Tentacle wrote:
Regarding a digicompact with EF(s) mount:
The distance between mount plane and sensor plane is pretty big. It doesn't matter that EF-S is allowed to extend deeper into this space, the sensor/mount distance is a few cm.
So, there is a lower limit to how thick/deep an EF-compatible digicompact can be. Of course, this could be solved by using a spacer ring. Its native lenses, designed with a closer rear-element to sensor distance, would go on directly and EF(s) lenses would go on with an exention piece.
But we've seen from the Leica M8 problems that you can not easily use a short sensor-lens element distance without running into problems. The increased angle of incident light at the sensor edge causes unsharpness. ...Show more →
One way around that would be the same as that on the Leica - off-set micro-lenses.
That might mean though that EF(S) lenses would not work even with a spacer
The APS-H sensor might be a good bet for use - just like in the Leica!
Regards,
DaveMart
woofes wrote:
I think a great idé should be to implement a function that detects an EF-S lens in 1.3x and FF bodys and automatically scales down to 1.6x crop. But ofcourse they need to fix the problem with the mirror hitting the back of the lens...
/Andreas
It's not that complex given Canon's in house technology. What about a pellicle mirror combined with native high ISO? A closed mirror box, effectively the result when a dust free pellicle mirror box is used, would also allow different viewfinder systems again. Something the F1 series had in the past but seems to be impossible to combine with dust sensitive sensors of current crop DSLR's.
Thank you Tentacle (Vincent?) for filling in - I was somewhat disturbed by my day job ...
To be a bit more precise: EF lenses have a rather long (lens) mount-sensor (/film) distance of ca. 47 mm (I don't remember the exact figure). EF-S lenses utilize a somewhat shorter back-of-lens distance, in spite of the compatible mounting flange, because the rearmost part of the lenses is located inside that ca. 47 mm. Canon could take the same approach further with EF-M, and locate all of the miniature lens inside the camera body, and achieve as short back-of-lens distance as desired, but still maintain the EF/EF-S compatible mounting flange. This would enable Canon to use the precisely same mirrorless camera body concept in their whole camera range, including all FF bodies.
The adaptorless/spacerless design would have at least these compromises:
- the miniature lenses must have an otherwise unnecessarily large mounting flange (presumably of plastic), which could make the unmounted lenses somewhat strange looking
- as Tentacle wrote, the body would need to incorporate that ca. 47 mm distance even if the miniature lens would be only 10 mm thick and able to utilize a 10 mm lens-sensor distance (which seems to be possible in the mobile phone cameras, with a sufficiently small active sensor area)
- a flush lens/body design leaves no room for manual manipulation of focus & zoom (OK, many P&S cameras don't have them either)
Backfocus of EF is 43mm. Lenses with a short focal length below 43mm could be built without the need to adapt the retrofocus design which does have some disadvantages. An ultrawide Hologon lens of 16 mm for instance goes deep into the camera only 16mm from the capturing medium (read film), just like many Leica M wide angle lenses that follow the same design principles. A mount that controls the mirror flip up or down when different type of lenses are adapted could be a solution. Just like a fixed mirror with a pellicle surface, although that construction would still limit the depth of back focus of lenses to a certain degree as I can't imagine a pellicle mirror with a depth of only 16mm. But a reduction of the back focus distance below 43 mm to about 30mm would definitely be a possibility with a pellicle mirror box. Have EOSfun!
Paul Gardner wrote:
1/16000 shutters sound good for a number of people. shooting hummunging birds for one. bullets, for another, any place the requires a high speed image. There is a market for everything.
There is no real market for pictures stopping bullets in flight. The shutter speed is the easy part (use an auto-exposure flash at close range which will quench the flash between about 1/25,000 to 1/50,000 second if you have a slow shutter). The problem is triggering while the bullet is in the frame. The classic pictures by Harold Egerton were taken with an open shutter in darkened rooms and flashes triggered photoelectronically or even electro-acoustically with a lot of fiddling and adjustment and many failed shots to get the ones we've all seen.
Koivulehto wrote:
Thank you Tentacle (Vincent?) for filling in - I was somewhat disturbed by my day job
[...]
Vincent? No. But then again, I did not choose this nickname the high individuality factor. Others are, no doubt, using this too on different fora and online communities.
DaveMart wrote:
That would be vignette city! The easy way for Canon to think about it is that APS-H uses FF lenses - if the format gets into more general use, all they do is release something similar to the Sigma 12-24 for great WA.
Regards,
DaveMart
Everyone keeps saying this, but I'm proposing that EF-S may have been designed to fit 1.6 and 1.3 crop cams from the beginning. Just because Canon didn't produce a 1.3 crop camera yet doesn't mean that they didn't have the foresight to design EF-S lenses to work with that system as well! I'm just speculating, but it really is hard to swallow the idea that they'd create a new mount and only have 1 or 2 bodies that can use it. Maybe I'm completely off base here. When you mount an EF-S lens to the camera, you still multiply the "real" focal lenghts by 1.6 to get the "recorded" focal lengths, right? As in that EF-S 17-55 is actually 27-88?
echomancer wrote:
Everyone keeps saying this, but I'm proposing that EF-S may have been designed to fit 1.6 and 1.3 crop cams from the beginning. Just because Canon didn't produce a 1.3 crop camera yet doesn't mean that they didn't have the foresight to design EF-S lenses to work with that system as well! I'm just speculating, but it really is hard to swallow the idea that they'd create a new mount and only have 1 or 2 bodies that can use it. Maybe I'm completely off base here. When you mount an EF-S lens to the camera, you still multiply the "real" focal lenghts by 1.6 to get the "recorded" focal lengths, right? As in that EF-S 17-55 is actually 27-88? ...Show more →
The first EF/EF-S camera was the 300D, announced in august '03. The first APS-H camera released after the EF-S introduction was the 1D Mk II, which was announced januari '04.
*IF* Canon had simply stuck to a smaller projection circle with EF-S, it would have been possible to get them to work on APS-H too. But given the fact that the EF-S allows for deeper rear-element penetration into the body it is not compatible with APS-H.
I mean, come on, even a 10D can not handle all EF-S lenses (after the modification) because some will wreck the 10D mirror. All EF-S compatible dSLRs have a modified mirror slide in order to allow more room inside.
echomancer wrote:
Everyone keeps saying this, but I'm proposing that EF-S may have been designed to fit 1.6 and 1.3 crop cams from the beginning. Just because Canon didn't produce a 1.3 crop camera yet doesn't mean that they didn't have the foresight to design EF-S lenses to work with that system as well! I'm just speculating, but it really is hard to swallow the idea that they'd create a new mount and only have 1 or 2 bodies that can use it. Maybe I'm completely off base here. When you mount an EF-S lens to the camera, you still multiply the "real" focal lenghts by 1.6 to get the "recorded" focal lengths, right? As in that EF-S 17-55 is actually 27-88? ...Show more →
No speculation is needed. At some focal lengths there is vignetting on some lenses using EF-S mount with a 1.6 sensor.
It would be a lot worse on a 1.3.
No point realy going for the advantages of EF-S - ie cheaper and lighter- and then sacrificing that by designing it to take a bigger sensor.
You are only talking about a couple of lenses anyway, since most EF-S lenses are cheap kit jobs that you would not want to use on another camera.
A 1.3 does very well with the 17-40 - or the Sigma 12-24 for that matter.
No point in using the 10-22 even if the mount would accept it.
Most cameras in the Canon range will continue ot take EF-S, as they sell loads more at the cheap end of the range using a 1.6, and there does not seem any immediate prospect of the xxD going to 1.3
Regards,
DaveMart
Tentacle wrote:
Regarding a digicompact with EF(s) mount:
The distance between mount plane and sensor plane is pretty big. It doesn't matter that EF-S is allowed to extend deeper into this space, the sensor/mount distance is a few cm.
So, there is a lower limit to how thick/deep an EF-compatible digicompact can be. Of course, this could be solved by using a spacer ring. Its native lenses, designed with a closer rear-element to sensor distance, would go on directly and EF(s) lenses would go on with an exention piece.
But we've seen from the Leica M8 problems that you can not easily use a short sensor-lens element distance without running into problems. The increased angle of incident light at the sensor edge causes unsharpness. ...Show more →
I'm wondering about the differences between the Leica mount and the EF mount.
If you stuck to a 1.3 sensor, is the EF mount enough bigger than the Leica that you would avoid edge issues, and not have to off-set the micro-lenses to avoid them?
Presumably if you were going to optimise the body you would still have to have a new mount, to stop the lenses bashing the sensor with the old EF lenses, and use a spacer on them.
It would simplify the design a lot if you could do 1.6 and 1.3 without off-set microlenses though.
Or would Canon be bothered about EF compatiblity? Perhaps if they see all cameras ging to EVF over time, it might make sense to have a totally new mount, with limited or even no compatiblity with EF
Regards,
DaveMart
The Leica lenses come out of the Rangefinder corner, EF lenses come out of the SLR corner. The rangefinder system had the rear element of the lens much closer to film than was possible with EF, since there was no need for a mirror in between. Well, that's all fine and dandy during the Film Age, but not so in the Digital Age, since film allows much more oblique angles of incidence than a digital sensor.
The one fixed thing for the whole EF and EF-S system is the distance beween mount and sensor. All lenses are designed to work with this distance. If you want to make a APS-C digicompact without the mirror and use live EVF, then you still have to respect that mount/sensor distance, otherwise the lenses will not work. So, once again: You either deal with A) a fat, thick digicompact to fascilitate this distance or B) you use a stepping ring to increase that distance if you want to use EF or EF-S, or maybe even C) they use an additional lens to effectively shorten the distance.
A will work, B will work (in fact, look at the Canon HD tv cameras that can take EF(S) lenses with an adaptor) and I don't know about optics to know if C is feasible.
But I have the feeling I'm "kicking in open doors" here. (A direct translation of the dutch proverb Een open deur intrappen, to state something which is obvious.)
OK, my worthless final prediction (I am vey much a pessimist):
No 30D replacement at photokina
No 5D replacement at photokina
possibly 1dsm3 announced at photokina, not shipped until dec or jan.
New camera line released, but nothing I want/can afford
DaveMart wrote:
I'm wondering about the differences between the Leica mount and the EF mount.
If you stuck to a 1.3 sensor, is the EF mount enough bigger than the Leica that you would avoid edge issues, and not have to off-set the micro-lenses to avoid them?
Presumably if you were going to optimise the body you would still have to have a new mount, to stop the lenses bashing the sensor with the old EF lenses, and use a spacer on them.
It would simplify the design a lot if you could do 1.6 and 1.3 without off-set microlenses though.
Or would Canon be bothered about EF compatiblity? Perhaps if they see all cameras ging to EVF over time, it might make sense to have a totally new mount, with limited or even no compatiblity with EF
Regards,
DaveMart...Show more →
Please don't even mention EF incompatibility! I have had a pretty wide selection of FD(n) lenses since 20+ years, and now I have finally bought even better EF lenses. And independent of that, it would be extremely bad for Canon lens business to obsolete the EF lens mount, while Nikon, Pentax and several others still maintain basic compatibility with FD(n) era lenses.
The difference between Leica M and Canon EF mounts is not so much about the size, but the fact that Leica did minimize the body depth; it was possible since a rangefinder Leica M has no moving mirror. Now that they finally made it digital while maintaining compatibility with 50+ old Leica M lenses, they are compensating for the steep difference of angle of light between the center and edge of the APS-H sensor. This sensor is pretty large for such a short lens-sensor distance. Unlike Tentacle accidentally mentioned a few hours ago, it is not sharpness which is the problem with a sensor vs. film as used by Leica before, but it is vignetting. In addition to offset microlenses the Leica body/capture SW also compensates for vignetting based on the focal length of the lens.
If Canon sticks with the current EF mount with 43 mm back-focus distance, they can probably optimise the design of in-body miniature lens to match whatever actual lens-sensor distance they choose to use with them.
There is absolutely no risk of EF(S) lenses bashing the sensor in the EVF digicompact design I have been today dreaming of - EF lenses require that 43 mm of air behind them (and EF-S a bit less), either with or without a spacer ring.
Koivulehto wrote:
[...] Unlike Tentacle accidentally mentioned a few hours ago, it is not sharpness which is the problem with a sensor vs. film as used by Leica before, but it is vignetting. In addition to offset microlenses the Leica body/capture SW also compensates for vignetting based on the focal length of the lens.
[...]
I see the error in my ways now...
But lets not forget that, appart from vignetting because of the angle at which light hits the edge of the sensor, that same too-far-from-perpendicular incidence will also cause some unsharpness. But that's not so easily corredted as brightness.
Echomancer wrote: "Everyone keeps saying this, but I'm proposing that EF-S may have been designed to fit 1.6 and 1.3 crop cams from the beginning."
Based on my experience with an EF-S 17-85mm lens, I don't think this is likely. There is already enough vignetting at extreme aperture/focal length that the result would likely not be acceptable with a larger sensor.
I can't say whether this is true or not for other EF-S lenses.
But lets not forget that, appart from vignetting because of the angle at which light hits the edge of the sensor, that same too-far-from-perpendicular incidence will also cause some unsharpness. But that's not so easily corredted as brightness.
Do you mean the difference of distance light has to travel from the microlenses to actual sensor photosites depending on which part of the sensor they are, or what do you mean? I can't figure out any other sources of possible unsharpness in the Leica M digital design which would be different to a film based Leica M, which is supposed to provide superb wide angle photos.
I haven't got any dimensional data (rear element diameter and distance to sensor and microlens dimensions, width and height) to know if the hypothetical situation can become a real-life problem.
Think of a thin ray of light, coming in straight ahead, lumininating a single microlens dead center. Imagine an identical ray coming in from the edge of the field of view. Geometrically speaking, if the angle of incidence is extreme enough, the beam will be smeared out and hit 2 microlenses instead of one.
I have to admit that I am not entirely sure if this will become a problem in real life. Like I said, I haven't got the information required to check.
So this went from a Photokina thread to just talking about how an ef-s lens works and full frame.
So the word all over the net seems to be saying the 40D should come out.
with 10.1MP, sensor cleaner, digic III and 2.5" screen
so i dont know if any of it will all hold up. I hope it does cause I really wanna upgrade my body but if this comes out I dont wanna buy the 30D now and this released.
