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Author Topic: I still don't get the crop debate  (Read 10104 times)

woollybear

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Re: I still don't get the crop debate
« Reply #45 on: April 12, 2012, 08:48:06 AM »
Quote
'm not a physicist but would it not be possible to produce a car that would operate in more than one car length mode? I don't mean glue 2 cars together, I mean car length -- for example, operate the car at 3m length with all the parking advantages thereunto appertaining, and also at 5m length to advantage the situations that the big cars depend on -- with a lot of space you get more people in when you don't need to fit into a small parking spot, AND you can size down to 3m for more "squeeze" and still have a 5m car that no other natively-small car would be able to rival.

And I don't need the big motor or transmission or lights thing.  I only operate at one speed and never turn or reverse.  And with a properly sized car who needs headlights at night.  If the car is designed right you should be able to see fine without them.  All those extra features are expensive and are for lazy people who don't really know how to drive anyway.


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Re: I still don't get the crop debate
« Reply #45 on: April 12, 2012, 08:48:06 AM »

neuroanatomist

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Re: I still don't get the crop debate
« Reply #46 on: April 12, 2012, 08:59:55 AM »
In a related note, I must've missed the white paper on AF-S lenses and why Canon bothered with making the short back focus things at all. I don't see any technical advantage; you get more incident angle of light on the sensor corners resulting in a bit more falloff (w-o adjusting microlenses on the sensor) and it's only slightly less likely to image dust sitting on the AA filter than the longer back focus distance from an EF lens.  Would make more sense to leave the same back focus distance as an EF lens and just position the AA filter a little farther from the sensor to reduce dust imaging. Then microlens positioning would also not have to be a compromise if all lenses used similar back focus distance... ignoring rear group focusing changing that anyway.  Can anyone enlighten me on this aspect of the design decision?  was it just to prevent the N-crowd from adapting Canon glass to their bodies w-o requiring an in-between optic?

You seem to be mixing up to different concepts.  The reason you can adapt Canon to Nikon and not Nikon to Canon has nothing to do with EF vs. EF-S lenses, it's the flange to focal plane distance - that applies all Canon EF lenses.  Lenses designed for a longer flange to focal length distance than the body cam be adapted without optics or losing infinity focus.  For the lenses with a shorter back focus (where the rear elements protrude past the mount, into the body) that makes the distance shorter not longer. 

The EF-S lenses are designed as such for several reasons.  FWIW, according to Canon the -S in EF-S stands for small image circle, not short back focus (yes, I know you read different on Wikipedia, but Wikipedia is wrong).   That smaller image circle means less glass is required, meaning lens can be produced more cheaply.  Also, it makes designing wide and ultrawide lenses much easier.  For example, compare the distortion you get on the 16-35L @ 16mm on FF vs. the EF-S 10-22mm @10mm on APS-C - same AoV, but the EF lens has massive barrel distortion, while the EF-S lens has relatively little. 
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V8Beast

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Re: I still don't get the crop debate
« Reply #47 on: April 12, 2012, 01:25:30 PM »
There appears to be a market need for a high performance crop body;  what I don't get is how (or if) Canon will fill that need if they are abandoning the 1.3.  It seems unlikely to me that we would see a 1.6x body as a worthy successor to the mighty 1D4, but if thats what Canon produces I doubt it will  have a 7 in the name. Canon's next move (or lack of one) in the performance crop body arena will be as newsworthy as the 5D3

I'd have to agree. There are a ton of sports shooters and photo journalists that have used APS-H bodies for years. Now that Canon is going to abandon that sensor, the only suitable body for them is the 1Dx. While the 1Dx is an impressive machine, if I were an APS-H shooter, I wouldn't be too thrilled about paying $6,800 for a full-frame body when I'm accustomed to paying $4,500-$5,000 for a 1.3x body.

That said, sports shooters spend loads of money on gear, so maybe that extra $1,800 isn't a big deal to them.

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Re: I still don't get the crop debate
« Reply #48 on: April 12, 2012, 01:41:23 PM »
There appears to be a market need for a high performance crop body;  what I don't get is how (or if) Canon will fill that need if they are abandoning the 1.3.  It seems unlikely to me that we would see a 1.6x body as a worthy successor to the mighty 1D4, but if thats what Canon produces I doubt it will  have a 7 in the name. Canon's next move (or lack of one) in the performance crop body arena will be as newsworthy as the 5D3

I'd have to agree. There are a ton of sports shooters and photo journalists that have used APS-H bodies for years. Now that Canon is going to abandon that sensor, the only suitable body for them is the 1Dx. While the 1Dx is an impressive machine, if I were an APS-H shooter, I wouldn't be too thrilled about paying $6,800 for a full-frame body when I'm accustomed to paying $4,500-$5,000 for a 1.3x body.

That said, sports shooters spend loads of money on gear, so maybe that extra $1,800 isn't a big deal to them.

$1800 may not be a big deal for the unless it was already earmarked for a kilobuck lense upgrade needed for the lost reach...  ;D
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Leon

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Re: I still don't get the crop debate
« Reply #49 on: April 12, 2012, 01:50:55 PM »
Quote
'm not a physicist but would it not be possible to produce a car that would operate in more than one car length mode? I don't mean glue 2 cars together, I mean car length -- for example, operate the car at 3m length with all the parking advantages thereunto appertaining, and also at 5m length to advantage the situations that the big cars depend on -- with a lot of space you get more people in when you don't need to fit into a small parking spot, AND you can size down to 3m for more "squeeze" and still have a 5m car that no other natively-small car would be able to rival.

And I don't need the big motor or transmission or lights thing.  I only operate at one speed and never turn or reverse.  And with a properly sized car who needs headlights at night.  If the car is designed right you should be able to see fine without them.  All those extra features are expensive and are for lazy people who don't really know how to drive anyway.

What's your point?

Aglet

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Re: I still don't get the crop debate
« Reply #50 on: April 12, 2012, 03:17:17 PM »
In a related note, I must've missed the white paper on AF-S lenses and why Canon bothered with making the short back focus things at all. I don't see any technical advantage; you get more incident angle of light on the sensor corners resulting in a bit more falloff (w-o adjusting microlenses on the sensor) and it's only slightly less likely to image dust sitting on the AA filter than the longer back focus distance from an EF lens.  Would make more sense to leave the same back focus distance as an EF lens and just position the AA filter a little farther from the sensor to reduce dust imaging. Then microlens positioning would also not have to be a compromise if all lenses used similar back focus distance... ignoring rear group focusing changing that anyway.  Can anyone enlighten me on this aspect of the design decision?  was it just to prevent the N-crowd from adapting Canon glass to their bodies w-o requiring an in-between optic?

You seem to be mixing up to different concepts.  The reason you can adapt Canon to Nikon and not Nikon to Canon has nothing to do with EF vs. EF-S lenses, it's the flange to focal plane distance - that applies all Canon EF lenses.  Lenses designed for a longer flange to focal length distance than the body cam be adapted without optics or losing infinity focus.  For the lenses with a shorter back focus (where the rear elements protrude past the mount, into the body) that makes the distance shorter not longer. 

The EF-S lenses are designed as such for several reasons.  FWIW, according to Canon the -S in EF-S stands for small image circle, not short back focus (yes, I know you read different on Wikipedia, but Wikipedia is wrong).   That smaller image circle means less glass is required, meaning lens can be produced more cheaply.  Also, it makes designing wide and ultrawide lenses much easier.  For example, compare the distortion you get on the 16-35L @ 16mm on FF vs. the EF-S 10-22mm @10mm on APS-C - same AoV, but the EF lens has massive barrel distortion, while the EF-S lens has relatively little.

Thanks for clearing some of that up, NA. I did not clarify flange to focal-plane distance vs actual rear-element to focal plane distance.  We both know what I meant tho. :)

So, if I'm understanding what you're saying here, the reduced back focus distance of EF-S lenses allows them to do a better job of making the wider angle lenses, necessary for crop sensor bodies, than they could if they had to use the longer back focus distance.

So EF-S was an engineering decision to improve WA lens geometry performance by, allegedly, allowing a simpler design process.
I guess that makes sense.  I just don't know enough about lens design to know why it's more difficult to do that considering all the light-bending going on already.

as for the 16-35mm vs the 10-22mm - I don't have the 16-35 but do have a 17-40mm and, on my FF, the distortion from it I find preferable to the very strong anamorphic distortion of the 10-22mm at similarly wide settings.  When it comes to these very wide angle optics, there must be a number of tradeoffs that need to be made regarding what sort of residual distortions are retained.  Similarly, I expected that these same criteria would be similar for whatever back focus distance was used.  It likely comes down to cost/benefit of simpler-cheaper to make good AF-S products in large numbers vs similar optics without the reduced back focus distance.



dlleno

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Re: I still don't get the crop debate
« Reply #51 on: April 12, 2012, 03:32:51 PM »
There appears to be a market need for a high performance crop body;  what I don't get is how (or if) Canon will fill that need if they are abandoning the 1.3.  It seems unlikely to me that we would see a 1.6x body as a worthy successor to the mighty 1D4, but if thats what Canon produces I doubt it will  have a 7 in the name. Canon's next move (or lack of one) in the performance crop body arena will be as newsworthy as the 5D3

I'd have to agree. There are a ton of sports shooters and photo journalists that have used APS-H bodies for years. Now that Canon is going to abandon that sensor, the only suitable body for them is the 1Dx. While the 1Dx is an impressive machine, if I were an APS-H shooter, I wouldn't be too thrilled about paying $6,800 for a full-frame body when I'm accustomed to paying $4,500-$5,000 for a 1.3x body.

That said, sports shooters spend loads of money on gear, so maybe that extra $1,800 isn't a big deal to them.

how are we certain that Canon will abandon the H? I don't mean what is the weight of evidence I mean what established the certainty.

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Re: I still don't get the crop debate
« Reply #51 on: April 12, 2012, 03:32:51 PM »

neuroanatomist

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Re: I still don't get the crop debate
« Reply #52 on: April 12, 2012, 03:52:14 PM »
So, if I'm understanding what you're saying here, the reduced back focus distance of EF-S lenses allows them to do a better job of making the wider angle lenses, necessary for crop sensor bodies, than they could if they had to use the longer back focus distance.

Just to clarify, I think that's part of it, but most of the advantage comes from the smaller image circle, less from the short back focus.  If you look at 3rd party equivalents to the 10-22mm (Tokina 11-16, Sigma 8-16), they have the small image circle but the optics don't extend beyond the lens mount (and thus, they can be mounted on FF cameras with no physical risk to the mirror, though obviously they vignette severely).
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grahamsz

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Re: I still don't get the crop debate
« Reply #53 on: April 12, 2012, 04:01:50 PM »
I did some back of the envelope math...and I'm not buying the cost of sensor reasoning.

If Canon is using a 300mm wafer, they will get roughly 80 sensor dies at full frame and 215 sensors at APC-C.  (Don't shoot me here, I didn't account for edges, targets, etc.  I just divided the area of the wafer by the sensor area).  If yields drop for the FF (yields decline more for larger die) and the yield works out to even 4 to 1, then you get about 50 FF and 200 Crop sensors per wafer.  If you account for pixel density I would expect the yields to even out (smaller feature sizes would see lower yields).  So I think I am being somewhat biased in favor of crops here.

I'm not sure that smaller feature sizes are likely to really reduce the yield that much, i suspect fixed defects on the wafer are more likely and i think your yield calculations sound reasonable (though it's anyone's guess how many of those defects really exist).

I suspect the features on the 5D3 and 7D sensors will probably be quite similarly sized. Just because the photosites are larger doesn't mean you can afford to make the other circuitry larger.

It depends more on economies of scale than anything else, I suspect Canon can probably sell 10x the number of crop sensors so that drives their price down more. It'll be interesting to see if they make a low MP full frame rebel. I've always wondered how many potential 5d sensors are rejected just because they have too many photosite defects. Perhaps with some clever mapping and downsampling they could be reworked to make a rebel sensor


LetTheRightLensIn

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Re: I still don't get the crop debate
« Reply #54 on: April 12, 2012, 06:01:48 PM »

yes, what I mean here is that the consequences of pixel density do come into play at normal ISO speeds at the same FOV  when pixel peeping.  This is evidenced by the fact that a 5D image, when cropped to 1.6x, is a lot closer in actual, realizable IQ to the 7D native image than the pixel calculations would imply.  So overall system resolution (I should have used the term IQ instead of resolution)  is not just about pixel count.   I do think it is astonishing that an 8mp (cropped) image from the 5D3 compares very well with the native 18mp image from the 7D.  I wish I had the reference (sorry) but in another thread this topic was discussed, and examples posted showing this. 

If you look at the better test carried out by Romy, the 7D actually showed noticeably better detail than the 5D2 when distance limited. One guy's test didn't show as much difference, but his results were the outlier.

thanks that is good to know.  now I'm even more anxious to know what the next gen crop bodies will be like.  perhaps more astonishing to me is that the 5D3 pixel density is approximately the same as the 40D.   Clearly, Canon is reluctant to push the pixel density on the FF sensors, but have no such reluctance to do so for the crop bodies.  and now, assuming the H crops are going away, Canon may push more IQ technology towards an upper end 1.6x crop. at least one can hope, which is (last I checked) what this site encourages lol :D

I think it's more been that they've been limited by processing power, since processing only cares about total MP count and not density, than not wanting high MP on FF, I think. 18MP on APS-C or FF requires the same processing power. But 48MP on FF takes a LOT more processing power than 18MP on APS-C (48MP is 18MP APS-C density scaled to FF).

true indeed.  Beyond that, there  are noise and ISO compromises that come with high pixel density, although Sony is demonstrating state-of-the-art advances there, in the Nikon D800, and Canon may be behind in that race.  That aside, the 7D really pushed the pixel density envelope to new levels, I'm presuming at the cost of noise and ISO performance, which the market apparently is willing to bear or even drive, as the megapixel wars seem to be most prevalent within markets that don't care as much about those things. I wonder, accepting the demise of "H"bodies, how Canon will please the pro wildlife crowd.   1D4 still fills that niche today,  but going forward wildlifers switching  to 1DX will have to make up that reach factor with glass.  not a bad, revenue-generating strategy.

The interesting thing is that if you check SNR, the 7D actually does a trace better than the 5D2 and couple that with the way the D800 does and it's the tech that makes much more difference than the pixel density (although the 7D CFA cheats even more by using split greens). Plus with more pixel density you can do advanced NR which is better than a simple downsize (as a lower MP cam basically is). So long as you don't take wildly different photosite densities you don't really seem to lose by higher MP at high ISO and, if anything, you seem to gain at low ISO DR.

V8Beast

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Re: I still don't get the crop debate
« Reply #55 on: April 12, 2012, 07:40:10 PM »
how are we certain that Canon will abandon the H? I don't mean what is the weight of evidence I mean what established the certainty.

I suppose the evidence is more circumstantial than definitive. With Canon announcing that the 1Dx represents an amalgam of the 1D and 1Ds lines, many have interpreted this to mean that they won't be updating the 1D line. Plus, new 1DIVs are very hard to find in stock. I do hope the APS-H platform resurfaces some day because it's a great sensor.
« Last Edit: April 12, 2012, 08:59:57 PM by V8Beast »

dlleno

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Re: I still don't get the crop debate
« Reply #56 on: April 12, 2012, 07:50:13 PM »
1Dx, 1D4 successor, 5D3,  7D2, rebel.  no xxd!

Aglet

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Re: I still don't get the crop debate
« Reply #57 on: April 12, 2012, 10:36:35 PM »
1Dx, 1D4 successor, 5D3,  7D2, rebel.  no xxd!

60D still has some life in it yet. it's a good little camera... with icky non-tactile buttons.

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Re: I still don't get the crop debate
« Reply #57 on: April 12, 2012, 10:36:35 PM »

dlleno

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Re: I still don't get the crop debate
« Reply #58 on: April 13, 2012, 02:13:39 PM »
yes, no argument there;  I just don't quite understand the need for three distinct 1.6x product lines.  Even from the marketing perspective they've forced themselves into corner, imho, because it would be silly to have both a 70D and a 7D.  My guess is that forcing this corner was no accident at the time, lets not forget that this decision was made probably 4 years ago.

But while we're speculating... consider that the 7D could be a marketing experiment, to test the acceptance of a premium 1.6x body, which we all recognize the naming convention suggests.  7D was either  successful or it was not:

If 7D was successful,  it either hurt xxD sales or it didn't.  If it hurt xxD sales, then Canon will likely merge the two lines into one, and they have a marketing decision as to what to call it, but odds are that 7D would win.  If it did not hurt xxD sales, then Canon has a real dilemma,  to effectively position both lines and name them something without conflict.

if 7D was not successful, then they just drop it, and focus on the xxD as the premium 1.6 body. CR -1 here of course I have no data to back this up;  just engaging in amusing speculation.

V8Beast

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Re: I still don't get the crop debate
« Reply #59 on: April 14, 2012, 08:22:19 PM »
Is there any way to look at the sales figures of the 7D compared to the other crop bodies? If I had to guess, I'd say the 7D has been quite successful. I've come across many 7D owners that are very happy with them, and sports shooters often pair them up with their 1D bodies. I can't see why Canon would drop it. Since there are so many APS-C lines, it seems logical to just merge the 7D into the xxD line. IMHO, the 7D has always been more of a successor - price and feature wise -  to the 50D. I can't figure out what the reasoning was behind cheapening up the xxD line.   

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Re: I still don't get the crop debate
« Reply #59 on: April 14, 2012, 08:22:19 PM »