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Respected Contributor
Posts: 1,029
Registered: ‎10-18-2016

Re: RF adaptor

[ Edited ]

@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.

 

 


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. Smiley Happy

 

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:

R6 Manual on Cropping.jpg

 

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.

 

 

cheers Trevor

"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
"A good swordsman is more important than a good sword" Amit Kalantri

Technique will always Outlast Tech - Me
Forum Elite
Posts: 14,424
Registered: ‎12-07-2012

Re: RF adaptor

"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.

EB
EOS 1DX and 1D Mk IV and several lenses!
Forum Elite
Posts: 14,424
Registered: ‎12-07-2012

Re: RF adaptor

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.

EB
EOS 1DX and 1D Mk IV and several lenses!
Respected Contributor
Posts: 1,029
Registered: ‎10-18-2016

Re: RF adaptor

[ Edited ]

@ebiggs1 wrote:

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.


Ernie, I think you and I actually both agree that for the vast majority of people this is a non-issue.  I have never disputed that.  I have simply maintained that the phenomenon IS actually true - which you seem to concur with - and that for some people it is an issue.  While I am responding to you, I am aware that others are reading this, so I am not trying to insult you by stating what you may consider is obvious.

 

I think here, it is apropos to comment on the inadequacy of terminology in discussing the results of the behaviour of lens+sensor combinations. For a start, let's get rid of the nomenclature issue:  like it or not, way back when digital came in the term Full-Frame was associated with standard 35mm film-sized sensors.   My research indicates that this was because of the dominance of that format in the stills film industry, within which most consumers and a significant number of professionals did their activities.  The terms 'medium format' and 'large format' had been well-established for quite some time before that.  The rise of the APS film format heralded a new subset of the film industry, but it was essentially killed off by the fast development of digital.  Nevertheless, it gave a name to the 1.5-1.6 crop sensor format, considering the similarity of their respective sizes and has been extended to all smaller sensor formats.

 

The term "crop" referred to a sensor's reduced ability, in comparison to the FF format, to capture an image from a constant AoV.  What I call the Field of View (FoV), is the area recorded by the sensor.  An APS-C sensor, being relatively smaller than that of the FF sensor, reduces the FoV captured, so in that context the term 'crop' as relating the output of the two formats was not unreasonable. Cropping on the captured image goes way back to the earliest large-format cameras, where there were full plates, half and quarter plates and then the multiples of exposures on one plate for cartes de visite, popular in the latter part of the 1860's - so this has history.

 

In the early digital cameras for example, Canon's first home-grown DSLR was the D30, had an APS-C CMOS sensor, and used only EF lenses which resulted in a smaller FoV compared to the same lens on 35mm film camera.  Like it or not, it became well established as a colloqual term, if not a genre. So, for simplicity's sake, I shall use the terms rather than search for something else.

 

For me, based on the questions and discussions to which I have been a party, the issue  appears under the following condition:  where outputs crop sensor and lens combinations are compared to the behaviour of FF sensor and lens combinations, and where people are considering the focal lengths of lenses as their only criteria.   As we all agree, a lens has a given focal length and aperture and they don't change.  But the lens is not the only element in deciding what is captured as an image - which is what a photographer wants in the end, after all. 

 

To tidy up the delivery path terminology as I understand it: the resultant image is initially defined by the focal length, producing a given AoV - measured in degrees or radians, but then the sensor size comes into play and it takes that potential and captures a specific area of that cone of delivery, determined by the sensor's dimensions - so to me it could be measured as either an angle (as we see in binocular design, or by dimensions, which seems more logical considering we are looking at producing some kind of image on a medium: ie. either a screen or a print - that I define as the Field of View, and for a 'crop' sensor it is considerably smaller that that of a 'FF' sensor.  Measuring the output performance of a sensor+lens combination should not be based soley on lens focal length, but it has become a general misnomer to do so, and FoV (or any other appropriate term someone could invent) rarely comes up in the documentation or discussions.  What is controversially called and Equivalent FL needs an agreed term and that used to quantify the performance of the image capture.  Equivalence is used somewhat inconsistenly in documentation and artlicles in an effort to reconcile this.

 

As you very correctly point out, a huge mass of people using cameras will look through the viewfinder and consider what they choose to include in their FoV, based on what they see rather than the numbers.  No argument there, but for a certain constituency there are issues, and it is in that context that I have responded to the OP.

 

In my experience, the cases where this rears its head, in practical terms, include:

1. Someone with a crop-sensor camera was starting up in real-estate photography.  They were looking for a super wide-angle lens for interiors and they looked at a lens that was recommended by someone who had a FF camera.  Based on their viewing of the images they saw looking through the viewfinder of the FF camera, that person purchased the same lens, but was very disappointed to discover that the width of coverage was much less, because they were using a camera with a smaller sensor.  Apparently neither of the two parties had any idea that the FoV changed with sensor size, and this resulted in the one the APS-C camera not getting the return on the investment they wanted.

 

2.  At the other end of the scale.  I do most of my shooting at the super telephoto end.  I have a Canon EOS 5DMkIII camera but I prefer to use the 7DMkII to shoot wildlife because of the fact that the reduced FoV of the 7D crops the image before it is recorded.  Sure, I could crop the image of the 5DIII afterwards, but since they both have about the same number of photo receptors they produce images of about 21MP.   The 7DII gives me the full 21MP on the resultant image, whereas the 5DIII would have effectively had its image cropped in PP to the same FoV reduced that to around 8MP.  In other words, I have greater pixel density for the same image outpuit which gives me more potential to crop the image further or produce larger prints.  A lot of photographers like me prefer crop sensors for that specific reason.

 

3.  In this particular thread, the OP was specifically inquiring about using AF-S lenses designed for crop-sensor bodies on his FF R6. It was that that brought to the fore the question of how those lenses would behave on the R6 body, which is not just a case of putting one on the adaptor and getting a 20MP image - which is what the unwary might expect when they bought the body.  Previously, that combination of APS-C lens and FF body would not have been possible with native Canon glass, although some other 3rd pary lenses would have permitted that.  Essentially, the new mirrorless design, coupled with the adaptor, has made possible the merging of the two lens technologies into the same body. 

 

Now with this new arrangement, one can put a Canon lens designed for a crop sensor body, onto a FF body, but because of the distance of the rear element being closer to the sensor, the FoV captured will remain smaller.  If Canon did not have software to compensate for that the resultant image would have massive vignetting, but they do have such a fix to tidy up the image. Essentially, sofware is now manipulating the image delivered by the EF-S lens and resulting in a tidy cropped image.  That is a new phenomenon on Canon cameras, but not on Nikon for example.  One could put DX lenses designed for their APS bodies on a FX (FF) body, but Nikon clearly stated that the resultant image would have major vignetting - i.e. cropped.  So, now we are not talking about someone simply playing with the numbers, we are looking at practical issues.  If someone had a body with a 20MP APS-C sensor, they are going to get considerably less resolution out of the R6, which is likely not what they were expecting...

 

For example I have a EF-S 60mm macro lens and an EF 100mm macro lens.  If I simply had a Rebel or other APS-C body, they would have rendered FoV's Equivalent to 96mm and 160mm respectivley - giving me different results.   If I had a FF DSLR body only, I could only have used the EF100mm lens and got 100mm out of it.  However, now both lenses can go on the same body, but if I put them on my R6 body they will render FoV's of 96 and 100mm respectively, which are almost the same!

 

Not only that, but the quality of the image will be different.  The image from the EF-S 60mm will be around 8MP, while that of the 100mm EF lens will be 20MP.   Depending upon what the user does with the image that could be significant.  This is not just an academic numbers game, I expect that there will be a constituency of people moving up from APS-C to R FF bodies with APS-C lenses that know they can use an adaptor but don't twig on the implactions to their FoV and image resolution.  Sure, if they just limit themselves to looking through the viewfinder they will see a corrected FoV, but the image size will be nowhere near the advertised 20MP - I expect at least some will notice that.

cheers Trevor

"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
"A good swordsman is more important than a good sword" Amit Kalantri

Technique will always Outlast Tech - Me
Occasional Contributor
Posts: 21
Registered: ‎02-05-2016

Re: RF adaptor

You may remember I initiated this thread at the start of the year.

I finally purchased a mirrorless camera and decided on the R as, unfortunately, I could not afford the R6 whoich I would have preferred. However, I can confirm that the adaptor works well with my 100 - 400 as does the 2 x converter with the camera's autofocus - so all in all very pleased.

 

One thing though. With the 2 x fitted, the IS on the 100-400 lens appears not to be working. Should it be compatible?

Frequent Contributor
Posts: 50
Registered: ‎10-16-2016

Re: RF adaptor

Have you used that lens + extender on another camera? I don't have a 2x converter but have used the 1.4x converter with the 100-400 mark II on my R, and IMO, the longer the zoom, the less I can tell the IS has kicked in or it takes longer for me to notice it. Also, is your camera firmware up to date?

Respected Contributor
Posts: 1,029
Registered: ‎10-18-2016

Re: RF adaptor

[ Edited ]

It would help to know what version of the 100-400 you are using: the Mk I is quite old - released in 1998, while the MkII was release in 2014.  The version of teleconverter is even more critical.  There are big differences on how AF and AE work with different combinations of camera body, lens and teleconverter, so your description of components needs to be very precise. 

 

I have the 100-400MkII, and the 1.4 and 2.0 MkIII teleconverters.  I shot with a Canon EOS R6 (I don't have an R) - hand-held.  I have used the 2.0 teleconverter (extender) and had no issue with focus.  The minimum f/stop is f/9 FWTW - I actually shot at f/10.

 

At 100mm (now 200mm)

_62_2067 copy.jpg

 

At 200mm (400mm)

_62_2066 copy.jpg

 

At 400mm (800mm)

_62_2064 copy.jpg

cheers Trevor

"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
"A good swordsman is more important than a good sword" Amit Kalantri

Technique will always Outlast Tech - Me
Occasional Contributor
Posts: 21
Registered: ‎02-05-2016

Re: RF adaptor

Thanks for the replies.

the lens is he older mark 1. It works fine on my 7D so I was wondering what effect the rf adaptor has on the IS.

It may be working, but it doesn't have the same immediate 'lurch' as I am used to. I've only just got the camera so lots more shots to take before I can give a better review of what's happening.

Frequent Contributor
Posts: 50
Registered: ‎10-16-2016

Re: RF adaptor

I agree that unfortunately it's probably the older electronics. I have an EF 300mm f/4 L (released 1997), and when paired with my R and my R5 I found it disappointing in a number of ways. On the other hand, my "newer" EF 100-400 mk 2 gives excellent results. I don't think the adaptor is to blame but the improved technology and resulting different electronics from when those lenses were designed. I'm currently on preorder for the RF 100-400, which isn't an L lens but I'm buying it because it weighs 1.4# vs 4# for the L and will be much easier for me to take on long walks.

 

You'll enjoy your R--it's a terrific camera. Two of the many things I love about Canon's mirrorless are the FV mode and that I can move the focus point around with my thumb while looking through the VF. And of course quality of images!

Highlighted
Forum Elite
Posts: 14,424
Registered: ‎12-07-2012

Re: RF adaptor

Once again Trevor, great shots. Beautiful!

EB
EOS 1DX and 1D Mk IV and several lenses!
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