Tips for taking sharper photos

[Stephen Locke]

what is beyond infinity . . . mush?

When I first started storm photography the easiest part of the process was getting sharp critical focus. Just grab the lens (on the Mamyia RB67) and crank it hard to infinity. A blind guy could do it. And I could do it in the rain standing on the side of the road on the darkest night. Now that we are trying to manually focus a lens designed for auto focus it is not that easy. Got this problem of Infinity Compensation. (whatever that is) A lens will now focus beyond infinity.

Problem is, as a weather photographer who shoots a lot of lighting at night I need to be at infinity focus or a tick this side of it. And, if need be, I want to be able to get it done at f1.2 or f1.4. (zero margin for focus error). And I need to be able to do this without excuses when it is dark, buggy, windy and rainy. Also, when weather phenomenon is rapidly evolving I don't want to take the time to analyse a 10X LCD view. I just wanna focus and shoot fast.

link to pics; http://www.stephenlocke.com/lenstest.html

A compromise between manual focus and auto-focus is focus assist.
Turning the focus barrel by hand and allowing the camera to aid focus with the little red indicator in the viewfinder and/or an audible beep. I have done this at night to focus on the horizon using a distant object usually a streetlight or something like that. I've also found out the focus assist indicator and viewfinder cannot be trusted. The indicator will light and beep but the picture will not be sharp. Most frustrating to me is the fact that the focus I SEE does not match what is about to happen on the sensor. In other words the focus on the view finder will not match the actual exposure. The blurry pictures I am posting here did not look that bad on the screen. I mean come on, if it really looked that mushy on screen I'd never press the shutter. I've long suspected a viewfinder to sensor discrepancy and these test pics prove it. What amazes me is the fact hat the problem is worse on the 24-mm. (wide angle lenses are supposed to be easy to focus esp. at infinity).

I realise I am handicapping myself by shooting at F1.2 & F1.4 but I am hell-bent on taking advantage of the fact that these prime lenses have been engineered to go very wide. I'm also hell-bent on using ISO 100 in the dark to eliminate noise.

It seems the most reliable thing to do is use the infinity "L" mark. (and avoid bumping the lens?). So now my most important piece of focusing equipment is an LED headlamp I wear on my forehead so I can fanatically check to see if my L mark is in the right spot. And what about this issue of focus drift because of temperature . . . is my L mark sweet spot going to move because it is a hot or cool night? I guess I'm gonna have to do more tests. (with each lens!)

Actually, I wish my lens really could focus beyond infinity. I'd like to know what is out there.

 

[Stephen Locke]

infinity focus test

Open graphic to review my test. It's over 2000 pixels
so you can scroll around to see details. The test reinforces
my suspicion not to trust what I see in the viewfinder or
the cameras focus confirmation indicators. The +1 and +2
exposures looked sharp enough to me when I released shutter.
click here;

http://www.stephenlocke.com/photos/infinity_test.jpg

 

[Greg Campbell]

Stephen,
How on earth do you shoot lightning at f1.2? I'd expect massive overexposure and blooming.

IMO, the 'temperature compensation' excuse is pure BS. C'mon, how many microns is your typical lens going to expand? With anything short of a loooong telephoto, the expansion effect will be absolutely insignificant. There's no reason the lens manufacturers couldn't put a calibrated infinite focus stop on prime and parfocal zoom lenses. Instead, they add extra travel and let the AF figure it out. It's easier and cheaper that way.

Granted, you don't want a miscalibrated AF system grinding the lens to dust in an attempt to over-focus. Do current AF lenses/bodies have some manner of stall sensor that cuts off drive to a jammed lens? (Edit - Yea, they seem to. My XT+kit lens shuts off the motor about a second after it stalls.)

-Greg

 

[Darren Addy]

When I first started storm photography the easiest part of the process was getting sharp critical focus. Just grab the lens (on the Mamyia RB67) and crank it hard to infinity.

You keep mentioning that you have a RB67. But you don't focus with an RB67 by "grabbing the lens". It is an "old-skool" camera where the lens is mounted to a bellows and you focus by moving the entire bellows (with the lens) forward and back. It's been long enough since I shot with one that I don't recall exactly where you focus at infinity (but, logically, it would relate to the focal length of the lens). Since I used them in a camera room, I don't know if I ever did focus one at infinity. In any event, the RB would definitely not be a good example of an "easy" camera to focus on infinity with. I think you must be confusing the RB67 with some other "easy-to-focus-on-infinity" system.

Also, it appears that your lens can/does focus past infinity. Your +1 and +2 focusing marks on the lens illustrate this. While focusing past infinity sounds like it is impossible, anybody who has ever used binoculars or a telescope can tell you it is possible. You can't get a much more distant object to focus on than a star and you can certainly rack in and out of focus on either side of that point. In fact: "Most new autofocus camera lenses now allow focus past infinity so the autofocus mechanism does not suffer a jolt when seeking focus and racking to the infinity setting."

I can certainly understand how an autofocus system could be less-than-foolproof. Some systems have particular problems in low light. And it is absolute folly to rely on the focus marks on the lens, which are (at best) an approximation of where you are actually focusing. You should be able to trust what you see in the viewfinder (however) unless you are having eyesight focusing problems (see your optomotrist). The focusing screen your camera uses may make things difficult, and you may wish to use a focuser magnifier for critical focus — like you had on the waist level viewfinders of those old medium format camera (like the RB67).

However, if you still can't trust your viewfinder, then you have something wrong with your camera. I am told that some cameras have a special service port which allows fine tuning such as fixing front focus or back focus problems by actually moving the location of your sensor front to back. Not familiar with your particular model, but the bottom line is that you should be able to trust what you see in the viewfinder (assuming you are seeing the viewfinder clearly - with the aid of a proper focusing screen and magnification.*

* some manual focus lens shooters long for the old-style focusing screens and there are companies that will provide them. But you must make sure that the thickness of the focusing screen matches your original or you will see a different focusing plane than the sensor is. Some places talk about using thinner focusing screens and "shimming" them, but for this critical area I would think you would want an exact match.

You are also incorrect that "wide angle lenses are supposed to be easy to focus esp. at infinity". Even autofocus systems will have a harder time with a wide angle lens — for the simple reason that wide angle is the opposite of magnifying your scene. Everything looks smaller and thus sharper (even if it isn't truly sharp). If it is an autofocus wide angle lens, then it will also probably have the "focus past infinity" design.

Also, Glen, temperature being an issue is not "BS" according to Canon lens manuals:

"To compensate for shifting of the infinite focus arising from changes in temperature, the distance scale can be rotated slightly past the normal infinity focus mark"

This whole "focus past infinity" issue is part and parcel of AF lens design. To avoid the problem completely, use "old skool" MF lenses that stop at infinity. For DSLRs that have a "lock focus" function, for lightning photography, focus on a distant street light (or something) and lock the autofocus there for the remainder of your lightning photography session.

 

[Greg Campbell]

Also, it appears that your lens can/does focus past infinity....
In fact: "Most new autofocus camera lenses now allow focus past infinity so the autofocus mechanism does not suffer a jolt when seeking focus and racking to the infinity setting."

Ah! Now, that actually makes some sense. I still think it's a sloppy solution, but it is much more believable than the temperature excuse.

However, if you still can't trust your viewfinder, then you have something wrong with your camera. I am told that some cameras have a special service port which allows fine tuning such as fixing front focus or back focus problems by actually moving the location of your sensor front to back. Not familiar with your particular model, but the bottom line is that you should be able to trust what you see in the viewfinder (assuming you are seeing the viewfinder clearly - with the aid of a proper focusing screen and magnification.

Stephen, I think he's on to something.
All my old 35mm film cameras mount the mirror stop pin on an eccentric screw. You rotate the screw to alter the light path length to your viewfinder until it and the film/sensor plane reach focus simultaneously. Other cameras use variable shims under the viewfinder screen. Tweaking the AF sensor location won't help if there is a mismatch between viewfinder and sensor focus. Hopefully there is a way to tweak your viewfinder's focus accuracy.

Also, Glen, temperature being an issue is not "BS" according to Canon lens manuals:

Derrik, it's called Marketecture.
You don't believe everything they tell you???

-Greg

 

[Stephen Locke]

Darren and Greg,

Thank you for the discussion, it is all informative. The good news is that the infinity L mark does provide a reliable way to accurately focus to infinity regardless of what I see or don't see in the viewfinder. It works and that is good enough.

 

[Hank Baker]

I am glad you mentioned window mounts. They are a must for me for shooting lightning and staying safe inside the vehicle.

 

[Rob Wadsworth]

Is this discussion limited to sharper shots w/o the consideration of light balance?
I'd like to see the use of 18% grey cards and exposure compensation in the mix too if possible.
Near-night under a dark meso may well require compensation - at least.
After all, having a sharp shot necessarily means that all of the ducks have to be in row.

If we just want a sharp shot, maximizing shutter speed vs ISO would have ended the discussion long ago.
Anybody want to discuss their steps in composing the sharpest photos from beginning to end?
Create your own example to qualify your steps...
Who's up to that challenge?

Edit: should I start another thread - or is this still on the subject?

 

[Stephen Locke]

fire by radio

I am glad you mentioned window mounts. They are a must for me for shooting lightning and staying safe inside the vehicle.

It is not unusual for me to put the camera on a tripod* and fire the shutter by radio from the (relative) safety of the vehicle. * I use a very heavy (18 lbs)
Bogen 3251. Gotta be that heavy if you are not going to sit within arms length of it. Heavy as it is I've had to catch it before it hits the ground in a wind gust.

 

[Laura Duchesne]

I think my focusing technique is similar to Stephen's. When I manual focus with my Tamron lens, I put it just before the L infinity mark. I look through my viewfinder to make sure it appears sharp enough. If I go beyond infinity, it gets blurry fast. I find I get my best results that way, so when I am setting up for lightning, I just put the focus before infinity and look through the viewfinder to find a light source to focus on. This way, I seem to get results I am happy with. The kit lens never had an infinity marker on it, so all my lightning pictures from that came out like crap.

 

[Greg Campbell]

Is this discussion limited to sharper shots w/o the consideration of light balance?
I'd like to see the use of 18% grey cards and exposure compensation in the mix too if possible.
Near-night under a dark meso may well require compensation - at least.
After all, having a sharp shot necessarily means that all of the ducks have to be in row.

If we just want a sharp shot, maximizing shutter speed vs ISO would have ended the discussion long ago.
Anybody want to discuss their steps in composing the sharpest photos from beginning to end?
Create your own example to qualify your steps...
Who's up to that challenge?

Edit: should I start another thread - or is this still on the subject?

Rob, why don't you spin off a new thread about exposure technique. It's certainly relevant for contrasty, often backlit, weather shots. I'd be curious to know what metering systems people are using.

-Moo

 

[Rob Wadsworth]

Rob, why don't you spin off a new thread about exposure technique. It's certainly relevant for contrasty, often backlit, weather shots. I'd be curious to know what metering systems people are using.

-Moo

Greg;

I am trying to learn what I can from the experienced photographers - like yourself.
From what I can see, you are a film guy that also does digital @ work.
I;m sure you could fill in the blanks if you wanted to.
Even a dissertation.
ooM-