at which distance do you set the focus?

Please first read Harold M. Merklinger's articles about "Depth of Field" and "About The INs and OUTs of FOCUS":

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

In my early panoramas I followed the usual approach and set the focus to hyperfcal distance, but was not satisfied with sharpness at infinity or far distant objects.

All the panoramas taken with Panasonic DMC-LC1 were made at f8, 7mm focal lenght (28mm equivalent), circle of confusion 0.002mm => lens focused at hyperfocal distance 3m

I then tried to focus at 5m, later at 8m with much better results... I even did test pictures, taken at different apertures and focus set to infinity, 8m, 5m, 3m ...

The sanssouci panorama is an example where I unfortunately set the focus to 3m or 5m.

What is your experience, at which distance do you usually set the focus?

Karsten

I am an enthusiast follower of Mr. Merklinger's DOF methodology. As he writes:

The general rule for scenic photographs, where one wishes to maximize the depth of field, is as follows. Set the focus at the distance of the most distant object. Then set the lens opening to the size of the smallest object to be resolved in the foreground. No calculations needed!

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So I usually focus close to infinity in case my f is small enough for the smallest details. If not, such as when I have smaller details in the foreground, I then focus on the most eye catching object in the frame (mostly it is closer than the hyperfocal distance). It works well for me most of the time. YMMV.

Cheers,

Cem,

thank you for sharing your experience. What is the smallest aperture you normally want use?

With my Sinar 4x5 in. camera I used almost f32 to f45 to obtain sharp results (food, product photography) in the past... but now with the small sensors sizes and diffraction limits starting at f8 I am unsure how to choose an appopiate f stop.

Karsten

Hi,

I'm also a fan of Mr. Merklinger's writings. Hyperfocal distance calculations are often based around a typical viewing distance for a 10x8 print, and so may not give you what you want if you want a large print with far distance detail at close viewing distances.

One useful rule that I remember is that when focused at infinity a lens will 'resolve' details of size FocalLength / FStop (e.g at infinity a 20mm lens at f10 will resolve close-up details of size 2mm or greater (20/10).

This comes from Merklinger's work somewhere, think there is an article about it on luminous-landscape.

My approach is much like Cem's, with the above calculation being factored into account.

On my 20D a like to stay at f11 or below if I can, f16 is not too bad, but diffraction really seems to kick in at f22

For Landscape work I'd be really interested to hear how people get on with a tilt-shift lens, allowing an aperture of f8, but with an optimised plane of focus. One of the inherent benefits of large-format!


Cheers,

Has someone already tried enfuse to enhance depth of field? Any experience?

Karsten Schneeberger said:

Has someone already tried enfuse to enhance depth of field? Any experience?

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Hi Karsten,

I assume you are referring to focus stacking? If so, I have done some tests on CS4, which does focus stacking. The tests were done using macro images and the results were rather satisfying. But I haven't tried doing focus stacking for landscape images. Having said that, it should work well especially if one uses a tripod. A rather good idea actually! I shall have a go at it soon.

Cheers,

Karsten Schneeberger said:

...What is the smallest aperture you normally want use?

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Hi Karsten,

I think you'll find some excellent answers to the aperture question in this thread.

Cheers,

sorry, my mistake... I didn't remember it was "tufuse" which allows for focus stacking:

http://www.tawbaware.com/tufuse.htm
http://www.tawbaware.com/tufusepro_help/tufusepro_help.htm

Karsten Schneeberger said:

In my early panoramas I followed the usual approach and set the focus to hyperfcal distance, but was not satisfied with sharpness at infinity or far distant objects.

Click to expand...

Hi Karsten,

I understand that you are seeking maximum DOF for your spherical stitched images.

You were probably not satisfied because the 'wrong' COC criterion was used for the Hyperfocal distance calculation. When you set the COC to a diameter of 1.5x the sensel pitch of a given digital camera, then you'll be able to get optimal sharpness (regardless of the magnification). In addition one should set the aperture at nothing narrower than COC / 1.354 <= Fnumber. In other words the narrowest Fnumber would be sensel pitch in microns multiplied by a factor of 1.108. This will allow pixel perfect sharpness (see post 13 at another thread for why I use those numbers).

Narrower apertures may be needed for more DOF, but diffraction will reduce overall resolution (which may be allowable with advanced (deconvolution) sharpening and/or downsampling).

What is your experience, at which distance do you usually set the focus?

Click to expand...

When I don't require the deepest DOF possible, I tend to focus at important features in the foreground. I then take the background blur for granted (it might even help the image), or use focusstacking if I want to beat physics. But focus stacking (and HDR or exposure stacking) and stitching will then produce a lot of images to be processed. The subject matter better be worth the trouble then.

Bart

Hi Bart,

could you please explain "sensel size" - just to prevent some misconception I may have on this topic? My mind is still at all that stuff I learned back in 1985, when I was taught photography the old way regarding film...

Karsten

Karsten Schneeberger said:

could you please explain "sensel size" - just to prevent some misconception I may have on this

topic? My mind is still at all that stuff I learned back in 1985, when I was taught photography the old way regarding

film...

Click to expand...

Hi Karsten,

I was (formally) taught photography almost a decade before that! I got my licence, which was needed in those days, as a professional photographer in 1978. I did my black and white and color processing in my own darkroom (ah, the smell of fixer and bleach).

Sensel is to be understood as Sensor Element, the individual elements of a sensor array. For the ease of calculation, the sensel pitch (distance between e.g. the centers of the sensels) is often stated to be the same size as the sensels, but the actual sensels are a bit smaller to allow separation of charge and connectors/gates for readout. So when I say sensel size I actually mean sensel pitch in this context.

Bart

Bart,

Let's imagine that one does want to do focus stacking as well as bracketing for light. Can one merely repeat the entire pano. Are they likely to overlay if processed as two sets, the first focused at say 200 feet and the second as 20 feet using a G10, a GX200 (Ricoh) or 5D.

Thanks,

Asher

Hi Bart,

so with Sinar eMotion75 and pixelsize 7.2 µm I should use max. f8, and with f11 already there is no further increase of dof or image quality? But how about Sinar eVolution 75H in 4-shot mode? Is the effective sensel size different to 1-shot mode?

Karsten

Karsten Schneeberger said:

Hi Bart,

so with Sinar eMotion75 and pixelsize 7.2 µm I should use max. f8, and with f11 already there is no further increase of dof or image quality? But how about Sinar eVolution 75H in 4-shot mode? Is the effective sensel size different to 1-shot mode?

Karsten

Click to expand...

Hi Bart,

Did you overlook this one perhaps?
Just curious.

Cheers,

Cem_Usakligil said:

Did you overlook this one perhaps?
Just curious.

Click to expand...

Hi Cem, thanks for pointing it out, I didn't have time to read it yet.

Karsten Schneeberger said:

so with Sinar eMotion75 and pixelsize 7.2 µm I should use max. f8,

Click to expand...

Only if you need uncomprimised pixel perfect sharpness.

and with f11 already there is no further increase of dof or image quality?

Click to expand...

Not quite. The DOF will increase with narrower apertures, but the maximum sharpness (at the pixel level) will start to decrease. It is similar to what I showed in another thread for a 6.4 micron sensel pitch camera (optimal pixel sharpness at f/7.1):



I know this type of macro shot (of a detail in a 50 Euro banknote) is a lot more critical than most other subjects, but it does demonstrate that DOF keept increasing, and that the material texture gets lost when it changes into a fuzzy looking surface.

I'm not saying that DOF is of lesser importance! It is still up to the photographer to decide where he draws the line. I'm just warning about the concequences of crossing over into diffraction limited territory, and where the border is to be expected.

On anything that's not going to be looked at from close distances (say >12 inches or >30 centimetres), or is going to be of relatively small output size (say >300PPI), we can go further before it can be noticed. And then there are also techniques to somewhat recover from diffraction ...

But how about Sinar eVolution 75H in 4-shot mode? Is the effective sensel size different to 1-shot mode?

Click to expand...

No. What 4-shot mode brings you is perfect color resolution in addition to already good Luminance resolution in 1-shot mode. That of course assumes stationary subjects and zero camera shake. The per pixel diffraction pattern is only controlled by the aperture. The sensel size just determines how accurately that diffraction pattern is sampled.

Bart