Work like this? Olympus crop factor!

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princeclan

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Matt
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Hi,

How does the 2x crop factor work olympus?

For example if i stood with my back to a wall and had a 300mm lens(300x1.5=450) on my samsung gx20 (1.5x crop factor) would i get exactly the same size pic if i stood there with an olympus with a 225mm lens(225x2=450) (if they made one)?

If thats the case then the panasonic g1 micro four thirds must be a good camera to have considering it has a good sized viewfinder (minus point in most olympus)

Matt
 
crop factor works as you said.

You get more dof though with the smaller sensor & the G1 has an electronic vf - DPreview said "While the user interface is equally well suited to photographers coming from SLRs and former compact users, the viewfinder is more of a double-edged affair. It's significantly larger than the optical viewfinders of other cropped sensor cameras and has a higher resolution than any other electronic viewfinder on a digital camera we've seen before. In good light it is therefore a very good substitute for an optical viewfinder but things become more difficult in dim conditions.

In very low light the viewfinder image gets so noisy, jerky and dark that it's almost impossible to use. Of course the electronic viewfinder does have some benefits, allowing the G1 to display considerably more information than any optical finder ever could, and to preview the effects of exposure settings, white balance and other parameters, and to magnify the preview for more precise manual focusing."

there are other issues with the G1 atm though like lack of lenses.
 
heidfirst said:
crop factor works as you said.

You get more dof though with the smaller sensor & the G1 has an electronic vf - DPreview said "While the user interface is equally well suited to photographers coming from SLRs and former compact users, the viewfinder is more of a double-edged affair. It's significantly larger than the optical viewfinders of other cropped sensor cameras and has a higher resolution than any other electronic viewfinder on a digital camera we've seen before. In good light it is therefore a very good substitute for an optical viewfinder but things become more difficult in dim conditions.

In very low light the viewfinder image gets so noisy, jerky and dark that it's almost impossible to use. Of course the electronic viewfinder does have some benefits, allowing the G1 to display considerably more information than any optical finder ever could, and to preview the effects of exposure settings, white balance and other parameters, and to magnify the preview for more precise manual focusing."

there are other issues with the G1 atm though like lack of lenses.
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Correct (y) Depth of field with 4/3rds format is two stops greater than full frame (Nikon/Canon crop is approx 1.25 stops).
 
Oops! Double post.
 
Just toying with the idea of geting one as i shoot daylight stuff mostly anyway (aircraft) and must admit my camera with the lens is very heavy for long periods

Matt
 
princeclan said:
Just toying with the idea of geting one as i shoot daylight stuff mostly anyway (aircraft)
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you'll struggle to find a lens atm for that purpose on that body with full AF & aperture control - should have stuck with Sony & got the 70-400 G SSM ;)
Any good lens with that kind of range is going to be heavy though & it's useful to have a body that counterbalances it.
 
Well the twin lens kit comes with 14-45 and 40-200 which equates to 28-90mm and 80-400mm which is awesome as far as im concerned.

Matt
 
but 400mm on Sony/Samsung APS-C is the equivalent of 600mm in 35mm terms.
My experience of aviation photography says that 400mm effective really isn't long enough - did you have a 70/75 - 300mm on your Sony or Samsung as that would be 450mm effective in 35mm terms?
 
I currently have a tamron 18-200 on my samsung. i find that long enough 90% of the time. the odd time i needed a bit longer. Just saying that causeof the crop factor the twin lens is a good deal as its effectively 28-400mm in just 2 lenses
 
princeclan said:
Well the twin lens kit comes with 14-45 and 40-200 which equates to 28-90mm and 80-400mm which is awesome as far as im concerned.

Matt
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You sure? The 2nd kit lens on oly is generally the 40-150?

the 50-200 is a different quality level (Off hand its around £900?) .

the 70-300 has a good rep and is around £300.
 
he's talking about a Panasonic body though - it comes with 14-45mm + 45-200mm.
 
Ahh, I see.

Shoddy thread title.
 
Seriously. Stop it. Sensor size DOES NOT CHANGE THE DEPTH OF FIELD. A 50mm lens at a given aperture produces a given depth of field NO MATTER HOW BIG OR SMALL THE SENSOR. Why does cropping an image increase the depth of field? It doesn't!

Let's look at some basic facts:
- A given focal length and aperture combination produces a given depth of field
- Wider apertures result in reduced depth of field at a given focal length
- Shorter focal lengths typically result in increased depth of field
- Angle of view from a particular focal length depends on the sensor size

What does this all mean? If you have a short lens and a small sensor at a given aperture, you get an image with a certain angle of view and a certain depth of field.
Now, you want to recreate the same angle of view on a bigger sensor. You now need a longer lens (think crop factor). Longer lens at the same aperture as before means LESS DEPTH OF FIELD.

In short, sensor size DOES NOT affect depth of field of a lens. It DOES affect angle of view. It also affect what lenses you use. Bigger sensor means you use longer lenses, hence reduced depth of field. A 50mm lens ALWAYS produces the same depth of field at a given aperture, no matter what sensor. You know why point and shoot cameras tend not to have shallow depths of field (even at wide apertures)? Because they have short short lenses to suit their tiny tiny sensors.

Simple.
 
mustanir said:
Seriously. Stop it. Sensor size DOES NOT CHANGE THE DEPTH OF FIELD.
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semantics depending on which way you approach it:
if you keep the lens constant & vary sensor then it doesn't affect dof but it does affect the image.
if you keep the image constant then to get the same image frame with a smaller sensor you require a shorter lens > shorter lens at same aperture=greater dof.
 
heidfirst said:
semantics depending on which way you approach it:
if you keep the lens constant & vary sensor then it doesn't affect dof but it does affect the image.
if you keep the image constant then to get the same image frame with a smaller sensor you require a shorter lens > shorter lens at same aperture=greater dof.
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^^^ (y)

Mustanir, I have got to agree with Heidfirst. You are playing semantics in a way that is incomplete, illogical and confusing. It is pointless talking about focal length and depth of field in isolation. You must also include sensor format, and of course focusing distance. (I prefer to talk about image magnification here, as it combines the twin effects of both focal length and focusing distance, and it avoids the common, and incorrect, assumption that telephotos inherantly deliver less depth of field, and wide-angles more DoF, when in isolation they do not, but that is by the way for now.)

In all these things the one thing that you cannot change on a camera is the sensor format, and so that is the fundamental that defines the angle of view and hence the focal length that you need to use. Smaller formats therefore do, fundamentally and inherantly, produce greater depth of field.
 
I know it's semantics but let's not abstract the actual causes of things. "You get more depth of field with a smaller sensor" and "you get more depth of field because you are using shorter lenses with your smaller sensor" effectively say the same thing, but without abstracting the reason for the observed effect. Call me pedantic.

As an aside, there are cameras where you can indeed change the format size without changing the lenses. When a photographer puts a 645 back on their 6x6 or a 6x9 back on their 5x4, they are not thinking "hey, I want more depth of field so let's use a smaller format back". The depth of field remains constant despite the change in format size.
 
mustanir said:
I know it's semantics but let's not abstract the actual causes of things. "You get more depth of field with a smaller sensor" and "you get more depth of field because you are using shorter lenses with your smaller sensor" effectively say the same thing, but without abstracting the reason for the observed effect. Call me pedantic.

As an aside, there are cameras where you can indeed change the format size without changing the lenses. When a photographer puts a 645 back on their 6x6 or a 6x9 back on their 5x4, they are not thinking "hey, I want more depth of field so let's use a smaller format back". The depth of field remains constant despite the change in format size.
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No, it does not. Changing the fomat changes everything. That's at the heart of it. But if you do not accept that (and I can see where you are coming from, I just think it's vital to put things in some kind of priority order) then it all gets very confusing ;)
 
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