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Focusing with tilt
- Thread starter Grayhand
- Start date
alajuela
Active member
Hi this week went out and tested all my lenses DF and Cambo. All at 1.5 and 4 meters and at infinity. At all apertures.
On the Cambo I have Rodenstock, 28 and 40 and a 70. I am convinced that all 3 perform best between 5.6 and 16 with the peak between f8 and f11. After F16 for example with the focus mask no green.
If anybody has a different experience - please share.
Thanks
Philip
Sometimes 100% focus check on the back is really useful, even for us hard-core ground glass users 
. I shot this picture yesterday, 72mm f/11, at first only with tilt (focused on ground glass) and it was sharp all over with a just a liiiiittle sharpnesss fall-off on the left side, probably due to a small slope of the ground.
This very slight fall-off I could see on the Leaf Aptus screen, and then compensated with a very small amount of swing (less than 0.5 degrees) which brought everything into perfect focus.
. I shot this picture yesterday, 72mm f/11, at first only with tilt (focused on ground glass) and it was sharp all over with a just a liiiiittle sharpnesss fall-off on the left side, probably due to a small slope of the ground.This very slight fall-off I could see on the Leaf Aptus screen, and then compensated with a very small amount of swing (less than 0.5 degrees) which brought everything into perfect focus.
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Grayhand
Well-known member
Well Torger, my P45+ is good for many things, buth checking for critical focus on the display is not one of its stronger points
But it is surprisingly how much you can se on the ground glass once you learnt what to look for, the small shift in contrast when you pass the point of optimal focus.
I have bought a new shift adapter for use on a 4x5 camera with the graflock back and Mamiya digibacks. Very good price and a surprisingly good quality.
The only point is that it is equipped with a plastic "ground" glass that which is not so good.
But I did a quick mount of it on the back of my converted Polaroid 4x5 and with a 150mm lens + my P45+ tethered to my Mac Air.
I did a sequence of focus shoot, refocus shoot, refocus shoot ...
And the shoots where all unambiguously with a bit of short focus. Very little variation between the shoots, taken about F8 on an 5.6 lens for 4x5.
And, focusing with a loupe of course
But now I will grind a new ground glass for this adapter.
I am just waiting for the number 600 grit powder from England. The number 400 arrived yesterday.
So then it is about 15 minutes of boring work and then I will have a very good ground glass, and I will then start to shims the glass for critical focus.
Then it is time to start focusing at 5.6 :angel:
Ray
But it is surprisingly how much you can se on the ground glass once you learnt what to look for, the small shift in contrast when you pass the point of optimal focus.
I have bought a new shift adapter for use on a 4x5 camera with the graflock back and Mamiya digibacks. Very good price and a surprisingly good quality.
The only point is that it is equipped with a plastic "ground" glass that which is not so good.
But I did a quick mount of it on the back of my converted Polaroid 4x5 and with a 150mm lens + my P45+ tethered to my Mac Air.
I did a sequence of focus shoot, refocus shoot, refocus shoot ...
And the shoots where all unambiguously with a bit of short focus. Very little variation between the shoots, taken about F8 on an 5.6 lens for 4x5.
And, focusing with a loupe of course
But now I will grind a new ground glass for this adapter.
I am just waiting for the number 600 grit powder from England. The number 400 arrived yesterday.
So then it is about 15 minutes of boring work and then I will have a very good ground glass, and I will then start to shims the glass for critical focus.
Then it is time to start focusing at 5.6 :angel:
Ray
Grayhand
Well-known member
Philip, I have no experience of the lenses in your example.
But your result seems to match what others have reported after practical tests with this type of lenses.
It is a dangerous game, better lenses and big pixel backs.
Generally it all just looks worse the more pixels you have and to check it out at 100%.
But if you have a 140, 160 and a 180 back on the same camera and lens you can see big differences between how a lens looks on the different back at 100%.
What is a good lens for a 40 MP back can bee a really bad lens for a 80 Mp back, at least at 100% on the screen.
But if you print all pictures at the same size, a size that is optimized for the 40 MP back, then you will see some thing different.
Then it is almost no difference between the pictures from the different backs.
And one point to meditate over is how much bigger is the printing area for the 80 MP back compared to the 40 Mp back, printed at the same resolution
Iif you normally don't print over 1 meter your biggest problem is seldom lens resolution, it is mostly bad focus and camera movements.
But that is maybe just me, all others only have problem with lens resolution
If you really want to save money on the lens side of the camera equipment, then you should print on Canvas
Ray
But your result seems to match what others have reported after practical tests with this type of lenses.
It is a dangerous game, better lenses and big pixel backs.
Generally it all just looks worse the more pixels you have and to check it out at 100%.
But if you have a 140, 160 and a 180 back on the same camera and lens you can see big differences between how a lens looks on the different back at 100%.
What is a good lens for a 40 MP back can bee a really bad lens for a 80 Mp back, at least at 100% on the screen.
But if you print all pictures at the same size, a size that is optimized for the 40 MP back, then you will see some thing different.
Then it is almost no difference between the pictures from the different backs.
And one point to meditate over is how much bigger is the printing area for the 80 MP back compared to the 40 Mp back, printed at the same resolution
Iif you normally don't print over 1 meter your biggest problem is seldom lens resolution, it is mostly bad focus and camera movements.
But that is maybe just me, all others only have problem with lens resolution
If you really want to save money on the lens side of the camera equipment, then you should print on Canvas
Ray
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Grayhand
Well-known member
I will shove a picture of the result from my focus test.
As the picture shows so the true focus point is a bit in front of where I focus with the ground glass.
And as long the test shows front focus, then it is easy to fix.
You just have to put some shims material under the mounting points of the ground glass, to lift it up.
If there is back focus, then it is harder to fix. Then you should move the ground glass closer to the lens.
But that is normally not so easy, depending on how it is mechanically mounted.
Then you might have to shims the mount for the digital back.
And that can be more complicated, ones again depending on the mechanical mount of the digiback.
BUT, when you do this test with a loupe, make really sure that the lope has its focus on the right plane, on the grounded side of the glass.
And if you have calibrated the loupe on another ground glass, is the next ground glass you use of the same thickness?
If your loupe is wrongly adjusted, any atempt to adjust the position of a ground glass can be a real exercise in frustration.
Can any one guess why I know that
Ray
As the picture shows so the true focus point is a bit in front of where I focus with the ground glass.
And as long the test shows front focus, then it is easy to fix.
You just have to put some shims material under the mounting points of the ground glass, to lift it up.
If there is back focus, then it is harder to fix. Then you should move the ground glass closer to the lens.
But that is normally not so easy, depending on how it is mechanically mounted.
Then you might have to shims the mount for the digital back.
And that can be more complicated, ones again depending on the mechanical mount of the digiback.
BUT, when you do this test with a loupe, make really sure that the lope has its focus on the right plane, on the grounded side of the glass.
And if you have calibrated the loupe on another ground glass, is the next ground glass you use of the same thickness?
If your loupe is wrongly adjusted, any atempt to adjust the position of a ground glass can be a real exercise in frustration.
Can any one guess why I know that
Ray
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So, for those of us not keen on maths and graphs, am I correct in thinking that the most basic way to set two points on the best plane of focus using a GG– say a foreground object and a background object – is to focus on one point using the a loupe then tilt until the second point is sharp. Keeping the tilt set, check focus on the first point and tweak if needed?
I realise this method is not taking into account the wedge of best focus and knowing this is key to getting consistent and predictable results, but is my thinking even in the ballpark to start getting acceptable tilt results?
I realise this method is not taking into account the wedge of best focus and knowing this is key to getting consistent and predictable results, but is my thinking even in the ballpark to start getting acceptable tilt results?
Great, thanks.
This is part of the reason why I love the Linhof Techno and using the GG to focus. I'm the kind of person that learns visually and by being hands on. The Techno is a fantastically engineered camera and even though I have to go under a dark cloth to focus and compose, it somehow feels more tactile, intuitive and less nonsense in terms of workflow than pancake cameras foregoing the GG, at least in terms of my sensibilities. The only thing I wish was better on the Techno is a finer pitched gearing for the tilt / swing. Also, the focus gearing is good, but I feel it could be slightly finer as well. Not too much, just a tiny bit.
As an aside, I recently purchased the new 12x loupe from Linhof & Studio. It has a 1cm square base which makes it very easy to check detail in corners. Plus because of the narrow field of view there is little to zero distortion. I was previously using a 10x Silvestri loupe and it was USELESS for finding focus when tilting because I couldn't get it close enough to the edge of frame to check fine details – things would get distorted and weird when looking through it off dead centre. (I'm shooting mainly with a 6x7cm film back and because the film area takes up the entire GG frame, it's very critical I can see to the edge.) It's amazing how such a small purchase can make such a big difference to getting consistent results and therefore developing an understanding of the technical process.
This is part of the reason why I love the Linhof Techno and using the GG to focus. I'm the kind of person that learns visually and by being hands on. The Techno is a fantastically engineered camera and even though I have to go under a dark cloth to focus and compose, it somehow feels more tactile, intuitive and less nonsense in terms of workflow than pancake cameras foregoing the GG, at least in terms of my sensibilities. The only thing I wish was better on the Techno is a finer pitched gearing for the tilt / swing. Also, the focus gearing is good, but I feel it could be slightly finer as well. Not too much, just a tiny bit.
As an aside, I recently purchased the new 12x loupe from Linhof & Studio. It has a 1cm square base which makes it very easy to check detail in corners. Plus because of the narrow field of view there is little to zero distortion. I was previously using a 10x Silvestri loupe and it was USELESS for finding focus when tilting because I couldn't get it close enough to the edge of frame to check fine details – things would get distorted and weird when looking through it off dead centre. (I'm shooting mainly with a 6x7cm film back and because the film area takes up the entire GG frame, it's very critical I can see to the edge.) It's amazing how such a small purchase can make such a big difference to getting consistent results and therefore developing an understanding of the technical process.
I agree the 12x loupe is really nice, and - although it's a very small niggle - that the gearing on the T/S could be finer. That said, they're 95% of what I would like them to be, and the fact that we have 10 degrees of both in such a compact body is great. I've actually grown to like the focus control - I think it's nicely balanced in order to pop things in and out of focus. That said it would be nice if one of the focussing knobs was finer geared so we had a choice between which to use. I've found that applying the 'brake' a little bit to the focussing action can make a difference when wanting to make very fine adjustments.
Yes, I agree. It's 95% perfect. I was out shooting today and thought that perhaps I'm thinking more of the action of the tilt / swing gears as compared to the ultra, ultra silky rise and fall action on the back it's a little tight – unless you're assertive with it it can be a tad jerky. I think with my Techno this might be because I bought it new and haven't "run it in" yet. How do you find the action on yours?
Reviewing scanned photos today (I scan using an Imacon 949) I see that my tilt technique has been working well. I'm getting what I want in focus, and that's the main thing! Gotta love the GG for that as I've never really second guessed myself in the field. I'm wondering what the new bright Linhof GG is like compared to my Silvestri GG. If it's brighter and finer grained, it'd have to improve the critical focus hit rate even more...
Also, I think it was reading one of your posts that I learnt Paula had finally received the new 12x loupe. Thanks for the tip!
Reviewing scanned photos today (I scan using an Imacon 949) I see that my tilt technique has been working well. I'm getting what I want in focus, and that's the main thing! Gotta love the GG for that as I've never really second guessed myself in the field. I'm wondering what the new bright Linhof GG is like compared to my Silvestri GG. If it's brighter and finer grained, it'd have to improve the critical focus hit rate even more...
Also, I think it was reading one of your posts that I learnt Paula had finally received the new 12x loupe. Thanks for the tip!
Rear rise/fall is indeed 'silky' smooth - really nicely done. The tilt gearing is nice and smooth. The swing is a bit stiff(ish) I would say - possibly to do with the small size of the knob and gearing perhaps? I sometimes use the 'acute' groundglass - the new brightscreen is a larger version i.e. fresnel + cover glass. The 'acute' screen is really bright but, like all fresnels, once you get off center with a wide angle lens, it gets a tad dark. That said, the new brightscreen is physically much larger than the old acute one (which was a Hasselblad screen in a Linhof holder) so it may not be as susceptible to this effect. From the pictures I've seen the holder seems also to have a redesigned 'top' which may restrict extraneous light from degrading the image. It would be nice to hear first hand from someone using it, at £600 it's too expensive for the college I work at to justify given we have the acute screen (unless it gets dropped on the floor by accident and *ahem* needs replacing ) I did read somewhere (here or on LuLa) of someone who had replaced the Hasselblad 'acute' screen with a Maxwell one (he can make the screens in a variety of focal lengths depending on what lens you use most with it). His screens are great. The 12x loupe is pretty small, but perfect in operation for getting into the corners - far, far better than any of the others I had used previously. Low magnification loupes intended for 4x5, 5x7, 8x10 just don't cut it anymore - which is one reason I suspect that people have had difficulty in the past adjusting to the demands of gg focussing in the digital age. Now, with this loupe (and the acute/brightscreen) it's gotten a whole lot easier, to the point where no one should be afraid of it.
) I did read somewhere (here or on LuLa) of someone who had replaced the Hasselblad 'acute' screen with a Maxwell one (he can make the screens in a variety of focal lengths depending on what lens you use most with it). His screens are great. The 12x loupe is pretty small, but perfect in operation for getting into the corners - far, far better than any of the others I had used previously. Low magnification loupes intended for 4x5, 5x7, 8x10 just don't cut it anymore - which is one reason I suspect that people have had difficulty in the past adjusting to the demands of gg focussing in the digital age. Now, with this loupe (and the acute/brightscreen) it's gotten a whole lot easier, to the point where no one should be afraid of it.
Grayhand
Well-known member
The number 600 grit powder arrived from England so I did try to grind my self a new ground glass for my new shift adapter.
Started with the 400 grit for about 10 minutes and then a quick grinding with the 600 grit for maybe 5 minutes.
For this quick and sloppy test I must declare the result an success :chug:
Way better than the original plastic ground "glass".
And quite bright with a nice "snap" to focusing.
Next time I will do a proper job without scratching the top side of the glass...
Then I will also do a proper calibration of the new ground glass.
I made two quick photos of one of my Sinar cameras with two standards mounted on different bearer.
To the left in the photos is a Sinar F and to the right a Sinar P.
In the first photo there is no tilt and in the second photo there is a tilt of 10 degrees.
As can be seen in the photo, for the "F" the tilt gives an rotation point way below the lens.
This makes the whole lens "fall forward" when tilting.
For the "P" there is a rotation point in the center of the lens optical axle.
Depending on the lens it also might be the nodal point for the lens.
When focusing and tilting in the same scene different things happens to the far and near focusing point as consequences of this two different methods.
Which is the best? It depends, in my opinion, on the scene I which to take a photo of.
If there is a middle object on the same plane as I want to put my far and near focus points,
then I think the "P" has a small advantage for me.
But if you understand the difference between this two construction, then it really doesn't matter how your tilting mechanism is constructed.
Observe that I only speaking about tilt and focusing without any other help than the ground glass and a loupe.
I will later make a detailed description with photos of how I focus this two different bearer.
But at the moment in a period with to much work. There seems to be some kind of natural law stating that "The more toys you want, the more you have to work".
This is of course utterly unfair, in my opinion
Ray
Started with the 400 grit for about 10 minutes and then a quick grinding with the 600 grit for maybe 5 minutes.
For this quick and sloppy test I must declare the result an success :chug:
Way better than the original plastic ground "glass".
And quite bright with a nice "snap" to focusing.
Next time I will do a proper job without scratching the top side of the glass...
Then I will also do a proper calibration of the new ground glass.
I made two quick photos of one of my Sinar cameras with two standards mounted on different bearer.
To the left in the photos is a Sinar F and to the right a Sinar P.
In the first photo there is no tilt and in the second photo there is a tilt of 10 degrees.
As can be seen in the photo, for the "F" the tilt gives an rotation point way below the lens.
This makes the whole lens "fall forward" when tilting.
For the "P" there is a rotation point in the center of the lens optical axle.
Depending on the lens it also might be the nodal point for the lens.
When focusing and tilting in the same scene different things happens to the far and near focusing point as consequences of this two different methods.
Which is the best? It depends, in my opinion, on the scene I which to take a photo of.
If there is a middle object on the same plane as I want to put my far and near focus points,
then I think the "P" has a small advantage for me.
But if you understand the difference between this two construction, then it really doesn't matter how your tilting mechanism is constructed.
Observe that I only speaking about tilt and focusing without any other help than the ground glass and a loupe.
I will later make a detailed description with photos of how I focus this two different bearer.
But at the moment in a period with to much work. There seems to be some kind of natural law stating that "The more toys you want, the more you have to work".
This is of course utterly unfair, in my opinion
Ray
You should try aluminium oxide (rather than silicon carbide, which I think you're probably using?) in 1 - 5 micron size - it's possible to make a groundglass that's virtually grain free up to about 20x. Takes longer than silicon carbide (unless you have access to a lapping table), but worth it.
Ray:When focusing and tilting in the same scene different things happens to the far and near focusing point as consequences of this two different methods.
Which is the best? It depends, in my opinion, on the scene I which to take a photo of.
If there is a middle object on the same plane as I want to put my far and near focus points,
then I think the "P" has a small advantage for me.
But if you understand the difference between this two construction, then it really doesn't matter how your tilting mechanism is constructed.
Observe that I only speaking about tilt and focusing without any other help than the ground glass and a loupe.
I will later make a detailed description with photos of how I focus this two different bearer.
But at the moment in a period with to much work. There seems to be some kind of natural law stating that "The more toys you want, the more you have to work".
This is of course utterly unfair, in my opinion
Ray
A nice way to show the different lens tilt methods.
The Pulitzer Prize winning photographer, Jack Dykinga, has a book titled 'Large Format Nature Photography', published by Amphoto Book, which shows in great details how to use View Cameras with diagrams and sample photos. It is one of the best books with both technical and artistic explanations on View Camera, in my humble opinion.
Jae Moon
Do you know of a link so one can see this loupe? I've searched previously and not found it. I'm a bit curious to see how it looks. I guess/hope it's larger than my 20x loupe...
How large is the field of view? 5mm? 10mm?
Grayhand
Well-known member
f8orbust: The plan is to go to smaller and smaller grinding powder, and the I have to sooner or later go for aluminum oxide.
Mostly to see how far there is reasonable to go. But it is an exercise that becomes more and more boring as the size of the grinding powder is reduced
Jae Moon: Thanks for the tip, I will look out for the book!
Ray
Mostly to see how far there is reasonable to go. But it is an exercise that becomes more and more boring as the size of the grinding powder is reduced
Jae Moon: Thanks for the tip, I will look out for the book!
Ray
Rough iPhone pics attached.
Square base is 1cm square. It's small but fine to use.
Beer bottle cap for reference.
TJV
Square base is 1cm square. It's small but fine to use.
Beer bottle cap for reference.
TJV