RF adaptor

[BryanShaw1]

I'm looking at purchasing an R6 with an adaptor so I can continue to use my existing lenses. I am told that the Canon adaptor is only good for EF lenses, but I see on Amazon that the Viltrox adaptor is good for both EF and EF-S lenses. Any information gratefully received.

[ebiggs1]

"In any case, only use the Canon adapter."

I, also, would strongly advise getting the Canon adapter.  It is always best to keep your Canon gear all Canon if possible.

[Tronhard]

Since you asked, I have the R6 and a Canon EF adapter.  I attached an EF-S 18-135 IS STM unit to the R6 via the adaptor, without any changes to the menu system and it worked ok, applying the crop function to reduce the FoV and image size accordingly.

Apologies if you know this already, but the APS-C will cause the camera to auto crop the image by a factor of 1.6, and also reduce the pixel count by a factor or about 2.56 (crop factor squared) from 20MP to around 7.7MP , so you are losing a lot of pixel density by using APS-C lenses - see p855 of the R6 manual. 

It is for that reason that I, and a lot of other long lens shooters who want the reduced FoV, would like to see a crop-sensor R7 with something like a 40MP sensor that would give a pixel density to the equivalent of cropping a 104MP sensor down to APS-C FoV.

[BryanShaw1]

Thanks for your reply. I am interested to know your circumstances for wanting to reduce the FoV.

[Tronhard]

I hope the attached link to an article I wrote will provide what you are looking for.  If you have any questions or queries please do respond.

My article on Focal Length, Crop Factor, Field of View and Pixel Density 

[ebiggs1]

Trevor, 

That's a fine article but I will take exception with. a "crop" sensor camera it does not crop anything. It only appears to crop if you intend on comparing it to a 35mm sized camera.  Most people today do not even think that and have to be told they have a crop sensor camera. All cameras give exactly what you see in the view finder or LCD.  They are all essentially full frame cameras.

I know some manufacturers tend to keep this falsification going, too. If you never intend on owning or using a FF camera, it is totally confusing and useless.  If you are an advanced or even just a hobbyists and have several bodies I suppose you can make a case for comparing equivalent focal lengths. However, IMHO, totally unnecessary which is born out by the fact guys that use medium or large format gear don't do it. Although they certainly could but would have to use an "enlargement" factor.

[Tronhard]

HI Ernie et al.

I was asked to explain why, as a long-lens shooter, I prefer sensors of a reduced size, which common nomenclature calls crop.  I have done so, using the terminology (which I admit is poorly defined in the industry) as best I can, trying to make sense out of a hotly debated subject.   

Ernie suggests that considering the impact of smaller sensors is only valid for those using both FF and crop sensors and that is not my experience - I have seen it with students I have taught.  It comes into effect when people describe images they shoot with ("my 300mm lens is actually a 480mm lens"), or the examples I gave in my article where someone bought a wide-angle lens they had seen work on a FF camera and could not understand why it didn't give the same results on their smaller-sensor camera.  It also comes into play when one looks at pixel density when choosing a format for super long tele images.  These are real issues.

The term crop is not one I invented, it is in common use in the industry because it IS smaller compared to a 35mm sensor and as these different formats exist beside each other there will be times when that terminology is needed..  See THIS ARTICLE  If we don't like the term crop sensor, then we need to come up with one that allows us to describe the relationship between sensors of different sizes, we can't just say 'no it's wrong'.  If one is going to take exception to the term crop then we must also take exception to the term Full Frame, as they are both arbitrary terms, as are the terms Medium Format and Large Format. Those were developed in the film era, not in digital to descibe succincly the relationship between formats of different sizes.  If one is going to avoid them, then we need to use an absolute terminology such as the actual dimensions, but that would be rather long-winded and clumsy considering the number of dimensional variations.  Call it what you like, but the effect is the same.

I am simply trying to make sense of a poorly-defined subject; however, leaving the semantics aside, the physics speak for themselves.  My description of the optics is well-supported by other articles on the subject, which is why I included them.  If you want to explore a very technical approach I would encourage you to view the whole series of lectures by Prof Emitus Mark Levoy, of Standford University, a link to which I enclose HERE. 

From the diagram I included with the single lense model, the smaller sensor reduces what  the lens delivers - to me term crop in this context is not unreasonable, but translate to a term of your choice.  Essentially, being smaller than the FF sensor, it crops (reduces) the image area (compared to what a FF sensor would accept) at the point of recording the image.  The diagram expresses this elequently, I believe.

The fact is, that by doing so it has done the work of effectively reducing the FoV delived by the lens (so if one has an issue with that then call it an Equivalent FoV), but using the total amount of pixels in that sensor and this is what is significant for long lens users.  A 20MP APS-C sensor will record the image on all 20MP, whereas to get the same FoV the FF sensor of the same capacity would have the effective sensor area reduced by the square of the crop factor.  The image capture of the smaller sensor is thus quite different from using a FF sensor and cropping it afterwards, either in PP or by taking a print and a pair of scissors, although the latter would reduce the final print area, whereas cropping in PP would allow one to produce a print of the same dimensions as a fully-captured image, albeit in reduced resolution.

Let me be clear, the image collected by the smaller sensor is not magnified at the point of delivery to the sensor - that is determined completely by the lens and that never changes: that magnification factor is consistant to all sensors. 

When the image is magnified is when it is taken and delivered either to a screen or a print, in comparison to the image area captured by a FF sensor.  That was shown in the diagram with the two birds.  Thus, if one takes the image from a FF sensor and produces, say a 10x8 image, it will appear to have a wider FoV compared to that of a 10x8 print of the same subject  from a smaller sensor.

So, argue against the terminology if you will, but we need some kind of identifier to describe the relationship between the image areas captured by the different sensor sizes.  The physics are demonstrable and clear: the terminology should not block us from recognizing that.   That is why the term Equivalence has been invented and that is why it should not be ignored.

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@ebiggs1 wrote:

Trevor, 

That's a fine article but I will take exception with. a "crop" sensor camera it does not crop anything. It only appears to crop if you intend on comparing it to a 35mm sized camera.  Most people today do not even think that and have to be told they have a crop sensor camera. All cameras give exactly what you see in the view finder or LCD.  They are all essentially full frame cameras.

I know some manufacturers tend to keep this falsification going, too. If you never intend on owning or using a FF camera, it is totally confusing and useless.  If you are an advanced or even just a hobbyists and have several bodies I suppose you can make a case for comparing equivalent focal lengths. However, IMHO, totally unnecessary which is born out by the fact guys that use medium or large format gear don't do it. Although they certainly could but would have to use an "enlargement" factor.

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[ebiggs1]

"Ernie suggests that considering the impact of smaller sensors is only valid for those using both FF and crop sensors and that is not my experience ...I have seen it with students I have taught."

However it is my experience.  People have to be taught crop "theory". And, I am guilty because I have done it in my DSLR 101 classes myself. And, I have come to regret it as I mature, too. The biggest misconception is a crop sensor actually crops a picture. It does not crop anything. You can cite as many sources as you wish as I have already conceded that this, IMHO, nonsense is propagated by several sources.

Trevor we are going to have to agree on this subject we disagree. All the advantages, or disadvantages, you make are physical characteristics of the sensor. They do not and have no relationship to any other sensor unless you want to, or think you need to, compare them. It is more of a use the right tool for the job. I guess it is human nature to think they need to compare all things to other things. They seem to do it a lot.

[Tronhard]

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@ebiggs1 wrote:

"Ernie suggests that considering the impact of smaller sensors is only valid for those using both FF and crop sensors and that is not my experience ...I have seen it with students I have taught."

However it is my experience.  People have to be taught crop "theory". And, I am guilty because I have done it in my DSLR 101 classes myself. And, I have come to regret it as I mature, too. The biggest misconception is a crop sensor actually crops a picture. It does not crop anything. You can cite as many sources as you wish as I have already conceded that this, IMHO, nonsense is propagated by several sources.

Trevor we are going to have to agree on this subject we disagree. All the advantages, or disadvantages, you make are physical characteristics of the sensor. They do not and have no relationship to any other sensor unless you want to, or think you need to, compare them. It is more of a use the right tool for the job. I guess it is human nature to think they need to compare all things to other things. They seem to do it a lot.

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Ernie my friend, you know that I have great respect for you and I believe you reciprocate that - certainly, there must be room for two divergent issues to be debated in open forum: it's part of a healthy society as long as we question the issues and not the individuals - and both of us have shown respect in this I think. 

Our views simply reflect the situation in the wider photography community.  I understand that you are saying that if one simply sticks to the format that what one sees in the viewfinder is what one gets, and for the vast majority of cases that is true.  Although, speaking for myself and a few of my associates who shoot across multiple formats, we are aware of these issue.  Nevertheless, the physics ARE there and under certain circumstances it will rear its head.  Thus, my view is that while it is not necessary for everyone to address this, when it rears its head it needs to be recognized for what it is and dealt with.  I find it particuarly comes to light at my university courses where I have a group of savvy students who are aware of the physics and want to explore the issues involved - I cannot just ignore that.

This very thread highlights a new aspect in this debate...

Before, my experience with the issue was people buying lenses for APS-C, etc. bodies based on their indicated focal length (and by implication, FoV) and then being disappointed at the wide end in particular because they did not get that FoV involves the interaction of the lens and the sensor.   While you or I would say that one should try before you buy, a certain number do so on-line - especially with current restrictions for walk-in commerce around the world. In many countries being able to return an item because the wrong one was chosen is quite limited.

In this current case we have a FF body of 20MP that anyone can NOW attach any EF-S lens to: a lens specifically designed for APS-C bodies with that reduced FoV, and thus losing about 60% of their resolution, because of the cropping of the image - clearly explained in the R6 manual. This also happened previously with some 3rd party lenses that were agnostic in their lens construction and did not foul the path of the mirrors in either FF or APS-C bodies, but that was a) comparitively rare, and b) glaringly obvious because of the massive vignetting that resulted.  Now, the issue comes with ANY native Canon APS-C lens, of which there is a mind-blowing number of out there.

This issue is a lot more subtle because the camera corrects the FoV and thus the resolution before the user is even aware of the phenomon.  One could still argue that ignorance is bliss, but not if it comes to light when the images are going to be used for display or print.

I refer to P866 of the R6 user manual:

Clearly Canon consider this an issue worth of attention to dedicate the documentation, (although I think the use of AoV reinforces my view on less than precise terminology) but I suspect that most people will not stumble upon that until they try to figure out why their images have such low resolution.  For many, shooting for social media, this may not even be an concern, but others will be perplexed and frustrated at this apparent anomaly without the context that I am expressing.

[ebiggs1]

"Clearly Canon consider this an issue worth of attention to dedicate the documentation, ..."

A lot of this is controlled by the bean counters. If they think people want this info they will print it. It really has nothing to do with, do they "need" it. The bottom line is and has always been, if you aren't going to compare your lenses to other camera formats, it is totally unnecessary. Far better to just stick with what you gear does and how it behaves on your gear.

I don't hoot croppers so I never give any of it a thought. And, so do all the folks that buy a Rebel and just want nice photos. The reason it is such a mess is most folks don't really care. Bottom line, my friend.

[ebiggs1]

Maybe my point isn't coming across. I am not disputing the information or its accuracy, I am claiming it isn't necessary. The only people that care about this stuff are like you. Me too, at one time but as I watched most people's eyes gloss over when you try to bring it up. Folks like us, a long time ago in my case, delve into the inner workings and have several cameras but most folks don't. They just want nice photos and don't care how it might look or work or be transformed on a different format camera.