Crop Factor, Low Light and Aperture with m4/3 lenses?

Started Jun 15, 2014 | Discussions
oneohone Forum Member • Posts: 77
Crop Factor, Low Light and Aperture with m4/3 lenses?

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or  1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

 oneohone's gear list:oneohone's gear list
Olympus OM-D E-M10 Olympus M.Zuiko Digital ED 14-42mm F3.5-5.6 EZ
Glen Barrington
Glen Barrington Forum Pro • Posts: 20,023
I found this video helpful
4
 Glen Barrington's gear list:Glen Barrington's gear list
Olympus OM-D E-M10 Olympus OM-D E-M10 II Olympus Zuiko Digital ED 9-18mm 1:4.0-5.6 Olympus Zuiko Digital ED 40-150mm 1:4.0-5.6 Olympus Zuiko Digital 14-54mm 1:2.8-3.5 +12 more
baxters Veteran Member • Posts: 5,157
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?
3

The crop factor is 2. That is why there is an Olympus 25mm f1.8 and a Panasonic 25mm f1.4. Both correspond to a 50mm lens on film.  For exposure, the aperture is unchanged by crop factor. Both of these lenses will act like your 50mm f1.7 lens for focal length and exposure.

Depth of field (DOF) calculations do require you to multiply the aperture by 2. So if you like to calculate  where a lens will start to go out of focus for blurred backgrounds, you will get less DOF in theory. In practice, you could show this in a lab. Out on the street, you could probably shoot someone with your 50 f1.7 on film or the 25mm f1.8 on an EM10 and both backgrounds will look the same because they are both far enough away.

The light sensitivity of digital cameras is far better than film. Any low light shooting you did with your 50mm f1.7 on film will be easily matched by the two above lenses on the EM10.

By the way, you can use your film lenses on the EM10.

 baxters's gear list:baxters's gear list
Panasonic Lumix DMC-GM1 Olympus Zuiko Digital ED 70-300mm 1:4.0-5.6
shutterbud Senior Member • Posts: 1,350
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?
1

The post above is correct. While not intuitive, the crop factor of two has been considered by the truly wonderful range of lenses available for the u4/3 mount. You could hardly ask for a better selection from such a young format. It all depends whether you prefer a thin DoF to your images. I've posted this picture before, but it is apposite to this discussion. This portrait was taken at f/1.4 on a GX1. You can see the OOF area starts just behind the mouth of the subject as I was at the limits of close focus for this lens. I will also try to find a decent bokeh image.

While this is almost a macro shot, the bokeh is instructive. Not unpleasant, but limited vs FF

Hope these examples help. The lens is the Panasonic/Leica 25/1.4 and the GX1 has an older sensor than the Oly, but the DoF and bokeh are representative.

Eric Nepean
Eric Nepean Veteran Member • Posts: 4,429
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

oneohone wrote:

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or 1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

The effective aperture (considering DoF) can sometimes help and sometimes hinder.

On the one hand, if the very narrow depth of field from a 50mm F1.7 lens is something you use a lot to separate your subject from your background, you will not get as much of that with M43 lenses.

On the other hand, if your style of photography doesn't demand narrow depth of field, and you use your 50mm F1.7 for its low light capabilities, then you will find that you get more depth of field for the same wide aperture in M43 - which you might consider a bonus.

For example, lets use the 50mm F1.7 35mm film lens focused at 15 feet as the basis for comparison, it will give you a depth of field of about 2.75 feet for 35mm film.

A 25mm F1.8 M43 (Olympus) lens focused at 15 feet would give you the same field of view, and allow you to use the same shutter speed and ISO, but give you a depth of field of 6.1 feet - and your background will be somewhat less blurred. Some people would like that, other would not.

But there are some alternatives:

The 25mm F1.4 M43 (panasonic) lens would give a depth of field of 4.75 feet, and allow a slightly faster shutter speed or lower ISO.

The Cosina Voigtländer Nokton 25mm f/0.95 M43 lens would give a depth of field of about 3 feet, and allow almost two stops faster shutter speed (but it won't have autofocus, nor auto exposure except in aperture priority mode)

Another choice would be to buy a Metabones speedbooster to adapt your 50mm lens to M43. This neat gadget (I think of it as an inverse teleconvertor) will reduce the focal length of your 50mm  to .71x, and increase aperture by stop - so your 50mm F1.7 will become a 35mm F1.2 lens, focused at 15 feet it will have a depth of field of 2 feet (but it won't have autofocus, nor auto exposure except in aperture priority mode)

-- hide signature --

Eric

Great Bustard Forum Pro • Posts: 43,017
Very simple:
1

oneohone wrote:

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or 1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

50mm f/2.8 on FF is equivalent to ~30mm f/1.8 on APS-C which is equivalent to 25mm f/1.4 on mFT.  By "equivalent to" I mean:

  • The same diagonal angle of view.
  • The same DOF for a given perspective (subject-camera distance) and same diffraction.
  • The same total amount of light falling on the sensor for a given shutter speed.

Any differences in noise will be due to differences in sensor efficiency (as opposed to differences in the ISO setting that is used to get the same brightness for a given shutter speed).

Keep in mind that the lower noise of larger formats (since, for a given exposure, as opposed to same DOF and shutter speed, more light falls on the larger sensor) necessarily results in a more shallow DOF, for better or worse.  So, unless low noise matters more to you than a deeper DOF, mFT will be a better choice than larger formats for handheld photography in low light.

0MitchAG Contributing Member • Posts: 538
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

 0MitchAG's gear list:0MitchAG's gear list
Panasonic Lumix DMC-G5 Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS Panasonic Lumix G Vario 14-42mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 45-150mm F4-5.6 ASPH Mega OIS Panasonic 20mm F1.7 II +6 more
TransientEye Forum Member • Posts: 70
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

As others have pointed out, you need to scale the focal length and aperture by the crop factor in other to maintain the same field-of-view and depth of field. The main limitation of u4/3 lenses is the small number of really really fast lenses - the best options being the new 42.5mm f1.2 or the excellent Voigtlander manual focus lenses.

Something else that is usually ignored is that the ISO noise also increases with the square of the crop factor. So notionally, a 16MP full-frame at ISO 800 has the same image noise as a 16MP u4/3 camera at ISO200 (assuming similar sensor tech - true if you are used to Nikon, less true if you are used to Canon...).

If you are interested as to why, I have a blog post (with diagrams...)  that tries to show how equivalence works.

Of course, real cameras have many more attributes that may matter more (like ergonomics, or Olympus' excellent image stabilisation).

-- hide signature --

Mark

Ulric Veteran Member • Posts: 4,558
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?
1

0MitchAG wrote:

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Not so. What Great Bustard wrote in the post above yours is correct: a picture taken with 50 mm on FF looks like a picture taken with 25 mm on m43 from the same spot.

Here are three pictures to illustrate the point, all taken on m43 but cropped to give 2x, 4x and 8x "crop factors" relative to FF. Apertures were also adjusted accordingly, so dof is very similar.

 Ulric's gear list:Ulric's gear list
Panasonic Lumix DMC-GF3 Olympus OM-D E-M5 Panasonic Lumix DMC-GM1 Olympus PEN-F Panasonic Lumix G 20mm F1.7 ASPH +13 more
eyeswideshut Regular Member • Posts: 333
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

If you come directly from a film SLR you will be amazed by the low light capabilities of probably all cameras on your short list. Differences between full format, APS and mft are hotly debated on internet forums such as this but in actual practice much of that is hardly field relevant.

When I switched from film to digital just about ten years ago I went from Canon / Pentax SLRs to the Olympus E-500, a four thirds DSLR. At the time crop factor et al. turned out to be the least of my worries since the switch from film to digital entailed so many other changes in terms of workflow, archiving, printing, post processing and on and on that you probably will be busy for a couple of years!

Good Luck.

oneohone wrote:

I am in the market for a DSLR/mirrorless camera and after initial research and trying various cameras the Olympus M10 has made my final shortlist. Now I have some experience shooting 35mm film and in my experience I often take my 50mm f1.7 lens which I enjoy a great deal and it s a good fit for the types of photography I do, candid street, a little landscape and also portraits.

Now I wonder, I have mostly shot film (not counting snapshots with my cellphone) and then crop-factor never enterted my mind. The M10 has a larger crop factor than the other cameras on my shortlist (1.5 or 1.6) how does that impact the choice of lenses? To get something similar to the 50mm focal length I would need a 24mm lens, but what about aperture? If I understand correctly (and maybe I don't) aperture is also influenced by crop factor, then how is it possible to get a f.2.8 lens or lower for the m10? And how does that further influence low light performance? I often take pictures in low light without flash or tripod and from my experience with the film camera I often use f.2.8 or lower.

I know the M10 is a good camera, and the m4/3 system is also really good, and obviously people are satisfied using this system, but I just need a little help understanding the problem with low light and lens selection for the m4/3 system.

-- hide signature --

Cheers
eyeswideshut

Fygaren Regular Member • Posts: 238
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?
5

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Perspective compression and distortion is ONLY dependant on distanse to subject.

Cheers

 Fygaren's gear list:Fygaren's gear list
Olympus OM-D E-M5 Olympus E-M1 II Olympus M.Zuiko Digital 45mm F1.8 Samyang 7.5mm F3.5 Fisheye Olympus M.Zuiko Digital ED 75mm F1.8 +3 more
0MitchAG Contributing Member • Posts: 538
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Fygaren wrote:

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Perspective compression and distortion is ONLY dependant on distance to subject.

Cheers

The photos Ulric provided are surely substantial to the discussion, but the effect I refer to is not apparent. So there, I am confused. Here is a (better?) demonstration of what I meant:

http://filmmakeriq.com/wp-content/uploads/2012/05/focal-length.gif

 0MitchAG's gear list:0MitchAG's gear list
Panasonic Lumix DMC-G5 Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS Panasonic Lumix G Vario 14-42mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 45-150mm F4-5.6 ASPH Mega OIS Panasonic 20mm F1.7 II +6 more
Fygaren Regular Member • Posts: 238
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Fygaren wrote:

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Perspective compression and distortion is ONLY dependant on distance to subject.

Cheers

The photos Ulric provided are surely substantial to the discussion, but the effect I refer to is not apparent. So there, I am confused. Here is a (better?) demonstration of what I meant:

http://filmmakeriq.com/wp-content/uploads/2012/05/focal-length.gif

The effect in the link is from different distanse to the subject.
If you would do the same using only one lens (cropping the picture as you move furter back to make it look like the subject is at the same distanse), the effect would be exactly the same using the same focal lenght on all pictures.

If focal lenght had anything to do with it, you would see fisheye effect on the tele end of compacts...

Cheers

 Fygaren's gear list:Fygaren's gear list
Olympus OM-D E-M5 Olympus E-M1 II Olympus M.Zuiko Digital 45mm F1.8 Samyang 7.5mm F3.5 Fisheye Olympus M.Zuiko Digital ED 75mm F1.8 +3 more
0MitchAG Contributing Member • Posts: 538
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Fygaren wrote:

Fygaren wrote:

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Perspective compression and distortion is ONLY dependant on distance to subject.

Cheers

The photos Ulric provided are surely substantial to the discussion, but the effect I refer to is not apparent. So there, I am confused. Here is a (better?) demonstration of what I meant:

http://filmmakeriq.com/wp-content/uploads/2012/05/focal-length.gif

The effect in the link is from different distanse to the subject.
If you would do the same using only one lens (cropping the picture as you move furter back to make it look like the subject is at the same distanse), the effect would be exactly the same using the same focal lenght on all pictures.

If focal lenght had anything to do with it, you would see fisheye effect on the tele end of compacts...

Cheers

Yes, cropping it will keep it the same but you lose resolution and detail. The pictures Ulric posted are at different focal lengths, the same as the link so I am not sure why the effect is not apparent. :? I'm just going by the exif data... are you saying that Ulric posted cropped photos rather than ones taken at different focal lengths, and different subject distances?

 0MitchAG's gear list:0MitchAG's gear list
Panasonic Lumix DMC-G5 Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS Panasonic Lumix G Vario 14-42mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 45-150mm F4-5.6 ASPH Mega OIS Panasonic 20mm F1.7 II +6 more
OP oneohone Forum Member • Posts: 77
Re: I found this video helpful

Thanks! I'll watch it when I have time!

 oneohone's gear list:oneohone's gear list
Olympus OM-D E-M10 Olympus M.Zuiko Digital ED 14-42mm F3.5-5.6 EZ
OP oneohone Forum Member • Posts: 77
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

I realize my understanding of the crop factor and aparture was somewhat wrong, like I suspected it might have been. The deeper DOF vs less subject isolation is in the end a neutral trade off for me. It's better for low light street, and slightly worse for bokeh.

 oneohone's gear list:oneohone's gear list
Olympus OM-D E-M10 Olympus M.Zuiko Digital ED 14-42mm F3.5-5.6 EZ
Fygaren Regular Member • Posts: 238
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Fygaren wrote:

Fygaren wrote:

Another thing that hasn't been mentioned is that only the FoV is cropped, perspective compression and distortion remain unchanged as they are dependant on focal length. For 50mm on FF, you still need a 50mm on m43, you will just have to be a bit further back. Or you can remain the same distance using a 25mm, but the photos are ultimately different.

Perspective compression and distortion is ONLY dependant on distance to subject.

Cheers

The photos Ulric provided are surely substantial to the discussion, but the effect I refer to is not apparent. So there, I am confused. Here is a (better?) demonstration of what I meant:

http://filmmakeriq.com/wp-content/uploads/2012/05/focal-length.gif

The effect in the link is from different distanse to the subject.
If you would do the same using only one lens (cropping the picture as you move furter back to make it look like the subject is at the same distanse), the effect would be exactly the same using the same focal lenght on all pictures.

If focal lenght had anything to do with it, you would see fisheye effect on the tele end of compacts...

Cheers

Yes, cropping it will keep it the same but you lose resolution and detail. The pictures Ulric posted are at different focal lengths, the same as the link so I am not sure why the effect is not apparent. :? I'm just going by the exif data... are you saying that Ulric posted cropped photos rather than ones taken at different focal lengths, and different subject distances?

Ulric took 3 photos with different focal lenght from the same distance. As he crops the wider ones he simulates a camera with a different crop factor and shows that the compression is exactly the same with different focal and crop factors. If he had changed his distance to the subject as he changed focal lenght, he would have the same effect as you showed in your link.
So changing the focal lenght does not change compression, but changing distance to subject does.

Cheers

 Fygaren's gear list:Fygaren's gear list
Olympus OM-D E-M5 Olympus E-M1 II Olympus M.Zuiko Digital 45mm F1.8 Samyang 7.5mm F3.5 Fisheye Olympus M.Zuiko Digital ED 75mm F1.8 +3 more
0MitchAG Contributing Member • Posts: 538
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?

Right, but I think in all practical situations, photographers do not crop their photos when using different focal lengths to achieve the same subject size. I was just confused between focal length and subject distance -- mind lapse on my part so thanks for clearing it up. It is important then to understand this when comparing FF->m43 focal lengths in practical situations related compression of foreground and background.

 0MitchAG's gear list:0MitchAG's gear list
Panasonic Lumix DMC-G5 Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS Panasonic Lumix G Vario 14-42mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 45-150mm F4-5.6 ASPH Mega OIS Panasonic 20mm F1.7 II +6 more
Fygaren Regular Member • Posts: 238
Re: Crop Factor, Low Light and Aperture with m4/3 lenses?
1

Right, but I think in all practical situations, photographers do not crop their photos when using different focal lengths to achieve the same subject size. I was just confused between focal length and subject distance -- mind lapse on my part so thanks for clearing it up. It is important then to understand this when comparing FF->m43 focal lengths in practical situations related compression of foreground and background.

The cropping here is only to simulate a different format sensor.

50mm crop 1, 25mm crop 2 and 12.5mm crop 4 will all have the same compression/ background and FOV when taken at the same distance to subject (no cropping on any of the photos).

50mm crop1 and 50mm crop2 without furter cropping of the photos will only be comparable if you move way back with the crop 2 camera so that the subject fills the frame in the same way. The compression/background will then show the same effect as showed in your link, as you have then changed your distance to the subject.

Cheers

 Fygaren's gear list:Fygaren's gear list
Olympus OM-D E-M5 Olympus E-M1 II Olympus M.Zuiko Digital 45mm F1.8 Samyang 7.5mm F3.5 Fisheye Olympus M.Zuiko Digital ED 75mm F1.8 +3 more
Franka T.L.
Franka T.L. Veteran Member • Posts: 8,148
Understanding the Basics and how digital are or are not exactly ..

Well nor exactly fellow thru with standards ... that is well we shall get to that later alright

Now FOA, there is no such thing as croo factor, that term is grossly misused by people who only want to think of measuring a lens coverage as per 35mm film ( still capture ) as somewhat a holy grail .. so they say you have 2.0 crop factor on 4/3 sensor, But wait that camera do not crop anything when they capture, its just having a different size sensor. Just as in old days when I put my Hasselblad Zeiss 80mm standard on my Nikon FM2, I do not say its getting a crop factor of so and so. I say its an 80mm lens and well that's the same for any digital DSLR or mirrorless. Lens focal length and aperture is a PHYSICAL property of the lens and it does not change whether you use it for film or digital, 35mmm or 4/3 .. the only time one can say crop factor perhaps ( somewhat ) is when one shoot on a digital platform and set for in camera JPEG that's not native to the sensor aspect ratio. Say you set the M4/3 camera to shoot 16:9 HD format JPEG, then the camera indeed is cropping from the top and bottom of the said sensor ( which is 3:4 aspect ratio sized ). I term these misleading issue " Equivalent Coverage " as that's what it is. So a 25mm lens for 4/3 is having a equivalent coverage as a 50mm lens on 35mm still film capture. Mind that there' some caveat .. when we say equivalent ( or when they talk crop factor ) its measured on the long axis length wide and the coverage measured in degrees of measurement ( go back to high school math ) But if you tally the Math you can tell the factor for equivalent 4/3 lens coverage when used in Portrait format is in fact more like 1.9 as the 4/3 sensor is of course 4:3 aspect ratio when 35mm film is 2:3

So for your said M4/3 prospective needs you are looking at a M4/3 body with a 25mm lens and there's several, Panny has a 1.4 and Oly has an 1.8 both are speedy enough I shall say. And the standard lens can easily be complemented by equally good fast long focal / short Tele Macro  like the Panny 45mm Macro / Oly 60mm Macro / Oly 45mm/1.8 or Zooms of various speed. Less choice on the wide end but they are there. And speaking of aperture, again they are physical to the lens and independent of the format of the said recording medium. So a said scene , being composed for exposure at ISO 100 needing f/4.0 at 1/125 shutter will still need that same exposure at ISO 100 when using your good old trusty Fujifilm Astia or whether you are using that new M4/3 set at ISO 100 ( effective, see below ) and no matter what kind of lens that might be.

One thing though, where we old film guys might need a new understanding is the speed of the medium , aka ISO setting for the film ( which is in build when we load the film ) and for these digital platform. Now here's a little fact that the Mfr probably do not really want to show around. The reality with almost all of todays digital platform is that they almost all cheat on the ISO setting . Not like film days when ISO had a rigid requirment for Film, Mfr to place a Ei / ISO setting on the film. The film must be able to reproduce that exposure set for a set light intensity to reproduce a set result to say it had that ISO. So when we load a ISO 1600 film we know we can safely use any measure to expose the film so long our exposure is based on calculating the medium to have an ISO 1600 sensitivity.

Well, no so for Digital platform. Their setting generally are over inflated. Say for the typical M4/3 camera, on a less than sunny day when we might want to use ISO 400 or ISO 800 so we can safely handheld and still use f/6.3 for that DOF. So we expose for that and WOW, that exposure just do not seems right .. because what , brasue almost all of the M4/3 bodies ( whichever model and brand ) had lablr their ISO in what they fashion as so. So ISO 400 on their camera is more like just having ISO 250 and ISO 800 is more like ISO 500 or even less. And this is also non linear Say if you take that same body and set the camera to ISO 3200, in most case you are only getting ISO 1200 and not 2000 ( as a linear rule would do ). So for anyone migrating from film to digital, there is a need to learn how the specific body ISO acually perform as ISO goes. The reason behind that is complex but mostly that had to do with the in camera JPEG which apply a tone mapping and the camera is usually configured to not to lost the highlight while boosting the shadow and then apply NR to made the exposure. Its not something magical, just the way it is. And for people who are more akin to shoot RAW or expose for control instead for in camera then one must realize this bit and work along it, and this is digital all of them, not just M4/3

So with old days and low light goes, most of us actually choose a fast lens not becasue of the speed but for the wide liberty to place exposure. And we trust our film to give that speed they labelled ( I swear on Ilford HP4 ) And we can do pretty much the same digitally, only for the fact that we need to work out our own effective ISO for the said body we choose. So if you have a particular setting for in camera JPEG you would want to test out to made sure that ISO 400 on that body is really how ISO 400 work for you, or might be you need to tune it up or down another notch or so. I shoot RAW, and do not particularly use Mfr's own processing and I've found DxO Mark's sensor review data of effective ISO pretty accurate ( as when I measure the exposure against my good old trusty calibrated light meter ).

There are other things to consider when switching from film to digital , but somehow we need to have a starting point right .. and getting the basic exposure right and in control is perhaps the first thing on the agenda ( other than actually going out and buying the gear in question )

-- hide signature --

- Franka -

Keyboard shortcuts:
FForum MMy threads