R.G. Loc: Scotland

According to the DOF chart, if you focus any closer than 19.5 metres at f/16 or 14.7 metres at f/22, you won't have the DOF extending to infinity. How important that is depends on how important the far field is.

If the rocks were your only subject you would want them to have optimum sharpness so you would focus on them - and ditto for the ice house (i.e. you would focus on the ice house).

But if you want both to be sharp, the DOF has to include both. You have a choice of prioritising which comes out sharpest, and that would have to be done by trial and error - and you would achieve it by shifting the focus point to a point that gives the desired distribution of sharpness. However, doing that in the field wouldn't be easy because it would involve making some very fine judgements based on the level of sharpness that you can see through your viewfinder or on your viewscreen.

A simpler approach is to choose the focus point that gives the widest possible DOF, and just accept the distribution of sharpness that comes with doing that. Maybe the ice house would be slightly sharper than the rocks, maybe it would be the other way round, but if they both fall within the DOF, they should both be acceptably sharp. Focusing at the hyperfocal distance is the way to maximise the DOF.

R.G. Loc: Scotland

It's hard to tell, since I wasn't there, but it looks like the rocks are well short of the 14-19 metres that hyperfocal distance focusing would require. You could have focused on the ice/water boundary that's just beyond the rocks and that would have extended the DOF closer to infinity, giving a sharper ice house. But the ice house seems fairly sharp, so you could have settled for the f/16 option and upped your shutter speed.

And since the shot's a bit hazy/misty, you could have upped your ISO for an even faster shutter speed (who's going to spot ISO noise when it's all a bit foggy anyway... ).

Nightski

Yes, I think the ISO is the way to go. Did you notice that I had 0 focus in front of the rocks? I'm just trying to gauge by eyesight how far away I need to be from the object I'm focusing on to get that infinity focus. I've never been sure with that lens and I do use it for landscape. I know I can look at the DOF calculator, but what does 50 feet look like? That's my problem. I'm thinking I was too close to the rocks to have infinity when focusing on them? But then my fish house is sharp. I'd really like to nail this down.

R.G. Loc: Scotland

You're right - it's guesstimations and a moving target at the same time. The good thing about primes is that the focal length isn't going to change. With zooms you have that added complication. Learning with primes is probably the best way to do it. Suss them out one at a time. That way you'll have a feel for what zooms are capable of.

And just memorise the HD (hyperfocal distance - to hell with writing that out in full every time :) ) for the smallest apertures for that lens. If you're after maximum DOF, you probably won't be using anything wider than f/16 anyway.

If changing your distance from the subject isn't practical, change the focus point to be near your intended subject. If you're using a small aperture there's a fair bit of leeway as regards the focus point.

Nightski

I would not be able to change my distance in this instance, but I could change the distance of the thing I focus on. I'm focusing manually for this, so it's more flexible. I don't have to find a contrasty place for the auto to lock on to.

R.G. Loc: Scotland

You're right - manual focus is the best option. I find using the viewfinder too much of a strain, and the viewscreen isn't accurate enough, so I tend to depend on autofocus.

R.G. Loc: Scotland

I find that thinking in terms of yards or metres is easier to envisage. A yard is one pace and a metre is a large pace. I can envisage what 20 paces looks like.

Nightski

No ... a yard is much more than one pace.

R.G. Loc: Scotland

Sorry - a yard is a man's pace or one and a half girlie paces :-D

Nightski

Okay ... you're right about them being similar in length ... man you must take big steps ... lol

R.G. Loc: Scotland

That's right - MAN SIZED lol.

Shakey Loc: Traveling again to Norway and other places.

This is a funny conversation: 1 metre = 3.28 feet (3 feet 3/8th inches.) A longish stride for a man is 30 inches. Military services of various countries accept 30 inches as a marching stride. That's roughly six inches short of a metre.
Why do I know this weird stuff? Because long ago I was into orienteering which is a sport that involves map reading and running. You need to know how to pace distances in order to get among the better participants. Therefore you mark out 100 metres and count how many strides it takes to walk and run 100 metres (plus up and down hill). That way when you have to find a lone tree in a forest, you can soon pace it out with great accuracy. To cut this tome short, I have never used it for photography - but you could. LOL.

R.G. Loc: Scotland

Hi, Shakey. I'm not going to query the details of what you said, but if you can translate it into a rule of thumb that can be used to help people to visualise distances, it would be answering a query that was raised earlier in the thread. Presumably you can visualise 100 metres - can you scale that down to work with shorter distances?

I know that the average stride falls short of one yard, and falls well short of one metre. But I would be struggling to visualise, say, 60 feet, whereas I can easily visualise 20 large paces. Maybe I should have stipulated that it was basketball player paces that I was referring to :) .

Nightski

I think you're onto something Shakey. I visualize in feet though ... not yards ... and certainly not meters. But it gives me an idea of something to do to begin judging distances better. Thanks.

wildconc2001 Loc: Chicagoland

Sandra,
Without charts and exact lens measurements, the hyper focal distance is approximately 1/3 of the way into a landscape image. That is about where you should focus and stop down as far as you can safely do without causing refraction. This applies a bit less to super wide angles which you focus in a bit closer and to macro shots where you focus approximately halfway in for the most depth of field. The wider angle the lens, the less you can stop down without causing refraction, usually f11 is getting close to where you want to stop. Telephotos, which generally aren't used for closer landscapes can be stopped down further because their apertures have larger openings than wide angle lenses and therefore can be stopped down more and be less likely to get diffraction. Compression of all of the light waves causes the diffraction.
Directly, yes you focus further out than those rocks.