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Tips and Tricks for Focusing


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#1 CDesperado

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Posted 08 July 2003 - 06:49 AM

I am starting this thread mostly out of curiousity, just to see where it goes since we have so many seasoned photographers that post replies and so many others who read the replies without posting. I am assuming a lot of these viewers are relatively new to underwater photography and might benefit from this thread.

Assuming that most of us here use Autofocus for macro work, I am wondering how many people set the camera's focus on a specific point and then move in/out on a subject to obtain focus and how many people will continually adjust the lens while shooting a specific subject.

Anyone want to share any tips or tricks related to obtaining a crisply focused picture?

#2 james

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Posted 08 July 2003 - 06:59 AM

Okey doke! A great thread - I was just talking about this the other day w/ Dave Haas and Craig.

For shooting macro in surge:, forget about autofocus. Use manual focus and set it at your minimum focusing distance (max magnification). Do a couple test shots at full power and adjust your fstop till you get the exposure you like (for a "neutral colored animal" black animal is another story). Then move in and out until the subject appears in focus in your viewfinder. BLAM! Fire off the shot. Repeat until you get it if the subject will let you.

For shooting macro w/ autofocus: This works pretty well in bright light and calm conditions. Autofocus on the animal and half press or focus lock button on the subject. If it's a small fish, you probably autofocused on the body, so move back a little until the eyes are in focus. Blam!

If you have a AF lock button, you may be able to get away with using autofocus in more difficult conditions if you use it expeditiously.

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#3 yahsemtough

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Posted 08 July 2003 - 07:23 AM

Holy autofocus Batman!

Another trick I have learned is sometimes the autofocus does not focus on the actual subject due to other items between the lens and the subject.

It maybe difficult to get the autofocus to pick up the desired subject because you cannot get in the position you require to get the proper focus point.

To remedy this you can focus on an object near the subject, estimating the distance that you will be shooting half press the shutter to lock focus then move to your desired subject.

And Whap! Blam! Zoowie! take a couple shots.
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#4 Alex_Mustard

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Posted 08 July 2003 - 11:29 PM

After reading the above posts I fear I am a lazy photographer! I always use autofocus on continuous servo because even if the fishy is still I rarely am!
With my Nikons (D100 & F100) I find that the off centre AF sensors are particularly helpful for focusing on the eye of a fish etc. I tend to look at the subject and decide on the sensor I want to use before moving in to take the shot.
Flash-wise I do all my macro on TTL (or DTTL with the D100). Again laziness! Just means I can concentrate on composition (can you see the smoke coming out of my ears with the strain?), usually the crucial element of a macro shot, and forget about the rest.
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#5 Helge Suess

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Posted 09 July 2003 - 12:02 AM

Hi!

Recently I wondered if it's worth the work to try out a line laser as AF support. A device that you may trigger with a button next to the release button. The device should be mounted in line with the lens and produce a vertical|horizontal|cross line on the target. This would maybe help the AF in low light conditions.
Has anyone down there tried something liek this? Pros and cons? Suggestions?

Helge ;-)=)
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#6 chrisg

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Posted 09 July 2003 - 01:19 AM

I never use autofocus for macro (I do generally use it for wide angle).

When taking macro pictures at close range (a couple of inches), it is generally not possible to have the subject entirely in focus.
The photographer must decide which pieces of the animal should be the sharpest. For creatures with eyes, this
generally means the eye. For nudibranches, worms, etc, this is usually the "head" and its features, etc. I've generally had no luck with pulling this off with autofocus. In theory, the multiple focus points could be used to perform this, but this requires that the feature be positioned
in the proper focus point and that that one be selected, AND that the feature be big and contrasty enough for the camera to lock on to.

Anyone sucessfully shot a properly focussed subject on the scale of a pygmy seahorse at >1:1 with autofocus? (Not that its particularly easy on manual focus either!!).

#7 Andi Voeltz

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Posted 09 July 2003 - 03:43 AM

After reading the above posts I fear I am a lazy photographer! I always use autofocus on continuous servo because even if the fishy is still I rarely am!

hocus pocus - out of focus! :D
I have to join in the choir with Alex.
So far I always used the Auto Focus, so it's...

hocus pocus - auto focus! B)
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#8 scorpio_fish

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Posted 09 July 2003 - 06:53 AM

Conventional wisdom would follow James' advice, with perhaps even more use of manual focus.

I use AF on everything. I've spent upwards of five minutes to get one shot of a creature inside a blowing anemone while in a constant surge using a 105mm with a 2x teleconverter at f/22, effectively at f/45.

Reality is that I can't do better than the cameras AF. I've tried it with the 200mm macro. With strobes extended out to the end of a very long and heavy flat port, keeping the camera steady becomes a real problem.

Using focus lock is an acquired skill and works better for me. Point at the desired focus spot, e.g. eyeball, lock, recompose, fire. This can be easily practiced.

Another technique is to AF on something in the distance range you want to shoot. Flick MSC to manual and reposition camera until you get the target in focus and fire.

Even if you or the subject are moving or bouncing, it is important to AF progessively on your subject. This way refocusing due to a minute distance change is almost instantaneous. Very important with the 105mm which tends to hunt a lot. I often use my hand as a target to get the lens to focus in that range.

Alex says lazy. Maybe I'm lazy, too. But the reality is that as soon as quit messing with camera settings, my composition improved.

1) Turn your SLR into as much a point and shoot as possible, i.e. aperture priority, f/22 and TTL.
2) Identify subject to be captured.
3) Figure out how you want it framed. Angle of subject, negative space, inclusions and exclusions in the scene.
4) Decide your approach based on 3), also look for something to grab to steady yourself.
5) Approach and fire.
6) Vary 3) and fire again.
7) Vary 3) and fire again.

Later I added strobe positioning to 4). Repositioning your strobe(s) on each shot greatly improves the odds of good exposure.

If possible, I really take my time on 4) and 5). Often, when my buddy points something out, I take so long that she thinks I can't see it.
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#9 pakclu

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Posted 10 July 2003 - 04:10 PM

Sorry for the neophyte DSLR question, but...
HOw does one focus "manually"? Does one actually have a focus gear controlled by the housing (ikelite md/fuji s2pro), or is it a matter of adjusting the range between the lens and critter?
Thanx
Peter :D

#10 craig

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Posted 10 July 2003 - 04:50 PM

Sorry for the neophyte DSLR question, but...
HOw does one focus "manually"?  Does one actually have a focus gear controlled by the housing (ikelite md/fuji s2pro), or is it a matter of adjusting the range between the lens and critter?
Thanx
Peter :D

It would be a lot of the first sometimes followed by a little of the second. You need a manual focus knob and a focus gear on your lens. On really small subjects you may have to do the final focus using minor movements of the lens.
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#11 davephdv

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Posted 10 July 2003 - 07:14 PM

I always use AF. Set it on continuous. With the D100's menu I set the back button to auto focus. Focus with the back lever and when my subject is in focus hit the trigger. If I have trouble with the focus I just focus on something close to my subject, flip the camera mode to manual focus and then adjust the focus by moving the camera distance a little. Be sure to flip the focus mode switch on the housing back to autofocus before the next shot.
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#12 CDesperado

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Posted 11 July 2003 - 05:08 AM

Dave,
Just to make sure I understand, are you saying your housing has a button connected to the lens switch that lets you move back and forth from manual and auto focus?

#13 Stewart L. Sy

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Posted 11 July 2003 - 08:53 AM

I personally use AF on all my shots (then again, I don't have the feature to switch to MF in my housing), however, I've been able to take shots of pygmy seahorse using AF (see my avatar? :freak: ) ....what I've ended up doing is to set my camera on focus tracking, therefore I will close in on the seahorse then once the camera locks on...and I do my job of keeping the AF sensor on the critter, the camera will do a great job tracking the subject...my main reasoning behind it was if the camera can track a speeding race car, why can't it compensate for the slight movement of surge, breathing, darting anemone fish (see my post on finding Nemo in the critique section) etc?

For static subjects then I switch to one shot AF.

Stu

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#14 craig

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Posted 11 July 2003 - 09:13 AM

my main reasoning behind it was if the camera can track a speeding race car, why can't it compensate for the slight movement of surge, breathing, darting anemone fish (see my post on finding Nemo in the critique section) etc?

I think the answer to this would be lack of light, contrast, viz and depth of field. Many get frustrated by the slow hunting that can occur trying to get a lock in the first place. I think it's very much a rig and dive subject/conditions thing. I don't even like AF with the 60 and a dome!
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#15 Stewart L. Sy

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Posted 11 July 2003 - 09:27 AM

I have a UK SL4 on an Aquatica light cradle mounted on top of my Subal housing....works great in the tropics, though in the Northern Pacific waters that I call home, I need the UK D4 to light my way...

Stu

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