Signs of RF Misalignment?

denmark.yuzon

denmark.yuzon

Streetographer
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Apr 27, 2009
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Hi, can anyone list the signs of RF misalignment? My Minolta 7s got banged up on a wall pretty hard while i was entering through the door. the camera didnt get any dings or dents, the lens hit the wall, good thing the cap was on it..

i tried focusing at infinity, it seems to be okay, focusing at 1m with a metric tape on the ground, the distance on the lens read at somewhere around 1.2 - 1.5m. tried to set the lens at 1m, the metric tape on the ground said i was standing at about 0.8-0.9m from the subject..

did i misalign the RF? what do i watch out for? i will finish my roll and see if the focus got messed up.. but is there any way i can determine if the RF was misaligned horizontally and vertically without having to develop the films?
 
You've figured it out. If the measurement doesn't match, the RF is off. Yours is backfocusing. Mine has since I got it, which is why its only had one roll of film through it...because I don't know how to adjust it myself and it isnt worth paying someone to do it on a $20 camera. Make sure when you measure, you measure from the film plane, not the front of the camera.
 
Yeah the focusing scales on all cameras are calibrated for distance from the film. I think the 7s has a film plane indicator on the top deck (a circle with a line through it...the line is the film plane). I think it has one..I'd have to dig it out and see. If not just estimate where the film actually sits in the camera
 
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i tried it again, this time i set the camera on the table on top of a metric tape, put the subject away from the "guestimated" film plane.. i set the lens at the minimum distance and it "appears" to be in focus.. jeez.. so the rangefinder is aligned? the image seem clear and appears to be in focus..
 
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denmark.yuzon said:
i tried it again, this time i set the camera on the table on top of a metric tape, put the subject away from the "guestimated" film plane.. i set the lens at the minimum distance and it "appears" to be in focus.. jeez.. so the rangefinder is aligned? the image seem clear and appears to be in focus..
Click to expand...

Yep. If the close distance matches the measuring tape and the infinity distance is correct (point the camera at something very far away, like a skyscraper from a couple of KM away and see if the image in the RF is perfectly aligned), then all the distances should be correct. I usually verify with a test roll of film too after doing those checks, just to be sure.
 
im finishing my roll now to confirm.. all i took after banging my camera, was the minimum and the maximum distanced subjects.. im hoping that it is still well aligned..

thank you chris for helping! truly appreciate it!
 
I read an idea and tried it out. If you have a laser pointer, set up the camera on a tripod 1m from a white wall. Set the focus to 1m.
In the half-dark shine the pointer thru the eye finder and when you get the angles all correct the two circles will appear superimposed on the wall.
It takes a few seconds to get the beam on the square of half silvered splitter and out the direct window at the same time.
Seemed to be OK when I tried it.
Murray
 
Go out at night and focus on a far away streetlight. If infinity is on then close focus is probably on also. Distances marked on the lens are not always that precise.
 
Murray Kelly said:
I read an idea and tried it out. If you have a laser pointer, set up the camera on a tripod 1m from a white wall. Set the focus to 1m.
In the half-dark shine the pointer thru the eye finder and when you get the angles all correct the two circles will appear superimposed on the wall.
It takes a few seconds to get the beam on the square of half silvered splitter and out the direct window at the same time.
Seemed to be OK when I tried it.
Murray
Click to expand...

That works, as far as it goes. It shows you whether your rangefinder is correct, but it doesn't show you whether your lens is focused at the same distance as the rangefinder.
 
My reasoning on this is that if the lens is set on 1m and the distance to the wall is 1m and the 2 dots align, where is the error? One assumes we are talking a coupled RF and the lens is OK? Otherwise you need to look to see the film plane image is correct. Is that what you're getting at?

Murray


FallisPhoto said:
That works, as far as it goes. It shows you whether your rangefinder is correct, but it doesn't show you whether your lens is focused at the same distance as the rangefinder.
Click to expand...
 
hi guys, my test roll after banging my camera against the wall came today.

these are shots taken from the minimum distance to the maximum infinity..

000040-1.jpg


000038-1.jpg


000034.jpg


000041-2.jpg


000042-2.jpg



what can you say? aligned or misaligned?
 
One thing to bear in mind -- if the focus is accurate at infinity, it almost certainly is accurate a closest focus, UNLESS there has been SIGNIFICANT damage to the camera, like a truck running over it.

The focus cam (or equivalent) is calibrated to pivot a certain number of degrees between 3-feet and infinity. For discussion, let's call it 100 degrees of travel.

With a misalligned rangefinder, the thing will still pivot its designed 100 degress, but the two images will line up at the wrong point in the travel. So you adjust to get them to line up accurately.

It would take significant damage to in some way change the 100 degrees of pivot.

That's why I like to find a distant building/tower to check RF accuracy at infinity. Should be at least a kilometer away. If you have a bright viewfinder and a clear night sky, ultimate test object would be a bright planet (single point of bright light).
 
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