SCHNEIDER SYMMAR-S 240MM QUESTION. PLEASE HELP!!!

[Leon West]

Hi everyone,

Thanks for looking at my thread. I have a Schneider Symmar-S 240mm lens, that, according to the barrel, stops down to f45. The arrow that you align to the markings travels a lot further than f45, I suspect to f90 and maybe even beyond. My question is this, does anyone know if the markings / measurements are the same as the ones that progress from f5.6 onwards? They seem to be fairly evenly spaced on the measurements. If so, I could calculate the distance from f45 on the barrel to f64 and even f90. Surely someone else has had this 'problem', as I'm lacking that extra little bit of depth of field. f45 on the Symmar-S looks more like f11 on a regular 35mm lens, there's still a lot of stopping down on this lens to be had. ANY help whatsover, would be so much appreciated. Thanks for reading!

Leon

[Chong]

Hi Leon,
Could you not improve DOF using front tilt?

Most lenses have an aperture where they are at their sharpest (usually between f16-32). As aperture becomes smaller the image begins to suffer from light diffraction. This is why pinhole photography is never sharp because of light diffraction.

Some of my lenses could stop down beyond the marked f numbers too. I seldom stopped down beyond f32.

I think the formula for aperture size is focal length divide by the f number. Eg 240mm / f45 = 5.33mm (diameter of aperture). So for f64 your aperture should have a diameter of 3.75mm. Someone please correct me if I am wrong.

Regards

Chong

[Leon West]

Thanks for the reply. I think the problem may be I am focusing to close in the foreground. What would you reccomend? The problem is infinity, not foreground.

[masch]

Leon,

Chong is pretty much correct. If you stop down too far, diffraction effects begin to degrade the overall resolution of the lens.

The fact that your DoF seems to be lower than on an equivalent 35mm camera lens is simple. The longer the lens, the narrower the DoF...
You will gain a little through the larger Circle of confusion, but that's it, I'm afraid.
DoF is roughly(!) distributed at 1/3 on the camera side and 2/3 on the infinity side of the focal plane, so focussing 1/3 into a scene should give you a good distribution.

You could also complse and focus, then stop down and check focussing on the GG with a lupe, and if not suffieient, try to focus closer in and check again.

Some small front tilt will also help, in most scenes.

One problem lens apertures have is that they may not be as round as they need to be at smaller openings, leading to distortions. This is why a lot of 35mm rangefinder lenses (small) tend to have 12, 16 or more aperture blades.

There are a few Depth of Field calculators floating about on the web. http://www.silverlight.co.uk/resources/dof_calc.html was the first one I found on google. With a 300 mm lens at f/45, you should be able to get anything from 7m to infinity into focus. focus distance is about 14 meters.

As a tool, there are printable DoF tables out there, or if you own a Palm, there is a little program, called the "Photographer's Vademecum", I believe which contains loads of useful calculators.

Hope this helps,

Marc

[Leon West]

Thanks Marc,
Your reply made a lot of sense of a bad first trip out with a 10x8. I use a 240mm lens, would you happen to know what the 'optimum' aperture is for the film format I am using? Would the rule of focusing a third into a scene still be relevant with front tilt and a smaller aperture than the 'optimum' one? Or would a tilt and optimum aperture and then obviously the correct length of focussing (a third into the image) give me desired results? If so, surely I could find the focus length on the ground glass a third down, tilt the lens, and shoot at the optimum aperture for my lens. Effectively turning my 10x8 into a camera that 'everything' from the the foreground to infinity would be in focus. So could I make a mark on my extension rail of what is essentially the optimum focus point for the lens / film combination? I hope I am making sense here! Most of my compositions are usually very simple land / sky or sea / sky images. I usually keep the verticals vertical and the horizontals horizontal. Very formal. I'm hoping I can always focus at a specific point on my ground glass everytime, stop down to the optimum aperture and get nice Richard Misrach type sharp photographs. From the very bottom to the very top of the print. Thanks again for your help, you've already been so helpful.

Leon

[Charles Twist]

I am not sure how much you know about LF but it seems you're struggling a bit. So apologies if what I say is already known. I would recommend 2 references in respect of this thread.
Firstly for the circle of confusion in relation to the optimum f-stop and the range of f-stops that are acceptable, I would recommend the latest issue of View camera magazine (available now through RWhite). There is a fairly technical article in there with a few simple equations and loads of graphs and tables to explain it all. I am so impressed, I am going to contact the author and see if I can make up a card of the graphs and tables, plasticate it and maybe even offer it along with Jo's card of reciprocity correction tables. The optimal f-stop and the range of acceptable f-stops are calculated from the distance you need to extend the bellows in order to go from focusing the far object to focusing the near object - which is a very usable starting point. When Marc talks about focusing 1/3 of the way in, you're basically approximating the findings detailed in the above VC article.
Secondly, for the depth of field, the best explanation I have found is Stroebel's book. When there is no tilt of lens or film planes, the focal plane is parallel to the two standards. And the 1/3 in rule of thumb applies very straightforwardly. When you introduce tilt, the focal plane also tilts. If you tilt the lens plane forward, maintaining the film plane vertical, the focal plane runs from ground close to you, to sky in the distance - traditionally what is used for landscapes. Now the depth of field on this slanting focal plane is not the same whether you consider that bit of the focal plane which is nearest you or that bit which is furthest. The DoF is greater the further the object is from you. And now the rotten bit. If you're careful, you'll realise that the slanting focal plane is not planar at all!! It is flatter (more horizontal) near you and straighter (more vertical) at infinity. So when you change the bellows extension with tilt applied, you'll see far more difference on the distant objects than the nearest ones. But remember that the DoF is shallower in the foreground, so you need to exercise as much care as with the background. The 1/3 in rule of thumb still exists. You still want to place your slanting focal plane 1/3 of the distance between the nearest and furthest bellows extension (1/3 of the distance from the furthest bellows extension - which corresponds to the closest object).
Don't forget that tilt can be applied to make the focal plane slant upward or downward or sideways. If you look at the picture below, I used a down-slanting focal plane to get the foreground in focus, making sure the focal plane went through the falls at roughly half way up. The falls are 45 metres high and approx 150 metres away. I was standing at the same height as the top of the falls. Aperture = f22.5.
Hope that helps,
Charles

[masch]

Leon,

focussing a view camera is one of the "oddest" things. You can really improve focussing, or screw it up completely, by just tilting a few degreed more or less...
Have a look at viewtopic.php?t=133 and look at the 4th picture in the first post. You can see the tilted plane of focus!

Have a look through the links I sent you in the PM yesterday, that should make things a lot clearer...

Otherwise, it is best learned by trying and being shown... Can you make it to the Glencoe Meeting? Loads of people there to show you. Otherwise, there are one or two people down in your area of the world. Maybe it could help meeting up for a shoot somewhere picturesque?

Marc

[Joanna Carter]

Have a look at viewtopic.php?t=133 and look at the 4th picture in the first post. You can see the tilted plane of focus!

Or even more obvious is Andrew's B&W picture of the gas lamp at the bottom of the same page.

[Leon West]

Thank you all so much for getting back to me. Yep, I am pretty new to LF, only ever used a Hasselblad before, so the whole LF thing to me is a revelation! I have a box of film, so I'm getting another trip planned, I'll make sure I get a load of practice in before I get 'out there'. I will keep my eyes peeled for the plane of focus, I'm sure this moves when I tilt the lens standard forward and back. In a nutshell, I think that I should focus on the farthest object, make a note of the bellows extension, focus on the closest object, make a note of the bellows extension, tilt the lens standard forward and slightly adjust the focus (3rd down?) knob until the plane of focus is evident. Stop down, check the focus. So am I right in thinking I'm not too far off with my technique of focusing a third into the image and stopping down to f45? I would now try and shoot between f16 - f32 and really check the focus after I have tilted the front. Ideally, I need someone to show me!!! Shame there's no mpeg clips of someone explaining this. If there was, that would be absolute gold dust to me!!!!! Again, thanks to one and all of you for your help.

Leon

[Charles Twist]

The bulk of what features in the View Camera magazine article (that I mention above) can be found here: http://www-unix.oit.umass.edu/~rbhome/finalpaper2.pdf.
Andrew: do you remember saying about Cornish's shot of the steps in Whitby? Look at the table on page 11 (Appendix) and you'll realise how little bellows extension difference there is between nearest and furthest object. Then look at Figure 1, and you'll see that with f32 (and no tilt), he achieves a circle of confusion below 0.1 - which is what is needed. As I said this article is really useful, as it narrows down when you need and don't need tilt.
For some reason I have not fathomed, focusing 1/3 in between nearest and furthest object actually means extending the bellows halfway between shortest and longest extension. Apologies for error in previous post.
Happy reading!
Charles

[Joanna Carter]

Leon, you don't need to think about the 1/3rd focusing rule if you are using movements. It is an either/or situation.

Take the example of trying to get everything, from an object on the ground in front of you, through to the horizon, in focus. You need to get the plane of focus to follow the ground, assuming it is fairly level with no big bits sticking up in the foreground.

Here is my quick and simple guide to using movements for a simple scene:

1. Ensure all movements are neutralised.

2. Set aperture fully open

3. Tilt the front standard forwards by a couple of degrees (the number is not important)

4. Using the rear focus, adjust until something in the immediate foreground is in focus.

5. Now look at the horizon and start to adjust the front tilt until it gets sharper. You may not get everything in focus in one go; you need to make small adjustments, repeatedly switching from rear focus knob to focus the foreground, followed by tilt to focus the horizon.

After you have established the plane of focus, closing down the aperture will increase the depth of field by opening up a wedge of focus with its point below the camera and the wedge increasing in height and depth above and below the line of focus, as it goes away from you. Unless you need to limit depth of field deliberately, a rule of thumb is to use an aperture 2 stops bigger than the smallest aperture on your lens.

Take a look at the little movies in the Merklinger articles which I believe Marc has pointed you to.

This is a first simple exercise which should get you used to adjusting the plane of focus; there is plenty more to come

[Leon West]

Joanna,
I couldn't ask for a more 'plain English' explanation that that! I was kinda getting flummaxed and going around in circles (of confusion!) with the seemingly complex and very in-depth features I have been so kindly pointed towards. Mind you, I have the latest View Camera issue now, and it really is a wonderful read. I'm getting there, slowly but surely! Thanks to one and all for your input, it really has helped me in getting to the bottom of this, without having to waste a load of film stock!

Leon

[Joanna Carter]

Leon, out of all the technical mumbo-jumbo, there are two articles that I have found just so useful.

http://www.trenholm.org/hmmerk/VuCamTxt+.pdf

http://www.trenholm.org/hmmerk/SHBG09.pdf

Try to ignore all but the simplest of formulae, and I think you will find some of the essential principles should become apparent.

The two main "index" pages for Merklinger's site are

http://www.trenholm.org/hmmerk/HMbook14.html

http://www.trenholm.org/hmmerk/HMbook18.html

Whatever you do, avoid getting technical and formulaic about this stuff, it really works better if you just "suck it and see"

But, above all, try and join with someone local to you and get some real, hands-on help.

[Apple]

Charles - I've read through the VC article and can see how Joe set up the Whitby picture - it's almost like having a set aperture on the camera per focus distance - almost like press photogs used to go round with camera set to hyperfocal distance all the time...

He know's what size print he's going to make and hence a viewing distance so he know's the CoC and bingo, the "optimum" aperture drops out from that graph as long as he knows the change in standards position which for landscape stuff is potentially small... Even if he includes a rock or so in the foreground (on the off-chance ) then if he's using a set focal length (say 90mm), all he has to do is position the camera x feet behind the rock and the far distance is infinity (hence extension = focal length) and the calculation drop into place - doddle this photography lark, init?

I think I now understand how the Sinar DoF calculator works on the standards as it's using the gear drive to work out the distance the rear standard moves - it's not bothered where the front one is due to being a monorail and it's working on you getting the front and back of the picture sharp to get the relative separation.

[Leon West]

For some reason I have not fathomed, focusing 1/3 in between nearest and furthest object actually means extending the bellows halfway between shortest and longest extension. Apologies for error in previous post.
Happy reading!
Charles

Hi Charles, so to recap on the above, to focus a third in is the equivalent of placing the focus halway between closest and farthest bellows extension?

Just need to double check, as the tilting of the front standard makes me go literally, in circles. I want to try and find an optimum focus technique, where everything is in focus, like keeping it in hyperfocal - like the old press photographers used to.

Thanks in advance, and happy new year!

Leon