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Messages - Mantanuska

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16
EOS Bodies - For Stills / Re: 6D viewfinder too big ?
« on: April 24, 2013, 03:43:06 AM »
Take off your glasses and use the diopter, perhaps?

17


They are noisier because the entrance pupils of their smaller lenses are generally smaller than on the lenses that provide the same angle of view for larger sensor formats. There are physical limitations in making large entrance pupils for smaller focal lengths, as pupils bigger than f/0.5 are impossible even theoretically.

You still get more light from a smaller focal length (at the same pupil size) .  Thats why we describe the amount of light coming through the lens as a function of the focal length and pupil size, or in other words we use F-stop notation.

a 10mm aperture on an 18mm lens that gives a certain fov on APS-C lets in more light than a 10mm aperture on a  28mm lens that would produce the same fov on FF.

Thats why zoom lenses that aren't constant aperture get darker when you zoom in. The pupil isnt getting smaller, you just have less light entering the lens because you are constricting the FOV.

An F-stop is and F-stop regardless of format or focal length

18
Quote from: AdamJ

If you read the thread, you'll understand that my objective was to dispel the notion that f/1.8 on APS-C is in effect the same as f/2.8 on full frame. That notion is actually an unhelpful and circuitous way of saying that APS-C sensors are, because of their typically smaller pixels, usually noisier than full-frame sensors - simple as that.


^^ THIS

And that FAQ table. All that needs to be said.

19
Regardless of all this arguing over APS-C vs FF noise, fact of the matter is this lens is not only  capable of doing f1.8 at 18mm, but it looks pretty good wide open based on those sample images. 

f1.8 is still f1.8 don't muddy the waters by bringing sensors into the picture

20


Given that we have the same angle of view, the amount of light falling on the sensor is purely a function of the pupil diameter. f/2 on full frame is not the same as f/2 on crop.

Exposition
In case you're still not convinced, now assume that you have a FF and APSC sensor using the same production process & the same overall resolution -- they will have the same sensitivity per photon. If you take a shot with the same shutter speed, given that more light falls on the full frame sensor you would expect to use less sensor signal amplification [ie a lower ISO setting].



More light falls on the FF sensor but it is spread out over a bigger area. actual intensity (or in this case it helps to think about it as density) of the light is the same.

The only reason why you are able to use a higher ISO on FF is because the pixels are larger on FF which means better signal to noise.

21
The reason why using an f1.8 lens wide open on crop gives a brighter image than f2.8 on FF (when both are at the same ISO and shutter speed) is the amplification of the crop cameras sensor is 2.56x greater, at the expense of noise at any given ISO rating.

What? That's wrong.

A crop f/1.8 lens and a full frame f/1.8 lens will provide exactly the same exposure when used at the same shutter speed and ISO. The full frame exposure WILL NOT be brighter.

You're right about an FF f/2.8 lens having more light gathering ability than a crop f/1.8 lens, but all that light it gathers is spread over a larger sensor, which makes the exposure more than a full stop darker than if you had used an f/1.8 lens.

So in terms of exposure, a f/1.8 lens is brighter than an f/2.8 lens, regardless of sensor size. Sensor size does affect depth of field, but that's a different story.

Exactly. Try it for yourself on a crop body and FF. f1.8 at 1/30 sec at 100 ISO will give you the same exposure on both cameras. FF will not be brighter.

22
This is great for crop shooters.  However, before everyone gets excited over the f/1.8 bit, you have to remember that f/1.8 on a crop sensor is nothing like f/1.8 on a FF sensor.  This lens will give the same angle of view, image noise for given exposure parameters (*1), depth of field at a given AOV and subject distance (*2), etc. etc. etc. as a 28-50mm f/2.8 full frame lens.

In other words, if the lenses and sensors are perfect, this lens on a crop sensor would give identical results to a 28-50mm f/2.8 on a FF sensor. 

You mean identical DOF. f1.8 will still give more light on APS-C than f/2.8 on full frame.

23
Third Party Manufacturers / Re: The Blackmagic Production Camera 4K
« on: April 10, 2013, 12:35:11 AM »
Interesting, I always thought super 35 was full frame. Looks like its more like APS-C

24
EOS Bodies - For Stills / Re: Just bought a 6D
« on: April 08, 2013, 08:43:22 PM »
After my first reply I've thought some more about how I feel about high ISO with the 6D

In my opinion, the camera handles noise well enough that the issue with high ISO is no longer noise but dynamic range. I tend to shoot in a lot of difficult lighting situations with a lot of latitude in them, so its nice to have some malleability with my RAW files. The noise even at 12800 is not that bad for a lot of the things I shoot, but there is a dramatic loss of dynamic range at such high ISOs. 

25
Macro / Re: Reverse a lens for macro.
« on: April 08, 2013, 04:11:16 PM »
I've had good results using a 50mm reverse mounted to a set of extension tubes. DOF is razor thin at the distance that ends up being in focus, so a manual aperture lens is needed so you can stop down. Getting enough light when sufficiently stopped down is another problem, so having some sort of softbox/ reflector that directs flash to your subject is needed. since this is generally a couple inches from the front of the lens you will need to get creative.

DOF still tends to be a little thin, so focus stacking in photoshop is also needed in most situations, but the results are good.

here is one of the better shots I've taken with the same setup, except I don't have the right flash setup, so IQ isn't as good as it would have been with the right lighting.


White Lined Sphinx Hummingbird Moth 2 by Mantanuska, on Flickr

26
EOS Bodies - For Stills / Re: Just bought a 6D
« on: April 04, 2013, 05:19:00 PM »
The 6D not only has less noise as the same ISOs as the 7D but it also has less banding, so the noise that does show up isn't as ugly in my opinion. just mess with it and see what you think looks good... personally I just got back from a trip where I didn't use a tripod the whole time and I was doing plenty of night shots, and I am pretty happy with the results. Even 10,000 ISO is pretty clean, esp if you do a little cleaning up in LR

27
EOS Bodies / Re: Canon EOS 7D L Announced, Shipping in May
« on: April 01, 2013, 09:16:48 AM »
Ah, finally we know what the 7D Mark II will be like

28
Lenses / Re: 25mm EF Pancake
« on: February 23, 2013, 04:41:03 PM »
It would be pretty tough if not impossible to make a 25mm pancake lens on a camera system with a 44mm flange focal distance .

29
EOS Bodies - For Stills / Re: New MFA method
« on: February 04, 2013, 05:50:08 PM »
I dont know much about AFMA since I've never owned a body that has the feature, but after finding the acceptable range with AF confirmation wouldn't you want to set it to a value that is on the first 3rd of the lower end instead of the midpoint, since the focal plane extends 1/3 in front of the subject and 2/3 behind?

30
EOS Bodies / Re: Expected reception of the 7DII / 70D
« on: February 01, 2013, 04:21:55 AM »
Quote
Either way, that doesn't close the door on an EOS 70D though - when asked when we can expect one, Maeda promises: 'some day in the future. Without fail.'

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