Manual Focus?

[TBAM]

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?

Sorry to dissapoint, but when your lens is at 14mm you are actually at 28mm.

The reason is, because the lens is standardised (like all SLR lenses) it is marked for it's physical focal length on a 35mm camera.

So with your lenses, you have a 28 - 84mm lens and an 80-300mm lens essentially.

But your images aren't cropped images, like on an APS-C or Nikon/Canon crop camera. They are "full-frame" images on a 17.5mm sensor.

For example:

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

This is not correct. the 50mm prime is still a 50mm prime, however the camera is only seeing 60% of the image. Because that 60% takes up the whole sensor, it equates to the "zoom" or focal length of having an 80mm lens. However, in this case they are getting 60% of the quality essentially, because the image from the lens is designed for a larger sensor. Although, the difference in quality in a realistic sense is often negligable or unnoticable, as the centre of the lens is often the sharpest point.

However on an Olympus 4/3 system you are getting 100% of the view, and 100% of the quality that the lens is providing.

Lastly, as previously stated, the bad side of this, is that because the sensor is half the size. They are trying tofit 10million pixels onto a 17.5 sensor as opposed to say the Nikon D3 fitting 12 million pixels into a 35mm sensor.

 

[monkeykoder]

Sorry to dissapoint, but when your lens is at 14mm you are actually at 28mm.

The reason is, because the lens is standardised (like all SLR lenses) it is marked for it's physical focal length on a 35mm camera.

So with your lenses, you have a 28 - 84mm lens and an 80-300mm lens essentially.

But your images aren't cropped images, like on an APS-C or Nikon/Canon crop camera. They are "full-frame" images on a 17.5mm sensor.

For example:


This is not correct. the 50mm prime is still a 50mm prime, however the camera is only seeing 60% of the image. Because that 60% takes up the whole sensor, it equates to the "zoom" or focal length of having an 80mm lens. However, in this case they are getting 60% of the quality essentially, because the image from the lens is designed for a larger sensor. Although, the difference in quality in a realistic sense is often negligable or unnoticable, as the centre of the lens is often the sharpest point.

However on an Olympus 4/3 system you are getting 100% of the view, and 100% of the quality that the lens is providing.

Lastly, as previously stated, the bad side of this, is that because the sensor is half the size. They are trying tofit 10million pixels onto a 17.5 sensor as opposed to say the Nikon D3 fitting 12 million pixels into a 35mm sensor.

Where did this data come from?

 

[icassell]

Unlike some others, I frequently use manual focus on my 30D (1.6x crop factor). One day soon I'm going to invest in a Katz Eye focusing screen. I am from the 35mm era and got used to manual -- have never really gotten used to AF, although I do use it.


http://www.katzeyeoptics.com/item--Canon-30D-Focusing-Screen--prod_30D.html

 

[epp_b]

Sorry to dissapoint, but when your lens is at 14mm you are actually at 28mm.

The reason is, because the lens is standardised (like all SLR lenses) it is marked for it's physical focal length on a 35mm camera.

So with your lenses, you have a 28 - 84mm lens and an 80-300mm lens essentially.

But your images aren't cropped images, like on an APS-C or Nikon/Canon crop camera. They are "full-frame" images on a 17.5mm sensor.

For example:


This is not correct. the 50mm prime is still a 50mm prime, however the camera is only seeing 60% of the image. Because that 60% takes up the whole sensor, it equates to the "zoom" or focal length of having an 80mm lens. However, in this case they are getting 60% of the quality essentially, because the image from the lens is designed for a larger sensor. Although, the difference in quality in a realistic sense is often negligable or unnoticable, as the centre of the lens is often the sharpest point.

However on an Olympus 4/3 system you are getting 100% of the view, and 100% of the quality that the lens is providing.

Lastly, as previously stated, the bad side of this, is that because the sensor is half the size. They are trying tofit 10million pixels onto a 17.5 sensor as opposed to say the Nikon D3 fitting 12 million pixels into a 35mm sensor.

Actually, you're both correct. Same ideas, just different ways of explaining it.

What the first person is referring to is called "field of view". It's the angle, in degrees, that a given focal length covers for the sensor or film size. 14mm on an Olympus 4/3rds sensor gives you the equivalent field of view that 28mm gives you on a full 35mm frame.

Yes, 50mm is 50mm, no matter what camera you mount it on, but it has a different field of view according to the sensor or film size. When we say "effective focal length", we are referring to the focal length as it's seen on a 35mm frame. 50mm on Canon or Nikon crop is an effective 75mm or 80mm, respectively. On an Olympus 4/3rds sensor, it's an effective 100mm. This can be good or bad, depending on how you want to use the lens. An effective 100mm f/1.8 would be pretty expensive and, as far as I know, is nonexistent.

However, effective length also affects depth of field. In order to have the same coverage and depth of field of a 50mm f/1.8 on a full frame, you would need to have a 25mm f/0.95 an Olympus crop, which surely does not exist and, if it did, would be prohibitively expensive.

What the second person is saying is that if you use a full-frame lens on a crop-frame camera, you are using more of the centre of the lens for the entire frame, which generally has better quality than the corners. This is true, but image quality may come down to the sensor when we're talking about sensors as small as half the size of a 35mm frame.

 

[maulrat]

Being a beginner, I really try my best not to use manual focus. I often use MF when I'm shooting moving objects that I'm relatively close to. Example, standing on the sidewalk and shooting moving cars. By the time I see the car, its far but coming in fast. If I use AF, usually two things happen.

1. I AF too far away and the shot becomes way OOF when the car in front of me for the shot.
2. I miss my subject because the AF isn't quick enough to AF a moving object that close to me and fire the shot.

In this situation, I usually manual focus on the road; about where the car tires should be when I fire the shot. I think take a couple of test shots of my subject, then adjust my focus accordingly.

 

[TBAM]

Where did this data come from?

I'll try and find specific quotes, however it is simple physics.

You don't call a 35mm camera a crop camera because medium format is larger do you?

Medium Format has lenses specifically built for it's film system.

35mm (Full Frame) has lenses specifically built for it's system.

Olympus 4/3 system has lenses specifically built for it's system, from the ground up.

An 80mm lens on a medium format camera has the same field of view as a 50mm lens on a 35mm format camera, however the 80mm lens isn't called a 50mm lens with a focal multiplier of 1.6.

Olympus 4/3 cameras and lenses are completely ground-up designs for essentially a "new format" equivalent to half frame (this is widely published) and are specifically designed for digital sensors, not film,, however when people talk about the lenses and the sensor, they compare it to the 35mm system.

Olympus has a 25mm f2.8 prime lens which has the same field of view as a 50mm. The image isn't cropped. The Lens is designed to focus the image on the sensor (unlike for example an Nikon FX lens on a DX body which would have 1.6x the field of view, however the image is actually cropped).

What I'm getting at is, for Canon and Nikon crop sensor cameras. When using full-frame lenses, you don't really have 1.6x the focal length, you are essentially cropping an image from a full frame camera down to 60% of it's original size. When using a full frame lens on a crop camera, there is 40% of the image that the sensor is not seeing. Whether the differences compromise the work you do, is up to you (full frame digital cameras only came out recently, so it can't be that bad).

I'm not sure of the Canon System, but i think an EF-S Lens (as far as I remember) is built specifically for the 1.6 sensor. It is then not a crop camera, or a crop of a larger image, you are getting 100% of what the lens is providing.

The same goes for my olympus. When using a 4/3 lens, I am getting 100% of the field of view that the lens provides. However when I use my OM-mount 50mm 1.8 I am only getting 50% of the image that the lens provides. However that 50% takes up 100% of my sensor, so it appears as though my field of view twice as far (which is the effective focal length multiplier).

With the 4/3 lenses on a 4/3 body, a 14mm lens may mean a 24mm focal length on a 35mm camera, however it is not a crop factor.

A 14mm lens on a 4/3 camera is a 14mm lens. However it provides the equivalent field of view as a 24mm lens on a 35mm camera.
Just the same as a 50mm lens on a full frame camera provides the same field of view as an 80mm on a medium format camera.

Sorry to keep harping on, or appear argumentative. I am just trying to correct a bit of public perception towards Olympus, which compares the Olympus system directly with Canon and Nikon or the 35mm system, when it would be like comparing 35mm cameras with medium format.
You can see that as a bad marketing point for Olympus, however you still have studio photographers shooting d3s or 5d mkIIs when they could afford medium format. It depends on what you want out of your camera.

You weigh up the pros and cons of each format (of which Epp B has outlined very well), then decide.

The benefit of the half frame format is it's size and portability, as well as it's ground-up design specifically tuned for digital sensors, hence the E-420 being the smallest and lightest DSLR on the market by far with the pancake f2.8.

Edit:
----------------------
Wikipedia article:
http://en.wikipedia.org/wiki/4/3_System
Some Dpreview comments:
http://forums.dpreview.com/forums/read.asp?forum=1018&message=10806051
About it being a new format:
http://www.4-3system.com/modules/newbb/viewtopic.php?post_id=682

 

[monkeykoder]

I'll try and find specific quotes, however it is simple physics.

You don't call a 35mm camera a crop camera because medium format is larger do you?

Medium Format has lenses specifically built for it's film system.

35mm (Full Frame) has lenses specifically built for it's system.

Olympus 4/3 system has lenses specifically built for it's system, from the ground up.

An 80mm lens on a medium format camera has the same field of view as a 50mm lens on a 35mm format camera, however the 80mm lens isn't called a 50mm lens with a focal multiplier of 1.6.

Olympus 4/3 cameras and lenses are completely ground-up designs for essentially a "new format" equivalent to half frame (this is widely published) and are specifically designed for digital sensors, not film,, however when people talk about the lenses and the sensor, they compare it to the 35mm system.

Olympus has a 25mm f2.8 prime lens which has the same field of view as a 50mm. The image isn't cropped. The Lens is designed to focus the image on the sensor (unlike for example an Nikon FX lens on a DX body which would have 1.6x the field of view, however the image is actually cropped).

What I'm getting at is, for Canon and Nikon crop sensor cameras. When using full-frame lenses, you don't really have 1.6x the focal length, you are essentially cropping an image from a full frame camera down to 60% of it's original size. When using a full frame lens on a crop camera, there is 40% of the image that the sensor is not seeing. Whether the differences compromise the work you do, is up to you (full frame digital cameras only came out recently, so it can't be that bad).

I'm not sure of the Canon System, but i think an EF-S Lens (as far as I remember) is built specifically for the 1.6 sensor. It is then not a crop camera, or a crop of a larger image, you are getting 100% of what the lens is providing.

The same goes for my olympus. When using a 4/3 lens, I am getting 100% of the field of view that the lens provides. However when I use my OM-mount 50mm 1.8 I am only getting 50% of the image that the lens provides. However that 50% takes up 100% of my sensor, so it appears as though my field of view twice as far (which is the effective focal length multiplier).

With the 4/3 lenses on a 4/3 body, a 14mm lens may mean a 24mm focal length on a 35mm camera, however it is not a crop factor.

A 14mm lens on a 4/3 camera is a 14mm lens. However it provides the equivalent field of view as a 24mm lens on a 35mm camera.
Just the same as a 50mm lens on a full frame camera provides the same field of view as an 80mm on a medium format camera.

Sorry to keep harping on, or appear argumentative. I am just trying to correct a bit of public perception towards Olympus, which compares the Olympus system directly with Canon and Nikon or the 35mm system, when it would be like comparing 35mm cameras with medium format.
You can see that as a bad marketing point for Olympus, however you still have studio photographers shooting d3s or 5d mkIIs when they could afford medium format. It depends on what you want out of your camera.

You weigh up the pros and cons of each format (of which Epp B has outlined very well), then decide.

The benefit of the half frame format is it's size and portability, as well as it's ground-up design specifically tuned for digital sensors, hence the E-420 being the smallest and lightest DSLR on the market by far with the pancake f2.8.

Edit:
----------------------
Wikipedia article:
http://en.wikipedia.org/wiki/4/3_System
Some Dpreview comments:
http://forums.dpreview.com/forums/read.asp?forum=1018&message=10806051
About it being a new format:
http://www.4-3system.com/modules/newbb/viewtopic.php?post_id=682

The only thing I have read that I don't see data for is your insistence that sharpness is more important on lenses for smaller formats. As far as I can tell the sharpness should be dependent on the resolution of the sensor (relative to it's size) rather than the size of the sensor. Meaning a 1MP camera conforming to the 4/3 standard would require the same sharpness in the lens that a 4MP camera of the Full frame variety (or a 1.6MP camera of the 1.6 crop factor or a 1.8MP camera of the 1.5 crop factor) I could be wrong though.

 

[TBAM]

The only thing I have read that I don't see data for is your insistence that sharpness is more important on lenses for smaller formats. As far as I can tell the sharpness should be dependent on the resolution of the sensor (relative to it's size) rather than the size of the sensor. Meaning a 1MP camera conforming to the 4/3 standard would require the same sharpness in the lens that a 4MP camera of the Full frame variety (or a 1.6MP camera of the 1.6 crop factor or a 1.8MP camera of the 1.5 crop factor) I could be wrong though.

Sorry, I didn't mean for it to come across like that. The resolution of the sensor is obviously important.

What I meant, however is that you have a half frame sensor at 10mp, and then you have a full frame sensor at 10mp, or even a "crop" sensor at 10mp.

You're generally going to need sharper glass to get an image to be crisp and clean on a half frame sensor at 10mp than you would a full frame or crop sensor. Because in general terms, the pixels on a half frame sensor at 10mp are going to be half the size of the sensors on a full frame sensor at 10mp.

There are links in some of the sites I quoted above, which go into more detail about OM-mount lenses on a 4/3 camera. The main problem is that a lot of the images from old OM-mount lenses on a 4/3 body are very soft, because the sensor is half the size of a piece of film and a lot of the glass just isn't sharp enough to translate to the very small pixels of the sensor.

The benchmark tests in some of those links is a better and easier to understand example of why sharpness in the lenses on a half frame sensor is absolutely imperative. Some of the old OM-mount lenses are very expensive and used to be considered premium glass in it's day, however they still come out very soft on the 4/3 sensor.

I hope that made sense.

However, in saying that. Olympus 4/3 lenses are designed specifically for a digital sensor, as opposed to being based around film technology amalgamated for digital.

In saying all of this super-positive stuff for Olympus, hehe. The noise on the sensor at the moment is a bit problematic. My E-420 is absolutely shocking at ISO 1600 (it's limit) even when the exposure is close to perfect. The noise isn't even acceptable random noise, it's almost like lines across the image.

But, if you need low-noise that badly, then you save up for a d3, d700 or 5d mk II.

Anyways, as for the OPs original question:

Get a split prism focusing screen and a lens that isn't focus-by-wire and it should assist with most manual focus issues.

 

[monkeykoder]

One thing I would think would happen with the 4/3 system (just contemplation) would be decreased consistency with the lenses (smaller elements means with the same precision you would get greater error). Has this been in your experience or not? What it is the build quality like on the Olympus cameras?

 

[reg]

One thing I would think would happen with the 4/3 system (just contemplation) would be decreased consistency with the lenses (smaller elements means with the same precision you would get greater error). Has this been in your experience or not? What it is the build quality like on the Olympus cameras?

I don't think that would be an issue since the glass is machine-guided when it's made anyway, to very specific standards.

Optics in my experience:

My $310 (used) 14-54mm f/2.8-3.5 has the IQ of an L lens. It's waterproof. I expect my forthcoming 50-200mm to be of the same quality. Even the kit lenses were great quality, much better than what I've seen from any other brands' kit lenses.

I ain't never seen an Olympus lens I don't like. They're all 100% tack sharp wide open, even the f/2 zooms (although sadly that's not first hand use). I've never had a QC issue, whereas I have with Sigma.

My E-510 is built fairly well, ummm I really don't have a pro body to compare it to but it feels a lot nicer than a Rebel/D40. There's a nice rubber gripping and finish on the outside that looks and feels a lot better than the plastic crap. The E-3 is waterproof, I've seen people on YouTube literally stick their E-3 and lenses under the faucet for 10-15 seconds then fire off shots, so I assume it's fairly tight.

 

[TBAM]

The 14-42 and 40-150 lenses are both amazing and they are just part of the kit lens selection.

However in reviews and various media, Olympus/Zuiko glass has always been top of the line premium. It's why it's so expensive.

As for IQ consistency, I would think it not to be an issue. I mean, 35mm lenses aren't called inconsistent because they're manufactured smaller than MF lenses.

In addition to the lenses being purpose-built for the 4/3 digital sensor, everything is very precise.

I'm looking forward to the E-3 dropping in price or the E-30 coming out. I think the future is very bright for Olympus.

P.S.
Req, how much did your 14-54 f2.8-3.5 cost you and where did you get it from?
I think that lens is changing to a constant 2.8 aperture for the release of the E-30 soom, hopefully they should be had for a steal.

 

[reg]

P.S.
Req, how much did your 14-54 f2.8-3.5 cost you and where did you get it from?

It was used, on ebay, BuyItNow for $319. With 30% ebay live cashback (no longer available, it's like 8% now) it cost me $223!

FWIW though, Olympus released a 14-54mm 2.8-3.5 II for the E-30. No constant 2.8.

*snippet*
Developed as a successor to the ZUIKO DIGITAL 14-54mm 1:2.8-3.5 – a favourite with advanced amateur and professional users – the new ZUIKO DIGITAL 14-54mm 1:2.8–3.5 II boasts High-Speed Imager AF support to bring joy to creative photographers everywhere.
In combination with the brand new Olympus E-30 D-SLR, the new lens’ High-Speed Imager AF lets photographers preview the E-30’s new Art Filter effects in real-time with the convenience of a compact digital camera – thanks to Live View.
*snippet*

http://www.dpreview.com/news/0811/08110501oly_14_54mm_II.asp

I'm not all that thrilled with the E-30. If you dig the "art filters", you might like it, but their usefulness remains to be seen. For the price difference between it and the E-3, I'd just as quickly get the waterproofing to go with my lenses, and have the pro body.

 

[abraxas]

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.

I use manual focus almost exclusively for my landscapes and architectural shots so what you're saying makes a lot of sense to me. It doesn't take long to get used to it.

 

[Battou]

I use manual focus exclusivly when using an SLR body, I have too many issues with incorrect subject with AF to trust it for anything serious but that is just me. I'll spare yall the rest of my anti AF retoric.