My response in-line below. On 8/30/06, Toralf Lund <[EMAIL PROTECTED]> wrote: > > > > > [Regardless of future technological developments, cameras with full- > > frame sensors will always cost much more than [ ... ] > > (Interestingly, the APS-H sensor of the EOS-1D MarkII N is the largest > > size that can be imaged in one shot onto a wafer. [ ... ] ] > > > That's "APS-H", though. Meaning 1.3x crop, not 1.5x, I think.
Yes, I'm fully aware of it. As I said, this was not the article I read the first time about the max size limit of a sensor. Nevertheless, the point is the same. The photo sensor size is limited by the max size of a given stepper which can be produced by a one shot exposure. Canon also produce steppers and it appears that they have invested a bit more dedicated machine for their own in-house mfg. At present, Canon are the only company that is offering 1.3 crop factor models (AFIK). However, at the time DSLRs came into mainstream, APS sized sensors, H or C, became standard. Perhaps sensor makers were using standard steppers designed mainly for the chip making, I do not know. But regardless of the crop factor, sensor size was NOT determined by the optical performance or other such factors, but they simply had no choice (so, it seems to me). Canon indeed are the wild card in this area, as they announced some time ago that they developed a process (or machine) that can produce FF sized sensors in one shot exposure process. But I am sure Nikon are developing something similar (or they may be holding it purposely for their own benefit? :-). > > I also saw an article just a couple of days ago, stating that the cost > > of FF sensor is 10 to 20 times larger than that of APS sized one and > > it won't narrow. But I have a bad habit of not bookmarking. Maybe I > > read it somewhere in this white paper. I will take a time to read it > > more in detail later ;-). > > > Really? *Someone* provided some info *somewhere* in the context of the > release of the Canon 5D that suggested it had actually narrowed quite a > bit since the release of the 1Ds, and that there was also a lot more > room for improvement. I think it said that the yield was up from 10% to > 25% - while it had remained stable for a while at 80% or whatever for > smaller sensors. But perhaps your article was written after that and/or > gave a good reason while this gap won't be reduced further? OK, I finally found where these descriptions were. They were right in the article of 8/28 which quoted the Galbraith's site (which quoted the Canon's white paper). It's the Japanese article but introducing the Galbraith's article and summarizing what the white paper was supposed to say, and that's why I thought I saw it in the white paper. But I could not find such phrases in the white paper. The original Japanese article was titled "the cost of FF sized sensor is more than 20 times that of APS-C". Sensational, isn't it? :-). There may be some additional part to this white paper which we do not see. But if you found such description in the white paper, don't blame me as I only skimmed through it diagonally (but it appears to be an interesting article). Anyway, here is what the Japanese article says; 1. yield from 8" wafer is 200/APS-C, 46/APS-H, 20/FF 2. number of LSI's on a single wafer is 1000~2000. If for example, there were 20 defects but rather uniformly distributed over the wafer, it could be possible that "ALL" FF sized sensor could be defective. 3. It requires 3 shots exposures to produce an FF sized sensor where as one shot produces APS-H or APS-C. 4. The cost of FF sized sensor is 10, 20 or more times that of APS-C. Even with the advancement of the technology in the future, the cost of FF sized sensor stay's very high and the gap won't narrow. So, above was what was burnt in my head and it's a recent article. As Graywolf said, stepper is for making "as small as possible" IC chips but when it is used for the sensor mfg which uses the larger spectrum of the process, there is a physical limitations. Theoretically, I suppose a dedicated stepper to produce larger size sensors in one shot exposure could be invested, but considering the market price of these machines, it must be so costly. But canon did announce that they developed such a machine. From the white paper though, it does not appear that they have any working/production model yet. Anyway, so much for this. All I ask is that makers (particularly Pentax :-), maintain models with APS sized sensors. As Canon themselves admit, cameras with FF sensors would be too big and heavy to carry. Cameras not carried would be photos not taken. Cheers, Ken -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
