December 19, 2014, 11:08:30 PM

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Messages - AlanF

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136
I'm sure this thread is full of bad information all around, and I'm not even going to read the previous posts.

What can one say to that?

137
That might be true in a testing scenario, but few of us shoot in those. Factor in AF, handholding, higher than base iso, less than ideal aperture or shutter speed etc etc etc and the differences become minimal, as so many people who have owned both have attested to.

That doesn't mean there is no point to a 7D, 70D 7D MkII, as a compliment to a 6D etc one might work very well, but the resolution thing really is a red herring unless you are using a heavy tripod, 10X live view manual focus blah blah.........


What the estimates tell you is that even if you have a heavy tripod, base iso etc you will gain only a small increase in reach, and not 60%.

edited for asking my question within the quote - sorry

Reach or resolution?

In the following context they are the same: if you can achieve 1.6x greater resolution with the crop, a subject 1.6x further away will have the same apparent resolution as for the FF and so you have 1.6x the reach.

138
I did the same calculations for the Nikon D800 and D7000. You would expect them to have virtually identical resolving powers since their pixel sizes are 4.88 and 4.78 ┬ÁM, respectively. And that is what I calculated, giving some credence to the calculations I did for the Canons.

MTFcrop/MTFff with identical lenses is close to 0.63 for all lenses (on the dpr widget), compared with 0.66 expected from the relative pixel heights of both sensors. The relative resolving power of the crop, given the 1.5x less field of view is:

R = 0.945   (compared with R= 1.02, calculated from the ratio of pixel sizes).

The 36.6 mpx ff beats out the 16 mp crop since, when cropped it is at least as good as the crop sensor and has all the advantages of FF when not cropped.

139
That might be true in a testing scenario, but few of us shoot in those. Factor in AF, handholding, higher than base iso, less than ideal aperture or shutter speed etc etc etc and the differences become minimal, as so many people who have owned both have attested to.

That doesn't mean there is no point to a 7D, 70D 7D MkII, as a compliment to a 6D etc one might work very well, but the resolution thing really is a red herring unless you are using a heavy tripod, 10X live view manual focus blah blah.........

What the estimates tell you is that even if you have a heavy tripod, base iso etc you will gain only a small increase in reach, and not 60%.

140
Here is a way of calculating the effective extra reach or resolving power of a crop body versus FF, which will amuse the geeks among us.

Measure the MTF of a lens on the crop (= MTFcrop) and the same lens on the FF (= MTFff). The ratio of the MTFs, MTFcrop/MTFff, gives the relative resolving power of the bodies with that lens. However, the crop body can be placed 1.6x further away to give the same field of view. Therefore, the true effective relative resolving power, R, is given by:

R = 1.6x MTFcrop/MTFff.

Photozone lists measured MTFs for a set of lenses on the 5DII and 50D. I calculated their ratios for the Canon 200mm f/2.8 II, 85mm f/1.2 II and 35mm f/2 at wide apertures below the DLA. MTFcrop/MTFff is very close to 0.726 in all cases.

This gives R for 50D/5DII = 1.16.

So the effective extra reach is 16%.  (Based on the ratio of their pixel sizes, a value of 36% is expected.

The dpreview widget gives values for the 5DIII and 7D only for a few lenses. I did the same calculations with the Tamron 150-600mm (between 150-400mm), the Canon 200-400mm and the Sigma 50mm f/1.4 A at wider apertures below the DLA. In all cases, MTFcrop/MTFff is close to 0.742.

This gives R for 7D/5DIII = 1.19.

So, the effective extra reach is 19%. (Based on the ratio of their pixel sizes, a value of 45% is expected).

There are always arguments about using MTFs quantitatively, but I think in this particular calculation it is reasonably valid to use them. It fits in reasonably well with experience - Jon has shown there is better resolving power in photos of the moon with the 7D, but it doesn't look 45% better. And my own experience is that the 7D and 70D aren't much better than the 5DIII, certainly not 1.6x.

141
The 300mm f/2.8 II is my favourite lens and I preferentially use it on birding trips at home. But, the Tamron 150-600mm is good enough and is just so convenient for travel when I have to fly for a holiday. But, if I were to go on a specialist birding trip abroad or go on safari again I would take the 300 + extenders on the 5DIII and the 70-200 f/4 IS + 70D.

142
EOS Bodies / Re: Are you planning to purchase a 7D2
« on: August 27, 2014, 12:11:50 PM »
My back up 70D is a moderate improvement in IQ and a significant improvement in AF over the my former 7D. If there is a more than expected improvement in its sensor, I'll sell the 70D for the 7DII. But, it will have to compete against the 5DIII, which is just so good.

143

Is the 1-stop improvement in JPEG or RAW?

Raw

I ask questions in order to learn. Having been stimulated by your comments to look at a series of careful reviews, I see that up to iso 3200 there is little difference in practice between the 1D X and 5DIII noise, then the 1 DX begins to pull away, as you intimate. As I am interested in very fine details in plumage etc, I tend to shoot at 640 and max out at 1600 so the difference doesn't really affect me but I can see where it would help some others. Thanks for your help as I have never handled a 1D X and have to rely on others for advice.

144

1Dx is at least 1 stop better for noise compared to 5D3.

Is that true - DxO rates the 1DX only 0.28 stops better (http://www.dxomark.com/Cameras/Compare/Side-by-side/Canon-EOS-5D-Mark-III-versus-Canon-EOS-1Dx___795_753 )? And Ken, bless his heart, Rockwell, rates both very similar ( http://www.kenrockwell.com/canon/comparisons/5d-mkiii-vs-1dx.htm#iso  )? Perhaps someone who has both could enlighten.

I think Ken Rockwell says the 1D X is half a stop better than the 5D III, although someone with both cameras like FEBS might know better.

He doesn't say that the 1DX is half a stop better, he says that Canon is cheating by having the real iso on the 1DX half a stop lower than the reading it is set at, relative to the 5DIII, so you think it is half a stop higher than it really is.

"Consumer warning

My 5D Mark III is about a half-stop faster at any given ISO setting than my 1D X.

In other words, at any given ISO, my 5D Mark III gives the same image with a half-stop less exposure. In other other words, my 5D Mark III actually runs at a half-stop higher ISO than marked, or my 1D X is actually running a half-stop slower than marked, or somewhere in between.

It's common for camera makers to cheat a little here, since Canon needs to make the 1D X look like it has better high ISO performance than the 5D Mark III. In this case, it's stacked the deck a little, since when anyone compares at the same indicated ISOs, the 1D X appear to have a half-stop advantage since it's really only operating at a half-stop less ISO than the 5D Mark III at any given ISO. When comparing images, you won't notice unless you shoot at the same manual exposure, in which case my 1D X is a little darker than my 5D Mark III, or if you get both to match, you'll notice that your 5D Mark III only needed about a half-stop less exposure."

Alan,

The best way to find out if the ISO on a 1dx is much better then on the 5d3 is by using them both. Just as camera makers cheat, it's the same for reviewers who try to explain differences based on poor test and reading manuals but not by using them extensively next to each other.

I read in the mentioned reviews for instance that the AF system of both cameras would be astoundingly the same with the exception of itr. So we forget that the spread of the af points of those 2 cameras is totally different? We forget that the battery voltage of those 2 cameras is different? The itr would be the only difference? But itr only works in af group or af 61 point mode. So even comparing this to the modern systems of nikon would be the same? The same when nikon can only automatically ( no switch off possibility) apply this to all focus point mode.

I'm not the only one on CR that finds the high ISO on the 1dx at least a stop better then the 5d3. I use max 6400 auto ISO on the 5d3, but on the 1dx it's 25600. That's the practical experience I have with both cameras. It's not that I want to say that the 1dx is a much better camera compared to the 5d3. I even use the 5d3 more then the 1dx. I know which camera I take when I want to do a shoot. That's always dependent on the object and my knowledge of the differences of those cameras. But high ISO and superior AF is a big advantage of the 1dx compared to the 5d3. No reviewer can convince me that those to cameras would be the same for this 2 issues. But that's all practical experience with both cameras for using them after a longer period.

Francois
Is the 1-stop improvement in JPEG or RAW?

145

1Dx is at least 1 stop better for noise compared to 5D3.

Is that true - DxO rates the 1DX only 0.28 stops better (http://www.dxomark.com/Cameras/Compare/Side-by-side/Canon-EOS-5D-Mark-III-versus-Canon-EOS-1Dx___795_753 )? And Ken, bless his heart, Rockwell, rates both very similar ( http://www.kenrockwell.com/canon/comparisons/5d-mkiii-vs-1dx.htm#iso  )? Perhaps someone who has both could enlighten.

I think Ken Rockwell says the 1D X is half a stop better than the 5D III, although someone with both cameras like FEBS might know better.

He doesn't say that the 1DX is half a stop better, he says that Canon is cheating by having the real iso on the 1DX half a stop lower than the reading it is set at, relative to the 5DIII, so you think it is half a stop higher than it really is.

"Consumer warning

My 5D Mark III is about a half-stop faster at any given ISO setting than my 1D X.

In other words, at any given ISO, my 5D Mark III gives the same image with a half-stop less exposure. In other other words, my 5D Mark III actually runs at a half-stop higher ISO than marked, or my 1D X is actually running a half-stop slower than marked, or somewhere in between.

It's common for camera makers to cheat a little here, since Canon needs to make the 1D X look like it has better high ISO performance than the 5D Mark III. In this case, it's stacked the deck a little, since when anyone compares at the same indicated ISOs, the 1D X appear to have a half-stop advantage since it's really only operating at a half-stop less ISO than the 5D Mark III at any given ISO. When comparing images, you won't notice unless you shoot at the same manual exposure, in which case my 1D X is a little darker than my 5D Mark III, or if you get both to match, you'll notice that your 5D Mark III only needed about a half-stop less exposure."

146
Lenses / Re: DxO and DPReview Getting Lazy?
« on: August 26, 2014, 03:45:43 PM »
You have lost me - not only are the graphs clearly different, the Sigma is on a 5DIII and the Canon on a 5DII!?

147

1Dx is at least 1 stop better for noise compared to 5D3.

Is that true - DxO rates the 1DX only 0.28 stops better (http://www.dxomark.com/Cameras/Compare/Side-by-side/Canon-EOS-5D-Mark-III-versus-Canon-EOS-1Dx___795_753 )? And Ken, bless his heart, Rockwell, rates both very similar ( http://www.kenrockwell.com/canon/comparisons/5d-mkiii-vs-1dx.htm#iso  )? Perhaps someone who has both could enlighten.

148
Canon General / Re: Lens Cleaning Techniques/Opinions
« on: August 23, 2014, 07:24:17 PM »
Yes Mitch I was just kidding, thought I would join in the humour!

Cheers, Graham.

No sense in wasting whiskey.  I should probably really clean my lenses that way to give me a fantastic excuse to drink a bit every so often.  Lol.

And I do hope you're kidding about following my directions.
Those of us who have a sense of humour get misunderstood by those with a sense of humor, especially as we drink whisky and they drink whiskey.

149
Great shot!

150
I had my first outing with the 300/28 II + 2XTCIII  this afternoon since coming back from Canada on Tuesday where I was using the Tamron 150-600mm. The Canon feels a bit heavier! Here are two mugshots of an Egyptian goose. Why can't I see those fantastic bee eaters or have a bird of prey come and sit next to me?

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