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christopherbwurzbach
2-Jun-2007, 16:20
For the past 5 + months my images have came back with incorrect focus. When focusing / viewing on the ground glass they are sharp as ever.

My camera movements are very slight if any at all.

On every image it is sharp about 6 - 12 inches closer to the camera than intended. I have checked the placement of the inner part of the ground glass and the film plane on my film holders and they are fine.

I have made many sharp images prior with this same setup.

Sinar F2 / Nikkor W 210 f5.6

I've visited an eye doctor and he prescribed eyeglasses, which I have worn for the past month and the problem still persists.

Could this be the lens, camera? Any suggestions would be greatly appreciated!

Example :

(I've shot 60 + negatives that have came back just like this)


http://www.christopherbwurzbach.com/helan/full.jpg

http://www.christopherbwurzbach.com/helan/face.jpg

http://www.christopherbwurzbach.com/helan/feet.jpg

Dave Parker
2-Jun-2007, 16:35
Christopher,

I am confused the main subject seems to be in focus, what part of the photo are you looking at? If it is the background the you are looking at, you need to learn a bit about Depth of Field But as far as the lady in the photograph, she looks in focus to me..

Dave

Alan Davenport
2-Jun-2007, 16:39
Is there a fresnel lens installed on the inside (toward the lens) of the groundglass? If so, that is most likely the problem.

christopherbwurzbach
2-Jun-2007, 16:46
Alan -

There is no frensel lens installed - never has been.

Dave -

I understand depth of field - I shot this at f8 - While viewing the groundglass her face and feet were sharp - now on the negative both are soft and the focus is lying 6 - 12 inches closer to the camera than intended.

- Christopher

Ron Marshall
2-Jun-2007, 16:57
Your image looks in focus to me, just not much depth of field.

You will not have much depth of field with a 210mm lens at f8. Try shooting between f22 and f32 if you want max DOF.

Toyon
2-Jun-2007, 16:57
I definitely see the problem in your shot. Is it possible the front standard is creeping forward or the rear standard moving when you put the film holder in? I know that Richard Ritter offers a service of calibrating cameras. It might be worth trying to get a second opinion. Good luck.

christopherbwurzbach
2-Jun-2007, 17:01
You will not have much depth of field with a 210mm lens at f8. Try shooting at f22.

HaHa!

I would like the ability to accurately shoot at f8.

christopherbwurzbach
2-Jun-2007, 17:04
I definitely see the problem in your shot. Is it possible the front standard is creeping forward or the rear standard moving when you put the film holder in? I know that Richard Ritter offers a service of calibrating cameras. It might be worth trying to get a second opinion. Good luck.

That may be a possibility - however it seems rock solid.
Thanks for the contact!

Could the lens cause this type of problem?

Richard Kelham
2-Jun-2007, 17:19
Could the lens cause this type of problem?



I doubt it – I don't see how the lens could shift focus all by itself. I have a 210mm Nikkor W and it's a great lens, but then I'm not in the habit of shooting at f8.

Glenn Thoreson
2-Jun-2007, 17:52
If the same setup used to work fine, something had to change somewhere. Has the camera or any of it's parts been worked on? Has it taken any knocks? Something has changed position. You just need to figure out what. I have to assume, since you seem to know what you're doing, that you are using a focus loupe. Has anything happened to change it? I can't see well, close up, but I can not for the life of me. focus a camera while wearing glasses. Could that be a problem?

Edit: One more thought - are you checking the focus at f/8? I have a hard time believing you could experience focus shift from stopping down with this lens, but...........?

John T
2-Jun-2007, 18:09
You are definitely rear-focused. Her hair in front of her face is sharper than the rest of her face/hair and the grass in front of her feet is sharper.

This probably means that it isn't post-focusing movement on her part since she would have had to move her feet. If it was just her face then it could have been she drifted back.

If the rear standard had shifted forward, the focus would have been behind her rather than in front.

So, it could be that the front standard is somehow drifting forward, (if it locks down securely, it is unlikely), the rear standard is drifting backward when you open up the spring back to insert the film holder (can be pretty common), or the film holder isn't seating properly (usually light leaks accompany this so, probably not the problem).

Did you ever remove the front or rear lens element groups and forget to replace a thin shim ring? If this was necessary, it could result in a focus shift when you change f stops, but I really don't think it would be this drastic.

Since the feet seem more out of focus than her face, could your rear standard be tilting a little when you put the film holder in place?

Sorry, that's all I can think of at this moment.

Good luck

John

christopherbwurzbach
2-Jun-2007, 18:12
If the same setup used to work fine, something had to change somewhere. Has the camera or any of it's parts been worked on? Has it taken any knocks? Something has changed position. You just need to figure out what. I have to assume, since you seem to know what you're doing, that you are using a focus loupe. Has anything happened to change it? I can't see well, close up, but I can not for the life of me. focus a camera while wearing glasses. Could that be a problem?

Edit: One more thought - are you checking the focus at f/8? I have a hard time believing you could experience focus shift from stopping down with this lens, but...........?

Yes, I am using a loupe. I've tried focusing with and without glasses, I don't have a problem with focusing with glasses. The loupe's inner plastic piece is slightly loose but I believe it has always been.

I usually focus wide open and then stop down - but I have shot at f5.6 with the same outcome - I have stopped down (f11 - f16) more lately hoping to achieve some sort of acceptable focus - for the critical focus is still 6 - 12 inches off.

I am hard on my equipment sometimes - I transport the camera on the tripod - not in a case. etc.

Yeah since I was making sharp images with this - something has changed - but what? - I have racked my brain trying to figure it out. I am considering a new camera or lens. But I am not sure which is the problem.

I am interested in a new field camera anyway. But I want to sell the Sinar and be sure I am selling a working piece of equipment.

Bill_1856
2-Jun-2007, 18:16
Did you remove the ground glass, and replace it backwards?

christopherbwurzbach
2-Jun-2007, 18:24
You are definitely rear-focused. Her hair in front of her face is sharper than the rest of her face/hair and the grass in front of her feet is sharper.

This probably means that it isn't post-focusing movement on her part since she would have had to move her feet. If it was just her face then it could have been she drifted back.

If the rear standard had shifted forward, the focus would have been behind her rather than in front.

So, it could be that the front standard is somehow drifting forward, (if it locks down securely, it is unlikely), the rear standard is drifting backward when you open up the spring back to insert the film holder (can be pretty common), or the film holder isn't seating properly (usually light leaks accompany this so, probably not the problem).

Did you ever remove the front or rear lens element groups and forget to replace a thin shim ring? If this was necessary, it could result in a focus shift when you change f stops, but I really don't think it would be this drastic.

Since the feet seem more out of focus than her face, could your rear standard be tilting a little when you put the film holder in place?

Sorry, that's all I can think of at this moment.

Good luck

John

John -

Thanks for your response!

This has happened consistantly with over 60 negatives. The Sinar F2 is built like a tank - the back standard is sturdy from my observations.

I've never taken the lens off the lens board.

The film holders are locking in place in the groove they were made to fit in.

christopherbwurzbach
2-Jun-2007, 18:25
Did you remove the ground glass, and replace it backwards?

Nope - I've never removed the Ground Glass.

Ben Chase
2-Jun-2007, 18:26
HaHa!

I would like the ability to accurately shoot at f8.

I don't think I've ever got this good of a shot at only f8 :)

I would say that the plane of sharp focus in this case is very, very close to what you have shot here...keep in mind that the plane of acceptable focus at f8 is going to be awfully small.

christopherbwurzbach
2-Jun-2007, 18:31
I don't think I've ever got this good of a shot at only f8 :)

I would say that the plane of sharp focus in this case is very, very close to what you have shot here...keep in mind that the plane of acceptable focus at f8 is going to be awfully small.

I am aware the plane of acceptable focus at f8 is small - but I have created tack sharp portraits at f5.6 many times.

I am also aware it is off just slightly - but when I open up to f11 - f 16 it is still obvious for portraits.

Donald Qualls
2-Jun-2007, 18:35
I'd agree with Ben -- at f/8, you have very little DOF, but beyond that, it's very, very difficult to focus well enough in ground glass to avoid this level of error.

However -- if you've had good results prior to the past 60 negatives, and now you're seeing consistent focus shift with the plane of focus closer than intended, you pretty well have to have had a change in the relationship of film plane to ground glass plane. The amount you have here would be less than a millimeter movement of the ground glass toward the lens, though if you haven't had the ground glass out that movement would have to come from some other source. Did you lose a layer of velvet inside the camera, in a location that would let the ground glass "fall" inward without letting a film holder do the same? Lose a layer of something off the inside of the focusing panel? Use film holders coated with sandpaper and just wear away the focus panel? ;)

Regardless how it happened, SOMETHING is causing the ground glass to be too close to the lens relative to the film plane, and the simple solution is to adjust it -- I'd start by adding a shim of about 1/4 millimeter (one hundredth of an inch, about two sheets of common laser printer paper -- though paper isn't a good shim material, because it compresses with age; you can get polystyrene sheet a precise .010" thin at a hobby shop) under the ground glass and see where you are. Test shots to verify this should obviously be done at f/8 or wider, so DOF doesn't cover the error...

Ben Chase
2-Jun-2007, 18:36
I am aware the plane of acceptable focus at f8 is small - but I have created tack sharp portraits at f5.6 many times.

I am also aware it is off just slightly - but when I open up to f11 - f 16 it is still obvious for portraits.

This kind of thing has happened to me a few times, usually I have found that I didn't have one of the standards locked down as well as I had thought, and there was a little creep. Not sure if this is the case here though...

Hope you find it...anytime I have a focus issue it drives me out of my mind.

Sheldon N
2-Jun-2007, 18:51
I agree with Don's approach. I had to do this with my Wista ground glass, but the degree of error that I was experiencing was a little larger.

My test setup involved setting up a plain piece of paper with a lined scale on it (http://www.photo.net/learn/focustest/scale45.jpg) and then placing it on a table and shooting at 45 degrees. Bang out a few frames of B&W film and scan them, and you can see the focus results easily.

If you use a wider angle lens, the degree of error will be more obvious than with a long lens. Shoot wide open so that focus shift isn't an issue, use the highest power loupe you have for critical focusing, and triple check everything. You might want to use several different types of holders to make sure there's no subtle variance between them.

Leonard Evens
2-Jun-2007, 19:49
I've tried to make some estimates based on a guess of how tall the woman is. I came up with an estimate of somewhere around 11-12 feet for the distance she was from the lens. Knowing that, it is possible to esimtate how far off the focus was, and I came up with something like 0.6 mm. It appears that when you took the picture, the film was about that far back from where it should have been.

There are several possible explanations. If you get consistent errors like this, the obvious explanation is that the ground glass position is displaced by that much from the film position. If so, shimming the gg by about that amount should help. One way to determine if this is the case is as follows. Take pictures wide open at a variety of distances. In each case, determine the magnification as follows. Take the subject distance, convert it to mm and divide the result by the focal length. Then subtract one and take the reciprocal of the result. That will give you the magnification. In the resulting pictures, make an estimate of how far in front of the subject the focus appears to be. Square the magnification and multiply the distance you are off by that number. That will give you the size of the shift in the camera. If all the numbers you get this way are pretty close, that means there is a systematic error, most likely the result of the position of the gg relative to the film as mentioned above. If the numbers are all very different, that suggest the cause is something else.

One other thing to keep in mind is that it is impossible to focus exactly. Your eye is limited in how well it can see and as a result there is a visual depth of focus. Using a loupe helps you see better and reduces this depth of focus, but it can't eliminate it. In my case, I've found that at f/5.6, using a 4 X loupe, the focusing error could be as much as 0.5 mm. Normally, this error is random and might go in either direction. For example, it could vary from -0.5 to +0.5 mm with anything in between being possible. But if you always focus the same way, you could produce a systematic error in one direction. Here is one way to avoid that. First focus by starting in back of the subject and focus until the subject just comes into focus. Note the position on the focusing knob. Then do the same thing starting in front of the subject, and again note the position on the focusing knob. Finally focus halfway in between those positions.

christopherbwurzbach
2-Jun-2007, 19:53
I've tried to make some estimates based on a guess of how tall the woman is. I came up with an estimate of somewhere around 11-12 feet for the distance she was from the lens. Knowing that, it is possible to esimtate how far off the focus was, and I came up with something like 0.6 mm. It appears that when you took the picture, the film was about that far back from where it should have been.

There are several possible explanations. If you get consistent errors like this, the obvious explanation is that the ground glass position is displaced by that much from the film position. If so, shimming the gg by about that amount should help. One way to determine if this is the case is as follows. Take pictures wide open at a variety of distances. In each case, determine the magnification as follows. Take the subject distance, convert it to mm and divide the result by the focal length. Then subtract one and take the reciprocal of the result. That will give you the magnification. In the resulting pictures, make an estimate of how far in front of the subject the focus appears to be. Square the magnification and multiply the distance you are off by that number. That will give you the size of the shift in the camera. If all the numbers you get this way are pretty close, that means there is a systematic error, most likely the result of the position of the gg relative to the film as mentioned above. If the numbers are all very different, that suggest the cause is something else.

One other thing to keep in mind is that it is impossible to focus exactly. Your eye is limited in how well it can see and as a result there is a visual depth of focus. Using a loupe helps you see better and reduces this depth of focus, but it can't eliminate it. In my case, I've found that at f/5.6, using a 4 X loupe, the focusing error could be as much as 0.5 mm. Normally, this error is random and might go in either direction. For example, it could vary from -0.5 to +0.5 mm with anything in between being possible. But if you always focus the same way, you could produce a systematic error in one direction. Here is one way to avoid that. First focus by starting in back of the subject and focus until the subject just comes into focus. Note the position on the focusing knob. Then do the same thing starting in front of the subject, and again note the position on the focusing knob. Finally focus halfway in between those positions.

THANK YOU

John Cahill
2-Jun-2007, 20:00
Check And Make Sure You Do Not Have A Loose Lens Element.

cyrus
2-Jun-2007, 20:04
That may be a possibility - however it seems rock solid.
Thanks for the contact!

Could the lens cause this type of problem?


I think the face front is fine and in focus.

The tip of the feet are in focus, obviously not the legs.

I am going to take a wild and uneducated guess: you are working with a very shallow depth of field. The plane of sharpness is curved like a bowl - so the face (center of the bowl, where you focused on) comes out fine but at the extremities (feet), the area of sharpness is a little bit closer to the camera.

vijayn
2-Jun-2007, 20:08
Is your film the same? Are your holders the same? Although the possibility is remote, it could be that you changed film or holders and now the film is not seating in exactly the same place as the GG.

The other thing I can think of is that the F2 rear standard has somehow loosened. I have seen this happen on my F2 in the past; and even slight loosening can cause the problem, because there is a backwards force on the rear standard as the film is loaded.

I would suggest that you make some controlled tests, indoors, of a flat surface at f/5.6, with the film freshly loaded in a few different holders, and with careful focusing and very careful handling of the rear standard when you push in the holder.

You aren't going to find answers unless you do controlled tests - there are so many variables that you have to eliminate as many as possible to arrive at a cause.

vijayn
2-Jun-2007, 20:13
And one more thing: there are little nylon pieces that are used to friction clamp the different movements in the F2; these can wear down, warp and even break, causing a less than secure fit. What you can do is measure the distance between the two standards before and after loading the film. If this is different, even slightly, you have a problem.

poco
3-Jun-2007, 04:13
If the margin of focus error is really .5 mm as has been mentioned, it's even possible you're seeing a film bow issue -- maybe caused by humidity/temperature issues. There are days when unloading my film holders that the film edge bows away from holder letting me take it out easily, and days when it clings flat to the holder making getting a fingernail beneath it almost impossible.

Anyway, if you fail to nail the problem down, I'd try focusing on the ears for such shots instead of the eyes and see what that gets you. Worst case is you end up with 61 unexceptable shots instead of 60 (though I think your attached shot is still acceptable).

Bill_1856
3-Jun-2007, 06:46
The place to start is to check if it really is off, or it's your technique. "Waste" a piece of film by doing the old "photograph a ruler laid out at an angle to your camera" being very careful to check the focus exactly with a magnifier. That's the only way you can tell whither it really is focusing in the wrong plane.

Brian Ellis
3-Jun-2007, 08:01
Other people must have much better computer monitors than mine. I've never been able to judge very fine focusing well on a computer monitor, I always judge focusing from a print. I also haven't read all of the responses. But FWIW, this is a person, not a static subject. Leonard, whose responses I always read because he always seems to know what he's talking about, estimates the error at half a mm. That's not a whole lot thicker than a sheet of writing paper. Isn't it possible that she every so slightly moved something somewhere between the time you focused and the time you tripped the shutter? Have you done a real focus test e.g. with an Air Force test chart or a ruler or even a piece of newspaper taped to a wall and gotten the same consistent error you see here?

Paul Fitzgerald
3-Jun-2007, 08:09
Hi there,

"On every image it is sharp about 6 - 12 inches closer to the camera than intended."

So the film is slightly farther away from the lens than the GG.

Loupe not adjusted to GG?
Are the springs tight enough?
Debris in the lock channel?
Movement inserting film holder?
Bump the tripod?

Good luck chasing the gremlins.

Ben Chase
3-Jun-2007, 16:04
If the margin of focus error is really .5 mm as has been mentioned, it's even possible you're seeing a film bow issue -- maybe caused by humidity/temperature issues. There are days when unloading my film holders that the film edge bows away from holder letting me take it out easily, and days when it clings flat to the holder making getting a fingernail beneath it almost impossible.

Anyway, if you fail to nail the problem down, I'd try focusing on the ears for such shots instead of the eyes and see what that gets you. Worst case is you end up with 61 unexceptable shots instead of 60 (though I think your attached shot is still acceptable).

Wild shot...but you aren't taking film right out of refrigeration and then shooting in a warm climate are you? I could see how this could happen if the film went from a cold to a warm environment in a hurry.

douglas antonio
4-Jun-2007, 00:30
christopher,

i haven't read all the posts and maybe i am repeating something ...
looking at your picture i believe to be able to make out, that the head (eyes) of your model ( i presume you focus on the eyes) is closer to the camera than the feet are. (and i believe that's a natural way of standing and keeping balance)
so at a shallow DOF it could possibly happen, that
a. the eyes are in focus whereas the feet are not, because the person is slightly leaning forward at the time you are focussing and shooting.
b. the person is slightly and unwillingly moving back and forth within the time you are finally putting the film holder into place, so the persons face maybe out of focus at the time of shooting.
c. your exposure time is too long ( i could imagine the ex-time on your picture is about 1/60?) so a slight blurr happens which seems to indicate "out of focus" which it is not?
and as somebody said, the film flatness could be an issue using wide open stops.


now all this could be possible if you shoot people standing. if that is not the case ... i am afraid i can't help.
hope you find the cause.

doug

douglas antonio
4-Jun-2007, 00:34
by the way:

have you experienced all this shift of focus when shooting a still? if not, you may want to try this to find out whether it is a matter of shooting "moving" objects or it is really a technical problem.

Steve Kefford
4-Jun-2007, 04:12
...The plane of sharpness is curved like a bowl - so the face (center of the bowl, where you focused on) comes out fine but at the extremities (feet), the area of sharpness is a little bit closer to the camera.

I don't think so. The plane of sharpness is a plane, i.e. flat.

Steve

cyrus
4-Jun-2007, 10:05
I don't think so. The plane of sharpness is a plane, i.e. flat.

Steve

As I understand it - and I'm hardly qualified - the "plane" terminology wasn't is simply an approximation of a flat surface & the more accurate description is the "focal surface" - which is curved. Or something like that.

Anyway this issue strikes me as a depth of field issue.

vijayn
4-Jun-2007, 11:04
I would hope that the designers of lenses for LF cameras ensure that the "focal surface" approaches a plane - it would be nightmarish doing Scheimpflug with curved surfaces.

ic-racer
4-Jun-2007, 11:22
Some comments,
1) The photograph of the lady is clearly not in focus.
2) The focal plane is in FRONT of her by about 25cm.
3) Film bulge shifts the focal point BEHIND the subject.
4) I think the original poster knows how to use a ground glass and a loupe.
5) Depth of field is irrelevant here, this is a focus shift.

I don't know how you all calibrate your ground glass, but this is a perfect example of a ground glass that is not at the plane of the film in the film holder. This is one of the first things I check when I get a new camera.

I agree with Leonard Evens that the ground glass needs to be moved back about half a millimeter.

My calculations as follows based on 4500mm subject distance (15 feet) and 210mm lens focal length and about one foot focal error (250mm).

1/4500mm + 1/210mm = 1/X ( X = 200.6369mm)
and
1/4250mm + 1/210mm = 1/X' (X' = 200.1121mm)

Subtract X' from X and the focal plane error is about .5 mm

What I do is to take about 10 pieces of electricians tape and stack them together. Then measure the size of the stack and divide by 10. This gives you the thickness of one piece of the tape. My guess is that you will need 2 thickneses, perhaps a little more.

Unless the camera was purchased new, I suspect some prior owner took the ground glass apart and did not get all the pieces back together correctly.

christopherbwurzbach
4-Jun-2007, 17:20
Unless the camera was purchased new, I suspect some prior owner took the ground glass apart and did not get all the pieces back together correctly.

First off - thanks to everyone for the input - it is greatly appreciated!

Second - This camera was purchased used however it worked without problems for at least 8 months, I have not removed the ground glass or anything.

However, I just made a .5mm metal piece that will allow more space between the gg and lens. I will try this out shortly and let everyone know how everything is going.

Thanks Again

- Christopher Wurzbach
www.christopherbwurzbach.com

cyrus
4-Jun-2007, 20:03
First off - thanks to everyone for the input - it is greatly appreciated!

Second - This camera was purchased used however it worked without problems for at least 8 months, I have not removed the ground glass or anything.

However, I just made a .5mm metal piece that will allow more space between the gg and lens. I will try this out shortly and let everyone know how everything is going.

Thanks Again

- Christopher Wurzbach
www.christopherbwurzbach.com


Yes yes but we're not done giving you advice yet!

Alan Davenport
4-Jun-2007, 23:08
Could the lens cause this type of problem?

Yes. If the front/rear cell spacing is not correct (as per the lens design) it might shift focus when you stop it down. (IINM, there are some lenses that exhibit some focus shift regardless of the spacing; happily those are rare.)

Steve Kefford
5-Jun-2007, 04:50
As I understand it - and I'm hardly qualified - the "plane" terminology wasn't is simply an approximation of a flat surface & the more accurate description is the "focal surface" - which is curved. Or something like that.

Anyway this issue strikes me as a depth of field issue.

No, it is not curved. Unless there are problems with the lens, the focal surface IS flat.

Steve

Dan Fromm
5-Jun-2007, 05:27
Christopher, I've had a similar problem. All of the shots taken just before a vacation were in focus. All trips taken on the vacation were out of focus. Very discouraging.

After I realized I had a problem I tried to diagnose it. I set up as carefully as possible and used a 12x instead of a 3.5x loupe to focus. Tried focusing through the subject from both directions. And used a test target that was canted with respect to the film plane so that I could see where I intended to focus and where I actually did. Shot wide open to minimize depth of field and make focusing problems easier to see.

I still don't know what the problem on vacation was, but I have to conclude that I was it. When I was as meticulous as I could be, the results were as expected. My gear's fine. I'm not, or at any rate I wasn't.

One thing to consider. Every once in a while, my visual acuity goes. So now when I'm not sure I've got things right I use the more powerful loupe. So far, so good.

Good luck,

Dan

Donald Qualls
5-Jun-2007, 09:31
Every once in a while, my visual acuity goes.

If you're past about 45, that can come from a prolonged time focusing at a different distance than is usual for you -- driving for several hours when you normally work at a desk, for instance (and never mind bifocals), or looking at ground glass under a dark cloth for a day's heavy shooting compared to a computer screen at a couple feet.

However, occasional blurred vision can also be a symptom of uncontrolled diabetes, which fairly commonly comes on in middle age (especially common in connection with obesity or gum disease, but those aren't requirements) -- have you been checked lately?

Dan Fromm
5-Jun-2007, 09:34
Donald, thanks for the concern. Yes I've been checked, I am diabetic, and my blood sugar is in good control.

James E Galvin
5-Jun-2007, 14:27
I can easily get .5mm of rear standard flex if I push the loupe against the ground glass. I must hold the loupe very lightly against the glass to avoid just this problem.

christopherbwurzbach
5-Jun-2007, 17:18
Christopher, I've had a similar problem. All of the shots taken just before a vacation were in focus. All trips taken on the vacation were out of focus. Very discouraging.

After I realized I had a problem I tried to diagnose it. I set up as carefully as possible and used a 12x instead of a 3.5x loupe to focus. Tried focusing through the subject from both directions. And used a test target that was canted with respect to the film plane so that I could see where I intended to focus and where I actually did. Shot wide open to minimize depth of field and make focusing problems easier to see.

I still don't know what the problem on vacation was, but I have to conclude that I was it. When I was as meticulous as I could be, the results were as expected. My gear's fine. I'm not, or at any rate I wasn't.

One thing to consider. Every once in a while, my visual acuity goes. So now when I'm not sure I've got things right I use the more powerful loupe. So far, so good.

Good luck,

Dan

Dan -

Initially I thought it was me too - so I went to an eye doctor and discussed my problems - he concluded that I have Accommodation Spasms due to weak eye muscles (due to the drug Advair !STAY AWAY FROM ADVAIR!) He prescribed glasses that were suppose to help or solve the problem. It obviously hasn't.

So I am concluding that I must make changes to my camera - calculate how far off my vision is - then have a metal machinist friend of mine make a piece to create more space between the gg and lens.

I was just needed to rule out any of my equipment as a cause.

Any other suggestions are welcomed!

Thanks!

- Christopher

CG
6-Jun-2007, 09:44
Were it the lens at fault, the error would get compensated for by the photographer refocussung to the new albeit faulty plane of sorta focus.

This sounds like an instance of the ground glass not being in the same plane of the film. The consistency of it suggests hard parts have shifted into a new and stable configuration. The ground glass is now nearer the lens than the film. Possibly the frame holding the ground glass has gotten bent or warped, pushing it back, or some bit has gotten into the works that holds the glass back somehow, but does not touch the film holders.

I'm grasping at straws a little when I say I suspect it more difficult for the film to get moved forward in a consistent way, than the glass to get moved back, but ....

Best,

C

JeffD
13-Jun-2007, 07:05
I have an Ebony RW45, and was making a mistake that might be creating your problem.
I would focus on the ground glass, using a loupe in my left hand, and turning the large rail adjustment knobs on the right side of the camera to obtain focus.

When I achieved focus, I would lower my loupe, and tighten the rail "lockdown" screw on the left side of the camera.

What would happen to me was that, when I adjusted the lockdown screw, the tightening down of the lockdown screw caused the rail to move just ever so slightly- just enough to throw the plane of focus off a small amount.

Now, when I have the lockdown screw tightened, I always go back with the loupe one more time, and check the focus. If it is off by a hair, there is usually enough play still left in the rail where I can correct it with enough torque on the focusing rail adjustment screw.

I'm not familiar with your camera, so maybe this isn't happening to you, but maybe this will be helpful to someone- Always check your focus one last time, when you have locked down your focusing rail!

JoeV
13-Jun-2007, 10:08
Dan -

Initially I thought it was me too - so I went to an eye doctor and discussed my problems - he concluded that I have Accommodation Spasms due to weak eye muscles (due to the drug Advair !STAY AWAY FROM ADVAIR!) He prescribed glasses that were suppose to help or solve the problem. It obviously hasn't.

So I am concluding that I must make changes to my camera - calculate how far off my vision is - then have a metal machinist friend of mine make a piece to create more space between the gg and lens.

I was just needed to rule out any of my equipment as a cause.

Any other suggestions are welcomed!

Thanks!

- Christopher


Christopher, I hope you get your vision issues resolved with your doctor soon. But the problem you're describing here sounds to me like a calibration shift between the ground glass and the film holder position.

When we focus the image on the ground glass we are viewing a 2-dimensional projected image. And then we evaluate the position of 'best focus' by qualitative clues in the image's sharpness. Regardless of the quality of your personal vision, 'best focus' is 'best focus'. Meaning that it may be in the range of from 'soft' to 'softer' with compromised vision, but best focus should be obtainable consistently, especially since you have been using this rig with no issues prior to this problem and have obtained consistent results.

This also means that it can't be the lens itself. You would be focussing for 'best focus' of the lens' projected image. If the lens were off, 'best focus' may not happen at the correct distance on the rail relative to a known good lens, but you'd still be able to focus it. And once you've evaluated the image on the ground glass as 'best', you should get the same result on film.

And as mentioned before, it can't be film bowing issues, since bowing would bring the film closer to the lens, shifting the plain of best focus in the image to the rear of the subject.

I would also doubt standards shifting or moving. Unless it's happening between focussing and inserting the film holder. Again, you're seeing 'best focus'; it's just that the film plane isn't at the same location as the ground glass.

Los
15-Jun-2007, 01:13
christopher,

i've had the same problem. i did a control test, and i think the problem was me. the last time this happened to me, i was shooting on carpet. i see from your photo, you're shooting on grass. any chance your stepping towards or away from the camera before tripping the shutter caused the camera and tripod to settle softly out of position? also, Jeff's technique for locking focus has given me something to think about as well. i have also resolved to shoot with more dof.

Armin Seeholzer
15-Jun-2007, 03:39
Hi Christopher
"I am also aware it is off just slightly - but when I open up to f11 - f 16 it is still obvious for portraits."
First you have to clear up your missunderstandings if you close down to f 11 - f 16 would be more correct!
You also talking about a loose lenselement on your loupe I would first buy a quality loup for example a Leica, Schneider or Rodenstock around 4x6 times and from then start new!
For me it sounds your loup is crap!
Have a good day, Armin