Alpa Max Vs Arca Swiss Rm3d

[tho_mas]

And how does these cameras compare to Sinar arTec?
Seems to be a lot like the Arca?

no. The arTec is the only camera that is designed around a sliding back. So the sliding back is not an attachable accessory... the rear standard of the actual camera is the sliding back.
Therefore the arTec provides rise/fall on the lens and lateral movements on the rear whereas the Arca provides 4way shift on the rear.

[buckshot]

Moved here.

[tho_mas]

You can in fact shim the Cambo Wide RS, and quite easily at that - basically following the instructions for shimming the Alpa. What you need are a set of shims, such as those available here (which are the plastic type, easy to cut and with good enough dimensional stability under temperature change and pressure). You then simply remove the four screws highlighted, which are set in bushings that allow the bracket that the adapter plate sits in to move back and forward), and insert the shims as required. Two of the screws are hidden behind the small plates that hold the adapter plate on, so you need to remove these to access them. The screws used in the bushings are M2 x 5mm. A useful trick is to use a dab of thread locker (blue for instance - easily removed if needs be) to fix the bushings in place (flush to the plate they sit in), and then when you tighten the screws they won't move and it will be only the shims that determine the fore/aft position of the digital back. Plastic shimming is available as thin as 0.0005" = 0.0127mm. This is really thin, probably not much more than the WRS (or Alpa or Arca) would expand/contract on a really hot/cold day (respectively), but if you think it makes a difference no harm using it. The thicknesses I bought were: 0.0005" (~0.01mm), 0.001" (~0.02mm), 0.0015" (~0.03mm), 0.002" (~0.05mm), 0.04" (~0.1mm), 0.0075" (~0.2mm) and 0.12" (~0.3mm)

Note, before doing all this check that you need to - see the optechs video on their website first. The way the rear plate on my Cambo was set up was perfectly parallel (well done Cambo) - but it did need moving back a fraction to match the position of the sensor in my DB. In this respect, the way Cambo have designed the rear of the RS is very clever, the bracket that the adapter plate sits in is infinitely variable (in respect of front/back movement) by adjusting the height of the four bushings and locking them in place with the internal screws (which you could just do in order to shim your back, but as I said above, plastic [or metal] shims are less hassle since they keep the bracket square to the camera).

awesome - many thanks!!!
Could you please re-post the link to the shims... the link posted above refers to this thread... not to the said shims.
Man, this is really cool - thanks a lot again!

[buckshot]

Moved here.

[tho_mas]

In the US: http://www.practishim.com/ is one place ($50 min order I think)

In the UK:

http://www.cromwell.co.uk/PCN9653710A

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0681407

Would be nice if Cambo offered the shims - making a design to fit perfectly would be pretty easy (given that they have all the dimensions, I had to use a vernier calliper), and machining them would be a no brainer - in fact plenty of places on the net will machine them for you if you send a design.

great - thank you!
Yes, the cutting of those pieces is not easy as the edges twist when you cut them.
A precsion mechnic here told me those things are cutted using a laser (at least with metal shims) when I asked him to make shims for my Contax 645 screen.

Thanks again - you made my day!

[buckshot]

Moved here.

[tho_mas]

super!
thanks again!

[buckshot]

Moved here.

[tho_mas]

Have some other tips - will post them next week.

please do so - I am looking foward to it!
Maybe I can add one or two tips...
It's probably better to start a new thread as these "WRS tips + tricks" do not refer to the Max vs. Rm3D topic.

[buckshot]

Good point - have moved everything here.

[Clyde RF]

I am saving up for the eventual purchase of an Arca rm3di, and at this time am attempting to absorb the extremely useful info posted here explaining how to make best use the camera's somewhat complex virtues. Thanks to everyone here for the explanations presented so far which I think I understand pretty well, but there is still one aspect that I am in the dark about. I do mostly landscape, and find myself using tilt whenever it can be of help, but from what I am understanding now, the rm3di's focusing devices cease to be applicable when tilt or swing is applied. This camera's design seems to be really brilliant overall, but what combination of approaches should be employed when a tilt or swing is indicated, and what can be done to account for the focus situation regarding three dimensional objects protruding slightly above a tilted focal plain? Can the rm3di's non visual focusing system be applied here as well? 

[Rod.Klukas]

The focus of an RM3di is still super accurate even with tilt or swing.  When you get your camera you can work out a number for maximum depth of field for all your lenses.
For instance if you look on Schneider Optics site and go to the page for 72mm Apo-Digitar (copal) and look at the 'sample' tab.  The landscape was made by me.  I set up and leveled the camera.  Then having predetermined for this lens the max depth for DOF and quality, sharpness etc., I dialed in focus '3' and 1.5 mks tilt along with 5 rise.  As you could see the picture is sharp from foreground to infinity.(F11)

This is a quite easy procedure you can work out for each lens and once you have done it won't change unless your back changes and then it might not change either.  I set up many customers for them if they have trouble or give them my numbers for where to start and they just tweak them to match their back. 
Rod

[TH_Alpa]

Since there is a lot said here about Alpa, I wish to jump in and make some remarks:

I couldn't agree more with "fuzzyfoto": unless you have seen it with your eyes, done step by step with the shims, you won't believe it. You may believe that you have got it all out from your x MPx sensor and from your best lens, but no, there is (much) more to get out of it by shimming your own back correctly.

It takes 15 min, but then you are done and sure to be set at infinity the most precisely possible. It is, IMO, the most simple way to achieve the precise focus. But don't believe my sole words, test it out by yourself.

And yes, any back has some misalignment and has to be shimmed, sometimes (often) in both directions.

Best regards
Thierry

edit: Unless you have shimmed a digital back or unless you've seen someone shim a digital back and see the before and after, you have no appreciation for the importance of shimming and what a difference it makes. You think you have a sharp image until you see the shimmed version.

[TH_Alpa]

Dear Rod,

That's not the case: the Alpa HPF ring is not only of a big help, but does in fact allow for perfect focus, there where you need it, on any point of the HPF ring scale. I have in fact tried it out a couple of weeks ago, and it's not limited like one can read it here and there.

Best regards
Thierry

The focus, as several people have stated, is much finer than the Alpa can provide.  The over ring accessory now available, does give a finer scale to the Alpa but you are still dealing with the limitations of the standard helical provided by the lens manufacturers, so not much help. 

[Rod.Klukas]

Thierry,
Not to argue, but as the helical focus does not rotate even 360 degrees it cannot possibly offer the fine focus adjustment of an Arca-Swiss.  With the 5 turns of an Arca-Swiss focus mechanism it is a much finer pitch and allows for much finer adjustments.
The Alpa over ring was an improvement but is still limited by the helical used by the lens manufacturers since the 1970's.
Having said that that I am sure the Alpa does OK within those limits. And it will focus fairly accurately with the lens stopped down a bit.  It will however not focus as close as an Arca-Swiss R camera nor as accurately and consistently when lens is wide open.  I have played with a 12 max and it is a nice camera.  Not quite as accurate as an ARCA but better, in my opinion than the rest of the competition.  The RM3di  can also use up to a 6x9 format without adapting the front and has body incorporated tilt.
Both are nicely finished cameras and can take excellent pictures...

Congratulations on your new position.  Glad to have a knowledgeable person on board.

[TH_Alpa]

Rod,

Thanks for your words

No problem, we simply exchange information here, with respect but on an open basis. I simply have to disagree, when I know how I am precise by using it practically, not in theory. It doesn't need to rotate 360 degrees to get precise focus, try it out. It doesn't need to rotate 360 degrees to get precise focus, that's just a theoretical view to believe so, when otherwise the camera is so well designed and built and the back shimmed correctly.

Then, the focus-mechanism of Arca may be able to move 5 turns (mechanically speaking), but one forgets to say that this is not the case with all lenses. With some lenses (I would have to find out which ones) one has only a very limited rotation available.

I would anyway suggest anyone to try the focusing on both cameras out, side by side, in field-conditions, as I have done it.

Best to you too, Rod
Thierry

Not to argue, but as the helical focus does not rotate even 360 degrees it cannot possibly offer the fine focus adjustment of an Arca-Swiss.  With the 5 turns of an Arca-Swiss focus mechanism it is a much finer pitch and allows for much finer adjustments.

Congratulations on your new position.  Glad to have a knowledgeable person on board.

[gazwas]

I simply have to disagree, when I know how I am precise by using it practically, not in theory. It doesn't need to rotate 360 degrees to get precise focus, try it out. It doesn't need to rotate 360 degrees to get precise focus, that's just a theoretical view to believe so, when otherwise the camera is so well designed and built and the back shimmed correctly.

Thierry, I'm with Rod on this one. The Alpa rings are a great method but to argue its as accurate as the Arca system is just plain wrong. The Arca R camera have by far the most accurate focus with any lens regardless of how many turns (5, 4, 3, 2 or 1) because of how finely geared the mechanism is. If using a wide aperture, I would think even after using a distometer to establish subject distance, a user could be slightly off applying these setting to the Alpa ring due to its limited helical range. A small error could possibly place the focus out enough to notice on the final capture.

[design_freak]

Each camera has its advantages and disadvantages. I am a happy owner of both cameras. Both, I think a great tool. I know from experience that each of these cameras can be very precise. That Arca has a large ring from the standpoint of mechanics should mean that it is more precise, but I am convinced that Alpa is not worse in this respect - simple design can be misleading. Just skill. Once I could not adjust quickly focus on the 503CW, it seemed impossible. But after a few days, it was child's play. The choice of equipment is a personal issue. I love both systems:) Maybe because they are well done which is unfortunately rare these days...

[Wayne Fox]

I can understand because one cameras focus ring turns more revolutions you could assume it is more "precise".  I'll agree technically it is certainly true, but in practicality for most (the exception might be a lot of very close up work where you are probably doing focus stacks anyway) the Alpa with the new rings is very precise - more than adequate.  Personally it would drive me nuts to turn the lens that much to get it focus.  As a landscape shooter, knowing that infinity is nailed is more important so I prefer shimming over an offset. But I think either system offers amazing stuff, and the real issue facing most tech camera shooters as the pixels get smaller is the lens design and resulting issues with wide angle lens.  At this point, unless there is something wrong with my back, my Schneider 35XL is not usable on my Alpa with IQ180 back - even LCC doesn't compensate for the falloff and color shift. I'm better off shooting my DF with the PhaseOne 28.

 Do the Arca lenses all turn past infinity in case the sensor plane requires that, or are the adaptors designed so that most of the time infinity needs to be fine tuned a little inside the infinity mark?  Just sort of curious how that works.

I assume the offset is very consistent, so you only have to remember "one" number?  How difficult is it to actually apply that, something easily done in the head or do you always have to refer to some guide or calculator? I feel like I'm in molasses when working with these cameras anyway, curious if this is a "no brainer" or if it slows you down a little more.  (Please don't get defensive on this one, just asking because I admit working with any tech camera is a different world than SLR)

[johnasmith]

HI I own the Arca Rl3D and use it for landscape,I love it and is a little bigger,but you have more movements and there will be
a sliding back for this camera soon,and you will be able to do with a p65 in there shots vertical with the right  lens a 30x60 image.The rodenstock  55 fits the bill and a very sharp lens,and  any lens with 125 mm image circle  can do the 30x60 image.Also for the shiming of the camera,you do not shim the camera but you can do  it by the numbers,and I might add that you can do this for every lens and not just
 one lens as on other cameras. Also every lens that  Arca mounts in there cones is shimmed and tested by shooting test shots.Also the sliding
back will be of 4x5 format so you will be able to see the whole image circle at one time,as whats around your format box,and
will also have crop marks for other pano sizes with the 30x60 max size and you can make about 11 differant image sizes from the 2x4 format.
I'am sure there will other camera backs with crop marks for them also.