Sigma 150-500

[tperzan]

The depth of field for my Sigma zoom is seriously short. I have been using Av mode with a set F to try to increase depth, but it doesn't seem to work. The spot focus is very sharp, but 2 inches beyond that it starts to blur. I'b usually shooting at 500 (wildlife) and unless the subject is parallel to the 'film plane' the only sharp area is where the focus is set. I use 1, center spot focusing.
Are there any settings which would improve quality? Is there a particular F which would give more clarity?
All suggestions welcome.
Thanks

 

[Stevepwns]

What do you usually set your Aperture too? The smaller the F stop the deeper your focus will be. When I am shooting wild life, I try to keep it above 5.6 but in the best situation I stop all the way down to F8. Since most of my wild life are birds thats more than enough for me. I usually find myslef shooting at F4 because I am always running out of light in the evenings after work. If I get the chance on the weekends to shoot during the day, and again, if the light is in my favor, Im at 5.6 to 8.

If you can post any pictures with an example and some setting, it would help us help you.

 

[Braineack]

what f-stop are you shooting at?

 

[480sparky42 41]

Welcome to the world of razor-thin telephoto DOF. It's not a defect of the lens, it's merely a function of the optics. All lenses of the same FL have the same issue.

One trick I use is to bracket the focus. Let the camera select the focus and take a shot. Then, turn the focus ring ever so slightly, hold down the shutter button, then slowly turn the focus ring back the other direction to where the camera focused then past that point..... shooting all the way. This spreads the focus point planes across the scene. I just pick the best in post.

 

[Solarflare]

Well, Fokus Braketing obviously only works if you have a stable tripod, and a still subject.

As others already mentioned, this is how optics work. Its physics. There is no way to avoid this behavior.

Theoretically you can of course use a smaller sensor. Thats why APS-C DSLRs like the Nikon D7100 are pretty popular with wildlife photographers.

 

[480sparky42 41]

Well, Fokus Braketing obviously only works if you have a stable tripod, and a still subject.

As others already mentioned, this is how optics work. Its physics. There is no way to avoid this behavior.

Theoretically you can of course use a smaller sensor. Thats why APS-C DSLRs like the Nikon D7100 are pretty popular with wildlife photographers.

Why do you need a tripod? I focus bracket hand-held. Once you get proficient, you can fire off a lot of shots with little subject movement.

Obviously, this won't work with things like sports and kids running around, but even birding & wildlife shooting can benefit from this technique.

 

[SCraig]

Yep, at 500mm, f/6.3 and 25' focus distance with a crop-sensor Nikon you'll have about 0.9' (1.1") each side of the focus point. Go up to f/8 and you get a whopping 1-1/4" each side of the point of focus. As was said, welcome to the world of long tele lenses.

Online DOF calculator

 

[hamlet]

So as the size of your sensor decreases and your focal length increases your dof decreases?

 

[480sparky42 41]

So as the size of your sensor decreases and your focal length increases your dof decreases?

Yep .

 

[hamlet]

Welcome to the world of razor-thin telephoto DOF. It's not a defect of the lens, it's merely a function of the optics. All lenses of the same FL have the same issue.

One trick I use is to bracket the focus. Let the camera select the focus and take a shot. Then, turn the focus ring ever so slightly, hold down the shutter button, then slowly turn the focus ring back the other direction to where the camera focused then past that point..... shooting all the way. This spreads the focus point planes across the scene. I just pick the best in post.

This post makes sense now.

 

[tperzan]

Thank you all.
I'm shooting at f8 minimum and 11 when there's enough light. I'm mostly looking at birds, so the sky comes into play frequently.
I'm gathering that it's not going to make a difference anyway. Alternatives?

 

[Solarflare]

Why do you need a tripod? I focus bracket hand-held. Once you get proficient, you can fire off a lot of shots with little subject movement.

Obviously, this won't work with things like sports and kids running around, but even birding & wildlife shooting can benefit from this technique.

I definitely envy your calm hands now. Even more at 500mm focal length.

 

[coastalconn]

The depth of field for my Sigma zoom is seriously short. I have been using Av mode with a set F to try to increase depth, but it doesn't seem to work. The spot focus is very sharp, but 2 inches beyond that it starts to blur. I'b usually shooting at 500 (wildlife) and unless the subject is parallel to the 'film plane' the only sharp area is where the focus is set. I use 1, center spot focusing.
Are there any settings which would improve quality? Is there a particular F which would give more clarity?
All suggestions welcome.
Thanks

Welcome to the forum. You might need to fine tune your lens. What camera body do you have? Are you missing focus? You should post some samples here so we can take a look...

 

[nzmacro]

Well, Fokus Braketing obviously only works if you have a stable tripod, and a still subject.

As others already mentioned, this is how optics work. Its physics. There is no way to avoid this behavior.

Theoretically you can of course use a smaller sensor. Thats why APS-C DSLRs like the Nikon D7100 are pretty popular with wildlife photographers.

Why do you need a tripod? I focus bracket hand-held. Once you get proficient, you can fire off a lot of shots with little subject movement.

Obviously, this won't work with things like sports and kids running around, but even birding & wildlife shooting can benefit from this technique.

People often ask how can you use hand held MF 500mm lenses for birds in flight and fast action motor sports. For manual focus there is the exact answer above Using a slow burst rate, focus backward or forward slightly at high shutter speeds.

Danny.