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Thread: Tech cameras and IQ.

  1. #151
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    Re: Tech cameras and IQ.

    Quote Originally Posted by TH_Alpa View Post
    My intervention was neither a sales pitch for Alpa, nor meant to try convincing, but rather a contribution with the wish to bring all the critical information concerning focus to those who wish to be fully informed before making a decision, nothing more.

    Therefore my apologies if some have felt hurt.

    Best regards
    Thierry
    On the contrary, information about these things is invaluable form people in the know but it got a bit more than that yesterday (Sunday).

    Info about the focusing on the Alpa is interesting but turning it into a mines more accurate than yours thread IMO isn't helpful to anyone. I would to hear your points Thierry.

    Info is power and helps perspective buyers when reasearching these exotic cameras and lenses. Tit for tat squabbles don't.

  2. #152
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    Re: Tech cameras and IQ.

    Theory is theory, but I agree with Thierry that the best thing to do is try both in person.
    Carsten - Website

  3. #153
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    Re: Tech cameras and IQ.

    Quote Originally Posted by TH_Alpa View Post
    After long thoughts (and a good night) I came to the conclusion that I won't bring my arguments to this topic, to the contrary of what I promised yesterday.

    It seems that it heats up the place, which I didn't mean to cause with my posts.

    I was of the opinion, that I have been very calm, respectful and understanding, and wasn't expecting such frontal attacks, having not myself attacked anybody.

    I have tried to give full information concerning a topic which is way too important that it can boiled down to a few claims or numbers on paper without having the possibility to discuss it with all the variables in the hands.

    My intervention was neither a sales pitch for Alpa, nor meant to try convincing, but rather a contribution with the wish to bring all the critical information concerning focus to those who wish to be fully informed before making a decision, nothing more.

    Therefore my apologies if some have felt hurt.

    Best regards
    Thierry
    Thierry

    We need to keep an open and honest dialog going otherwise the information that is shared can become too one-sided. Your area of expertise is Alpa and the information shared by you is valuable thus should not be stopped. I neither felt your contribution as a sales pitch or an attempt to convince one is better than another.

    A person considering leaping into the wonderful world of tech cameras needs as much information both pro and con of all systems and they get it from you when it comes to Alpa. Likewise hands-on experience is invaluable, what works what doesn't work, or the work a rounds that were found from hard experience. It irks me that we don't have the same level of openness (for a lack of another term) from other manufactures. Why isn't there a rep from Cambo? Or if there is how the heck did I miss the post?

    In short (or as short as I can be) - please keep it up. The one thing that brought me here in the first place is the open, frank discussions.


    Don
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  4. #154
    Senior Member Thierry's Avatar
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    Re: Tech cameras and IQ.

    Thanks Gareth,

    May I simply refer to the earlier posts claiming that as such a helical ring had to be more accurate than the Alpa-type of focusing (this is better than that), basing these claims only on some calculations and numbers, but not all calculations and numbers coming in the equation.

    If I want to do my "job" correctly" (inform and give accurate information), and knowing the whole story (without wanting to be pretending, since I had to look for it as well) and that it isn't that simple and that true as it was/is presented, I have to intervene and try to clarify with complete information.

    Therefore I answered that it was true in se (that the helical ring of a Arca camera was in theory more accurate), but far from taking in count all the parameters, which when they are (taken in count in the theory and in practice), make the whole story look completely different. And there are some few more parameters in addition to the sole precision of this ring.

    One sometimes tends (me included) to look, analyze and conclude only with the provided information, which sometimes isn't presented in extenso, sometimes purposely and sometimes by lack of knowledge (me included). This lack of full information unfortunately sometimes costs a lot.

    But all that isn't that important if the sole result is to hurt others in their beliefs. That I don't want.

    Therefore we can close this particular chapter.

    Best regards
    Thierry

    Quote Originally Posted by gazwas View Post
    On the contrary, information about these things is invaluable form people in the know but it got a bit more than that yesterday (Sunday).

    Info about the focusing on the Alpa is interesting but turning it into a mines more accurate than yours thread IMO isn't helpful to anyone. I would to hear your points Thierry.

    Info is power and helps perspective buying when reasearching these exotic cameras and lenses. Tit for tat squabbles don't.

  5. #155
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    Re: Tech cameras and IQ.

    +1 (Don)

    Good on Alpa for actually having a presence on forums like this. Even if the debate gets heated, at least there is a debate. Trying to hold a similar conversation with Arca, Cambo, Linhof, Sinar etc. would just leave you talking to yourself...which, unless you're as old as the hills, is never a good thing.

  6. #156
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    Re: Tech cameras and IQ.

    Thierry

    Your comments here have surely made interesting reading for us all.

    Being the proud owner of both an Arca Rm2d and an Alpa STC, I agree with your point of view. Although I admire the conceptual simplicity of the Arca's helical ring, I find myself almost always reaching for the Alpa for a couple of reasons

    (a) I find the STC with HPF rings to be quicker and easier to gain acceptable focus at a known distance. (This may no longer be the case when the Arca eModule surfaces.)

    (b) the somewhat smaller size and weight of the STC and shape of its wood grip make it easier to get a secure hold and IMO more pleasant to work with. I can remove the camera from its case and mount it with no fear of dropping it. I must say here, though, that my trusted Arca dealer Walter Borchenko recently provided me with an optional grip extension which has made the Rm2d much easier to handle. Highly recommended.

    (c) mounting a lens with the Alpa clamps is more definitive. I'm never quite sure that the degree of tightness of the screw mount of lenses on the Arca is the same as it was when I did the calibration. Paranoia, perhaps?
    Last edited by David Duffin; 4th July 2011 at 13:56.

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    Re: Tech cameras and IQ.

    Emails and postings are difficult to do as they are often misinterpreted. It is a dangerous business.

    Thierry, I would hope that you would basically ignore any confrontational responses in the future as I hope to learn from you why I made such a great decision!

    Though I've been following this thread closely, I have to admit that there are some aspects to the helical focus and the lens complexity of the Arca system that concern me. Firstly, when you tilt, having to turn the lens focus rings four entire turns to determine nearest and farthest points (which is what I do before I begin tilting) seems incredibly painful. With tilt, I am constantly adjusting both tilt and focus until the parts of the image I want in focus are; it's a combination of these two controls that provides what I want. Often I use them simultaneously, which with so many turns of the helical would be, to say the least, inhibiting. Sure, I could do a Schiemflug calc each time and set it accurately, I guess, with the helical focus and the tilt measurements, but I trust my eyes more than a calc. And each scene is different. Studio shooting is different, but for what I do (landscapes) no two are the same...

    So for MY type of shooting, MY workflow (without an IQ back) I saw the helical focus as a negative, not a positive.

    And IMO and from MY real world experience, much of this discussion is counting angels on the head of a pin. The MFDBs are outstanding; Phase, Leaf, Hasselblad/Imacon/Whomeverownsthemnow. And all of the tech cameras being bantered about here are going to give you results that will simply blow your shorts off.

    So thanks to EVERYONE who contributes to the thread (I certainly learned a lot and have a lot of respect for all who go into such terrific detail in their testing). Think about these wonderful test results; think of how you shoot; think of what is REALLY important to your workflow. All important factors and all valid contributions to this great forum...

    I'll go take my meds now...

    Best,
    Bob

  8. #158
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Porpoise View Post

    Jack, focusing on 360m at f/8 gives you maximum resolution from 34.7pm and beyond. Focusing at 90m makes maximum resolution start at 26.9m.
    Question, what CoC did you use? I just had some time to pull my calculator out and by some loosey-goosy reverse analysis, it appears you used approximately 2-pixels or just over 10u as your CoC. And I'd agree that is a conservative CoC to choose even for super critical print purposes. However, if you use actual pixel view (CoC~=5.2u on teh IQ180/Aptus 12) to confirm precise infinity focus, I assure you you can "see" 90m, 180m and 360m pop into focus at different settings, and then have your 5Km infinity look a little "soft" at either the 90m or 180m focus point relative to the 360m focus point, again using f7 for a little more criticality than f8. Now I agree this difference may be academic, but with the IQ180 sensor, it is now VISIBLE, so IMHO it is worth discussing... In use and IMHO only, I think a realistic "infinity" for practical PRINT uses would be 90m with this 40 at f8 over the IQ180/Aptus 12 back.

    Cheers,
    Jack
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Jack Flesher View Post
    Two areas for me Stephen: First is minor: allowing me to define a few different "infinity" focus points -- ie; 360 meters or 180 meters, or 90 meters. With the Arca I can hit these pretty precisely at f8, and while not impossible is going to be more difficult with a tradition tech helical. Will the differences be significant in a large print? Certainly not if you don't have the three versions to compare, but maybe yes if you do .
    Jack, could you explain the advantages of having 'different infinity focus point' for me? I am trying to learn the 'in and out' of technical/view camera focusing.

    Also, does Arca Rm3d have a 'calibrated tilt' dial so you can set to an exact angle (1.8 degree or 2.5 degree, etc) the same way focusing are done in micron?

    Jae Moon
    Last edited by Jae_Moon; 5th July 2011 at 07:40.

  10. #160
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Jack Flesher View Post
    Question, what CoC did you use? I just had some time to pull my calculator out and by some loosey-goosy reverse analysis, it appears you used approximately 2-pixels or just over 10u as your CoC. And I'd agree that is a conservative CoC to choose even for super critical print purposes. However, if you use actual pixel view (CoC~=5.2u on teh IQ180/Aptus 12) to confirm precise infinity focus, I assure you you can "see" 90m, 180m and 360m pop into focus at different settings, and then have your 5Km infinity look a little "soft" at either the 90m or 180m focus point relative to the 360m focus point, again using f7 for a little more criticality than f8. Now I agree this difference may be academic, but with the IQ180 sensor, it is now VISIBLE, so IMHO it is worth discussing... In use and IMHO only, I think a realistic "infinity" for practical PRINT uses would be 90m with this 40 at f8 over the IQ180/Aptus 12 back.

    Cheers,
    An Epson 9900 started my spiral dive into digital MF territory. As PhaseOne asks .0615 dollar cent per pixel, I want full use of each and every pixel. So I always use the pixel size as CoC in the formula
    Front DoF = CoC x Fstop x Distance^2 / ( FocalLength^2 + CoC x Fstop x Distance )

    When focussing at 360m with a 40mm lens at f/8, at 90m you should get a CoC of .0019mm. Focusing at 90m you get a CoC of .0022mm at infinity. So the results seem quite consistent.

    The formula I use, could be wrong, but I start to suspect the interaction between pixel size and CoC might be more subtle than we think, and perhaps CoC should be a lot less than pixel size, more like .002mm. That would explain what Jack is seeing, but makes me worry about diffraction. More experiments, perhaps with ABX-comparing, seem necessary. :-D

  11. #161
    Senior Member Thierry's Avatar
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    Re: Tech cameras and IQ.

    Dear David

    Thanks for your contribution.

    I don't want to "pollute" this thread, but there are some more options available, when it comes to handgrips for the STC, namely the rotatable handgrip (add-on handgrip left/right, available in rosewood natural and in black).

    Shown in the pictures is the alternative with release cable, with or without STC handgrip.

    The rotatable grips can be set in over 20 securely locked positions by loosing one single screw. In this position and with the viewfinder one can shift vertically up by 18 mm (18 mm vertically down on the backside).

    The viewfinder can obviously as well be mounted on the side, allowing for rise/fall shifts simultaneously

    These handgrips are not displayed currently in the Alpa catalog of products, but some are available from stock and can be manufactured any time.

    Best regards
    Thierry

    Quote Originally Posted by David Duffin View Post

    (b) the somewhat smaller size and weight of the STC and shape of its wood grip make it easier to get a secure hold and IMO more pleasant to work with. I can remove the camera from its case and mount it with no fear of dropping it. I must say here, though, that my trusted Arca dealer Walter Borchenko recently provided me with an optional grip extension which has made the Rm2d much easier to handle. Highly recommended.

  12. #162
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    Re: Tech cameras and IQ.

    Beautiful!
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    Re: Tech cameras and IQ.

    Thierry,
    Win some major points here ....... Market a metal adapter for your beautiful rosewood handles to fit other cameras.
    Joseph
    (RL3d owner, hint, hint, wink, wink)

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    Re: Tech cameras and IQ.

    I have to admit, those rotating exotic hardwood handles look very cool!
    Jack
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    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    I am a longtime Arca user (4x5" film cameras, 6x9 film cameras, M2 digital studio), but I have to say, the Alpa's are prettier! I have black rubber hand grips on my Alpa Max and do find it to be a 'sexy tech' camera. Where function meets beauty is an easy sale for me.

    What I am interested in (without opening a can of worms here), is focus stacking and the better focusing technique to get my dof stacks. Using a rail has been the standard, but reading through this thread has me thinking maybe there is a better way with helical lenses. I would not buy into the 120 macro with the Alpa because I felt the rail system for macro focus stacking was still better. I find myself sometimes blending 25+ exposures. Maybe there is something better now.

    Anybody try the Arca R seies or Alpa cameras with the Schneider 120 macro and focus stacking?
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    Anybody try the Arca R seies or Alpa cameras with the Schneider 120 macro and focus stacking?
    Darr, I would imagine the lens to focal distance to be too great to practically use a pancake camera for macro. Unless that is I'm not understanding helical mounting of lenses. IMO rail cameras and their bellows between lens and sensor are better suited to macro work.

  17. #167
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    Re: Tech cameras and IQ.

    Quote Originally Posted by gazwas View Post
    Darr, I would imagine the lens to focal distance to be too great to practically use a pancake camera for macro. Unless that is I'm not understanding helical mounting of lenses. IMO rail cameras and their bellows between lens and sensor are better suited to macro work.
    Thanks Garth, I thought that was the case, but you never know where technology goes these days.
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    Re: Tech cameras and IQ.

    got me curious...
    all you have to do is this

    http://www.diyphotography.net/create...image-stacking

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    Re: Tech cameras and IQ.

    I'm an Arca ML2 user but have casually been looking at pancake cameras recently and I wonder if Thierry, or any other Alpa user could please explain a question about the Max. Why have Alpa put rise and fall on the lens side and lateral shift on the back? I don't know any situation why this would be a better solution than both movements on the back of the camera like the RM3di. So much so, Alpa make an adapter to convert the camera so it functions in this way.

    Any ideas why the Alpa method is preferable to the Arca?

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    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by jlm View Post
    got me curious...
    all you have to do is this

    http://www.diyphotography.net/create...image-stacking
    I appreciate the info and cool video, but moving the object to achieve dof is not always an option--I wish it was. It sure was entertaining to see what a techie can come with with only $20 worth of electronics and a 5.25" floppy drive!

    Pretty cool!
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Joe View Post
    Thierry,
    Win some major points here ....... Market a metal adapter for your beautiful rosewood handles to fit other cameras.
    Joseph
    (RL3d owner, hint, hint, wink, wink)
    Joe, Arca-Swiss does offer handgrip extensions which work very well.
    Allowing easier handling in a carry or hand-holding situation.


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    Re: Tech cameras and IQ.

    gazwas,
    You should watch this video on the Alpa site:
    http://www.alpa.ch/en/products/camer...pa-12-max.html

    Firstly, you can put the lens on either side and the back on either side (but not both on the same side at the same time ). But with the stitching adapter, which you see in the video, you can do three levels of "rise" and leave the lens in one position. Then you can do 3 shift pics at each level of rise, giving you 9 images to stitch without the lens being moved.

    IMO this is the best way to do panos; don't move the lens. You can also, with the T/S adapter, incorporate either tilt or swing depending on the way you mount the adapter. The T/S adapter can either be mounted on the lens side or the back side.

    Hope this helps,
    Bob

    Quote Originally Posted by gazwas View Post
    I'm an Arca ML2 user but have casually been looking at pancake cameras recently and I wonder if Thierry, or any other Alpa user could please explain a question about the Max. Why have Alpa put rise and fall on the lens side and lateral shift on the back? I don't know any situation why this would be a better solution than both movements on the back of the camera like the RM3di. So much so, Alpa make an adapter to convert the camera so it functions in this way.

    Any ideas why the Alpa method is preferable to the Arca?

  23. #173
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    Anybody try the Arca R seies or Alpa cameras with the Schneider 120 macro and focus stacking?
    Does a Linhof count? For macro work, you are better off with a rail for the reasons stated above and for the fact you can focus with the back.

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    Re: Tech cameras and IQ.

    Quote Originally Posted by rga View Post
    gazwas,
    You should watch this video on the Alpa site:
    http://www.alpa.ch/en/products/camer...pa-12-max.html

    Firstly, you can put the lens on either side and the back on either side (but not both on the same side at the same time ). But with the stitching adapter, which you see in the video, you can do three levels of "rise" and leave the lens in one position. Then you can do 3 shift pics at each level of rise, giving you 9 images to stitch without the lens being moved.

    IMO this is the best way to do panos; don't move the lens. You can also, with the T/S adapter, incorporate either tilt or swing depending on the way you mount the adapter. The T/S adapter can either be mounted on the lens side or the back side.

    Hope this helps,
    Bob
    Hi Bob, I have watched the videos and that is what prompted my question. I know I can convert the camera with the purchase of an additional bracket but I wasn't really asking how you do stitch but more of a camera design related question. Why have Alpa designed the Max with movements that are usually done together on the back or lens rather than seperate on the Max?

    Is is just a design decision or is there a specific reason/movement I'm not seeing.

  25. #175
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Shashin View Post
    Does a Linhof count? For macro work, you are better off with a rail for the reasons stated above and for the fact you can focus with the back.
    I am unaware of a Linhof pancake type camera. Thank you for your comment, but when does it matter if you focus with the front or the back if the plane of focus is stationary? The image perspective does not change with these rail-less cameras as with view cameras + movements from my experience.

    I am curious about macro done with a pancake type tech camera (Arca R series or Alpa) with helical lenses + extensions.
    Anybody?
    Last edited by darr; 6th July 2011 at 03:03.
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    Re: Tech cameras and IQ.

    moving the lens to set focus will change the image size and perspective

  27. #177
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by jlm View Post
    moving the lens to set focus will change the image size and perspective
    Yes, thank you, that is what focus stacking is for.

    I would like to know if there is a benefit to creating stacks from a helical focusing device rather than rail movements. Rail movements made on my Arca M2 may not be as precise as the movements made from the R series helical device. I have read that the R series' helical device has 4-5 spins for incremental focusing and that is probably more precise than my rail which has some slop in it (view camera slop). I am curious if anyone has put it to the test for focus stacking in macro with a macro lens and extensions.
    "Creativity takes courage." ~ Henri Matisse
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    Re: Tech cameras and IQ.

    darr

    You can combine your ARCA-SWISS M-two camera with a Rm3Di
    and use the rear carrier for coarse focussing, the helical focus mount
    of the Rm3di for fine focussing or stacking.

    Marc
    ARCA-SWISS
    Customer Support

  29. #179
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    I am unaware of a Linhof pancake type camera. Thank you for your comment, but when does it matter if you focus with the front or the back if the plane of focus is stationary? The image perspective does not change with these rail-less cameras as with view cameras + movements from my experience.

    I am curious about macro done with a pancake type tech camera (Arca R series or Alpa) with helical lenses + extensions.
    Anybody?
    Sorry, I was not clear. The Linhof is a rail camera (I have used a Horseman technical camera as well though, but it was not great for macro). Focusing from the back with a rail camera keeps the lens to object distance the same and makes camera positioning easier. Before we motorized our scopes, the focus stack was done manually by turning the focus knob a certain number of degrees, usually about a quarter turn. I would expect you can do the same with your rail camera. You may also be able to add a scale to the focus knob.

    Most of the focus stacking I done is under compound microscopes. The focus increment is related to the depth of field, so the precession of focus movement is relative. Capturing more stacks is just adding data, but no real change in results.

    Have you ever been to this forum?

    http://www.photomacrography.net/

    This might give you some great information.

  30. #180
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Shashin View Post
    Most of the focus stacking I done is under compound microscopes. The focus increment is related to the depth of field, so the precession of focus movement is relative. Capturing more stacks is just adding data, but no real change in results.

    Have you ever been to this forum?

    http://www.photomacrography.net/

    This might give you some great information.
    Thanks for the info and yes, I am familiar with that forum. It has a lot of valuable info. I use the millimeter scale on my rail for stepping and I am sure a focus knob scale may be a little better, but there is always a tiny bit of slop with the view camera. Still wondering however, if the Arca R series focusing device is better than my rail (without motor).


    Thanks again,
    Darr
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    Re: Tech cameras and IQ.

    Question

    IF we agree that precise shimming of a Tech Camera setup within 1/100 can make a big difference
    in terms of IQ, why shouldn't we use this precision at any distance?

    quote: Jim post 94

    brain wandered while i was running a machine...came up with this comparison to jack's findings. I am using Cambo lenses on I assume, Cambo helical focusing mounts

    43mm lens: closest focus is 400mm with lens-to sensor calculating to 48.17mm. focus barrel rotates about 110 degrees. that works out to .047 mm (47 microns) per degree of rotation

    70mm lens: closest focus is 800mm with lens-to sensor calculating to 76.7mm. focus barrel rotates about 270 degrees. that works out to .025 mm (25 microns) per degree of rotation

    120mm lens: closest focus is 2,600mm with lens-to sensor calculating to 125.8mm. focus barrel rotates about 250 degrees. that works out to .023 mm (23 microns) per degree of rotation

    Looking at what jack posted, he was getting 170 ticks per full revolution, so each tick is about 2.11 degrees. His result of 14 microns per tick is then 7 microns per degree

    So the Arca is 7 microns per degree for all lenses
    the Cambos (and probably the Alpa's) are from 47 to 23 microns of lens movement per degree of barrel rotation...
    Rod
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  32. #182
    Member David Duffin's Avatar
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    Re: Tech cameras and IQ.

    A very impressive comparison, Rod! Thank you

  33. #183
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    Still wondering however, if the Arca R series focusing device is better than my rail (without motor).
    Darr, not sure about the RM3d as there is very little info around about anything Arca but if things work like the Alpa site suggest you could test the sort of image magnification with you ML2.

    The details of the Schneider 120M Digitar lens are:

    Shutter: Copal 0
    Aperture: f 5.6 - f 45
    Image circle at full aperture: 110 mm (1:1)
    Image circle at f 11: 110 mm (1:1)
    Max. angle: 48
    Distance settings: 1.1 m - infinity
    Helical mount: special helical mount with 17 mm travel

    So if the minimum focus distance is 1.1m, that doesn't sound that close/macro to me.

    If you camera suffers view camera slop, imagine hanging that (pic attached below) thing off the front of an Alpa at full stretch....... You'd get pancake droop I'd imagine.

    Sorry if I'm breaking any rules posting an Alpa image?
    Last edited by gazwas; 11th August 2011 at 23:52.

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    Re: Tech cameras and IQ.

    Hi Darr ...
    "but when does it matter if you focus with the front or the back if the plane of focus is stationary?"

    The problem with Macro is that by changing the focus (therefore the distance between the lens and the film), you actually change the size of the image projected to the film. The more magnification of the subject the more you will see this effect. So stitching becomes potentially more error prone. If you use a macro rail to actually move the whole camera you'll be better off, but you are limited to how much of the subject the macro rail can accommodate.

    By focusing with the back it is less of a problem but it's still there.

    The big problem with focus stacking is the stuff that is wider than can be accommodated with your focus rail but still close enough that changing the focus changes it's size.

    With regards to tilts. I am still working through the math and until I actually get an Alpa tilt adapter, will not really know if what I am seeing is true ... basically as you tilt, you loose DoF and need smaller apertures. It seems more and more that tilt will be quite limited on the new backs.

    Paul

  35. #185
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by RodK View Post
    Question

    IF we agree that precise shimming of a Tech Camera setup within 1/100 can make a big difference
    in terms of IQ, why shouldn't we use this precision at any distance?

    quote: Jim post 94

    brain wandered while i was running a machine...came up with this comparison to jack's findings. I am using Cambo lenses on I assume, Cambo helical focusing mounts

    43mm lens: closest focus is 400mm with lens-to sensor calculating to 48.17mm. focus barrel rotates about 110 degrees. that works out to .047 mm (47 microns) per degree of rotation

    70mm lens: closest focus is 800mm with lens-to sensor calculating to 76.7mm. focus barrel rotates about 270 degrees. that works out to .025 mm (25 microns) per degree of rotation

    120mm lens: closest focus is 2,600mm with lens-to sensor calculating to 125.8mm. focus barrel rotates about 250 degrees. that works out to .023 mm (23 microns) per degree of rotation

    Looking at what jack posted, he was getting 170 ticks per full revolution, so each tick is about 2.11 degrees. His result of 14 microns per tick is then 7 microns per degree

    So the Arca is 7 microns per degree for all lenses
    the Cambos (and probably the Alpa's) are from 47 to 23 microns of lens movement per degree of barrel rotation...
    Rod
    So Rod, can I give up my rail for more accurate focus stepping?
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    Sr. Administrator Jack's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    So Rod, can I give up my rail for more accurate focus stepping?
    Darr,

    If I shot a lot of studio product and/or macro, I would own an Arca M-line 2 rail camera AND the RM3D. You can get the R lens-mount for the M-line 2 and use all your existing tech lenses in the R mounts, best of all worlds in tech land

    Edit: For whatever weird reason, Rod's post above was not visible when I posted this comment -- Sorry Rod!
    Jack
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  37. #187
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by gazwas View Post
    Darr, not sure about the RM3d as there is very little info around about anything Arca but if things work like the Alpa site suggest you could test the sort of image magnification with you ML2.

    The details of the Schneider 120M Digitar lens are:

    Shutter: Copal 0
    Aperture: f 5.6 - f 45
    Image circle at full aperture: 110 mm (1:1)
    Image circle at f 11: 110 mm (1:1)
    Max. angle: 48
    Distance settings: 1.1 m - infinity
    Helical mount: special helical mount with 17 mm travel

    So if the minimum focus distance is 1.1m, that doesn't sound that close/macro to me.

    If you camera suffers view camera slop, imagine hanging that (pic attached below) thing off the front of an Alpa at full stretch....... You'd get pancake droop I'd imagine.

    Sorry if I'm breaking any rules posting an Alpa image?
    I looked at getting the Schneider 120 macro for my Max for about 15 seconds. I realized I would need to buy some very expensive extension plates, plus, as you stated, the front weight distribution would appear awkward . The advantages of using the M2 always comes back into play when I look at the cost of lenses, accessories and bellows extension.

    I think I am looking for a 'magic bullet' in helical focusing.
    Last edited by darr; 6th July 2011 at 08:13.
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    Re: Tech cameras and IQ.

    You can add the macro tubes to the lens and/or back side to balance it Also I think the 120 has a special extended helical that means you might not need as much extension via tubes

  39. #189
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by Jack Flesher View Post
    Darr,

    If I shot a lot of studio product and/or macro, I would own an Arca M-line 2 rail camera AND the RM3D. You can get the R lens-mount for the M-line 2 and use all your existing tech lenses in the R mounts, best of all worlds in tech land
    That Jack is one of the reasons I am trying to make it to New Hampshire this Fall. Other reasons are the scenery and people, but I want to try the R series and pick the heads of all the photogs there. I will know in a few days if I can swing it.
    "Creativity takes courage." ~ Henri Matisse
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  40. #190
    Senior Member darr's Avatar
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    Re: Tech cameras and IQ.

    Quote Originally Posted by wentbackward View Post
    Hi Darr ...
    "but when does it matter if you focus with the front or the back if the plane of focus is stationary?"

    The problem with Macro is that by changing the focus (therefore the distance between the lens and the film), you actually change the size of the image projected to the film. The more magnification of the subject the more you will see this effect. So stitching becomes potentially more error prone. If you use a macro rail to actually move the whole camera you'll be better off, but you are limited to how much of the subject the macro rail can accommodate.

    By focusing with the back it is less of a problem but it's still there.

    The big problem with focus stacking is the stuff that is wider than can be accommodated with your focus rail but still close enough that changing the focus changes it's size.

    With regards to tilts. I am still working through the math and until I actually get an Alpa tilt adapter, will not really know if what I am seeing is true ... basically as you tilt, you loose DoF and need smaller apertures. It seems more and more that tilt will be quite limited on the new backs.

    Paul
    Thanks for this Paul.
    "Creativity takes courage." ~ Henri Matisse
    Darlene Almeda, photoscapes.com

  41. #191
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    Re: Tech cameras and IQ.

    Quote Originally Posted by wentbackward View Post
    You can add the macro tubes to the lens and/or back side to balance it Also I think the 120 has a special extended helical that means you might not need as much extension via tubes
    What a contraption that would look!

  42. #192
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    Re: Tech cameras and IQ.

    Ah no, the special helical is so that you can buy lots of extension tubes and switch between them and have all magnification ratios down to 4:1 with no gaps between the tube heights.

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    Re: Tech cameras and IQ.


  44. #194
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    Re: Tech cameras and IQ.

    Quote Originally Posted by wentbackward View Post
    Any idea what that little rectangular box with buttons mounted on the bubble level is???

  45. #195
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    That Jack is one of the reasons I am trying to make it to New Hampshire this Fall. Other reasons are the scenery and people, but I want to try the R series and pick the heads of all the photogs there. I will know in a few days if I can swing it.
    Great, hope you can make it -- should be an awesome workshop!
    Jack
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    Re: Tech cameras and IQ.

    Quote Originally Posted by rga View Post
    Any idea what that little rectangular box with buttons mounted on the bubble level is???
    That is a Elinchrom Skyport radio trigger for studio strobes.

  47. #197
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    Re: Tech cameras and IQ.

    Quote Originally Posted by darr View Post
    That Jack is one of the reasons I am trying to make it to New Hampshire this Fall. Other reasons are the scenery and people, but I want to try the R series and pick the heads of all the photogs there. I will know in a few days if I can swing it.
    Love for you to be there Darr. Hope you can swing it
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: Tech cameras and IQ.

    Quote Originally Posted by Guy Mancuso View Post
    Love for you to be there Darr. Hope you can swing it
    Thanks Guy, I am pushing for it! Scheduling is the hurdle, but I will know in a few days. (Fingers crossed!!)
    "Creativity takes courage." ~ Henri Matisse
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    Re: Tech cameras and IQ.

    to address Rod's question:
    "IF we agree that precise shimming of a Tech Camera setup within 1/100 can make a big difference
    in terms of IQ, why shouldn't we use this precision at any distance?

    let's say we do require that precision at any intermediate distance: if you calculate what the effect is in object distance by moving the sensor .001mm, it is going to be small, obviously affected by the focal length and the magnitude of the distance. i would venture, so small that it would not create a measurable change in object distance.
    just did a quick calculation:
    70mm lens: lens-to sensor is 75.000mm = object distance 1,050mm
    so adding a .001 shim: lens to sensor is 75.01mm = object distance is 1,048mm
    .01 shim would change the object distance by 2mm at around 1 meter
    all my arithmetic subject to error, of course

    more numbers, just to give this some scale, again, the 70mm lens: not sure how meaningful in reality, but by the formula:
    lens to sensor: 70.01mm = 490 meters
    lens to sensor: 70.02mm = 245 meters (here a .01mm shim makes a 245 meter difference!)
    lens to sensor: 70.05mm = 98 meters
    lens to sensor: 70.10mm = 49 meters
    lens to sensor: 71.0mm = 4.9 meters
    lens to sensor: 72.0mm = 2.5 meters
    lens to sensor: 75.mm = 1.0 meters



    Infinity is another bag, though, and if you cannot get the lens close enough, because the shims are too thick, inf will not come into focus. if the shims are not thick enough, you can reach focus at inf, just not at the inf stop on the ring. My guess is that the arca can "focus" beyond infinity and so you use the table, making shims irrelevant
    Last edited by jlm; 7th July 2011 at 02:58. Reason: changed the .001mm entries to .01mm

  50. #200
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    Re: Tech cameras and IQ.

    Gareth,

    There is obviously a reason to this design.

    Alpa didn't want to overlap the 2 shift planes one over the other, but to have 2 completely separate H and V shifts with in-between a fix "carrier" plane.

    The reason is obvious: getting a much stabler and more long-term-suited design responding to professional needs.
    That's also the reason why all Alpa carriages are designed with roller bearings: best possible stability and precision with long-term use.

    Best regards
    Thierry

    Quote Originally Posted by gazwas View Post
    Why have Alpa designed the Max with movements that are usually done together on the back or lens rather than seperate on the Max?

    Is is just a design decision or is there a specific reason/movement I'm not seeing.

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