Help with focusing

dickelfan

Senior Member
I need some suggestions on how to make sure the entire picture is in focus. I'm using a Nikon d7000, and generally shoot in aperture mode. The pics posted here were taken using shutter priority and a 35mm 1.8 lens. They just don't seem as sharp as I would like them to be. Any tips would be appreciated.

9 month7.jpg 9 month9.jpg 9 month12.jpg
 
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WayneF

Senior Member
The question is: What f/stop and shutter speed were used?

Next question is: Why? Was it your learned experience that decided it, or did you just leave it up to the camera to do something?

You said: "how to make sure the entire picture is in focus", which sounds like depth of field, and the pumpkins certainly suggest that. Stopping down to a smaller aperture (larger f/stop Number) increases the depth of field, the depth that the focus appears sharp. This necessarily also involves slower shutter speed, or higher ISO.

Sharpness generally depends on:

Focus accuracy: It is good rule of thumb to focus about 1/3 deep into the scene (a third into the range you want sharp) to maximize the depth of field. You still need depth of field too of course. Portraits though, generally best to focus on the near eye, unless unusual factors, like the pumpkins (which is extended range, more than just a face).

Depth of field: This is the f/stop, which controls the range of the depth of acceptable focus. Stopping down increases depth of sharpness (to a point, not at all unlimited).

Shutter speed: Slow shutters can blur motion, and also allows blurring due to camera shake. Faster is better. Tripods are better.

What were these numbers?


A very good book for beginners is: Understanding Exposure, 3rd Edition: How to Shoot Great Photographs with Any Camera: Bryan Peterson: 9780817439392: Amazon.com: Books

Highly recommended for ANY beginner. This is a very easy read, and it is the most fundamental basics that every photographer knows, and beginners that don't yet need to give it some serious attention.


 
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dickelfan

Senior Member
Looks like the f stop was at 1.8

I generally shoot in aperture mode, but for some reason decided to shoot in shutter. I shot all of these on a tripod. ISO was at 800 ( I had it set on auto) Shutter speed was 1/200 and I did use a flash. When shooting in aperture mode with a smaller aperture the shutter speed is really slow....guess I need to read up on how to increase this at the smaller aperture.

Thanks for the recommendation on the book.
 

WayneF

Senior Member
I should mention that this book is only about ambient light, daylight, incandescent, etc, and it does NOT mention flash. Flash is sort of a different world. The book does explain about basics and purpose of f/stops and shutter speed and ISO however, as introduction for a beginner. It is very popular, in that regard. Odds are good it may be in your local library. But it is not about flash. The same author has one called Understanding Flash, which I would NOT recommend, some other one would be better.

Without flash, in ambient low light situations, camera mode S will likely simply open the aperture wide open, your f/1.8.
Or camera A mode then will likely use a very slow shutter speed.
It meters the ambient to decide this (however, you are using flash).
Higher ISO is the only solution to increase those - speaking of ambient light.

But flash is a very different story. Flash is NOT a low light situation, more likely you have about all the light you can use. (Speedlights in umbrellas at f/11 may need the lights to be fairly close). Flash is a different world, with different rules. Easy, but different.

Flash is NOT affected by shutter speed (a fundamental). Regardless if you use 1/2 second or 1/200 second, your flash duration is even faster. The shutter just has to be open when the flash fires. So... we really would never consider camera S mode with flash, certainly not indoors - since the flash does not care about shutter speed (we still cannot exceed Maximum sync speed however, about 1/200 second).

The shutter speed might read low in dim places, but in camera A or P modes, when you turn the flash on, the shutter speed will jump up to 1/60 second. I don't know your camera model, there can be minor ifs and buts and a couple of options, but generally 1/60 second is Minimum Shutter Speed with flash (you do not need it slower if you are using flash, and are ignoring the dim ambient).

In a studio situation (like yours), it is normal to use camera M mode with flash, so we can set any shutter speed, and normally 1/200 second is used (Maximum Sync Speed), to keep out the orange incandescent room light. The TTL flash is still fully automatic flash exposure in any camera mode. The camera mode only sets up for the ambient light, but we couldn't care less about proper ambient exposure (in dim indoor settings).

And, Flash Compensation is how we control what automatic TTL flash does. Add a bit of -EV flash compensation to reduce overexposure, or add a bit of +EV flash compensation to increase flash to fix underexposure.

These basics so far are about all you have to know (but there is more that we can use to good benefit).

So, with flash (and camera A or M modes), you can probably set f/8 or f/11 to increase depth of field. Maybe the shutter speed reads extremely slow then in the dim ambient, but so what, we are not using ambient. When you turn on the flash in camera A mode, it jumps to 1/60 second, and the flash is even much faster than that (called a speedlight). Or in camera M mode, it is good to set 1/200 second (to keep out any orange ambient). Again, camera M mode is about the ambient, about which you are not concerned now. You are using flash instead. If the flash is TTL mode, it is still fully automatic flash exposure in any camera mode. Good stuff to know.

But by choosing camera S mode, you kept that from happening. You set 1/200, and S mode aperture went to f/1.8 (due to the low ambient light, which you were not even using), and then the flash had to use that f/1.8. You should have set the aperture you needed, maybe f/8. And set a low ISO for flash, maybe ISO 100 to 400, but you do NOT need ISO 800 or higher with flash).

Assuming DX camera and 35 mm lens at maybe 6 feet, at f/1.8, you only had maybe 3 questionable inches depth of field in front of and behind point of focus. And lenses are never very sharp when wide open, even stopping down one or two stops works wonders. But f/11 would increase that to maybe 18 inches front and back, still not much at the close range (we need to plan it just a bit, to center it on our scene), but lots more than f/1.8 can do.

So, this flash use (at least the pumpkins greater range) requires:

Camera mode A or M
Lower ISO
Maybe f/8 or f/11


One last point, about camera M mode in similar studio situations.

If you set M mode so you can set 1/200 second, and f/8, and you take this same picture, but with all the flashes turned OFF, you get a very black picture (solid black nothingness). Which is the goal of camera M mode - the 1/200 second kept out any traces of the orange incandescent room lights. But turn the flash on, and TTL will meter it and set its power level and you get your picture then. And the flash is even faster duration, to stop all motion easily. Or of course, you can set manual flash levels too, but the illumination is flash, not the ambient (in studio settings). So - don't meter the ambient with camera S mode.

And I should clarify (correct) a previous statement. Focusing about 1/3 of the way into the depth field is good for greater distances, like landscapes. But for close portraits, and macro esp, about 1/2 way is the right number.
 
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dickelfan

Senior Member
Wayne....I really appreciate all of the information. I generally like shooting in natural light, but when I shot these this morning it was really dark, due to weather, and I thought I needed to use the flash to help with that. I wanted to shoot at f11 or so, but again, the speed is so slow, and when shooting a child you have to be quick. Thanks again, I'll read up more and try again.
 

WayneF

Senior Member
I wanted to shoot at f11 or so, but again, the speed is so slow, and when shooting a child you have to be quick. Thanks again, I'll read up more and try again.

Well, the speedlight is one of the fastest motion stopping techiques we have. If the flash duration is only 1/1000 or 1/4000 second or 1/40,000 second, and the scene is dark black without flash, that is as good or better than any possible shutter speed. If the ambient is dim, it does not matter what the shutter speed is, the flash handles it.

This is a radically different concept than what you are expressing, but it is the way that works. And it is so very simple.

In dim light, where you need flash, just set maybe f/8 in camera A mode (or maybe better, also 1/200 second in camera M mode), with TTL flash mode, and you will love it. TRY IT. (bounce power has to be more like f/5).

For anyone actually interested in details, naturally I would suggest reading at the signature link below. :)
 
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aroy

Senior Member
I need some suggestions on how to make sure the entire picture is in focus. I'm using a Nikon d7000, and generally shoot in aperture mode. The pics posted here were taken using shutter priority and a 35mm 1.8 lens. They just don't seem as sharp as I would like them to be. Any tips would be appreciated.
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. To get every thing in focus you need mode DOF. So shoot at F8 or F11. As suggested instead of focusing on the distant most object, focus some where in between the subject and 1/2 way point. The DOF will take care of the rest.
. With Flash and tripod you need not bother about speed. The flash will fire at around 1/4000 of a second. If you set the metering mode to "Matrix" mode then flash acts as a fill flash, but if you use "Spot" metering then the flash will be in TTL 'non fill" mode, in short it will just stop action.
. To calculate the range of the flash (in feet), just divide the guide number (in feet) by the F number. The on-board flash is not as powerful as an external one. If you have an external flash of sufficient power, then you can point it upwards to get more diffused light.
 
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