Manual Focus?

[pulse]

Ok, So this probly sounds like a retarded question, but do people always use manual focus? To me, when i manual focus, there seems to be quite a distance of rotating the 'focus ring' that i cannot tell with my own eyes what is perfectely spot on and clearly focused. I mean it may look good at the time, but when you view in up on the computer theres i good chance it wont be perfectly clear. I would like to be able to have more control over my camera especially because auto focus is not all that great in low light situations.
I dunno, am i tottaly out to lunch on this or is there any sence to it? Your guys' input would be appreciated.

 

[Overread]

Most people today don't use manual focus if they are using a DSLR unless they have to. Modern DSLRs are designed to be used with auto focusing and thus screen aids (such as brighter screens and other features) which aided manual focusing in the past are no longer included. There are some cameras which can be modded (by 3rd party groups) to have some of these aids installed though I have heard some can mess up your in camera metering.

I only really use manual focus when I am shooting macro - and that is a standard practice since AF is not so good at those ranges due to hunting; the fact that AF does not know what you want in focus and because you freaquently can't just point the middle point at the subject and shoot

 

[dxqcanada]

You will find that most Digital users do not use manual focus.
If they do, it will probably be used in conjunction with the AF sensor.

Like Overread, I primarily use MF with my macro lens.

Coming from 20years of MF it is still hard for me to let the camera do it ... though I do appreciate this function on moving subjects.

I would shoot more manual focus if I put a split screen in my DSLR ... hmmmm.

 

[tsaraleksi]

I don't think there's a need for manual focus unless you need it, which is why full time manual focus is a really nice lens attribute. When you need it, you need it right then.

 

[monkeykoder]

my standard practice when manually focusing a DSLR is to find the ends where it is difficult to tell and set the focus halfway inbetween it is a little bit easier with the 50mm f1.8 or the 200mm f4 as the DOF is really shallow.

 

[Phranquey]

I use manual focus at both ends of the spectrum....for macro, because the lens will sit there racking back-and-forth while hunting, and for the long telephoto because, well, it's a manual focus lens.... For everything in between, I let the autofocus do it's job.

It's kinda nice after 20+ years of MF to let the camera do it for me.

 

[epp_b]

It's common to use autofocus on crop frame digital SLRs because they have comparatively tiny viewfinders that are pretty lousy for manually focusing. Even worse, Olympus DSLRs have such a huge crop factor (2x, compared with 1.5x and 1.6x of Nikon and Canon) that the viewfinders are, frankly, pathetic and manually focusing is near useless.

I'm not sure about Olympus, but Nikons have an LED dot in the viewfinder that indicates correct focus. This is very helpful, but it's still not as good as having the big, bright, clear viewfinder of a film camera.

 

[viridari]

Ok, So this probly sounds like a retarded question, but do people always use manual focus?

My film cameras don't have an autofocus, so the answer is "yes" for them.

On my Canon XTi, the auto focus is faster than me, and the viewfinder is so uselessly tiny that I can't focus with it anyway.

 

[elemental]

My film cameras don't have an autofocus, so the answer is "yes" for them.

On my Canon XTi, the auto focus is faster than me, and the viewfinder is so uselessly tiny that I can't focus with it anyway.

Same here, although I also use the old lenses on my K100D. It's tough under some conditions, but a focusing screen upgrade in the near future will take care of that if I decide to get one. For now, it really isn't that bad.

I like manual focus because it doesn't hunt and when it misses, it's my own fault. I am used to using it all the time on my film cameras, so it sometimes feels simpler than picking autofocus points and making sure the computer picks what I want it to.

 

[pulse]

Good to know... I just always kinda figured for some reason that using manual is what you should generally be using.

Olympus DSLRs have such a huge crop factor (2x, compared with 1.5x and 1.6x of Nikon and Canon)

I have read this in a lot of places but have never been able to really understand what it means. Basically i just have a smaller sensor? what does this nessisarily mean in terms of the photos being produced?

 

[viridari]

what does this nessisarily mean in terms of the photos being produced?

It changes the effective focal length of your lens!

On my Canon XTi, with a 1.6x crop factor, my 50mm prime is effectively an 80mm lens.

On a 2x crop sensor camera, a 50mm would effectively be 100mm.

Great news for bird watchers. Lousy news for street photography, architecture, anywhere that you might want a wide angle lens.

 

[seaain.gray]

I dunno, am i tottaly out to lunch on this or is there any sence to it? Your guys' input would be appreciated.

No you are not out to lunch. Yes, there are good reasons to learn MF as a skill. Low light is a very valid one.

One of the best commonly available aids to MF is a split focusing screen. I have one in my second/backup DSLR body. I use it a lot with old manual lenses. With respect to use with AF, it does help in low light to both evaluate the AF accuracy and to tweak it somewhat when necessary.

Here's a link. You camera is probably easily modified to add a split screen, though it may interfere somewhat with some functionality. Some people report that spot metering is not as accurate... look into your specific user community to see what, if any issues obtain...

http://www.katzeyeoptics.com/

 

[TBAM]

It changes the effective focal length of your lens!

On my Canon XTi, with a 1.6x crop factor, my 50mm prime is effectively an 80mm lens.

On a 2x crop sensor camera, a 50mm would effectively be 100mm.

Great news for bird watchers. Lousy news for street photography, architecture, anywhere that you might want a wide angle lens.

Now now, this is not correct.

The 4/3 system isn't a crop system. It's not a 2x crop factor.

Crop factor is cropping your field of view.

A 4/3 lens on a 4/3 camera is a crop factor of 1. Just like a Nikon DX lens on a "crop" sensor.

You are seeing all that the lens sees.

It is true that the 4/3 sensor is half the size of a 35mm piece of film, however the lenses designed for the system "shrink" or focus the image so that 100% of the field of view makes it onto the sensor.

However, as the entire DSLR industry is based on 35mm equivalents, to retain consistency, they are still marked in the industry standard.

An example:

Say I have the Olympus 4/3 (4/3 is the mount) Zuiko Digital 25mm F2.8 Lens and the Olympus Zuiko OM (OM is an old film mount) 50mm f1.8.

The OM lens is a manual lens from the 70s 80s and 90s. The Zuiko Digital lens is a 4/3 lens.

With the Zuiko digital 25mm lens on the camera I would be getting 100% field of view at 50mm focal length. The sharpness and quality would be as though I had a 50mm f2.8 lens on the body.

Now, if I put the OM 50mm f1.8mm on my body, I would have a 50% field of view at a focal length of 50mm, however due to the size of the sensor, the 50% field of view would create an image that has the same focal length(or field of view) as a 100mm lens. The image would be half as sharp as it would appear on a 35mm film or full frame sensor. So to get an image of the same quality as a full-frame / 35mm piece of film, the lens would need to be twice as sharp.

Which is why, on 4/3 Olympus cameras it is usually only advantageous to use OM Prime lenses, because they have the sharpest optics.

OM Zooms are not recommended to be used on 4/3 cameras as the optics are not shalf enough, and often the images garnered from using OM zooms are a little soft.

So whilst the above may have sounded quite confusing, essentially:
- Olympus 4/3 Cameras and Lenses are not cropped. Say you had a 17.5mm piece of film. The Olympus camera system would be a "full-frame" system. Much in the same way, a 35mm full-frame camera is not considered a crop factor of a medium format system.
- Olympus Lenses are twice as sharp as their counterparts, because they need to provide twice the clarity to the sensor.
- The 2x "crop factor" is not limiting in any way. You can get 7-14mm ultra-wide angle lenses if you want to go wide.
- The Olympus 4/3 system is a system all to itself. It has been designed from the ground up, and is essentially to 35mm photography, what 35mm photography is to medium format photography.
- The only limiting factor is that the sensor is half the size, so fitting similar amounts of pixels to a full frame sensor on half the size is obviously going to have it's own difficulty.

As for manual focus. The biggest problem I have found with my olympus, is that the view-finder is dim, and no focusing guides are provided such as a split prism. Although you can get katzeye screens for $100 which should help greatly.

As for the viewfinder being dim, so are all comparitive SLRs, if you want a bright viewfinder you pay for it, or you use an old film camera.

Lastly, the kit lenses have focus-by-wire focusing systems, the focus ring generates little feel or feedback, and it is difficult to gauge where you are focusing, especially without a split-prism viewfinder.

If you ever buy yourself an OM lens and adapter, focusing is a LOT easier with a focus ring that has a minimum and maximum focus point. The only limiting factor there is the viewfinder still being dim.

Anyways, I hope this post wasn't narky, but as an Olympus fan, I hate people getting the sensor details and "crop factor" specifics all wrong.

 

[OregonAmy]

I don't think there's a need for manual focus unless you need it

exactly.

I've used it a few times when the lighting wasn't quite right.

 

[pulse]

Wow TBAM, thanks for all the info!
Thats really good to know, and you explained it very well.
Kinda relieves me that you clarified that, thinking that at 14mm i was really at 28mm kinda scared me lol, almost ran out and got a new camera.

Now lets say i was to purchase a Sigma lens (compatible is it not?) or any other third part lens, is that when cropping issues and all that come into affect?