New M43 lens: Noktor 50mm f/0.95, native M43

I don't understand why you are reducing the maximum apperture on these lenses. A 50mm f/1.2 on an m43 is equivalent to a 100mm f/1.2. The only time the max aperture decreases as you are showing is when a TC is involved. THat is not the case here - it's just a smaller portion of the image circle utilized. Apertures stay constant. Or am I off the wall?
 
Traut said:
I don't understand why you are reducing the maximum apperture on these lenses. A 50mm f/1.2 on an m43 is equivalent to a 100mm f/1.2. The only time the max aperture decreases as you are showing is when a TC is involved. THat is not the case here - it's just a smaller portion of the image circle utilized. Apertures stay constant. Or am I off the wall?
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The DOF is equivalent to x2 or f/2.4.

In other words, if you have a 50 f/1.2 lens on m43, it's going to perform the same as a 100 f/2.4 on full frame. It will still gather light like an f/1.2 though.

In order to get the equivalent to a 50 f/1.2 on m43, you'd need a 25mm f/0.6
 
Why don't we wait until we know if it is either a 50mm focal length or 46 degree field of view, before discussing DOF ? 🙂
 
I would have thought that the DOF is just the same, but there is just not as much of it - i.e. it is restricted in size - but I'm no expert
 
DRabbit said:
The DOF is equivalent to x2 or f/2.4.

In other words, if you have a 50 f/1.2 lens on m43, it's going to perform the same as a 100 f/2.4 on full frame. It will still gather light like an f/1.2 though.

In order to get the equivalent to a 50 f/1.2 on m43, you'd need a 25mm f/0.6
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Surely DOF is the same for the same focal length at the same aperture at the same focus distance, regardless of how much you crop the image? The FOV is different, of course.
 
Andy Kibber said:
Surely DOF is the same for the same focal length at the same aperture at the same focus distance, regardless of how much you crop the image? The FOV is different, of course.
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That is exactly what I thought. Only the FOV changes - not the max aperture or the depth of field.
 
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Traut said:
That is exactly what I thought. Only the FOV changes - not the max aperture or the depth of field.
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This is a persistent, totally incorrect myth. DoF has got to be one of the most poorly understood concepts in photography, probably because the optical calculations are relatively complicated and few people spend enough time with them to understand them properly.

Ctein describes DoF nicely here: http://tinyurl.com/nu3h3q This is the specific issue he discusses in that article: on-film or sensor magnification matters, focal length matters and circle of confusion matters. Look at the formulae and think about them.

Read carefully. Remember that if you use a smaller sensor you need to enlarge more so the magnification changes. That changes the depth of field. There is vast misinformation out there, related to the complexity of calculating exact depth of field and differences between DoF at macro/micro distances and in longer image distances.

Marty
 
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I just did a quick experiment with an online DOF calculator. It seems there is more DOF with larger sensors, all things being equal.

Nikon D90 with 50mm lens at f/5.6 focused at 10 ft. Total DOF: 2.76 ft.

Nikon D700 with 50mm lens at f/5.6 focused at 10 ft. Total DOF: 4.25 ft.

Good to know!
 
It's a trick question really. Assuming that the camera is left in exactly the same position, keeping the focal length and aperture the same will yield the same DOF on different sensor sizes. BUT - the composition will be wildly different, which is something often overlooked.

Taking it to extremes: Take a large-format camera, put a 200mm lens on it (what would this be btw? Normalish or wide-angle?) , take a photo of your grandmother in front of the Eiffel tower. Compose the shot so that the photo includes gramma and tower, all OK. Now change to your usual happysnapper camera, sensor size 1/1.7" or something similary fingernail-sized, keeping the tripod just where it is. Now mount the 200mm ultra-tele lens on the camera. Shoot.

Congrats, you have a photo of your grandmother's bellybutton, you can probably count the hairs on the navel-fluff. Probably not quite what we were looking for when changing sensor size, no? You have taken a very, very different photo than you started out with.

If you want to keep the Eiffel tower and grandmother both in the photo, you either have to A) Keep the camera stationary and mount a shorter lens (which will give larger depth of field for the same aperture), or B) Keep the lens mounted and move the camera backwards, quite a bit backwards in this case (which will give a greater depth of field) to keep the same composition (or as close as we can manage, obviously we won't match it 100%) as we started out with.

Hence: Smaller sensors mean larger depth of field for a given focal length and aperture compared to a larger sensor. For all practical purposes, that is; in other words, given that we want to maintain a similar composition to our photo.

If you are perfectly happy with chopping people's heads and feet off in your photos, this will not apply to you.
 
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Andy Kibber said:
I just did a quick experiment with an online DOF calculator. It seems there is more DOF with larger sensors, all things being equal.

Nikon D90 with 50mm lens at f/5.6 focused at 10 ft. Total DOF: 2.76 ft.

Nikon D700 with 50mm lens at f/5.6 focused at 10 ft. Total DOF: 4.25 ft.

Good to know!
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Two notes on "all things being equal":

1. You used the calculator at DOF Master. Note that it uses different circles of confusion for the two cameras. In other words: Your results aren't comparable anyway.

2. Do compare the fields of view as well:
Horizontal field of view on the D90: 26.5°
Horizontal field of view on the D700: 39.5°

So much for "all things being equal".

Now let's look for a lens which on the D700 gives us 26° field of view as well. After all we're usually interested in comparing teles to teles, and normal lenses to normal lenses, not 50s to 50s whose results look completely different on different cameras.

So here we are:
Nikon D700 with 75mm lens at f/5.6 focused at 10 ft. Total DOF: 1.81 ft.
That's the equivalent of your 50 on the D90. To get the same DOF, you have to open the lens on the D90 by a stop. This is exactly what everybody has been discussing in this thread. Note that that's already with the bigger circle of confusion for the D700. If you assume the same small circle of confusion in comparing both cameras, the result is even more pronounced.

So it's exactly the opposite as you presumed: Larger sensors give smaller DOF.

Take that with a grain of salt, DOF is a tricky matter.

Now I will go and take some pictures with my 90/f8 wideangle.
 
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rxmd said:
Two notes on "all things being equal":

1. You used the calculator at DOF Master. Note that it uses different circles of confusion for the two cameras. In other words: Your results aren't comparable anyway.

2. Do compare the fields of view as well:
Horizontal field of view on the D90: 26.5°
Horizontal field of view on the D700: 39.5°

So much for "all things being equal".
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I understood what I was doing with my little experiment. I understand that a cropped-sensor DSLR will have a narrower FOV than a full-frame DSLR with the same lens .

The point (which I was incorrect about earlier in the thread) is that the same lens at the same focal distance and aperture will yield a different amount of DOF depending on sensor or film size. I never realized that before and found it interesting.
 
Brian Sweeney said:
Yes- the C-Mount adapter for the 4/3rds should have plenty of clearance. This lens was used on a C-Mount camera before. The C-Mount adapter that came with the lens gives a good extension. It can be used for Canon Breech-Mount and for 39mm thread mount lenses.
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No, it will not work, the bayonet to c mount adapter is too big to fit into the needed recess of the C-mount to m4/3rds adapter. However, an M converted 0.95 will work fine with the M adapter.
 
They probably will sell quite a few of them. I think many people adopt the "sheep" approach. They buy things simply because others buy them without any thought as to how they plan to use them. This isn't limited to photography.
 
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