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Hoppet
5-Aug-2011, 02:54
Hi there
I recently bought a sinar 8x10. Before I had a 4x5. I'm doing a photo where the near section to be focus is around 10 meters and the far one is almost infinit. When i've got the negative i was surprised cos shooting at f22 the DOF wasnt more than 20meters.

I wanted to know if this is normal? as with the 4x5 i didnt have that problem. Is necesary to do the Scheimpflug theory to get full focus at short apertures? or there is something wrong with my lens? does 8x10 loose light through the bellows or wat?

thanks to all and hope someone can help me

Ken Lee
5-Aug-2011, 03:54
It's not the film size, but the focal length of the lenses: 2X the focal length results in 1/4 the depth of field. When we double the focal length, we need to stop down by 2 stops to get the same depth of field.

A 300mm lens at f/22 has the same depth of field as a 150mm lens at f/11

A 300mm lens at f/45 has the same depth of field as a 150mm lens at f/22

So in the old days of Group f/64 (http://en.wikipedia.org/wiki/Group_f/64), they were probably shooting 8x10, where f/64 is a fairly routine f-stop.

Here's a nice Depth of Field Calculator (http://www.dofmaster.com/doftable.html). Choose your film size and focal length. You'll see that with 8x10 and a 300mm lens, you start getting decent depth of field around f/32. A good search of the web will find some online calculators which accommodate longer lenses and smaller apertures.

ic-racer
5-Aug-2011, 04:16
http://www.largeformatphotography.info/fstop.html

Frank Petronio
5-Aug-2011, 05:12
Hard to believe anyone would invest in an 8x10 without realizing this.

Frank Petronio
5-Aug-2011, 05:14
When you can see what is in focus if you stop down and look at the ground glass!

ic-racer
5-Aug-2011, 06:34
When you can see what is in focus if you stop down and look at the ground glass!

However with 8x10 camera at f45 your DOF preivew is 32 times dimmer than the DOF preview button on a hand-held camera at f5.6. Thus the utility of double checking things using the 'focus spread' system on a big camera. Your point made in post #4 is a very good one ;)

Ole Tjugen
5-Aug-2011, 07:17
There are ways to "cheat" the hyperfocal problems.

http://www.trenholm.org/hmmerk/#TIAOOF

It works, is all I can say...

Jim Michael
5-Aug-2011, 08:48
Here are instructions (http://www.sinar.ch/en/infos/depth-of-field) for the DoF scale on your Sinar. The other tools at your disposal are your camera movements, which may be of use depending on where things are placed in the image. Did you take a look at this guide (http://www.largeformatphotography.info/how-to-focus.html)?

E. von Hoegh
5-Aug-2011, 12:59
Hi there
I recently bought a sinar 8x10. Before I had a 4x5. I'm doing a photo where the near section to be focus is around 10 meters and the far one is almost infinit. When i've got the negative i was surprised cos shooting at f22 the DOF wasnt more than 20meters.

I wanted to know if this is normal? as with the 4x5 i didnt have that problem. Is necesary to do the Scheimpflug theory to get full focus at short apertures? or there is something wrong with my lens? does 8x10 loose light through the bellows or wat?

thanks to all and hope someone can help me

You haven't told us what lens you are using, or the arrangement of your subject.
Sounds like the camera and lens are behaving perfectly normally, though.
If you go to the homepage of this site, you will find much information on all aspects of view camera use. It isn't "plug & play", as you are finding out.

Hoppet
8-Aug-2011, 15:41
You haven't told us what lens you are using, or the arrangement of your subject.
Sounds like the camera and lens are behaving perfectly normally, though.
If you go to the homepage of this site, you will find much information on all aspects of view camera use. It isn't "plug & play", as you are finding out.

Thanks to all

I'm useing a 300mm . there is a field with a city landscape at the very end like 1000m . On the field around 12m from the camera is a person. Between the person and the city is a road crossing under the field plane. I attached a a little drawing so u can visualy it

59717

Through Scheimpflug theory i've got the plane of city and field on focus. but the road Under this plane) and above the person knees is all out of focus. So i follow the sinar manual to find the aperture to get this two subjets on focus and it gives me f32 ( the manual saids u need to go back two stops on the aperture scale) but at least trought the glass seems to not be enough cos there is always something out of focus, head or feet

Hope someone can help me with this and again thanks for sharing your experince

Ken Lee
8-Aug-2011, 16:08
Stop down the lens until everything is in focus. Try f/64 or smaller if the lens allows.

ic-racer
8-Aug-2011, 16:31
Hope someone can help me with this and again thanks for sharing your experince

If you read those depth of field articles or "Ins and outs of Focus" books, you will see that any deviation from lens and film being parallel REDUCES depth of field. What you need to do in you situation is to make the film and lens parallel, then check your focal spread and put the standard in the middle of the spread and use the indicated aperture.

In real life I do what Ken suggests and just use f45 or f64. The keys to success and maximizing depth of field in your situation are parallel standards and getting the focusing standard set so it exactly splits the focal spread.

Leigh
8-Aug-2011, 20:10
On the field around 12m from the camera is a person.
Your text says 12m, but your drawing says 8m. Big difference in this case.

At 12m you need f/45 or smaller, while at 8m you need f/64 or smaller.

You can check the calculated DoF for any combination using the online calculator at www.dofmaster.com

It's a bit hard to find sheet film on that calculator but it's there, before the movie cameras.

- Leigh