F- Stop question

[Scotttyd]

So, I am still perfecting my manual photography skills (still a long ways to go).

Background info: I am usuing a nikon p5100 (manual controlls, P&S) and inon z240 strobe. The highest my f-stop goes is 7.6.

Is there anytime where I would not use the highest f-stop possible?

Macro - is there any reason not to set the f stop to the highest at 7.6? I obviously can product many times more light than is needed with the strobe.

Wide angle or "regular lense". I guess the only time I could see when I would not set the f-stop to the highest is if I am doing a close focus wide angle shot where I would want to set my strobe to the strongest possible to light up some depth and I would use a lower f-stop so I do not over expose the closer items of the shot.

Is my thinking even close to correct?

 

[noreastDIVER84]

Well an f-stop of 7.6 is actually a fairly wide aperture. The lowest(biggest) aperture on my dSLR is 2.5 and I go up to a 36(smallest). An aperture of 7.6 isn't going to be the best you can do for macro shots, but it should do. I think that your biggest problem is going to be the strobe over-exposing the shot.

And just to make sure you are clear on this, the lower the number the bigger the opening in the lens, the higher the number the more you close the lens. In other words there will be less light getting into the lens at a higher f-stop.

With a higher f-stop you will get a greater depth of field(more focused background) With a lower f-stop you will get less depth of field(blurred background).

 

[Scotttyd]

Well an f-stop of 7.6 is actually a fairly wide aperture. The lowest(biggest) aperture on my dSLR is 2.5 and I go up to a 36(smallest). An aperture of 7.6 isn't going to be the best you can do for macro shots, but it should do. I think that your biggest problem is going to be the strobe over-exposing the shot.

And just to make sure you are clear on this, the lower the number the bigger the opening in the lens, the higher the number the more you close the lens. In other words there will be less light getting into the lens at a higher f-stop.

With a higher f-stop you will get a greater depth of field(more focused background) With a lower f-stop you will get less depth of field(blurred background).

I may have used the wrong terminology as far as largest f-stop. I am aware that the bigger the number, the smaller the aperture. Since I have a P&S, not dSLR, I am thinking 7.6 is about the smallest aperture that is usually available. My macro shots have been descent - I obviously have room to improve thou.

 

[noreastDIVER84]

I may have used the wrong terminology as far as largest f-stop. I am aware that the bigger the number, the smaller the aperture. Since I have a P&S, not dSLR, I am thinking 7.6 is about the smallest aperture that is usually available. My macro shots have been descent - I obviously have room to improve thou.

I was guessing that you had them mixed up, someone who has an idea of what macro photography is, has an idea of how this all works.

The 7.6 is probably the smallest you will get, and if you could get a smaller aperture that may make for some improvement. I only work with a p&s underwater and I have not ventured into macro shots yet. I have found that you have to work with the f-stops and the strobe level to keep from getting washed out shots.

 

[Scotttyd]

Wide angle or "regular lense". I guess the only time I could see when I would not set the f-stop to the highest is if I am doing a close focus wide angle shot where I would want to set my strobe to the strongest possible to light up some depth and I would use a lower f-stop so I do not over expose the closer items of the shot.

Is my thinking even close to correct?

So after re-reading what I posted, I guess it does not make sense, if I opened up the aperture (lower number f-stop) that would just make the over exposure even more evident if I used higher power on my strobe.

So my question remains, is there any time (unless using natural light) where I would want to use a lower f-stop provided I can get an proper exposure at the highest f-stop I have available to me.

 

[Divernoob]

So after re-reading what I posted, I guess it does not make sense, if I opened up the aperture (lower number f-stop) that would just make the over exposure even more evident if I used higher power on my strobe.

So my question remains, is there any time (unless using natural light) where I would want to use a lower f-stop provided I can get an proper exposure at the highest f-stop I have available to me.

Depth of field, or, how much is in focus from front to back. If you're shooting in macro mode, the smaller the aperture (higher the f-stop), more is in focus. In macro, I was taking pics of a praying mantis which was facing away from me. My f-stop was low enough (aperture too wide) at 3.5 such that his butt was in focus, while his head was out of focus. The distance between in focus and out of focus was less than 2 inches. See here:

 

[Scotttyd]

Depth of field, or, how much is in focus from front to back. If you're shooting in macro mode, the smaller the aperture (higher the f-stop), more is in focus. In macro, I was taking pics of a praying mantis which was facing away from me. My f-stop was low enough (aperture too wide) at 3.5 such that his butt was in focus, while his head was out of focus. The distance between in focus and out of focus was less than 2 inches. See here:

I do know how the f-stop relates to depth of field, and not to sound like a smart ass (I am not trying to), but that does not answer my question. (unless I am missing something)

 

[MauiScubaSteve]

Are we just talking about macro? This post is not about macro per se.

For strobe photography I now mostly shoot f5.0. I mostly shoot 1/125 sec exposure (the Nikonus V defaults to 1/90 sec). My strobe is rarely at 1/2 power, more than rarely at 1/4 power, mostly at 1/8 power and nearly never at Full power. My ISO is set to 64 or 100. I often move the strobe behind the plane of the lens to effectively have ~1/10 strobe power or less.

Just talking about one setting is not a discussion about manual photography. Other than some historic references, settings from other cameras operators have little relevance. My camera would probably give crappy results at f5.0, 1/60 sec, ISO 400, 1/2 power,,,,,,,,,,,,, unless it was Molokini's Backside, 120 fsw, 7 AM, Dec 21.

My camera can shoot f1.8. It does often when shooting ambient in P (full auto). If I was shooting ambient manually, often I should use f1.8.

 

[Saltwater Junky]

Divernoob is correct about depth of field being another reason to consider your aperture. The correct aperture setting can help emphasize your subject.

 

[Larry C]

You need to balance your f-stop and shutter speed. Sometimes, you may not use a strobe at all. The shutter speed will determine how much of your light is provided by the strobe and how much by natural light. If you are taking a picture that has an interesting background, and you want to include background beyond the reach of your strobe, a slow shutter speed will provide more ambient light in the background.
A bigger aperture (lower f-stop) will do the same thing. If your shutter speed and f-stop are both low, you may blow out the picture. If your shutter speed and f-stop are too high for the available light, it will be too dark. Shutter speeds and f-stops are generally stepped equally, providing double the light for each step up. When you reach a balance, and get the correct lighting, adjusting the shutter speed down one step and the f-stop up one step should keep that balance, but change the picture. When you set "P,A or S" modes on your camera, the camera does this for you.
Depth of field is the distance, front to back that your shot will be in focus. A larger aperture will result in less depth of field, a smaller aperture will result in greater depth of field. Also, bigger lenses generally provide less depth of field, so my DSLR, with an f-stop of 22 or 32 may be equivalent to the 7.6 minimum aperture on your point and shoot. On the other hand, you might not be able to blur out your background, even at f2.8 or whatever your maximum aperture is, where I can do it a f5 or f6.2.
If you want a blurred background or you don't have enough light at the slowest shutter speed that will allow you to capture your picture without blur, open your aperture with a lower numerical f-stop. If you want an extra sharp macro picture with lots of detail and a black background, max out your f-stop and set your shutter speed as high as you can and still light your subject.