PDA

View Full Version : DOF calculator for a Chamonix



bomzi
27-Jan-2015, 05:18
I recently purchased a Chamonix 045N2. This is my second 4x5, the first being a lovely Sinar F2. The Chamonix is fantastic (my shoulders and back are rejoicing!) but I am missing the Sinar's extremely helpful DOF Calculator (also missing the swing and tilt but I tend to use that less).

I looked through this thread on how to make one for the Chamonix but I don't like the idea of attaching a plastic film can to the camera:
http://www.largeformatphotography.info/forum/showthread.php?53102-Making-a-DOF-calculator-for-Chamonix-045n1-cameras

How are other Chamonix users dealing with this?

Also, would the method indicated in the thread above work as a flat card? So you focus to the far point, place the card with the DOF markings on something that doesn't move, then focus on the near point and read off the number?

I hope this makes sense. I'm also considering buying a Rodenstock DOF calculator.

vinny
27-Jan-2015, 05:58
Magnetic strips they sell in a roll. Or rare earth magnets. Both stick to the stainless steel rail.

Preston
27-Jan-2015, 09:41
"(also missing the swing and tilt but I tend to use that less)."

Changing the subject just for a moment, but to which swing and tilt are you referring to?

I have an 045N-2. It has front swing and tilt (and shift), and rear swing and tilt. If you're referring to tilting the back toward you, there are two slide locks at the bottom of the back, one on each side. If you slide those inboard, you can tilt the back toward you. Similarly, there are locks at the bottom of the front standard. Slide those inboard and you can tilt the lens.

--P

ic-racer
27-Jan-2015, 12:15
I recently purchased a Chamonix 045N2. This is my second 4x5, the first being a lovely Sinar F2. The Chamonix is fantastic (my shoulders and back are rejoicing!) but I am missing the Sinar's extremely helpful DOF Calculator (also missing the swing and tilt but I tend to use that less).

I looked through this thread on how to make one for the Chamonix but I don't like the idea of attaching a plastic film can to the camera:
http://www.largeformatphotography.info/forum/showthread.php?53102-Making-a-DOF-calculator-for-Chamonix-045n1-cameras

How are other Chamonix users dealing with this?

Also, would the method indicated in the thread above work as a flat card? So you focus to the far point, place the card with the DOF markings on something that doesn't move, then focus on the near point and read off the number?

I hope this makes sense. I'm also considering buying a Rodenstock DOF calculator.

I just have a single mark on the knob and eyeball it. One hour = f8, three hours = f32, etc. If you want to use a 'flat card' scale you can mount it on the focusing rail (maybe with a magnet or velcro, so you can move it to zero it).

C. D. Keth
27-Jan-2015, 21:46
I don't. I use the ground glass to tell me what is and isn't in focus.

bomzi
28-Jan-2015, 03:39
Yeah these magnets sound like a great idea. I guess I'll have to adapt the circular DOF scale to a flat card first.

TXFZ1
28-Jan-2015, 04:35
Yeah these magnets sound like a great idea. I guess I'll have to adapt the circular DOF scale to a flat card first.

The DOF article on the front page has a flat card scale for 4x5, 5x7, 8x10, 11x14.

David

dave_whatever
28-Jan-2015, 23:54
The problem with a flat card on the bed is for wide lenses the difference in extension you're trying to measure is very small and hence doing it that way can be very imprescise, its much better on the focus knob for wide lenses.

On my 045F1 I've attached a scale to the back edge of the carbon base board by the knob but its not ideal. I need to come up with a better solution really.

To whoever said just use the ground glass; nice idea but in my experience if you,re stopping down to f/22-45 area in low loght, even with a maxwell screen its pretty hard to determine the point at which acceptable sharpness/focus is reached. Much easier and more reliable to use a DOF scale. The first time I added one to a large format camera was a revelation to me, suddenly I no longer had to just guess what aperture to use having focussed and applied tilt etc.

There's also the issue that what might appear to be acceptable focus on the glass through whatever loupe you carry in the field could easily then not be acceptable when scanned or enlarged to a large print size later on. Whereas, a DOF scale can be calculated to balance max sharpness and losses due to diffraction and be a max sharpness to aim for to cover you for big prints later (see the kenrockwell dof scale article, probably the only valuable thing on his site).

Eric Woodbury
29-Jan-2015, 13:49
I'm with ic-racer. The pitch on my Chamonix is 10mm/360 degrees. I have the DOF numbers on a tiny piece of paper taped to the side of my camera. 0.7mm spread is f/16, 1.3mm is f/22, etc.; doubling ever stop. It would be easy for Chamonix to add this feature with, as a minimum, markings on the focus knob. --EW--

StoneNYC
29-Jan-2015, 23:48
I don't. I use the ground glass to tell me what is and isn't in focus.

Agreed.

To be honest I don't understand how this works... Wouldn't you need a different scale for each lens? I've just never found these useful, even shooting smaller formats I never used the scale on the lens, I mean unless you're actually going out and using a ruler to measure, you're still estimating anyway...

I also don't have trouble using the GG at f/22 or f/45, in fact I was just outside in the dark at night and focussing and checking depth at f/32, just use the loupe and I can still make out what's clear from the light off the snow from the white mini-lights. 2 minute exposure kind of light.

Unless you're doing product, and then why would you be using a field camera anyway...

dave_whatever
30-Jan-2015, 00:21
No you don't need a different scale for each lens. Read up on the physics of it, it's determined by extension, and hence the same scale works for every lens.

I'm sure you can in some cases do it fine by loupe, but why bother performing what is in essence a purely mechanical mathematical task manually when a scale is faster, more reliable and repeatable? It's basically converting a focus spread based on extension into the sharpest aperture to stop down to. There needn't be any human decision making there. Likewise we could probably all make a decent guess at exposure just by eye but most of us tend to use a light meter. Same idea.

StoneNYC
30-Jan-2015, 00:42
No you don't need a different scale for each lens. Read up on the physics of it, it's determined by extension, and hence the same scale works for every lens.

I'm sure you can in some cases do it fine by loupe, but why bother performing what is in essence a purely mechanical mathematical task manually when a scale is faster, more reliable and repeatable? It's basically converting a focus spread based on extension into the sharpest aperture to stop down to. There needn't be any human decision making there. Likewise we could probably all make a decent guess at exposure just by eye but most of us tend to use a light meter. Same idea.

YMMV I go by the feel of an image, I don't really measure, I'm an artist, not a physicist or mathematician, I lose my creativity and the image looks like crap if I get too distracted by all the tech (to an extent). It's very rare that I shoot under F/16 ever, these were both f/22.... Everything I wanted was in focus and everything I wanted out of focus was too...

128692
128693

I still don't get the extension thing, f/22 in this image gave me a DOF of about 3 inches, if I were shooting a field and mountain my DOF would be multiple meters... then there's all the tilting and shifting, hard to measure all those planes, But again YMMV.

vinny
30-Jan-2015, 05:20
If you don't understand it, read up in it before you discount the method. It's available on the home page. Have you seen QT's Luong's prints in person? You say you spend 15+ minutes setting up a shot (your words elsewhere on this forum) getting all the movements right. Then say you've used every movement the camera has to get it just right. Sounds like art. Meanwhile, those using other methods (dof calculator) are off setting up the next shot.

StoneNYC
30-Jan-2015, 08:34
If you don't understand it, read up in it before you discount the method. It's available on the home page. Have you seen QT's Luong's prints in person? You say you spend 15+ minutes setting up a shot (your words elsewhere on this forum) getting all the movements right. Then say you've used every movement the camera has to get it just right. Sounds like art. Meanwhile, those using other methods (dof calculator) are off setting up the next shot.

If it's not broken, don't fix it... ;)

I'm not adverse to learning I just know after 20 years of shooting film that judging by eye works just fine for me.

Bob Salomon
30-Jan-2015, 09:18
Here, it is free:

http://www.linhof.de/download/depth-of-field-chart.pdf

StoneNYC
30-Jan-2015, 10:42
Here, it is free:

http://www.linhof.de/download/depth-of-field-chart.pdf

yea, that looks way to complicated, I would surely screw that up, hope it's useful for the OP. Pretty sure by the time I worked that all out it would be midnight and I would started at 6am and have not taken my first shot yet...

dave_whatever
30-Jan-2015, 12:36
Bob's chart is complicated, which is exactly why people chose to use a simple knob-based DOF scale instead of a complicated chart where you have to measure repro ratios.

Bob Salomon
30-Jan-2015, 12:57
Bob's chart is complicated, which is exactly why people chose to use a simple knob-based DOF scale instead of a complicated chart where you have to measure repro ratios.

So you focus on the near point and then the far point and read off the mm scale the distance between them. Set the indicated F stop for that distance on the scale and then reposition the rear standard the indicated amount on the chart.

That's how the knob type ones also work. Just it is flat and fits your pocket.

dtheld
30-Jan-2015, 13:16
Thanks Bob. Your input is always appreciated.

Dave

dave_whatever
30-Jan-2015, 13:25
That's how the knob type ones also work. Just it is flat and fits your pocket.

And because it's flat and doesn't benefit from the gearing of a knob scale it's much less precise, especially with wide lenses. Not to mention it can be lost, dropped, or forgotten. But each to their own.

Bob Salomon
30-Jan-2015, 13:35
And because it's flat and doesn't benefit from the gearing of a knob scale it's much less precise, especially with wide lenses. Not to mention it can be lost, dropped, or forgotten. But each to their own.

It also compensates for image ratios which many knob types don't and then you get the wrong results. And, you can always download another one. Once you forget it it becomes much more unlikely that you would forget it again.

C. D. Keth
30-Jan-2015, 21:15
Agreed.

To be honest I don't understand how this works... Wouldn't you need a different scale for each lens?

It's sort of a sliding scale version of those little scales on SLR lenses.

bomzi
31-Jan-2015, 00:29
Thanks for all the great input guys! And Bob, thank you for the card. I'm going to try this method out.

I've only been shooting with a 4x5 for about a year and have found that using a measurable scale takes some of the guess work out of the process. There are so many ways to screw up a shot! Keeping things simple and repeatable are key for me.

ailsa
16-Apr-2015, 00:36
To ascertain the profundity of field, one needs to first choose what will be considered acceptably sharp.