Great to see you here. Join our insightful photographic forum today and start tapping into a huge wealth of photographic knowledge. Completing our simple registration process will allow you to gain access to exclusive content, add your own topics and posts, share your work and connect with other members through your own private inbox! And don’t forget to say hi!
Theoretical yes, but with digital requiring much stricter positioning of sensor than film (read 10x), it requires micro drive adjustments and a possible more tedious adjustment for each shot. The issue is also to see the adjustments well since a 645 sensor is much smaller than film size... Can be possible, but a tech camera such as Alpa, Arca or Cambo will enable lens perfect parallel to sensor plane (if camera is adjusted) and accurate adjustment of focus using a helical, assuming system is shimmed (or fudge factors such as Alpa). An Alpa can be shimmed to 0.01mm accuracy, it seems merely difficult to place the plane of focus to same preciseness with a viewcamera.If you want to go digital, an 80 megapixel back, some Rodenstock and Schneider lenses, and the view camera body of your choice would be the best available solution.
Are you sure that you mean Alpa regarding 'fudge factors'? I wouldn't necessarily refer to it as such myself but I think you meant Arca here - i.e. independent lens adjustment offsets. With the Alpa you basically adjust to the back via shims which is anything but a 'fudge factor'.... but a tech camera such as Alpa, Arca or Cambo will enable lens perfect parallel to sensor plane (if camera is adjusted) and accurate adjustment of focus using a helical, assuming system is shimmed (or fudge factors such as Alpa). An Alpa can be shimmed to 0.01mm accuracy, it seems merely difficult to place the plane of focus to same preciseness with a viewcamera.
Exactly!The ultimate kit is when you get the shot out of any gear you use
The ultimate kit is light and quick to set up and allows you to get "any" shot without compromise... this, to my mind, means getting it right in camera, and not having to crop off a third of the pixels you paid for, or distorting in post.The ultimate kit is when you get the shot out of any gear you use,
Not an issue any more with 'live view'Theoretical yes, but with digital requiring much stricter positioning of sensor than film...
Hi Graham,Not an issue any more with 'live view'
Not sure I understand your point. If "what you see is what you get" and what you see in live view is the focus you want, then you're already there.Hi Graham,
Tolerances (sensor location, lens movements) for digital remain as big issue to adjust for digital with live view as without live view, simply since the sensor will more or less need be adjusted to within 0.02mm tolerance for optimum sharpness. That is a number I was told by Schneider as a tolerance to depth of focus for digitar lenses. In comparison film flatness seems to be referred to within 0.2mm tolerance, thus 10x more accuracy required.
What live view on a back can help with is to see "what you see is what you get", but I will assume that at the high resolution of 60-80MP sensors it can benefit to use teathered for the larger display thus to see even better. It will however be interesting to hear how well the focus mask on new IQ backs will work in practice in regards to tolerances for adjustment of lens movements. Nevertheless it will require fine adjustments using micro adjustments, e.g Linhof, Arca. The Linhof Techno seem interesting for that use.
Regards
Anders
I think that the focus tolerances are only that tight for short lenses - this would be an argument for using a specialist WA camera for short lenses.Hi Graham,
Tolerances (sensor location, lens movements) for digital remain as big issue to adjust for digital with live view as without live view, simply since the sensor will more or less need be adjusted to within 0.02mm tolerance for optimum sharpness.
Anders
While I'm sure the info you got fro SK is very accurate I'd take the advise with a pinch of salt. Remember, what we photographers consider to be acceptably sharp and what a lens design/engineer considers sharp are probably also within a tolerance of its own.Tolerances (sensor location, lens movements) for digital remain as big issue to adjust for digital with live view as without live view, simply since the sensor will more or less need be adjusted to within 0.02mm tolerance for optimum sharpness. That is a number I was told by Schneider as a tolerance to depth of focus for digitar lenses. In comparison film flatness seems to be referred to within 0.2mm tolerance, thus 10x more accuracy required.
I don't think live view on a tech camera will be as accurate as people think, especially if were talking fractions of millimetres as Anders above. The live view back just takes the place of the GG and a perfectly calibrated GG can still be slightly out. The problem lies with the fact that LF lenses are usually f5.6 or f4 at best and at those apertures, depth of field starts to effect the point of critical focus. You would still need to check the focus in the captured image either tethered or on an Phase IQ screen to be 100% accurate.Not sure I understand your point. If "what you see is what you get" and what you see in live view is the focus you want, then you're already there.
The point is two-fold:Not sure I understand your point. If "what you see is what you get" and what you see in live view is the focus you want, then you're already there.
The focus travel will be smaller for wide lenses yes. I gather that this may be why my own design and custom made sliding adapter works for lenses 72mm and longer on a 28MP back. Another reason can also be that on a groundglass subjects tend to be small for focusing with shorter lenses. My adapter is for sale here if someone is interested ... http://forum.getdpi.com/forum/showthread.php?t=23733I think that the focus tolerances are only that tight for short lenses - this would be an argument for using a specialist WA camera for short lenses.
Well, when there is a factor of 10x in film/sensor flatness of difference between digital and film it seems they have a very valid point. + why does Alpa provide shims to thickness of 0.01mm? That makes perhaps the question reduced to what we prefer, absolute optimum sharpness or lens movements?While I'm sure the info you got fro SK is very accurate I'd take the advise with a pinch of salt. Remember, what we photographers consider to be acceptably sharp and what a lens design/engineer considers sharp are probably also within a tolerance of its own.
But AFAIK the shims are to get your lens and back calibrated to some reference point (infinity) and nothing to do with focus. I very much doubt you could focus an Apla helical mount lens to an accuracy of 0.02mm. The only camera possibly able to focus to that accuracy would be one of the Arca R cameras.+ why does Alpa provide shims to thickness of 0.01mm? That makes perhaps the question reduced to what we prefer, absolute optimum sharpness or lens movements?
Very true! Why, though, would you need to focus any more accurately than 0.02mm? All of the Tech lenses are meant to be shot at f8 or f11 which induces enough dof to compensate for any slight mis-focus at that level....But AFAIK the shims are to get your lens and back calibrated to some reference point (infinity) and nothing to do with focus. I very much doubt you could focus an Apla helical mount lens to an accuracy of 0.02mm. The only camera possibly able to focus to that accuracy would be one of the Arca R cameras.
Just think your being a little too technical about this and reading too much into the Apla marketing machine.
The bottom line is that there is error in any system, even one as well-marketed as Alpa's. Although I am sure Alpa (rightly or wrongly) will argue that their system has the LEAST error of it's competitors. :toocool:But AFAIK the shims are to get your lens and back calibrated to some reference point (infinity) and nothing to do with focus. I very much doubt you could focus an Apla helical mount lens to an accuracy of 0.02mm. The only camera possibly able to focus to that accuracy would be one of the Arca R cameras.
Just think your being a little too technical about this and reading too much into the Apla marketing machine.