Blummin Noob Question - DoF, time and, er ... stuff

[Myky D]

Hello there,

I put a thread up in the welcome section, but I thought I'd just dive in as well.

Basically I'm a noob to grown-up stuff, but do have a grasp on the basics. I was wondering what the real differences are in terms of f-stops when doing landscape photography.

I get the whole DoF/larger number-smaller apeture thing, but say you're taking a pic of a building or whatever at night - you get the whole thing in shot - why would you use a smaller apeture and thus a longer exposure?

I can understand if you, say, wanted to get the water in front of it looking smooth, or the sky to have movement, but other than that - what's the difference?

I know that sounds like a completely amateur question, but I live and photograph in Mordor, so when I take my camera out - which is often at night due to having to w**k 9 to 5 - I'm not really that keen on having it out for any significant amount of time if I'm on my own.

Ironically, I'm also intrigued as to how to do REALLY long exposures - an hour or so. Am I right in assuming one uses the heaviest neutral filter on can, has a remote control, and simply sits sipping one's tea and smoking one's cigarettes for the entire duration?

Apologies if this is the most vague and annoying post ever to be written on here; but I'm genuinely interested in any help you can give me.

Cheers,

Myky D

 

[Itti]

If you have a smaller aperture you will have a wider depth of field, so if you're taking a picture of a landscape where you want focus "at infinity" and at your feet then you want as small an aperture as poss. Similarly city scenes if they go off into the distance.

Also, as you say, slower shutter speeds are generally used for capturing movement - water, sky, people, light trails, etc., so you might want to stop down the aperture for this reason so that you can decrease the shutter speed.

Really long exposures are usually done at night in my experience, but I guess if you did one in daytime you'd want a ND filter on. The tea/coffee and remote control sound about right.

 

[Toothie]

Ironically, I'm also intrigued as to how to do REALLY long exposures - an hour or so. Am I right in assuming one uses the heaviest neutral filter on can, has a remote control, and simply sits sipping one's tea and smoking one's cigarettes for the entire duration?

Cheers,

Myky D

Yes you simply sip your tea and smoke your ciggys or you could enjoy the moment.

I was shooting star trails on a course one night the instructor said 2 hour exposures so the camera were set up and the other 3 went and slept int he car. I stared at the sky for ages it was so clear, no natural light and tbh it was amassing to this day i can't believe they missed it.

 

[Myky D]

Hi Itti & Toothie - thanks for your replies.

So I think I'm on the right track - yeah - if I was doing say a hill-top daytime landscapes I'd go with f36 or something, but I was thinking more of buildings in Mordor where I want the whole building in shot shooting from about 100 yards away.

Toothie - did you use ND filters when shooting the stars? Did you get good colour from the sky?

 

[singlespeed]

Hi Itti & Toothie - thanks for your replies.

So I think I'm on the right track - yeah - if I was doing say a hill-top daytime landscapes I'd go with f36 or something, but I was thinking more of buildings in Mordor where I want the whole building in shot shooting from about 100 yards away.

Toothie - did you use ND filters when shooting the stars? Did you get good colour from the sky?

Welcome Myky.

Most lenses give the best image quality in the middle of the apparture range. Wide open, most tend to be a bit soft and if you stop right down, you risk the light diffracting. Just because you can stop down to F36 doesnt mean its usable. Theres normaly a compromise to be made somewhere f8-16 should give an adequate depth of field for most landscape shots.

 

[Myky D]

Welcome Myky.

Most lenses give the best image quality in the middle of the apparture range. Wide open, most tend to be a bit soft and if you stop right down, you risk the light diffracting. Just because you can stop down to F36 doesnt mean its usable. Theres normaly a compromise to be made somewhere f8-16 should give an adequate depth of field for most landscape shots.

Hey Singlespeed,

That's a cracking piece of advice - thanks for that!

I took a picture of the London Eye at night a couple of weeks ago, and got slight blurring 'round the edges, even though I was at f29 - I take it that that was the diffraction you're on about. The only time I generally use the smaller fs is for macro stuff. I was advised that f8-11 is about the "normal" sort of range?

I did deliberately do some longer exposures on the South Bank as well - was trying to get that silky-smooth effect on the water. Was quite pleased with the results, but I had to really up the f number in order to get the exposure time necessary.

Please would you tell me if the following is the wrong way to think about it? If I want to picture something straight as it is, I use the fastest time - and thus the lowest f-number I can. However - if I want to - like above- get a blurr on something - generally the sky or water - I'll deliberately use a higher f-number in order to use a longer exposure.

If I want to do macro stuff, I use the lowest f-number I possibly can.

Is that the right way to approach it?

 

[Blapto]

Most lenses perform best about 2 stops down from wide open.

Depending on your camera you'll actually start lose quality beyond a certain aperture due to diffraction softness. Look it up! It's about f/9 on the 450D.

With macro you'll find you want to use a small aperture because depth of field will be insanely small otherwise.

Edit:
Depending on the subject you can use long exposures and still get things as they appear in real life. A mountain thousands of yards away isn't going to move that much over a 30 second exposure (though clouds will and stars will show movement over an exposure of mere seconds).

 

[jerry12953]

Is that the Mordor just outside Milton Keynes?

 

[singlespeed]

Hey Singlespeed,

That's a cracking piece of advice - thanks for that!

I took a picture of the London Eye at night a couple of weeks ago, and got slight blurring 'round the edges, even though I was at f29 - I take it that that was the diffraction you're on about. The only time I generally use the smaller fs is for macro stuff. I was advised that f8-11 is about the "normal" sort of range?

I did deliberately do some longer exposures on the South Bank as well - was trying to get that silky-smooth effect on the water. Was quite pleased with the results, but I had to really up the f number in order to get the exposure time necessary.

Please would you tell me if the following is the wrong way to think about it? If I want to picture something straight as it is, I use the fastest time - and thus the lowest f-number I can. However - if I want to - like above- get a blurr on something - generally the sky or water - I'll deliberately use a higher f-number in order to use a longer exposure.

If I want to do macro stuff, I use the lowest f-number I possibly can.

Is that the right way to approach it?

The avaliable light will play a very important factor here, but... To freeze action, you need to get the shutter speed up, probably 1/200 as a bare minimum or faster like 1/400 depending on the speed of the movement to be captured. So a wide apparture as far as the required depth of field is concerned ( or sacrifice the dof and and maybe ultimate sharpness by going wide open ), then also adjust the ISO speed up to 400-800 or even 1600.

To blur a shot, decrease the ISO, then go for a small apparture size f18-f22 limitted by difraction. ND filters will alow the shutter speed to be reduced still further

At close focus macro distances, the depth of field will still be fairly small, even with a relatively small apparture. With some lenses, at wide open f2.8 for instance, the dof is tiny, so adjust the apparture to give the required dof then adjust the shutter speed/iso

 

[Toothie]

Hi Itti & Toothie - thanks for your replies.

So I think I'm on the right track - yeah - if I was doing say a hill-top daytime landscapes I'd go with f36 or something, but I was thinking more of buildings in Mordor where I want the whole building in shot shooting from about 100 yards away.

Toothie - did you use ND filters when shooting the stars? Did you get good colour from the sky?

I didnt use any NDs on the night shots, tbh they didnt work too well ended up out of focus

 

[who?]

Is that the Mordor just outside Milton Keynes?

And I was just wondering how you get goblins and elves to pose properly

 

[who?]

I didnt use any NDs on the night shots, tbh they didnt work too well ended up out of focus

Was that because the autofocus counldnt handle such low light levels or were you using manual and some other problem?

 

[Toothie]

Was that because the autofocus counldnt handle such low light levels or were you using manual and some other problem?

that would be human error

 

[ROFL2K9]

Am I right in assuming one uses the heaviest neutral filter on can, has a remote control, and simply sits sipping one's tea and smoking one's cigarettes for the entire duration?

Yes you simply sip your tea and smoke your ciggys

I've got to say that I'm more than a little deflated... Night photography was one of the things that I was really looking forward to having a go at... but didn't realise that I'd have to take up smoking Cripes this IS turning into an expensive hobby...

 

[Toothie]

I've got to say that I'm more than a little deflated... Night photography was one of the things that I was really looking forward to having a go at... but didn't realise that I'd have to take up smoking Cripes this IS turning into an expensive hobby...

you could just sip your tea

 

[Cranky]

I know this book is a love or hate thing but "understanding exposure" covers most of this in a nice newbie way, this is available via amazon or torrent.

Its a good read if your learning like me

 

[The Matt]

I did deliberately do some longer exposures on the South Bank as well - was trying to get that silky-smooth effect on the water. Was quite pleased with the results, but I had to really up the f number in order to get the exposure time necessary.

Since you've not mentioned ISO here: if you haven't already done it you should set it to its lowest number. Not only do you get longer exposure times, there's less sensor noise.

Please would you tell me if the following is the wrong way to think about it? If I want to picture something straight as it is, I use the fastest time - and thus the lowest f-number I can. However - if I want to - like above- get a blurr on something - generally the sky or water - I'll deliberately use a higher f-number in order to use a longer exposure.

Don't forget your depth of field. The wider your aperture, the less of your scene will be in focus. Don't use a shutter speed faster than you need. You won't see a difference between a landscape taken at 1/100th and at 1/1000th except that there will be less of the scene in focus