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Thread: Rodenstock 23mm lens performance

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    Rodenstock 23mm lens performance

    Interested in the observations of other photographers on the performance of the Rodenstock 23mm wideangle lens. Using on a Arca RM3di body with an IQ180 back I like the wide angle aspect but have found 2 main drawbacks to using this lens. Firstly, it is extremely prone to flare - a scene that includes a forest canopy with gaps through which light from clouds appears will invariably produce blue halos around these highlights on the image. See this image for an example of the flare, in this case controlled to some degree by fairly extreme highlight recovery.

    http://www.getdpi.com/gallery/files/...frcf009526.jpg

    And secondly, the lens is very distorted and soft at the corners with a close focussed subject.

    Anyone else with similar experiences?

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    Re: Rodenstock 23mm lens performance

    The R/S lenses are know for their propensity to flare. Difficult to avoid (in certain situations) given the number of large, curved glass surfaces in these retrofocus design lenses.

    When you say close focused, just how close do you mean? Even a lens as wide as the 23mm, if focused at (say) 2m on an IQ180, only has about 2.8m depth of field @ f11 (0.7 in front of the subject, 2.1m behind).

    Jim
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    Member AreBee's Avatar
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    Re: Rodenstock 23mm lens performance

    Jim,

    Quote Originally Posted by f8orbust View Post
    ...a lens as wide as the 23mm, if focused at (say) 2m on an IQ180, only has about 2.8m depth of field @ f11.
    This surely cannot be correct.

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    Senior Member etrump's Avatar
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    Re: Rodenstock 23mm lens performance

    You also have to take into account that the DOF is curved due to the RF design which seems to exaggerates itself at closer fields of focus.

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    Re: Rodenstock 23mm lens performance

    Quote Originally Posted by AreBee View Post
    This surely cannot be correct.
    Actually, it's a bit less - more like 2m - I was lazy and used data for a P65.

    The sensible way to shoot this lens (@f11 on an IQ180) is to focus at ~4.7m, and then everything from about 2.4m away will be in focus.

    Here's the IQ180 data (using a 2-pixel CoC):
    Last edited by f8orbust; 23rd May 2014 at 16:52.
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    Re: Rodenstock 23mm lens performance

    sigh - I'm looking for a wide lens that can accommodate tilt/shift movements and that will focus down to 30cm or less and be sharp throughout. Spoilt by the Canon 17TS on a DSLR:-)

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    Re: Rodenstock 23mm lens performance

    What's worth remembering is the extreme angle of view of the 23mm - something like 98/82/111 (h/v/d) on an IQ180 - so, if you choose to shoot at the HFD (@ f11) of 4.7m, the lens only needs to be at least 4' or 1.22m above the ground plane in order that everything within it's field of view (i.e. that it can 'see') will be within the dof.

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    Workshop Member Wayne Fox's Avatar
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    Re: Rodenstock 23mm lens performance

    Quote Originally Posted by Robblakers View Post
    sigh - I'm looking for a wide lens that can accommodate tilt/shift movements and that will focus down to 30cm or less and be sharp throughout. Spoilt by the Canon 17TS on a DSLR:-)
    Seems the 28mm is pretty close to the coverage of the canon 17 on a FF Canon. I had the 23 and I really just felt it was too wide. Just sold it, and have the 28mm coming. I think its a little less prone to the flare problem.
    wayne
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    Re: Rodenstock 23mm lens performance

    Wayne.

    Congratulations on the 28mm. I have found with mine that the Rodenstock CF makes a positive difference in overall image quality. The corners of the frame can get pretty noisy when the lens is used without the CF. Rodenstock uses the same CF for both the 23 and 28 and it takes you from 72mm to 95mm. Just wish this lens had the 90mm image circle as the 32mm.

    Paul

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    Re: Rodenstock 23mm lens performance

    I use my 23 for probably 90% of my images. I am a little surprised at the extent of flare the image you have posted is exhibiting. I regularly use mine in very similar circumstances without the problem you are having. It makes me wonder if you have a condensation issue or a smear on a lens element.
    The flare the 23 often gives me usually manifests as what I call the twin red disks of death. I've found that even with the most careful lens shading, these can still occur, especially when shooting interiors under down lights. I've found a simple post-production cure and accept that I will sometimes have to just deal with it, so if the shot needs the 23, I use it anyway.
    In short, the lens your lens is displaying is not what I am used to seeing, at least not to this extent.
    Siebel
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    Re: Rodenstock 23mm lens performance

    It would be greatly appreciated if folks (not just Siebel but others too) would share whatever "simple post-production cure" is effective in dealing with flare in the 23. Thanks.

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    Re: Rodenstock 23mm lens performance

    Quote Originally Posted by siebel View Post
    I use my 23 for probably 90% of my images. I am a little surprised at the extent of flare the image you have posted is exhibiting. I regularly use mine in very similar circumstances without the problem you are having. It makes me wonder if you have a condensation issue or a smear on a lens element.
    The flare the 23 often gives me usually manifests as what I call the twin red disks of death. I've found that even with the most careful lens shading, these can still occur, especially when shooting interiors under down lights. I've found a simple post-production cure and accept that I will sometimes have to just deal with it, so if the shot needs the 23, I use it anyway.
    In short, the lens your lens is displaying is not what I am used to seeing, at least not to this extent.
    Siebel:

    With the flare you describe, can you share your processing steps to remove it? I get the discs every once and a while with my 28 a Rodenstock or at least something that sounds similar.

    Sincerely
    Paul

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    Re: Rodenstock 23mm lens performance

    I have been dreading being asked this question as no matter what one says, someone will tear you to pieces.
    For what it's worth, these are my observations and practices. They are not absolutes as each image is slightly different. Use these as a guide, but engage your eyes and more importantly, your brain and adjust accordingly.

    The flare I am discussing here always appears close to the centre of frame in the form of an out-of-focus iris-shaped area with reduced Dmax (maximum density) and a red (not magenta) colour cast. If you look closely, you will notice a second, smaller flare within the confines of the first. I have only ever seen it when using the 23mm and 28mm HR Digarons and Alpagons.
    If the area and extent of the flare are not obvious, it can be helpful to dramatically steepen the curve in order to increase contrast and saturation, which makes it easier to identify the affected area. You are going to have to select it with your tool of choice, so you need to know where it is.
    The next step is to select the larger flare area (we use the same method on the smaller area after the larger has been dealt with). I usually use the lasso or pen tool with a feather of approximately 77 pixels (IQ180 processed to 100%). The feather will vary according to shooting aperture and output pixel dimensions. You will have to work out your own. My figures are just to give you a starting point.
    Once I have the selection, I bring up the curve tool and go to the red layer. You will always see that the histogram drops off well before Dmax (bottom left corner). Drag the bottom of the curve towards the drop off point of the histogram, but not all the way, whilst closely observing the image. You will need to stop just before the shadows start showing a Cyan cast. I usually find that the red curve will need to be dropped or 'bent' a little at the 3/4 tone as this seems to manifest the strongest red cast.
    Once I've done this, I then go to the RGB curve and make much the same adjustment, moving all 3 channels together. The reason is that the flare will have scattered non-image-forming light (i.e. "flare"), into all 3 colour channels, reducing shadow density or 'clipping' the shadows. This density needs to be restored and I do this by moving the black point.
    If you have done this right, you will have mostly eliminated the larger flare and will now have the smaller flare to deal with. I use the same method.
    This is a global fix that works most of the time. I sometimes find I have to do a little local detailed colour management to tiny parts of the corrected area, or have to use the history brush a little because I wasn't as accurate with my selection as I should have been.
    This may sound a little complex but with practice, it's pretty simple and the result is effective.
    I cannot recall a single instance where I have spent more than 5 minutes on doing this.
    As with any colour management work, it goes without saying that a calibrated workspace is essential as is working in 16bit colour mode.
    As I've indicated at the beginning, this is how I deal with the problem. There are many other ways to skin the same cat.
    Cheers,
    Siebel
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    Re: Rodenstock 23mm lens performance

    Siebel.

    Thanks for the info. The flare is as you pointed out quite destructive. I am always looking for a better solution for when I screw up and allow it to occur.

    Paul

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    Re: Rodenstock 23mm lens performance

    Don't beat up on yourself. I've found many occasions where the scene is such that you get the flare no matter what you do.
    Siebel
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Rodenstock 23mm lens performance

    Another trick that I use is in the field to shoot the desired image with LEE wide angle hood and then either extend the hood so that it vignettes or remove it and shoot covering ANY possible off center light source using your hand as a shade (even in the image) and shoot again. You'll have two images, one for the scene and the second essentially flare free which can be blended in post.

    I do a similar trick when shooting sunbursts - shoot for the scene and a second shot masking the sun or bright spot with your finger.
    Remember: adventure before dementia!

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    Re: Rodenstock 23mm lens performance

    Quote Originally Posted by GrahamWelland View Post
    Another trick that I use is in the field to shoot the desired image with LEE wide angle hood and then either extend the hood so that it vignettes or remove it and shoot covering ANY possible off center light source using your hand as a shade (even in the image) and shoot again. You'll have two images, one for the scene and the second essentially flare free which can be blended in post.

    I do a similar trick when shooting sunbursts - shoot for the scene and a second shot masking the sun or bright spot with your finger.
    You're right Graham, this is very useful but not always possible. I shoot quite a lot hand-held and if there is a lot of detailed content where the shade intrudes (as opposed to plain skies, handheld or on tripod) and sometimes this just won't work.
    Siebel
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Rodenstock 23mm lens performance

    Agreed that it's not an option for handheld - definitely tripod only tricks.
    Remember: adventure before dementia!

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

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