closer -- the lower rock is against my tripod leg, the moss maybe 20cm away from the camera and the far bank about 3 meters distant. Moreover, the camera is only about 0.5m off the ground. (Camera height affects final tilt angle.) Additionally, I had compounded my set-up by adding 15mm fall to get the perspective on the close rock I wanted. So I focused mid stream and wanted to see how many frames using Focus Mask plus 100% reviews while tweaking tilt and focus it would take to nail it. Seriously, I gave up after about 2 dozen frames -- I simply could not get anything in critical focus no matter what I tried!

    Here is the full frame:



    So I went into LV and while it still took about 3 or 4 minutes of iterative tilt and focus movements, I finally got it -- turned out because I had so much fall and pretty extreme tilt, I had originally estimated I'd need 3, I actually needed to move my focus to almost infinity to get the extreme plane I was after sharp!!! In the end, I added even more tilt to 4, then had focus probably around my 20 meter mark and got this result.

    Here is a crop of the moss on the near rock -- again remember this has 15mm fall, so the rock is quite a ways from center IC:



    And here is a crop of the far bank of the stream. Note this portion of the frame is near the center of the IC:



    Try to get this range of DoF without tilt! I did the online calculator (http://www.dofmaster.com/dofjs.html) using a 2-pixel average diagonal CoC of 12u, an aperture of 64 (smallest it goes) and even assuming zero diffraction, if I focused on the moss at 0.3m my total DoF extended from .29 to .31m! If I focussed at 2.1m, the far bank at 3m was my far DoF and I got my close DoF at 1.59m. At f11, the DoF at 3m was still only 0.5m -- totally explains why I could not get this nailed without using live view!

    In conclusion. When I first received my IQ back, I tested LV and almost immediately dismissed it as a viable or practical field shooting tool. The image is noisy, the refresh rate is painfully slow and I felt it more a gimmick than a serious tool. Well, that opinion changed last week. My new opinion is simple: If you are going to use tilts and want to have anything less than an exercise in frustration getting your camera set up, you'll want to use some form of "live" view. This can be live viewing of a ground-glass of course. But if you have an IQ back, do not assume the LV feature isn't valuable -- it is a valuable feature.
    Jack
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    "Perfection is not attainable. But if we chase perfection, we can catch excellence."

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    Re: Using IQ Live View with a tech cam

    Thanks for this update on using Live View with the IQ back.

    You do not mention Focus Mask capability. Is this feature of the IQ180 (or other IQ back) not usable when using Live View for focusing with tilts?

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    Sr. Administrator Jack's Avatar
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    Re: Using IQ Live View with a tech cam

    Excellent question David,

    Focus mask is only active on image review, so does NOT show up in the live view screen. But you can zoom in live view, so I am basically focusing on my selected points of interest using 100% zoom, then scrolling to the other point of interest and confirming -- hence why it's still an iterative process. Anybody who has shot a view camera can tell you that even there with loupe on GG, it's still an iterative process

    Moreover, folks should know that FM does not show in zoomed review either, only in the full-frame image review. It shows the range of focus depending on your actual settings; for my tech lenses, I use 70 as my normal, and often have to ramp it all the way up to 80 (max) because the lenses are so sharp or I get too much mask lighting up in the display. On my DF lenses, I use a setting of closer to 40.
    Jack
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Using IQ Live View with a tech cam

    It would be great to put together a short video of the iterative process using the IQ live view.

    I know that the first couple of times I tried to use it I was initially put off by the image rendering and white balance - the image builds and if exposure is too great then it completely falls apart on screen with colour shifts and regions not displayed. (Truthfully I thought oh crap, my back isn't working!). Once you have the exposure limited by stopping down or an ND filter (I haven't tried the filter yet) then things become a lot clearer. However, it's important to recognize that this isn't anywhere near the same live view quality as folks may have grown used to on Nikon & Canon pro DSLRs.

    Jack, what are your thoughts about using a loupe for assessing the IQ display? In daylight I actually found it somewhat tricky to view the image contrast as it felt kind of like watching a 1950's TV running off bunny ears.

    Having watched Jack work an image I'm impressed with the capabilities of the system with assessing tilts. You are definitely also going to want to have a very accurate and long throw helicoid for some of the adjustments described here - more so at distance than close up though.

    What is impressive is when everything is dialed in correctly and you see an image with focus mask illuminated right across the frame. Tough to do when just doing this by trial and error and a testament to the new IQ back's features.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Sr. Administrator Jack's Avatar
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    Re: Using IQ Live View with a tech cam

    Quote Originally Posted by GrahamWelland View Post

    Jack, what are your thoughts about using a loupe for assessing the IQ display? In daylight I actually found it somewhat tricky to view the image contrast as it felt kind of like watching a 1950's TV running off bunny ears.
    A good point Graham... To date, I have found shading the LCD with my hands enough to allow it to work for me, but then I have not shot it a lot under desert sun yet I have a shaded 4x loupe as well as a shaded and angled 3x loupe. The 3x is pretty small and it may come out for a test spin on my next shoot, if for nothing else than to comment on its practicality.

    A corollary point is I had a cell phone screen protector on my LCD and it was so fuzzy I had to remove it to get practical confirmation at 100% review. I just ordered some protectors based on Charles' advice from "ScreenPatronus," special cut for the IQ back -- I hope to put one on tonight and check it out. FWIW they are around $9 "each" plus shipping -- Charles warned me they were 3-packs but at $9 each I couldn't believe it, so I ordered 3. Sure enough they arrived and each unit is a 3-pack, so I have 9 total. I suspect I'll be handing a few out on the next workshop LOLOL!
    Jack
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    Re: Using IQ Live View with a tech cam

    Jack, are you focusing at the working aperture or fully open? Thanks.

    Cheers, -Peter

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    Sr. Administrator Jack's Avatar
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    Re: Using IQ Live View with a tech cam

    I am using the working aperture -- and hence need to add an obligatory for LF shooters (I added a DoF calculation on the last crop example above that explains why it does not matter.)

    The reality is at 5.2υ the effective CoC and associated DoF is so small, that using the working aperture is still generating a visible, usable result; a side benefit being it further eliminates concerns of focus shift from stopping down...
    Jack
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    Re: Using an IQ back with Live View on a tech cam

    "the reason I could not get the frost perfect is the DoF of even the R40 HR at f11 was so shallow that a fractional turn of the focus helical on my Arca, meaning about half a full number, went in front or behind the frost rim almost immediately."


    that's the proof that the arca helical mount precision is handy !
    Last edited by archivue; 10th October 2011 at 22:21.

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    Re: Using an IQ back with Live View on a tech cam

    Liveview is of significant value to all tech cam users, irrespective of focal length and regardless of whether they have tilt capable cameras or not.
    I have found it useful even when shooting with my non-tilting Alpa STC and the Rodie 23. You might think that the 23 has so much DOF that LV would be of limited value. My experience has shown me otherwise. Keep in mind also that the new 5.2micron sensors put more demands on critical focus.

    My current style involves frequently using foreground elements in the composition. Unlike a lot of people, I am also comfortable using selective focus even with ultrawides. I regularly shoot at f5.6 to f8. Working on cramped industrial sites with lots of visual clutter (I am writing this from an oil pipeline construction barge in Iraqi waters), I like to get very close to my subject, or to an element that will lead the viewers eye to the subject. Critical focus placement is essential, even with the ultra-wide lenses.

    Using LV with the lens wide open, I am able to place focus exactly where I want it. In some situations, it is quicker to pop a frame and zoom in, but in many, LV is quicker and more precise.

    I have found that viewing the screen is a little difficult in bright conditions. I carry a small black cloth that I use as a darkcloth when I need to, but a more elegant solution would be helpful. Some kind of bellows hood would be great.

    Has having LV changed how I work? Yes, I now have a lot more confidence shooting at larger apertures and this is creating picture opportunities where I might have previously passed up on a potential shot. I do wish it was a little faster to refresh and a little higher resolution, but as it is, it does work.

    Cheers,
    Siebel
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    Re: Using an IQ back with Live View on a tech cam

    +1
    TO Add what Bryan wrote I think another benefit is the speed of framing on tech cams. My productivity has increased significantly with live view and often don't bother stewing on the A'lpa view finder to frame my shots
    Grischa

    Quote Originally Posted by siebel View Post
    Liveview is of significant value to all tech cam users, irrespective of focal length and regardless of whether they have tilt capable cameras or not.
    I have found it useful even when shooting with my non-tilting Alpa STC and the Rodie 23. You might think that the 23 has so much DOF that LV would be of limited value. My experience has shown me otherwise. Keep in mind also that the new 5.2micron sensors put more demands on critical focus.

    My current style involves frequently using foreground elements in the composition. Unlike a lot of people, I am also comfortable using selective focus even with ultrawides. I regularly shoot at f5.6 to f8. Working on cramped industrial sites with lots of visual clutter (I am writing this from an oil pipeline construction barge in Iraqi waters), I like to get very close to my subject, or to an element that will lead the viewers eye to the subject. Critical focus placement is essential, even with the ultra-wide lenses.

    Using LV with the lens wide open, I am able to place focus exactly where I want it. In some situations, it is quicker to pop a frame and zoom in, but in many, LV is quicker and more precise.

    I have found that viewing the screen is a little difficult in bright conditions. I carry a small black cloth that I use as a darkcloth when I need to, but a more elegant solution would be helpful. Some kind of bellows hood would be great.

    Has having LV changed how I work? Yes, I now have a lot more confidence shooting at larger apertures and this is creating picture opportunities where I might have previously passed up on a potential shot. I do wish it was a little faster to refresh and a little higher resolution, but as it is, it does work.

    Cheers,

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    Re: Using an IQ back with Live View on a tech cam

    Quote Originally Posted by rupho View Post
    +1
    TO Add what Bryan wrote I think another benefit is the speed of framing on tech cams. My productivity has increased significantly with live view and often don't bother stewing on the A'lpa view finder to frame my shots
    Grischa
    I use LV to compose. If working off a tripod, LV is much more precise than the viewfinder. I still use the VF if shooting a lot of handheld images.
    Bottom line for me is that LV adds to the benefits I chose the little Alpa STC for - light weight and speed of handling combined with superb precision. For the way I work, there's currently no other camera that comes close.
    Siebel
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    Re: Using an IQ back with Live View on a tech cam

    I often use the VF to find and compose my images before even pulling the camera out of the bag
    Jack
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    Re: Using an IQ back with Live View on a tech cam

    Quote Originally Posted by Jack View Post
    I often use the VF to find and compose my images before even pulling the camera out of the bag
    What's the camera doing in the bag?
    Mine's usually on my shoulder.
    Siebel
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    Sr. Administrator Jack's Avatar
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    Re: Using an IQ back with Live View on a tech cam

    LOL. Mine is usually on the tripod to shoot, and then in my bag for protection during transport to the location. So the finder comes out to help me frame first and decide if my current location is even going to become a shooting location!
    Jack
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    Re: Using an IQ back with Live View on a tech cam

    By the way, when using live view is there a way to capture a picture without going out LV first ?
    Today I make adjustments in LV, then quit LV, take the shot, relaunch LV.
    The Phase white papers don't explain the right process for taking pictures when LV is engaged.

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    Re: Using an IQ back with Live View on a tech cam

    Quote Originally Posted by anGy View Post
    By the way, when using live view is there a way to capture a picture without going out LV first?
    I'd be surprised if this was possible with a CCD - if it was, the back could take over the function of a shutter. As far as I know, no light must hit the (CCD) sensor right before the exposure, and no light must hit it while the result of the exposure is being read.

    Chris

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    Re: Using an IQ back with Live View on a tech cam

    Correct -- you must exit LV to take a picture. So my workflow is compose and focus with LV until it looks right at 100 LV, then take a picture and confirm focus with FM and 100% review of critical areas in the image. So far, that's been adequate -- keep in mind I just started using it. But if I found an issue during the above, I would re-engage LV and repeat the above process to tweak the composition to my satisfaction. Note too that I only use LV for difficult composition/focus situations, there are plenty of straight shots that don't require it.
    Jack
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    Re: Using an IQ back with Live View on a tech cam

    Quote Originally Posted by anGy View Post
    By the way, when using live view is there a way to capture a picture without going out LV first ?
    Today I make adjustments in LV, then quit LV, take the shot, relaunch LV.
    The Phase white papers don't explain the right process for taking pictures when LV is engaged.
    No. You must exit Live View, capture any normal images, and if desired re-enter Live View.

    It's a good idea to wait a few seconds (literally 2-10 seconds depending on how long you were using live view and the ambient temperature) to allow any heat which has built up during extended use of live view to dissipate off the sensor. This is more critical if you are shooting at higher ISO or capturing longer exposures.

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    Re: Using an IQ back with Live View on a tech cam

    expecting my upgrade to IQ 160 to arrive today so enbarking on a new journey - was planning to get either a Cambo or Hoodman sort of focusing loup - the sort for the Canon etc LCD to use on the GG - any reason one could nto be used on this LCD as well ?
    too much mag ? fit issues ?

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    Sr. Administrator Jack's Avatar
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    Re: Using an IQ back with Live View on a tech cam

    You can and it may help some, though it magnifies the screen pattern too. But speaking for myself, I find the 100% zoom view (on review and live) more than adequate for determining critical focus.
    Jack
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    Re: Using an IQ back with Live View on a tech cam

    I don't think a loupe will help at all. The image onscreen can be zoomed in to 400%, waaay beyond the 160% or so that I find works well for checking focus.
    The real issue is that because the screen in reflective, it reflects your face in the image you are trying to view.
    What is required is come kind of shade that covers both the screen itself, and your face.
    Siebel
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    Re: Using an IQ back with Live View on a tech cam

    Quote Originally Posted by siebel View Post
    ...
    The real issue is that because the screen in reflective, it reflects your face in the image you are trying to view.
    What is required is come kind of shade that covers both the screen itself, and your face.
    I agree, I use this old Schneider 6x6 loupe (with the black skirt of course, I had it sitting around) and it shades perfectly in direct sunlight, it's about x2.5, but as you say not really needed. However, it works very nicely for me on the IQ screen. Just an idea.

    Cheers, -Peter

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    Re: Using an IQ back with Live View on a tech cam

    Just got this for my IQ

    Product page: http://www.peakoptics.com/index.php?...roducts_id=103

    B&H Link: http://www.bhphotovideo.com/c/produc..._4x_Loupe.html

    Not full screen but light and easy to check focus.
    It has no eye cup but keeps out light when your eye is looking through it.
    It works in full sun with the black plastic housing.
    The view covers about 95% of the preview when the tools are visible at the same time.

    Easy to see whats going on in harsh light.
    Have needed to use it many times.

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