El Profe
Senior Member
CMOS sensors are just cheaper to manufacture than CCD. That was the reason originally was used in P&S cameras. Canon was the first company to start using CMOS sensors in their SLR cameras.
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Full Frame Lens and FF Sensors!
- Thread starter jamesm007
- Start date
Msroberts
Leading Member
No: My FA*300/2.8 and many other very expensive lenses won't work on a 645D (I know people with the 600/4 and the 250-600/5.6, too). I'm seriously considering looking into getting one or two of these lenses adapted to fit my Sony A850, even though it would mean manual focus and manual exposure.
If Pentax introduced a camera with the 24MP full-frame sensor I'd buy it in a heartbeat (and sell my Sony).
--
Mark Roberts
Web site: http://www.robertstech.com/
Photoblog: http://www.robertstech.com/peso.htm
Qwntm
Veteran Member
One of the BIG advantages of FF for Nikon and Canon shooters is access to real primes.
One of the BIG advantages to the Pentax APS-C system is access to real primes.
Pentax really throws a wet blanket over the desire for a FF camera.
--
Edward
http://www.youtube.com/photouniverse
http://www.edwardthomasart.com
http://www.pbase.com/edwardthomas
Qwntm
Veteran Member
I owned and shot the D700 two years ago and the 5DII last year.
Both cameras were as boring as watching grass grow.
I shoot the K-5 now and I'm excited about photography again. Image quality is as good as, or better than, what I've grown accostomed to shooting the FF cameras.
Passion is everything, gear is just gear.
--
Edward
http://www.youtube.com/photouniverse
http://www.edwardthomasart.com
http://www.pbase.com/edwardthomas
Both cameras were as boring as watching grass grow.
I shoot the K-5 now and I'm excited about photography again. Image quality is as good as, or better than, what I've grown accostomed to shooting the FF cameras.
Passion is everything, gear is just gear.
--
Edward
http://www.youtube.com/photouniverse
http://www.edwardthomasart.com
http://www.pbase.com/edwardthomas
jamesm007
Veteran Member
Watch this video of the 645D and note at 4:55 what the Pentax rep says about Digital compared to film. Digital is very demanding of lens.
http://www.luminous-landscape.com/videos/pentax-645d.shtml
--
jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
http://www.luminous-landscape.com/videos/pentax-645d.shtml
--
jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
Gerry Winterbourne
Forum Pro
His point seems to be that because film emulsion has a real thickness it tolerates minute amounts of difference in focus of different colours, whereas digital has zero thinkness so the colours can focus differently and show fringing.
OK, but with digital we can deal with fringing in PP. Now, as the slight focus differences on film lead to corresponding softness, with care in PP the same lens should offer better resolution on digital than on film.
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Gerry
First camera 1953, first Pentax 1983, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
I am not going to dispute the lens phenomenon as this may be applicable to some lenses and some Pentax lenses in particular. It could be a factor in the Pentax decision making process as they feel that they may need to make a complete lens line for FF due to what you have stated. Who knows? However, I think the reason that Pentax has not gone FF is due more to market share and lack of sales of a potential FF Pentax camera. As it stands, Pentax only has about 5% of the market even with APS C, so a FF market would possibly only be 5-10% of that 5%!! Tiny at best, I do believe.
Pentax has long been a camera company that concentrates on smaller cameras and to go FF, a DSLR will need to be large. However, this all depends on what the major two brands end up doing themselves with regards to the price of FF sensors. If FF sensors end up allowing Nikon and Canon to produce a small FF DSLR, then we may see one from Pentax, but this depends on a number of factors.
Unless the cost of FF sensors reducing to a level where a manufacturer can make one for the price of an advanced amateur level APS C camera, I do not think you will see a FF camera that is smaller than they are now and even then I think they may be pushing it depending on features of the FF camaera compared to the top spec APS C version. Why? Because they are made for pros and semi pros users first and therefore need to be made to withstand the rogours of pro use. Therefore, to withstand the rogours of pro use, they use heavy, more robust materials and have features and facilities that are what pros require. For a start, the mirror box needs to be bigger to accommodate the large mirror and shutter assembly, so this part of the camera needs enlarging to start with.
It's not a case of whether they can make one small enough so much, that is the deciding factor, it is whether they can justify the tiny market share that a small bodies, possibly "dumbed" down FF camera would attract. In other words, the market for a FF camera of this sort compared to those who would rather fork out for a top spec APS C camera are very limited, IMO.
For pro use, things like the lens mount area is more robust, stronger chasis, heavier plastics used, weather sealed, more robust switchgear and buttons, larger buttons so that pros are not fumbling about trying to press a tiny button because the camera is small, etc, etc. The mirror needs more damping and the actuation gear more robust than that of an APS C camera. A more powerful inbuilt flash which requires a larger capacitor - I saw the guts of a DSLR and the capacior for the flash was huge in relationship to the camera. It was about 40mm long and 16-18mm in diameter!! All of this stuff takes up room and adds weight.
In order to make a FF camera small, it needs to then be attractive to amateurs at a cost basis and I just can't see this happening until FF sensors are way cheaper than they are now. Added to this, to get long lens benefits they have to fork out for a 300mm instead of a 200mm on APS C or a 600 over a 400etc. So, the amatuer needs to factor in that fact that long lenses cost more as well!
So, until sensors are cheaper, then FF cameras will be made for pros because they cost more and they are made to suit their requirements. There will be a very limited market for advanced amateurs forking out money for a "dumbed" down FF camera that is less than robust. There will be less features as to have all the features adds weight and cost. The pros won't buy them as they need the more advanced tougher camera for the pro work as well as all the features that tye use now. Most normal amatuers will stick with APS C as they do not need FF,APS C is smaller and lighter and fulfills 99% of their needs, and lond lenses cost more. So, there will be no market in most of the amateur ranks.
The only market I can see is for a few advanced amatuers and they will quickly abandon the "dumbed down" FF camera as they will quckly learn that it is limited. I think the market is too small for such a camera even if FF sensors were cheap enough and I think Nikon and Canon realise this. Why sell a D3100 type camera when a camera like the D700 is such a market smash hit that suits many markets, ie pros and advanced amateurs.
The IQ from the current K-5 is remarkable anyway, and I doubt that most would tell the difference between it and many FF images even up to A3.
--
Lance B
http://www.pbase.com/lance_b
Pentax has long been a camera company that concentrates on smaller cameras and to go FF, a DSLR will need to be large. However, this all depends on what the major two brands end up doing themselves with regards to the price of FF sensors. If FF sensors end up allowing Nikon and Canon to produce a small FF DSLR, then we may see one from Pentax, but this depends on a number of factors.
Unless the cost of FF sensors reducing to a level where a manufacturer can make one for the price of an advanced amateur level APS C camera, I do not think you will see a FF camera that is smaller than they are now and even then I think they may be pushing it depending on features of the FF camaera compared to the top spec APS C version. Why? Because they are made for pros and semi pros users first and therefore need to be made to withstand the rogours of pro use. Therefore, to withstand the rogours of pro use, they use heavy, more robust materials and have features and facilities that are what pros require. For a start, the mirror box needs to be bigger to accommodate the large mirror and shutter assembly, so this part of the camera needs enlarging to start with.
It's not a case of whether they can make one small enough so much, that is the deciding factor, it is whether they can justify the tiny market share that a small bodies, possibly "dumbed" down FF camera would attract. In other words, the market for a FF camera of this sort compared to those who would rather fork out for a top spec APS C camera are very limited, IMO.
For pro use, things like the lens mount area is more robust, stronger chasis, heavier plastics used, weather sealed, more robust switchgear and buttons, larger buttons so that pros are not fumbling about trying to press a tiny button because the camera is small, etc, etc. The mirror needs more damping and the actuation gear more robust than that of an APS C camera. A more powerful inbuilt flash which requires a larger capacitor - I saw the guts of a DSLR and the capacior for the flash was huge in relationship to the camera. It was about 40mm long and 16-18mm in diameter!! All of this stuff takes up room and adds weight.
In order to make a FF camera small, it needs to then be attractive to amateurs at a cost basis and I just can't see this happening until FF sensors are way cheaper than they are now. Added to this, to get long lens benefits they have to fork out for a 300mm instead of a 200mm on APS C or a 600 over a 400etc. So, the amatuer needs to factor in that fact that long lenses cost more as well!
So, until sensors are cheaper, then FF cameras will be made for pros because they cost more and they are made to suit their requirements. There will be a very limited market for advanced amateurs forking out money for a "dumbed" down FF camera that is less than robust. There will be less features as to have all the features adds weight and cost. The pros won't buy them as they need the more advanced tougher camera for the pro work as well as all the features that tye use now. Most normal amatuers will stick with APS C as they do not need FF,APS C is smaller and lighter and fulfills 99% of their needs, and lond lenses cost more. So, there will be no market in most of the amateur ranks.
The only market I can see is for a few advanced amatuers and they will quickly abandon the "dumbed down" FF camera as they will quckly learn that it is limited. I think the market is too small for such a camera even if FF sensors were cheap enough and I think Nikon and Canon realise this. Why sell a D3100 type camera when a camera like the D700 is such a market smash hit that suits many markets, ie pros and advanced amateurs.
The IQ from the current K-5 is remarkable anyway, and I doubt that most would tell the difference between it and many FF images even up to A3.
--
Lance B
http://www.pbase.com/lance_b
moving_comfort
Veteran Member
.
The DA 14 + K-5 is one combo that doesn't make as much sense, though. The 'little' K-5 + that largish prime is only about 180g lighter than the 'huge' D700 + 20 f/2.8D combo, negating the size advantage. Plus, the 20 on FF is equivalent to a 13mm f/1.8 on aps-c with regard to FOV/DOF, which can be fun and useful.
The DA15ltd makes more sense on the k-5 - yes, it's not quite as fast or as wide as the 14, but I think it's optically more compelling and really takes advantage of the aps-c size advantage in combo with the k-5.
.
--
Here are a few of my favorite things...
---> http://www.flickr.com/photos/95095968@N00/sets/72157626171532197/
Redteg94
Senior Member
This problem you speak of exists in all image sensors. Please explain why you are singling out FF? Also, how is an APS-C specific lens, which only covers APS, any different from a 35mm lens that covers the FF format? And why would this edge issue be more problematic with a bigger sensor? An edge is an edge. Finally, how do you explain the fact that many FF lenses have superb image quality corner to corner, some of these having been designed before digital?
Canon makes smaller than 35mm formats because 35mm is extremely expensive. Look at the 5DII: it was $3200 when it came out and is now $2000 3 years later (in my market), yet it has worse specs than most $700-1000 cameras. This is because it costs something like 10-20x more for each FF sensor than APS.
Why don't you compare like to like then?
Standard Zoom:
Canon 24-70 f/2.8L:
http://www.photozone.de/canon_eos_ff/528-canon2470f28ff?start=1
Pentax 16-50/28 DA* (it isn't very impressive, so you could also use the Canon 17-55IS linked below)
http://www.photozone.de/pentax/405-pentax_1650_28?start=1
Canon 17-55IS
http://www.photozone.de/canon-eos/425-canon_1755_28is_50d?start=1
Telephoto zoom:
Canon 70-200/2.8L IS II:
http://www.photozone.de/canon_eos_ff/510-canon_70200_2is28?start=1
Pentax 50-135/2.8 DA*
http://www.photozone.de/pentax/137-pentax-smc-da-50-135mm-f28-ed-if-sdm-review--test-report?start=1
Canon 16-35/2.8L II:
http://www.photozone.de/canon_eos_ff/435-canon_1635_28_5d?start=1
Pentax 12-24/4:
http://www.photozone.de/pentax/133-pentax-da-12-24mm-f4-al-ed-if-review--test-report?start=1
As you can see, the FF example easily outperforms the APS example and not all of the FF lenses used are considered spectacular either. You can fee free to compare others, but I doubt you'll successfully find an APS-C combo that outperforms FF.
Well of course they receive less light, all lenses vignette. The steeper the angle of light, the more difficult it is for the sensor to capture, but this is true for all sensors.
They haven't though. A high quality Canon APS lens like the 17-55IS only has slightly less vignetting (1.5EV at 17mm/2.8) than a high quality 35mm equivalent such as the 24-70L(1.95EV at 24/2.8), even though the 24-70 is a much more extreme lens (effectively 1 1/3 stop faster and somewhat wider). In fact, at f/4 which is approximately equivalent to f/2.8 on APS, the 24-70/5D combo has less vignetting than the APS-C. Same goes for any lens I've ever seen, with the exception of course of a 35mm lens used on APS. Obviously there is way less vignetting in this case, as the sensor is only using 40% of the lens.
When did this become a discussion of pixel-pitch? It doesn't have anything to do with the discussion at all. No one seems to know why Canon only went with 18MP; perhaps the relatively large pixels are actually the only way to go to astronomical ISO levels in real life, despite the fact that theory suggests otherwise.
They used APS-H sensors on the old 1D cameras because FF was expensive and couldn't provide the pixel density they wanted while allowing high FPS (using the 1DIII of 2007, it's easier to transfer 10MP at 10FPS than it is 18MP at the same pixel density, for example).
I do think there is room for improvement and do think APS has it's place (I use an APS-C camera), but that doesn't change the fact that FF is better in every image quality metric. Physics can't be overturned here and bigger will always be better when it comes to image sensors. This doesn't mean that smaller sensors can't continue to be improved on of course, and we're at the point where some APS-C sensors are better than older FF models.
--
-Scott
Redteg94
Senior Member
The fact is that it's not most lenses, but few others. You have to cherrypick the very worst ones to prove your point, which effectively disproves your point.
--
-Scott
Redteg94
Senior Member
These papers you quote have nothing to do with the statements you made in your OP. They basically say that the microlenses on digital sensors don't have wide enough apertures to be able to make use of fast aperture lenses. This is a problem throughout the sensor, not at the edges. And it refutes your argument, as the worst offenders are APS-C cameras and the best ones are FF cameras.
They claim it's an issue related to small pixels, though it looks more complicated than that. At any rate, I don't see how or why you would choose these documents to support your argument.
-Scott
They claim it's an issue related to small pixels, though it looks more complicated than that. At any rate, I don't see how or why you would choose these documents to support your argument.
--
-Scott
jamesm007
Veteran Member
Agree, you have said things I have never thought of. I really do agree 100%! And at least you understand agree or not what I was trying to say about old film lens on FF Digital sensors.I am not going to dispute the lens phenomenon as this may be applicable to some lenses and some Pentax lenses in particular. It could be a factor in the Pentax decision making process as they feel that they may need to make a complete lens line for FF due to what you have stated. Who knows? However, I think the reason that Pentax has not gone FF is due more to market share and lack of sales of a potential FF Pentax camera. As it stands, Pentax only has about 5% of the market even with APS C, so a FF market would possibly only be 5-10% of that 5%!! Tiny at best, I do believe.
Pentax has long been a camera company that concentrates on smaller cameras and to go FF, a DSLR will need to be large. However, this all depends on what the major two brands end up doing themselves with regards to the price of FF sensors. If FF sensors end up allowing Nikon and Canon to produce a small FF DSLR, then we may see one from Pentax, but this depends on a number of factors.
Unless the cost of FF sensors reducing to a level where a manufacturer can make one for the price of an advanced amateur level APS C camera, I do not think you will see a FF camera that is smaller than they are now and even then I think they may be pushing it depending on features of the FF camaera compared to the top spec APS C version. Why? Because they are made for pros and semi pros users first and therefore need to be made to withstand the rogours of pro use. Therefore, to withstand the rogours of pro use, they use heavy, more robust materials and have features and facilities that are what pros require. For a start, the mirror box needs to be bigger to accommodate the large mirror and shutter assembly, so this part of the camera needs enlarging to start with.
It's not a case of whether they can make one small enough so much, that is the deciding factor, it is whether they can justify the tiny market share that a small bodies, possibly "dumbed" down FF camera would attract. In other words, the market for a FF camera of this sort compared to those who would rather fork out for a top spec APS C camera are very limited, IMO.
For pro use, things like the lens mount area is more robust, stronger chasis, heavier plastics used, weather sealed, more robust switchgear and buttons, larger buttons so that pros are not fumbling about trying to press a tiny button because the camera is small, etc, etc. The mirror needs more damping and the actuation gear more robust than that of an APS C camera. A more powerful inbuilt flash which requires a larger capacitor - I saw the guts of a DSLR and the capacior for the flash was huge in relationship to the camera. It was about 40mm long and 16-18mm in diameter!! All of this stuff takes up room and adds weight.
In order to make a FF camera small, it needs to then be attractive to amateurs at a cost basis and I just can't see this happening until FF sensors are way cheaper than they are now. Added to this, to get long lens benefits they have to fork out for a 300mm instead of a 200mm on APS C or a 600 over a 400etc. So, the amatuer needs to factor in that fact that long lenses cost more as well!
So, until sensors are cheaper, then FF cameras will be made for pros because they cost more and they are made to suit their requirements. There will be a very limited market for advanced amateurs forking out money for a "dumbed" down FF camera that is less than robust. There will be less features as to have all the features adds weight and cost. The pros won't buy them as they need the more advanced tougher camera for the pro work as well as all the features that tye use now. Most normal amatuers will stick with APS C as they do not need FF,APS C is smaller and lighter and fulfills 99% of their needs, and lond lenses cost more. So, there will be no market in most of the amateur ranks.
The only market I can see is for a few advanced amatuers and they will quickly abandon the "dumbed down" FF camera as they will quckly learn that it is limited. I think the market is too small for such a camera even if FF sensors were cheap enough and I think Nikon and Canon realise this. Why sell a D3100 type camera when a camera like the D700 is such a market smash hit that suits many markets, ie pros and advanced amateurs.
The IQ from the current K-5 is remarkable anyway, and I doubt that most would tell the difference between it and many FF images even up to A3.
--
Lance B
http://www.pbase.com/lance_b
Take care Lance B.
--
jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
Redteg94
Senior Member
Have you ever heard of halo products? People often buy into certain companies because of successful flagship models, even if they don't buy that model themselves. The D300 was a great camera, but the D3 and associated FF lenses are the reason many professionals moved back to Canon. They would have sold quite a few D300s anyways, but the D3 and D700 are why Nikon are back where they are.
Look at the days of the D200; it was also probably the best prosumer camera out there (along with the 20D), but the D2x/h were a joke and Nikon wasn't considered top of the game because of that.
Canon wasn't exactly releasing crap in 2007.
--
-Scott
Redteg94
Senior Member
Your links don't refer to what you say they were. They complain that the microlenses that cover the entire sensor don't properly pick up the light given by lenses with apertures larger than f/2 because the microlenses themselves have small(ish) apertures. The effect is that the cameras electronically have to boost the ISO to compensate. This occurs with all cameras and is especially problematic with small pixels, hence why APS-C cameras are WORSE in this case than FF. This means that unfortunately for me, my 7D with my 24/1.4 is much worse than a 5D2 with a 35/2.
Again, you are misunderstanding what you are reading. Also, you keep saying that APS-C cameras crop the edges of lenses. This is true if you are using 35mm lenses, but many times this isn't happening. When you are using a APS-C lens (EF-S in Canon speak, I'm not sure what Pentax calls them, but I understand most lenses released by them in a decade or so are APS-C) you aren't cropping out the edges. This means you have the same issue as FF.
--
-Scott
M R Padmaraju
Veteran Member
Though I have a dozen of Pentax SMC full frame lenses, my observation is that digital specific kit lens behaves better than the lenses for full frame film format. But the macros responds quite well. Hence my work force as of now is, Kx, M 100 f.4.0, 18-55 and 55-300, in that order. Other lenses for full frame film format are sitting in the warmth of my bag. I think it is a compromise!
Gerry Winterbourne
Forum Pro
I agree with this, in that James has misunderstood. However, the DxO discussion is more about well depth than microlenses.
Let's use a 50/1.2 lens for ease of explanation. The max aperture is 42mm diameter, almost equal to the image diagonal. Look at a pixel in the centre of the frame - light through the optical axis goes all the way down but round the edges the walls create a shadow. In cross section this shows as a strip of dark on each side.
Now go to a pixel 1/2mm in from the corner: the light at the outer side now comes in vertically so there's no shadow, but on the other side the shadow is about twice as wide as the strips on the central pixel.
The result is a loss of light capture that is very close to equal across the frame. Microlenses seem to reduce but not eliminate the loss.
No need to imagine it. Many thousands of photographers use FF lenses on FF bodies with outstanding resullts. My son, for example, has been using his 5D since it first came out (so pretty old-fashioned by digital standards) without ever bemoaning the problems you claim to exist.
In fact any prime lens longer and wider than about 35/2.8 covers the FF image circle: it's just the way things are. Some lenses (wider primes and some zooms) have circles bigger than 28mm, too, so they crop the softer areas away.
So this isn't a total misunderstanding ...
--
---
Gerry
First camera 1953, first Pentax 1983, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
CharlieDIY
Veteran Member
It is as if APS-C were totally unsatisfactory to a great many people. If I want shallower depth of field, I'd think the 645D would do that job even better than so-called full frame.Me too, I would be willing to tolerate the faults of old FF lenses in corners, for the added creative benefit of shallower DOF. And my vintage zooms starting at 28mm would become much more interesting. I would still keep one APS-C Pentax at hand anyway.I still want a FF!
As it is, I cannot really see a benefit to full frame, at least for my kind of photography where extended depth of field is usually helpful. I doubt most magazine editors (assuming any are left in a few years) care much about anything over 11" x 17"--a bit of extra for cropping is nice for those double spreads, but, otherwise, why FF? If I choose to hang a shot at home, I can easily go up to 24" x 36" with APS-C (using a K20D) that is extremely detailed and sharp at normal viewing distances.
I'd still like to be able to afford the 645D, but I would have trouble raising my head to check out a FF.
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Charlie Self
http://www.charlieselfonline.com
That's a common legend, but once you consider the fact that the aperture should also be changed in order to be truly equivalent, there is not so much differences in price/size/weight between the two systems, and FF even often costs less for similar performances (or offers unique possibilities)...
For instance, take the Tamron 60/2 (APS-C) vs Tamron 90/2.8 (FF). You get:
- a slightly more versatile lens in FF (a slightly bigger equivalent aperture).
- only difference is in the overall length, and that's because the 90 has a recessed front lens (so it could have been made shorter).
- Same weight,
- same price...
- the FF lens has a greater range and better equivalent aperture!
- the FF lens is smaller/lighter (545g vs 755g)
- the FF lens is cheaper (700€ vs 1250€!)
Or Canon's 70-200/4 and Pentax's 50-135/2.8:
- FF lens slightly more versatile (f/4 instead of the true equivalent f/4.5) and stabilized!
- nearly same weight (760g vs 685g)
- nearly same size (172mm vs 136mm)
- same price point (1050€ vs 950€)
- more versatile FF lens (bigger equivalent aperture, by 1.3 stops!)
- price: 720€ vs 880€
- size: 74x105 vs 87x120
- weight: 545g vs 600g
jamesm007
Veteran Member
Sorry Gerry ...
Here is DXO problem
"“We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f 2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.”"
So the above says with "present sensor technology" there seems to be a loss of light.
“We can suspect,” Guichard continued, “that sensors collect the incoming light all the more improperly, in that this light comes from a more oblique angle. Since faster lens have, by definition, a wider opening, they raise the proportion of oblique light, hence the proportion of lost energy which never lands on the pixels.”"
He says sensor don't collect with 100% efficiency there is a light loss. Then he says (He being Guichard) that the more oblique light hits a sensor the more of a loss there is. Since fast lens tend to spray light out light there is more of a loss.
So we go back to Luminous Landscape whos author had a meeting with these guys about the data presented. I hope everyone knows oblique means not perpendicular! So the above says that non-perpendicular light that comes out the back of a lens will create more light loss. There can be no question of that interpretation! If you understand?
Now Mark Dubovoy of Luminous Landscape wrote in the link I gave, which links to the above article from DXO the following.
" When you look at the structure of CMOS sensors, each pixel as basically a tube with the sensing element at the bottom. If a light ray that is not parallel to the tube hits the photo site, chances are the light ray will not get to the bottom of the tube and will not hit the sensing element. Therefore, the light coming from that light ray will be lost. It appears from this graph that when using large aperture lenses on Canon cameras, there is a substantial amount of light loss at the sensor due to this effect. In other words, the "marginal" light rays coming in at a large angle from near the edges of the large aperture are completely lost."
This shows digital sensor do not like light coming at them oblique. Now my argument. The larger the sensor used for older film lens the more oblique the light will hit the photo-diodes at the edges and in fact this is a well known problem because there is a light loss at the edges. All though DXO spoke of t-stops they say current digital sensors are not very sensitive even with microlens to light coming in at an angle.
Natural one can concur an APS sensor would be better for older film lens then a FF digital sensor as far as IQ goes.
Digital lens are designed to make the light strike as perpendicular as possible! Hence the very good performance we get today with digital lens. Now some old lens on a larger than APS format may not be so good!
--
jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
Here is DXO problem
"“We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f 2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.”"
So the above says with "present sensor technology" there seems to be a loss of light.
“We can suspect,” Guichard continued, “that sensors collect the incoming light all the more improperly, in that this light comes from a more oblique angle. Since faster lens have, by definition, a wider opening, they raise the proportion of oblique light, hence the proportion of lost energy which never lands on the pixels.”"
He says sensor don't collect with 100% efficiency there is a light loss. Then he says (He being Guichard) that the more oblique light hits a sensor the more of a loss there is. Since fast lens tend to spray light out light there is more of a loss.
So we go back to Luminous Landscape whos author had a meeting with these guys about the data presented. I hope everyone knows oblique means not perpendicular! So the above says that non-perpendicular light that comes out the back of a lens will create more light loss. There can be no question of that interpretation! If you understand?
Now Mark Dubovoy of Luminous Landscape wrote in the link I gave, which links to the above article from DXO the following.
" When you look at the structure of CMOS sensors, each pixel as basically a tube with the sensing element at the bottom. If a light ray that is not parallel to the tube hits the photo site, chances are the light ray will not get to the bottom of the tube and will not hit the sensing element. Therefore, the light coming from that light ray will be lost. It appears from this graph that when using large aperture lenses on Canon cameras, there is a substantial amount of light loss at the sensor due to this effect. In other words, the "marginal" light rays coming in at a large angle from near the edges of the large aperture are completely lost."
This shows digital sensor do not like light coming at them oblique. Now my argument. The larger the sensor used for older film lens the more oblique the light will hit the photo-diodes at the edges and in fact this is a well known problem because there is a light loss at the edges. All though DXO spoke of t-stops they say current digital sensors are not very sensitive even with microlens to light coming in at an angle.
Natural one can concur an APS sensor would be better for older film lens then a FF digital sensor as far as IQ goes.
Digital lens are designed to make the light strike as perpendicular as possible! Hence the very good performance we get today with digital lens. Now some old lens on a larger than APS format may not be so good!
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jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
jamesm007
Veteran Member
Oh something else on L landscapes article is said
"By the way, this type of light loss is the main reason that modern lenses designed for digital photography place great emphasis on the direction of light rays behind the lens. It is also an important reason why Medium Format backs (often used with camera movements such as tilt, rise/fall and shift) and the Leica M9 (with lenses that produce mostly oblique light rays) use CCD sensors with a very different structure, rather than CMOS sensors."
This is why the Pentax 645D uses CCD sensors. They have larger light gathering diodes. CMOS are just cheaper to make. Although you can argue one it not better than another (from my research) in performance cost aside.
Mark Dubovoy flat out says digital sensors need digital lens because of the problem of light at an angle hitting any digital sensor. My simple argument is the claim of all those FF pentax lens laying around will be back to their full glory with a full frame sensor is false. They will suffer in some cases a loss of IQ. Better to use a smaller format.
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jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
"By the way, this type of light loss is the main reason that modern lenses designed for digital photography place great emphasis on the direction of light rays behind the lens. It is also an important reason why Medium Format backs (often used with camera movements such as tilt, rise/fall and shift) and the Leica M9 (with lenses that produce mostly oblique light rays) use CCD sensors with a very different structure, rather than CMOS sensors."
This is why the Pentax 645D uses CCD sensors. They have larger light gathering diodes. CMOS are just cheaper to make. Although you can argue one it not better than another (from my research) in performance cost aside.
Mark Dubovoy flat out says digital sensors need digital lens because of the problem of light at an angle hitting any digital sensor. My simple argument is the claim of all those FF pentax lens laying around will be back to their full glory with a full frame sensor is false. They will suffer in some cases a loss of IQ. Better to use a smaller format.
--
jamesm007,
http://www.flickr.com/photos/jamesm007/
http://s195.photobucket.com/albums/z77/jamesm700/
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