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Kevin
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I actually find that when I am shooting still life, or indoor floral images, that I can manage without a dark cloth. However that's probably because of the way that I choose to light the subject:

a) Set up a dark background
b) Position the subject as far away as possible from the background, to reduce light falling on the background.
c) Draw the curtains (in the room I usually use, they are very thick curtains)
d) Switch on one or two lights which are aimed towards the subject. I use anglepoise lamps.
e) Switch off the room lights
f) I now have a very clear view of the subject set against a dark background.

In short there is a fair bit of light on the subject and as little as possible anywhere but the subject. The dark cloth isn't needed because there isn't any extraneous light that needs to be cut out.

That approach will give lighting something like this:

Phalaenopsis
by Kevin Allan, on Flickr

However if you want natural lighting then, as suggested above, shining more light temporarily on the subject whilst you focus will help.
 
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Chris
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I struggle with focussing indoors as well as the image can be very dark, but if I use a torch with the beam focussed to a small bright dot, I can use it to light up the small area that I'm focussing on. Makes a world of difference, although looking at the screen and aiming the torch at the same time takes some getting used to when up is down and left is right!
^^THIS^^ when the object is too dark to see clearly or a bright table lamp alongside the object, compose, focus, remove lamp, meter, shoot frame.
That's a good idea. I did try turning the lights on, but nowhere near enough.

I'm no specialist regarding this but I'm presulmng that you had the bellows extended longer than 135mm ( the lens focal length) which makes a difference.
Also be aware for next time that depending how extended the bellows are, some exposure compensation is required!
Aha, of course! It would probably have been more like 180mm than 135mm. Thanks.

I have the Reciprocity Timer app, which has options for putting in bellows extension as well as the reciprocity. I would have used the bellows exgension bit if I'd been able to focus. As it was, I had used F-Stop to calculate depth of field, which suggested I needed f/32 to get 2 inches, and my first attempt at working out the required exposure (still not allowing for bellows extension) with Fomapan 100 would have been a 24 minute exposure!

And thanks @Peter B for that site, I'll have a look later.
 
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Great explanation, @Kevin Allan thanks. I've thought of a dark background like that, but I can't think how to suspend it. (This all has to be set up, shot and taken down while my OH is out!)

Just remembering, I was much earlier toying with the idea of putting a chair on the table, draping some black velvet (which I don't yet have) over it and the table, and proceeding much as you suggest... except then I was thinking of using the side lighting from the window. Your method must be better.

Even with indirect window light, I've been struggling with over-bright highlight reflections on the subject. None of my bodge methods so far seem to have controlled it. I'll try and dev the 135 film tomorrow and see what it looks like once it's dry and scanned.
 

sirch

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Dark slide thickness and focussing?

I had not thought about this before but one of my darkslides is thinner than the others, I guess it is more modern, but that means that the film will be a few millimetres closer to the lens than when using the other darkslides. This got me thinking, how do I know that the film is the same distance from the lens as the ground glass on which I have focussed? Given that the GG is a few millimetres thick and ground on one side does it matter which way around it is because again that will move the focus plane a few mm.

Does it really make much difference?
 
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Dark slide thickness and focussing?

I had not thought about this before but one of my darkslides is thinner than the others, I guess it is more modern, but that means that the film will be a few millimetres closer to the lens than when using the other darkslides. This got me thinking, how do I know that the film is the same distance from the lens as the ground glass on which I have focussed? Given that the GG is a few millimetres thick and ground on one side does it matter which way around it is because again that will move the focus plane a few mm.

Does it really make much difference?
This is "depth of focus" rather than the more usual depth of field, ISTR. I don't know the answer, but assume it depends to an extent on the lens design, and maybe on the focal distance. But, I hope one of those who actually knows will be along in a minute!
 
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The Wikipedia article suggests that for small magnification, the depth of focus t approximates to:

t ~ 2Nc

where N is the f-number and c is the circle of confusion, which they also suggest should be the diagonal of the image size divided by 1000 or 1500 (!). For 4*5" sheet, I think the diagonal is 6.5" or 165 mm, so c would be ~ 0.17 mm. So at f/32 you'd get depth of focus t to be around 10 mm, which should be fine. Even at f/5.6 you'd get a smidgen under 2 mm.

All that's if I managed to do those calculations correctly, dodging back and forth between different windows. It's easy to miss a factor of 10 doing that sort of thing!
 
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Steve
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Dark slide thickness and focussing?

I had not thought about this before but one of my darkslides is thinner than the others, I guess it is more modern, but that means that the film will be a few millimetres closer to the lens than when using the other darkslides. This got me thinking, how do I know that the film is the same distance from the lens as the ground glass on which I have focussed? Given that the GG is a few millimetres thick and ground on one side does it matter which way around it is because again that will move the focus plane a few mm.

Does it really make much difference?
There are ASA standards for all dark slides (measurement 'T' in the linked document);

https://www.dropbox.com/s/dkr83a2eykjcwek/ASA_FILM_HOLDER.pdf?dl=0

For 4x5 holders, the distance from the face of the DDS to film is around 5mm. The flange depth of the lens itself is largely irrelevant as you'll be moving it closer/further away from the glass to gain focus anyway. More important is that the ground side of the glass is the same distance from the lens as the film inside the holder, otherwise you'll never get a sharp image. Even a few mm out will impact overall sharpness of the image, assuming you're using relatively wide apertures. If you stop the lens down, the depth of focus may account for some differences but it's not an exact measurement.

With regards to the ground glass, the ground side is mounted towards the front of the camera, leaving the glossy surface facing outwards. If you spin the glass round the other way, as well as affecting your focus point, you'll also lose some clarity from the image on the glass.
 
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StephenM

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Does a thicker double dark slide equate to a greater distance of the film from the leading edge, which is what will determine the film position when mounted, or is it just the parts between the two sheets which is thicker?

Film position matters more with wide angles than longer focal length lenses, and less as you approach macro distances - at 1:1 depth of field and depth of focus are the same.
 

sirch

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Thanks Steve and Stephen. I get the impression that the new DDS is thinner because all the parts of it, the slot that holds the film, the frame, the slide it's self are thinner and so that would put the film a little closer to the lens. The older DDS just seem to be made from thicker materials and to larger tolerances. I'll do some measuring up when I get chance.
 
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Thanks Steve and Stephen. I get the impression that the new DDS is thinner because all the parts of it, the slot that holds the film, the frame, the slide it's self are thinner and so that would put the film a little closer to the lens. The older DDS just seem to be made from thicker materials and to larger tolerances. I'll do some measuring up when I get chance.
No problem. Like you say, the only way to know for sure is to measure the holder/ground glass and compare them.
 

StephenM

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at 1:1 depth of field and depth of focus are the same.
Not convinced that that's correct - except the part that says that film position matters less with close up.
 
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So that Wikipedia article also says there are "two slightly different meanings. The first is the distance over which the image plane can be displaced while a single object plane remains in acceptably sharp focus;[...] the second is the image-side conjugate of depth of field. [...] With the first meaning, the depth of focus is symmetrical about the image plane; with the second, the depth of focus is greater on the far side of the image plane, though in most cases the distances are approximately equal." Not quite sure of the implications of these points, or which meaning is used in the rest of the article.

Also yes, the depth of focus is inversely proportional to the lens focal length (other things being equal). And the actual formula behind the approximation I gave above is

t = 2Nc(1+m)

So presumably for 1:1 images, the magnification m is 1 so the depth of focus would be getting on for twice what it is when the magnification is small.
 
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Mike
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Not convinced that that's correct - except the part that says that film position matters less with close up.
It is correct, 1:1 is a special case, It wouldn't be true form any other conditions.
At 1:1 image distance = subject distance & the principle of reversibility applies - the lens doesn't care which way the light is travelling it will follow the same path .
It wouldn't be true form any other conditions.
 
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So, swing. There's a scene not far away that I've shot with my Pentax, in passing, but I'd quite like to go back with the big camera. It's basically a holly hedge, with slightly twisted stems. I'd be taking it one the diagonal, as it were, rather than straight on. I had enough depth of field with the Pentax to make a reasonable job of focus, but with LF I think I'm going to need some swing.

I'm guessing I'd be about 6 ft from the middle of the scene, say 10 ft or so from the far right hand side, and 2-3 ft from the near left hand side. That might prove much too much, and I may also find when I get there that I need to be a bit further out. Anyway, the line of focus I want is from near at the left to (relatively) far at the right.

My first thought was to swing the lens towards the left, but I think that must be wrong. To focus closer, you must move the lens further from the film, while infinity has the lens closer to the film. So, do I swing the lens towards the right?

(This is doing my head in!)
 
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Tilting (or swinging) the lens doesn't change the nature of focus on the film because all parts of the image are formed by rays that hit all parts of the surface of the lens where the internal rays go on to pass through the aperture.

It's about tilting the plane of focus - the near-to-far band of sharpness that constitutes the depth of field. When the lens plane is parallel to the film plane, the plane of focus is also parallel. When you tilt the lens plane by X amount, the plane of focus tilts away in the same direction by a greater amount. It's formalised mathematically in the Scheimpflug principle...

https://en.wikipedia.org/wiki/Scheimpflug_principle

Tilt or swing in the opposite direction (to the right in your example) will result in a narrow band of sharpness somewhere along the hedge with blurring of the near and far parts. Reverse tilt is the method that's used to make conventional full size scenes look like a photo of a scale model - it looks similar to a photo taken at a short distance with a lens that isn't stopped down much.
 
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Kevin
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I think you need the right hand edge of the lens panel (looking from the behind the camera) to be the most forward edge - how much forward, can only be judged on the spot and can be confirmed by looking at the image on the ground glass. If that's what you mean by "swing the lens towards the left" then you're on the right lines.
 
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Tilt or swing in the opposite direction (to the right in your example) will result in a narrow band of sharpness somewhere along the hedge with blurring of the near and far parts.
I think you need the right hand edge of the lens panel (looking from the behind the camera) to be the most forward edge - how much forward, can only be judged on the spot and can be confirmed by looking at the image on the ground glass. If that's what you mean by "swing the lens towards the left" then you're on the right lines.
Aha, two opposite opinions, mirroring my own confusion! Oh dear, looks like I'm going to have to read up about the Scheimpflug principle... my head's hurting already ;) ...
 
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Aha, two opposite opinions, mirroring my own confusion! Oh dear, looks like I'm going to have to read up about the Scheimpflug principle... my head's hurting already ;) ...
I think it would be much easier to sit your camera on the table and focus on something running at a similar angle. Of the top of my head, I'd agree with Kevin but it's definitely quicker to do a quick setup that try to figure it out on paper :0)
 

Asha

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Aha, two opposite opinions, mirroring my own confusion! Oh dear, looks like I'm going to have to read up about the Scheimpflug principle... my head's hurting already ;) ...
Chris the easiest way is to see what heppens to the image that you see on the GG.

So to save you trying to understand how and why atm, why not simply wait until you get to the location and play with the movements until you get the result that you wish for and then see physically which way the standards are facing.
Alternatively, and possibly a better idea would be to set camera up at home and try out the different movements to at least get some idea of what to expect in the field.

Learning the in depths of trigonometry etc can come in time at a later date if you should so wish to learn.
For me personally, the practical makes things much more clear and actually helps to understand the text book!
 
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Aha, two opposite opinions, mirroring my own confusion! Oh dear, looks like I'm going to have to read up about the Scheimpflug principle... my head's hurting already ;) ...
Turned out not to be as bad as I'd thought; there's a diagram in the Wikipedia article that shows almost exactly this case...

Scheimpflug diagram

Approach seems to be:

a) extend a lie through the image plane
b) extend a line through the preferred line of focus (in my case, the hedge)
c) turn the lens so that an extended line transversely through the lens meets the other two lines at their intersection.

Ie, turn the lens towards the left...

PS, how do I turn that link into an embedded image, please?
 
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Sorry, I should have clarified that whilst I've got 'several' Chroma's in my workshop, I haven't got any lenses at the moment so I couldn't test it out for you! I'm also currently sitting in the office of my day job so even less useful..

Glad you found the answer, I thought it was basically a matter of turning the front standard in the direction to follow where you want the plane of focus to run (y)
 

StephenM

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My simplistic way of thinking about it is that the focussed image of a near object is further back than the focussed image of a far object (remembered by what extension tubes do).

The image produced by a lens is upside down and laterally reversed.

Therefore the image of the left side of the scene as the photographer views it is on the right hand side of the film.

And from that, if the right hand side of the scene viewed from the camera is closer, you need to move the right hand side of the front standard closer to the subject, or the left hand side of the rear standard further away.

N.B. Check that last paragraph according to my reasoning - I've been known to say the exact opposite of what I meant when writing :)
 

Asha

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My simplistic way of thinking about it is that the focussed image of a near object is further back than the focussed image of a far object (remembered by what extension tubes do).

The image produced by a lens is upside down and laterally reversed.

Therefore the image of the left side of the scene as the photographer views it is on the right hand side of the film.

And from that, if the right hand side of the scene viewed from the camera is closer, you need to move the right hand side of the front standard closer to the subject, or the left hand side of the rear standard further away.

N.B. Check that last paragraph according to my reasoning - I've been known to say the exact opposite of what I meant when writing :)
S**t I need to sit down, that's made me dizzy! :LOL:
 

StephenM

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I can provide the maths if that's easier for you to follow :p

:jaffa::jaffa::jaffa:
 

Asha

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I can provide the maths if that's easier for you to follow :p

:jaffa::jaffa::jaffa:
It may help others if not me.

Tbh I find it much easier to just get out there and learn in practice by making inevitable mistakes.

That method always has worked better than the texts and maths for me personally with most things in life including photography.
 
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Turned out not to be as bad as I'd thought; there's a diagram in the Wikipedia article that shows almost exactly this case...

440px-Scheimpflug.gif

Approach seems to be:

a) extend a lie through the image plane
b) extend a line through the preferred line of focus (in my case, the hedge)
c) turn the lens so that an extended line transversely through the lens meets the other two lines at their intersection.

Ie, turn the lens towards the left...

PS, how do I turn that link into an embedded image, please?
Yes the diagram helps a lot. Makes it easier than pronouncing the principle.
 
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Aha, two opposite opinions, mirroring my own confusion! Oh dear, looks like I'm going to have to read up about the Scheimpflug principle... my head's hurting already ;) ...
They're not two opposite positions. I was working on the assumption that you wanted to get the maximum in focus (but I didn't state my asssumption) whereas Nomad was stating a way of getting only a narrow slice in focus.
 
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They're not two opposite positions. I was working on the assumption that you wanted to get the maximum in focus (but I didn't state my asssumption) whereas Nomad was stating a way of getting only a narrow slice in focus.
Exactly correct.

The diagram on the wiki page makes it clear - the lens plane has to lie somewhere between the image plane and the plane of focus. Hence, if the plane of focus has the near end on the left, then the lens plane is rotated to the left.
 
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Richard
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I have a similar Fuji SW lens, except it's 90mm, which also has a Seiko shutter like the one for sale. Mine also came from a Japanese ebay selller. Those with Seiko tend to have slightly lower sale prices than those with Copal shutters. My shutter did freeze up within a few months from purchase, and had to go to Miles Whitehead for repair. That's a totally unscientific sample of 1 of course, and we might assume that Seiko know how to make timing devices since they provide the precision behind international athletics events and so on.
 
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Interesting.... but I believe it's an uncoated lens, for whatever that's worth!
 

StephenM

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About 5% light scatter at every air to glass surface, against about 1% with multicoating. Hence lower contrast (can actually help not hinder with subjects with extreme subject brightness range) and more chance of veiling flare and flare generally when shooting into the light.
 
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Woodsy

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About 5% light scatter at every air to glass surface, against about 1% with multicoating. Hence lower contrast ....
I've seen this written in a few places now. Do you know a physical process/explanation for why this would be the case?
 
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About 5% light scatter at every air to glass surface, against about 1% with multicoating...
I've seen this written in a few places now. Do you know a physical process/explanation for why this would be the case?
Not sure if it's actually scatter, but surely there's some reflection and some transmission at any glass-air or glass-glass (different RI) surface... the multicoating cuts down the reflected part (EDIT through interference effects /EDIT), increases transmission. At least, that's what my dim memory of 2nf year optics suggests...
 
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Woodsy

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Not sure if it's actually scatter, but surely there's some reflection and some transmission at any glass-air or glass-glass (different RI) surface... the multicoating cuts down the reflected part (EDIT through interference effects /EDIT), increases transmission. At least, that's what my dim memory of 2nf year optics suggests...
I understand how Fresnel reflection and AR coatings work, what I don't understand is how it affects the contrast. Reducing transmission by a constant factor across all intensities and then renormalising to get the same overall exposure shouldn't affect contrast... to my understanding.

Also, scattering and reflection are different processes. In the absence of a 'scatterer' and and an associated scattering process, light not transmitted through a smooth interface such as a polished glass surface is almost completely a reflective process.
 
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StephenM

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I can give an explanation based on my understanding (which at least has the merit of making sense to me) but I'd rather cite a textbook or two, which will take me some time to look up. Hopefully not as long as it's taken me to photograph some bottles of malt Scotch :)
 
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Not sure if it's actually scatter, but surely there's some reflection and some transmission at any glass-air or glass-glass (different RI) surface... the multicoating cuts down the reflected part (EDIT through interference effects /EDIT), increases transmission. At least, that's what my dim memory of 2nf year optics suggests...
Indeed it's not scatter, but reflection my sources put it at ~4% for clean uncoated air/glass interfaces, but I remember it being ~1% for single coated interfaces & significantly lower for multicoated interfaces.
Dirty or scratched surfaces of course will give rise to other issues where absorbtion & scatter will occur.

There will be some reflection at glass/glass interfaces (in bonded doublets etc) but the refractive indexes are much closer so this is fairly negligable.

Without multicoating the modern zoom (often having 10 or more groups - 20 air glass interfaces) would not be practical.

Even with a simple lens design like the cooke triplet about 20% of the incoming light is lost to surface reflections on an uncoated lens, resulting in flare & reduced contrast.
 
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Edit: nvm, found it after sifting through a lot of wishy washy opinions.
 
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