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04-10-2013, 04:44 PM   #766
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QuoteOriginally posted by Uluru Quote
Yes, and light will change too, together with Earth's position on its orbit around the Sun.
So what is your point exactly? People don't use lenses as per your statement above; they use them same way as always, and complain about results. And switch systems.
The point is that, for any given image composition, your camera to subject distance would not be the same for FF and APS-c, hence the DOF comparison has to be done for the desired composition, not for a fixed distance.

Alternatively, you could maintain the same distance, but use a different FL in order to obtain the desired composition, so now you would be comparing DOF of different lenses.


Last edited by bxf; 04-10-2013 at 06:29 PM.
04-10-2013, 05:09 PM   #767
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QuoteOriginally posted by Uluru Quote
Yes, and light will change too, together with Earth's position on its orbit around the Sun.
So what is your point exactly? People don't use lenses as per your statement above; they use them same way as always, and complain about results. And switch systems.
I think you are missing bxf's point.

If you're using an FF camera to take a tight headshot, using an APS-C camera with the same focal length and subject distance will result in a picture of the person's nose.

Okay, that's an exaggeration, but the point is this -- you won't use the same lenses and the same subject distances. So the "APS-C actually has thinner DOF" is kind of a red herring. True, in an academic sense, but not in a practical setting.
04-10-2013, 05:09 PM   #768
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QuoteOriginally posted by Ash Quote
the more glass, the higher the cost.
Agree.

QuoteOriginally posted by Ash Quote
FA Ltds still cost more than the DA Ltds.
There's no great comparison like-to-like between FA Ltd's and DA Ltd's. Without thinking too much, a close example in equivalent focal lengths is the 21mm f/3.2 compared to the 31mm f/1.8.

The 31mm costs $400 more. The FA Ltd (as specified) lets in 7.6x as much light than the DA Ltd (as specified). So The FA costs more, yes, but at least *some* of that price difference (I argue more than 100%) is due to the 7.6x more light.

The 40mm f/2.8 vs the 77mm f/1.8 is about the same - the FA Ltd lets in 5.6x more light.

And of course there's 50%more margin for error in terms of CA, PF, resolution, etc., with the FA.

I believe that if you measured actual light throughput rather than specified light throughput, the differences wouldn't be so shocking. I also believe that if you designed a lens from the ground up for the K-mount, to produce exactly equivalent pictures in terms of DOF and SNR, the full-frame would be lighter, cheaper, smaller, and less expensive.
04-10-2013, 05:10 PM - 1 Like   #769
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at the end of the day it matters not what the system, lens, apreture, mega pixels, or fairy dust is in Canon, Nikon, Sony, Pentax, Olympus... blah blah blah, it matters on what works for the user, and if it meets his or her needs. Thats all.

all this armchair camera designing and arguing about proper terminoligy only gets you so far. Need to get out there and shoot, find what your limitations are as a shooter and see how you can overcome them. If you the only way you can overcome them is by upgrading to FF, then so be it. But don't sit here and armchair about how you need this because of this. Each system has their advantages and disadvantages, its up to you, the shooter, to adapt to overcome them.

Sigh...sometimes I wish we all still shot on K1000's

04-10-2013, 05:23 PM - 2 Likes   #770
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QuoteOriginally posted by ElJamoquio Quote
to produce exactly equivalent pictures i
But I think exactly this is the issue. Why would we need that? Why do we need to pretend that our APSC is actually FF? Why do we need to compare lenses in terms of "exact same output, but on different sized sensors/film" rather than instead of specific features and usages? And why would DoF be the one standard by which to compare lenses across mediums, instead of talking about rendering, colour reproduction, sharpness, light transmission, AF capabilities? We could just as well say that FF is useless because Pentax FA lenses have longer focus throw and therefore slower AF than DA lenses. Or we could try to find two different lenses with the exact same perceived sharpness on two different sensors, then declare one sensor as inferior.
04-10-2013, 06:15 PM   #771
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QuoteOriginally posted by Na Horuk Quote
But I think exactly this is the issue. Why would we need that? Why do we need to pretend that our APSC is actually FF? Why do we need to compare lenses in terms of "exact same output, but on different sized sensors/film" rather than instead of specific features and usages? And why would DoF be the one standard by which to compare lenses across mediums, instead of talking about rendering, colour reproduction, sharpness, light transmission, AF capabilities? We could just as well say that FF is useless because Pentax FA lenses have longer focus throw and therefore slower AF than DA lenses. Or we could try to find two different lenses with the exact same perceived sharpness on two different sensors, then declare one sensor as inferior.
Exactly. So much of this does not really center around photographs, it centers around concepts. But the question isn't really maximum high iso or dynamic range as measure by dxo or even how narrow a depth of field you can get with a 20mm lens. The question really is can you take the photos that you imagine with the camera and lenses that you own, or someday hope to own. And so, if I go out shooting with my K5 and a couple of lenses (say DA *55 and DA 15 limited), I know what they can do, where their strengths are and I look for light and subjects that I can capture with them.

Honestly, I haven't met a full frame lens that has the capabilities of the DA 15, with its resistance to flare, amazing colors. Maybe the FA 31 would be close in some respects, but certainly it flares a lot more than the DA 15. But I digress. In the end, it is the image, not the format that makes the difference. I wouldn't mind seeing Pentax come out with a full frame camera, but I know it will cost me quite a bit. Figuring 2500 dollars for the camera body and then 2000 for a 80-200 f2.8 zoom and 1500 dollars for a 24-70 f2.8 zoom, that's a lot of money for a small improvement in image quality -- and a stop less depth of field.
04-10-2013, 07:40 PM - 1 Like   #772
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Me too. But with a sensor.

QuoteOriginally posted by Wired Quote
...

Sigh...sometimes I wish we all still shot on K1000's
Which are FF.

.
04-10-2013, 07:53 PM   #773
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Paging Bob Atkins...

QuoteOriginally posted by Uluru Quote
Gosh,
I'm not sure what people are talking about here? You are turning things upside down.
Using the same focal length(*) and the same aperture, and a subject at the same distance, an APS-C camera will produce a thinner DoF than an FF camera....
.

You're describing completely different images, though, with different field of view.

What folks typically do when they move between formats and still want to shoot the same types of things is change the focal lengths used. If you don't do that, your images change radically and become something you don't want. Probably the most typical example is 'normal' - on FF, you shoot a fast-50, on aps-c, you shoot a (hopefully) fast 35. (or, you simply adjust your zoom FL to fit the subject.) Those are very 'workhorse' focal lengths, especially for indoor shooting.

And what you'll find is that although the FOV is the same between the two (50 on FF vs 35 on aps-c) the DOF is not, when using the same apertures. 50mm f/2.8 (FF) = 35mm f/1.8 (aps-c,) for example.

Anyone reading this who hasn't checked out of the discussion should cut/paste and save the bullet points from Bob Atkins below - these can be considered the Cliff's Notes for DOF-format discussion:

• For an equivalent field of view, an APS-C crop sensor camera has at least 1.5x MORE depth of field that a 35mm full frame camera would have - when the focus distance is significantly less then the hyperfocal distance (but the 35mm format needs a lens with 1.5x the focal length to give the same view).

• Using the same lens on a APS-C crop sensor camera and a 35mm full frame body, the APS-C crop sensor camera image has 1.5x LESS depth of field than the 35mm image would have (but they would be different images of course since the field of view would be different)

• If you use the same lens on an APS-C crop sensor camera and a 35mm full frame body and crop the full frame 35mm image to give the same view as the APS-C crop image, the depth of field is IDENTICAL

• If you use the same lens on an APS-C crop sensor camera and a 35mm full frame body, then shoot from different distances so that the view is the same, the APS-C crop sensor camera image will have 1.5x MORE DOF then the full frame image.

• Close to the hyperfocal distance, the APS-C crop sensor camera has a much more than 1.5x the DOF of a 35mm full frame camera. The hyperfocal distance of an APS-C crop sensor camera is 1.5x less than that of a 35mm full frame camera when used with a lens giving the same field of view.


.

04-10-2013, 07:56 PM   #774
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QuoteOriginally posted by Wired Quote
Sigh...sometimes I wish we all still shot on K1000's
I still have my K1000 SE (with split screen).. I love that camera, but don't use anymore.
04-10-2013, 08:08 PM   #775
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QuoteOriginally posted by Na Horuk Quote
.. And why would DoF be the one standard by which to compare lenses across mediums, instead of talking about rendering, colour reproduction, sharpness, light transmission, AF capabilities?.
Because rendering, colour reproduction, sharpness, light transmission don't change when you move the lens between formats - FOV/DOF does. It's important to know how it changes, because it could affect your photography and help you decide whether or not you even want to bother with another format.

For example, some landscape or macro shooters might dislike the effect and it might make things harder for them - but some portrait, candid or street shooters might really like it.

.

Last edited by jsherman999; 04-10-2013 at 08:25 PM.
04-10-2013, 08:14 PM   #776
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QuoteOriginally posted by Rondec Quote
...Figuring 2500 dollars for the camera body and then 2000 for a 80-200 f2.8 zoom and 1500 dollars for a 24-70 f2.8 zoom, that's a lot of money for a small improvement in image quality -- and a stop less depth of field.
Tamron 28-75 f/2.8, $280 used, and pretty small!



.

Don't let them sucker you into the 'gotta buy the biggest and most expensive glass' camp. Those zooms are nice, but not necessary. (Nikon/Canon would love it if everyone thought they were necessary, though.)

.
04-10-2013, 08:23 PM   #777
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QuoteOriginally posted by Rondec Quote
Honestly, I haven't met a full frame lens that has the capabilities of the DA 15, with its resistance to flare, amazing colors. .
Me either.

The Zeiss 21 (on FF) rules the class, but it's expensive and MF. The Nikon 14-24 is more versatile in a way and faster, probably sharper, but doesn't do as well with flare and is honkin' big with a huge bulb of a front element, and is very costly. For me personally it's not a fun lens to shoot.

15 still wins in size + IQ + price combo. Now, if Pentax intends to stay aps-c-only, we need to see more like that.



.

Last edited by jsherman999; 04-10-2013 at 08:29 PM.
04-10-2013, 09:03 PM   #778
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QuoteOriginally posted by jsherman999 Quote
Me either.

The Zeiss 21 (on FF) rules the class, but it's expensive and MF. The Nikon 14-24 is more versatile in a way and faster, probably sharper, but doesn't do as well with flare and is honkin' big with a huge bulb of a front element, and is very costly. For me personally it's not a fun lens to shoot.

15 still wins in size + IQ + price combo. Now, if Pentax intends to stay aps-c-only, we need to see more like that.



.
I don't think the Nikon is sharper than the Zeiss. My Zeiss 21mm is sharp at f/2.8 and is clean into the corners on my D800E. It does start to suffer badly from diffraction from f/12 onwards though and is almost unusable at those apertures for me.
04-10-2013, 09:12 PM   #779
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QuoteOriginally posted by Na Horuk Quote
But I think exactly this is the issue. Why would we need that?
You don't.

QuoteOriginally posted by Na Horuk Quote
Why do we need to pretend that our APSC is actually FF?
You don't.

QuoteQuote:
Why do we need to compare lenses in terms of "exact same output, but on different sized sensors/film" rather than instead of specific features and usages? And why would DoF be the one standard by which to compare lenses across mediums, instead of talking about rendering, colour reproduction, sharpness, light transmission, AF capabilities? We could just as well say that FF is useless because Pentax FA lenses have longer focus throw and therefore slower AF than DA lenses. Or we could try to find two different lenses with the exact same perceived sharpness on two different sensors, then declare one sensor as inferior.
I've talked about sharpness, light transmission, AF, etc, in other threads. It's really started to bore me, I waste too much time correcting claims in this manner. People still throw out generic claims like 'APS-C lenses are smaller, lighter, faster, cheaper' when in fact the opposite is true for many purposes that DSLR users have... especially enthusiast DSLR users.

When we start talking hypotheticals, like a Pentax FF, it's kinda silly to assume the rest has to be hard-grounded (To me, things like 'rendering' only start making sense when you're comparing two 'real' systems rather than two 'possible' systems)

FYI if you did conduct your 'two different lenses' on two sensors comparing only perceived sharpness, it would be difficult IMO to find a lens on FF that was bad enough to make the same perceived sharpness as a APS-C lens. It's not impossible, but you'd have to do what would be, in my mind, a silly comparison - a $20 FF lens vs a $1k APS-C lens. It's also not correct to say without qualification that Pentax FA lenses have worse AF than DA lenses - are you comparing a 1.8 lens to a 2.8 lens? In what light?

I'm all for people deciding the for themselves what is best... however the information available to them on forums seems to have more bad data than good data.
04-10-2013, 09:21 PM   #780
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QuoteOriginally posted by bossa Quote
I don't think the Nikon is sharper than the Zeiss. .
I was saying the 14-24 is probably sharper than the DA 15, not the Zeiss. I was comparing them both to the 15.

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