sensor size question

[J. Cobble]

OK, I am trying to figure out the 1.6/1.3/1 sensor size to pixels per mm theory. I have done the search in past threads and have look at the previous info. I have a DRebel and am about a day away from buying the 1ds used. However I read in the past threads that if you shoot long shots, the longer they are the more advantage there is in the sensor factor to crop for the same crop size. In otherwords, if I shoot 400mm with the DRebel for the same crop on the 1ds I will have fewer pixels. Is this correct and where is the break even area? Is the MarkII really the answer because it is in the middle? The reason I am considering the 1ds is that I like large pics. But if, after the crop factor I have the same pixels or less for the same long shot, I am going to reconsider.

[EXA1a]

If you're asking for the pixel density of a given sensor type, here it is. Number given in MegaPixel per SquareMillimeter.

Model___Mpix/sqmm
1D_________7.4
D30________9.1
1Ds_______ 12.9
1DMkII____ 14.9
10D/300D__18.4

Hope that helps.

--Jens--

[karusel]

You surely did not mean megapixels per square milimeter.... in your case it would be kilopixels.

[hmhm]

The reason I am considering the 1ds is that I like large pics. But if, after the crop factor I have the same pixels or less for the same long shot, I am going to reconsider.

If you're trying to take a shot that requires the angle of view that a 640mm lens would yield on a full-frame camera (1Ds or 35mm film), you can either achieve that by having "enough lens" on a 1Ds or by having too little lens on the 1Ds, and then cropping in post-processing.

"enough lens"
640mm lens on a 1Ds: 14mp
400mm lens on a 10d: 6mp

"not enough lens, crop on 1Ds in post-processing"
400mm lens on a 1Ds, post-processing crop: 5.5mp (this is 14/(1.6*1.6))
400mm lens on a 10d: 6mp
-harry

[PacAce]

OK, I am trying to figure out the 1.6/1.3/1 sensor size to pixels per mm theory. I have done the search in past threads and have look at the previous info. I have a DRebel and am about a day away from buying the 1ds used. However I read in the past threads that if you shoot long shots, the longer they are the more advantage there is in the sensor factor to crop for the same crop size. In otherwords, if I shoot 400mm with the DRebel for the same crop on the 1ds I will have fewer pixels. Is this correct and where is the break even area? Is the MarkII really the answer because it is in the middle? The reason I am considering the 1ds is that I like large pics. But if, after the crop factor I have the same pixels or less for the same long shot, I am going to reconsider.

If you are going to use the same focal lenth on both cameras, then, yes, you are correct. However, if you shot the cameras so that you get the same images in the viewfinders of both cameras, then the 1Ds will give you more pixels for the same image. The drawback now is that you have to use a longer focal length on the 1Ds to achieve the same image. AAMOF, you'd have to shoot at 640mm to get the same image as the DRebel shot at 400.

However, I'm sure there's a middle ground compromise where you won't lose pixels and you won't need such a long lens although you'll still have to use a little longer focal length than the DRebel and then crop the image. You just won't be cropping as much.

[EXA1a]

You surely did not mean megapixels per square milimeter.... in your case it would be kilopixels.
you're right. please don't tell anybody. they'd deprive my science PhD...