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Front and rear standards parallelism in the field with the Actus

vjbelle

Well-known member
Although I have a good way to make sure my front and rear standards are parallel with each other I would hate to have to make a field calibration using levels. It can be done but kind of a pita.

Another way that I have found to be very accurate and accomplished quickly just involves finding a good target and panning the camera (with shift) and matching the edges with your eyes.

This can also be a quick way to set up the front and rear standards before going out for a shoot without the need for levels.

The distance to the target isn't as important as the target itself. The target should be something that you could easily distinguish with your eyes if either in or out of focus - even slight focus. At best maybe something with print which could be a white balance card set at a distance where it can be clearly seen at 100% pixels - maybe 10 to 20 feet. A tree trunk also could be used especially if something distinguishable can be used for repeatability.... anything that can be reliably repeated.

Once you have determined a good target adjust your camera [Actus] to 10mm of horizontal shift either left or right and pan the camera until the target is at the very edge of the frame. Go to 100% pixels and focus until as sharp as possible. Next shift the opposite direction with the same amount of 'MM' and pan the camera to the opposite direction until the target as at the edge of the frame (other side). If it isn't in the same focus then 'slightly' - 'very slightly' adjust the swing until focus matches. This shouldn't be much of an adjustment but with the Actus you will be adjusting while in the 'more freely' movement detent area so you can go a little back and forth until you find focus acceptable. Then...... go back and check the other side. You should be 'almost' if not already there. Maybe you will have to do that one more time but with a little practice you will have this alignment procedure done in no time. This has nothing to do with focusing in the center as the concern is with the edges to make sure that 'swing' is neutral - 'zeroed'.

Bottom line is this really works. Swing is the most important parallel adjustment to be made. If you shift for stitching and that camera movement isn't parallel there will be skew in the image.

I have also found that the tilt adjustment can easily be adjusted in the field if necessary. I have two front standards and they both have a noticeable hard stop detent that is really close to perfect. Close enough that I trust it. But if you have to adjust the tilt movement you have to then find a wall of any kind - brick would work well - and assuming the wall is pretty close to plumb set your camera up to it so that you can have full rise and fall movements while still seeing a brick or whatever. Just follow the same procedures as above except now working with rise and fall instead of shift. My results with both of my front standards have me trusting the stop but I suggest you practice maybe a couple of times to determine this for yourself.

What I have learned from all of this is that the criticism regarding the front standard movements as being 'sloppy' are not warranted. I appreciate the fact that I can actually perfectly 'Zero' my standards in the field - just took a little time to figure out.

Cheers.....

Victor
 
Although I have a good way to make sure my front and rear standards are parallel with each other I would hate to have to make a field calibration using levels. It can be done but kind of a pita.

Another way that I have found to be very accurate and accomplished quickly just involves finding a good target and panning the camera (with shift) and matching the edges with your eyes.
So long as you're not using the DB version, yet another (IMO) easy way is by using a spring-loaded, telescoping "snap" gauge -- available in a set of six from Harbor Freight for $14.99 (Item 5649) -- as a "go-no go" measuring device:



Remove the bellows and place the collapsed gauge in the gap between the front and rear standards, on either the right or left side if you're zeroing swing or the top and bottom side if you're zeroing tilt, then release it so makes contact with both standards at once, as shown in the photo above.

Lock the gauge in place, then move it to the opposite side of the standards.

When the gauge makes equal contact with both sides of both standards, the swing movement is zero'd out and you're done. If the gaps are different side to side, then adjust the front standard until the gaps on both sides are equal.

Repeat the procedure for the top and bottom sides of the standards and the tilt movement will be zero'd out as well.

Reinstall the bellows and you're good to go! :)

FYI, I photograph mostly late at night, with my camera usually setup in darkness, and with some practice, the method I've detailed above can be done pretty much by feel alone, which is a big plus.

Alternatively, if you don't use tilt or swing movements very often -- *raises hand* -- then you can simply replace the front standard with a piece of .25" thick aluminum angle, as I did earlier this year, and save yourself nearly 11 ounces of weight to boot:



And on those infrequent occasions when I do need tilt and/or swing movements, it takes all of maybe three minutes to swap back to the original Actus setup.
 
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GrahamWelland

Subscriber & Workshop Member
I do believe that the Cambo front swing is very easy to have offset by mistake. I hadn't noticed it too much when shooting with my IQ3100 but I definitely notice it with my IQ4 150.

I shot a morning scene in Vermont across a lake and didn't notice at the time that the right side of my shot was slightly off compared to the rest of the image. Thinking that it was user error with not having the front standard 100% square I went back a couple of days later to double check and reshoot - the swing set to zero but the same result. Only occured at infinity.

Shooting with the same set up in other scenes with more close focus examples I didn't get the same behaviour.

So, I guess I need to double check everything for square against a planar target vs out in the field. Of course it could be the lens (70Hr) but I'm dubious about that vs slight front swing.

If Cambo had a front tilt ONLY option I'd buy it. I just never use swing and a guaranteed square front mount would be more useful to me.
 

dchew

Active member
The one nice thing about having a lens in the Alpa Mount is the ability to easily rotate the lens. You can tell for sure what is lens vs camera.

Dave
 

vjbelle

Well-known member
Graham.... you are so right regarding the sensitivity of the swing movement on the Actus. At least now I can predictably 'zero' the front swing movement in a very short period of time in the field. It would be great if the front movements could be locked.

Victor
 

Boinger

Member
I do believe that the Cambo front swing is very easy to have offset by mistake. I hadn't noticed it too much when shooting with my IQ3100 but I definitely notice it with my IQ4 150.

I shot a morning scene in Vermont across a lake and didn't notice at the time that the right side of my shot was slightly off compared to the rest of the image. Thinking that it was user error with not having the front standard 100% square I went back a couple of days later to double check and reshoot - the swing set to zero but the same result. Only occured at infinity.

Shooting with the same set up in other scenes with more close focus examples I didn't get the same behaviour.

So, I guess I need to double check everything for square against a planar target vs out in the field. Of course it could be the lens (70Hr) but I'm dubious about that vs slight front swing.

If Cambo had a front tilt ONLY option I'd buy it. I just never use swing and a guaranteed square front mount would be more useful to me.
Tighten the swing axis so you can't move it.
 
Tighten the swing axis so you can't move it.
I tried doing that with both the tilt and swing movements on my Actus, but was not able to tighten either one to the point where they would not move, hence my ultimate decision to eliminate them completely.

Have you actually tried this and/or were you successful?
 

Boinger

Member
I tried doing that with both the tilt and swing movements on my Actus, but was not able to tighten either one to the point where they would not move, hence my ultimate decision to eliminate them completely.

Have you actually tried this and/or were you successful?
Yes I have been able to get mine parallel to within 0.03mm deviation between the left and the right side measurements.

19.17mm / 19.20mm respectively. I have a extremely precise digital caliper. (One thing to keep in mind is that the actus is not rigid enough to put lots of pressure when measuring between the standards. You may put to much pressure and get a false reading. You have to be very careful to just barely touch the standards with the caliper)

This screw in front on my actus tightens it to the point where the swing knob is not movable.

Another interesting point of note that screw is a standard M3 or M4 thread I forget which one now exactly. But I had a thumb screw lying around and I replaced the factory screw with the thumb screw and then I could unscrew / tighten the friction or lock it down as needed and on demand.


actus swing lock.jpg
 
This screw in front on my actus tightens it to the point where the swing knob is not movable.

Another interesting point of note that screw is a standard M3 or M4 thread I forget which one now exactly. But I had a thumb screw lying around and I replaced the factory screw with the thumb screw and then I could unscrew / tighten the friction or lock it down as needed and on demand.
Very interesting!

Obviously, I should check mine again ... thanks!
 
Yes and you can also adjust it to where it is tight to increase the friction.
FWIW, on my Actus (an early production one, if that matters), I can readily increase the force required to turn the knob -- and I have! -- but I cannot increase it to the point where the knob won't turn at all.
 

Boinger

Member
FWIW, on my Actus (an early production one, if that matters), I can readily increase the force required to turn the knob -- and I have! -- but I cannot increase it to the point where the knob won't turn at all.
Have you adjusted the tension from the top of the swing mount?

There is a plastic black cap if you remove that you can adjust from there too. So if you tighten that up then tighten the front screw you may be able to lock it down.
 
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