yet a crop vs. full frame question (500mm f4 + 7d) vs. (500mm f4 + 1.4x + 1dx)

[bluenoser1993]

As I said, smaller sensors have shallower DOF at the same aperture, f/stop, and subject distance. The amount of magnification required is more which makes the CoC smaller.

7D2 + 400mm f/4 subject distance 50m: 2.36m of DOF
1Dx + 400mm f/4 subject distance 50m: 3.73m of DOF

If we do it in real-life and actually MOVE 1.6x closer for the FF, then the FF is shallower.

1Dx + 400mm f/4 subject distance 31m: 1.45m of DOF

No matter what, the DOF is different.

We hold constant the viewing size and the viewing distance of the image.

Very sorry. In the previous statements you didn't actually say the crop would have shallower DOF when shot at same distance and focal length, just different. So I made the ignorant assumption that you meant greater DOF in that situation. I completely agree with what you've said here and I'm glad you clarified before I put my foot even deeper!

 

[bdunbar79]

Oh for heavens sakes it's no big deal, no need to apologize. I wasn't clear in my first posts at all I agree. Good discussion.

 

[jdramirez]

If I can hijack the thread a little... I'm wondering if I'm better off going t4i + 70-200 f/2.8L IS mkii + 1.4x mkiii or 5d mkiii + 70-200 f/2.8L is mkii + 2x mkiii... I'm just hanging out in the outfield video'ing my daughter at bat... then she she gets a hit... zooming from 200 to 70 (plus the convertor) and watching her round the bases...

My thinking is that I'd rather destroy a t4i with 1/1000 of a shutter in daylight recording 10 minutes of game footage per game.. 2-4 games per day... than put the stress on the 5d mkiii.

I think the video quality will be good enough with the t4i... 1080p, 30 fps, but maybe I'm just making assumptions that are way off base.

Sorry to jump in with my own full v. crop question... but I'm good with one answer... I don't think it requires a whole thread...

 

[faustino]

If I can hijack the thread a little... I'm wondering if I'm better off going t4i + 70-200 f/2.8L IS mkii + 1.4x mkiii or 5d mkiii + 70-200 f/2.8L is mkii + 2x mkiii... I'm just hanging out in the outfield video'ing my daughter at bat... then she she gets a hit... zooming from 200 to 70 (plus the convertor) and watching her round the bases...

Your question is in line with mine and adds an additional pertinent example. Thanks.

 

[faustino]

The 1Dx/800mm combo in your scenario would be sharper than the 7D2/500mm combo, ASSUMING everything else is equal

I understand, I am coming to the conclusion that this is the reason why the full frame combo is actually superior to the crop combo.

 

[faustino]

To get a better understanding, please let me simplify my question, even if, in part, I am going to repeat myself.


I am trying to understand wether the following "equivalence principle" is correct or not, and why.


The principle would state that the following two combos (Full Frame and Crop) would be perfectly equivalent and would give the same identical image:


Full Frame:
----------------------------
Camera sensor: 20mp, full frame, ISO 8000
Lens: 400mm, aperture setting F8.0
Shutter speed: 1/2000
Distance from subject: 20 meters filling the frame


Crop:
----------------------------
Camera sensor: 20mp, 1.6 crop, ISO 3125 (it is 8000 divided by the square of 1.6; we may set the camera to 3200 and tweak in post production)
Lens: 250mm, aperture setting F5.0 (it is 8.0 divided by 1.6)
Shutter speed: 1/2000
Distance from subject: 20 meters filling the frame


Assuming the lens to be excellent in both combos (both focal length may be obtained with the excellent EF100-400ii), do you think we will notice any difference in the final output?


What if I add the 1.4x iii extender to the full frame combo in order to get the 400mm focal length? (I know it would be not needed, it would be just to make the comparison closer to what I actually want to compare: "going crop" or "going extender")


Thank you for your replies, I will really appreciate getting a clear understanding on this topic.

 

[bdunbar79]

It would be my opinion, and my opinion only, that the FF choice would always be superior. I'm repeating things you already know of course, but if I put 20 MP's on subject with a 1Dx2 and 640mm lens at subject distance X and put 20 MP's on subject with a 7D2 and 400mm lens at subject distance Y, I think the FF will always be sharper. ANY differences in ISO (ISO likely doesn't compare with noise in a linear fashion between two differently sized sensors) will always keep making the crop worse. The differences will always influence the crop image worse than the FF image. You can set "equivalent" ISO's and apertures of course and follow theory but my observations is that the affect on crop is as I mentioned, worse. Let's say you set ISO 8000 on the 1Dx2 and 3200 on the 7D2. If the 7D2 has slightly less QE (which it probably does) then it is a little noisier, for instance, than theory would predict.

Assuming equal lens performance, and of course that is a big if, more magnification and less ISO ability will always hurt the crop image vs. FF, which has better ISO ability and requires less magnification.

 

[Loswr]

Practical summary: you can contrive situations in which APS-C will deliver better IQ. Generally speaking, the best-case is they deliver similar IQ, and in many common scenarios FF will be better. APS-C costs less.

 

[Mikehit]

Suppose you have an image of a bird that covers 5MP on the 7D2 sensor and engineer situation that you can get the same image covering 5MP on a FF camera, then the FF image will IMO generally be superior if only because of the superior noise performance of the FF sensor and the greater tonal range of the larger pixels.
However, what people forget in these discussions is you must also be aware of sensor generation (technology) and the processing engine in the camera - nowadays the recording medium (unlike film) does not work in isolation.

Interestingly Art Morris compared the 7D2 and 5D3 and found the 7D2 was equal (maybe better) at a much lower price
http://www.birdsasart-blog.com/2014/10/19/eos-7d-mark-iieos-5d-mark-iii-comparison-they-thought-that-it-would-be-easy/

However the evolution of the 5DSR has swung him back the other way because of the greater pixel count in focal-length limited situations.

 

[faustino]

Bdunbar79, I believe your point is correct, the full frame combo will be sharper even if we add the 1.4 extender in the optical path. I got a confirmation selecting two comparisons on the-digital-picture site, which shows a better sharpness on the FF combination vs the crop:


http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=972&Camera=963&Sample=0&FLI=4&API=1&LensComp=972&CameraComp=453&SampleComp=0&FLIComp=5&APIComp=2

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=962&Camera=963&Sample=0&FLI=0&API=0&LensComp=962&CameraComp=453&SampleComp=0&FLIComp=1&APIComp=0


The autofocus on the FF would be penalised because of the extender, but, as Neuro stated, the 1dx better system should compensate for that (and I tend to believe it is true).


So I made my final decision: I will not buy the 7d, but use the 1.4 extender on the FF camera instead.


Thanks.

 

[bdunbar79]

Suppose you have an image of a bird that covers 5MP on the 7D2 sensor and engineer situation that you can get the same image covering 5MP on a FF camera, then the FF image will IMO generally be superior if only because of the superior noise performance of the FF sensor and the greater tonal range of the larger pixels.
However, what people forget in these discussions is you must also be aware of sensor generation (technology) and the processing engine in the camera - nowadays the recording medium (unlike film) does not work in isolation.

Interestingly Art Morris compared the 7D2 and 5D3 and found the 7D2 was equal (maybe better) at a much lower price
http://www.birdsasart-blog.com/2014/10/19/eos-7d-mark-iieos-5d-mark-iii-comparison-they-thought-that-it-would-be-easy/

However the evolution of the 5DSR has swung him back the other way because of the greater pixel count in focal-length limited situations.

I'm not even sure pixel size matters nearly to the degree sensor size matters. The 7D2 and 5Ds have the same pixel size, but the latter is superior in image quality. AlanF tested even cropping the 5Ds to 20 MP and still found it to be better. I suppose in those situations though, the difference might have no practical meaning. Just another thought.

 

[Ozarker]

My choice would be to go with the 1DX Mark II and use what would have been spent on the 7D mark II for a gimble or something.

I keep thinking I want a 7D mark II for birding and sports. But nawwww. If I had the $$$, and apparently you do, I'd go 1DX Mark II all the way.

I still want a 7D mark II, but I ain't gonna do it, I ain't gonna do it, I ain't gonna do it, I ain't gonna....

Gonna go take my meds now.

 

[takesome1]

I didn't read every response because I settled this in my mind years ago.

The simple answer is the 7D II would only be superior in the situation where you have to crop or use an extender.
It would be lacking in any situation where you can fill the full frame of a full frame sensor.
The 1Dx and II will have better AF, better ISO performance.
There are more negatives than positives.

I had the 7D II on my 500mm for one reason, resolution. If I wanted frame rate or AF accuracy I used my 1D IV. After I bought the 5Ds R that reason went away. With the 1DX II pre-orderd and since it will do 4K video, once I receive it I doubt I have much use at all for my 7D II.

 

[gpolly]

Guys,

This is not a great shot, but i carry a 5d mark2 and a 7d mark 2....for just this reason.

This shot was taken with the 7d2 with the 100-400 II. 1/2500, 5.6 ISO 320 at full 400mm. I love the extra reach of the 7d gives in relation to full frame.

this was taken at jaws in maui last week. I am on shore on a cliff well out. this is a 50% crop no modification just raw to jpeg. 50% crop due to file size limits.

 

[Loswr]

This shot was taken with the 7d2 with the 100-400 II. 1/2500, 5.6 ISO 320 at full 400mm. I love the extra reach of the 7d gives in relation to full frame.

In relation to your full frame camera, you mean. The 7DII does not offer any 'extra reach' in relation to the full frame 5DS, for example.

 

[gpolly]

yes in relation to full frame.

I shot 35mm for 30 years and still carry my EOS-1 HS....my mind still processes everything in full frame. So in my mind I base everything I do from a full frame perspective. this crop, sensor side has been hard for me to adjust, used to doing that stuff in the dark room.

glad I don't have to use the darkroom anymore. 8)

 

[Loswr]

yes in relation to full frame.

I shot 35mm for 30 years and still carry my EOS-1 HS....my mind still processes everything in full frame. So in my mind I base everything I do from a full frame perspective. this crop, sensor side has been hard for me to adjust, used to doing that stuff in the dark room.

glad I don't have to use the darkroom anymore. 8)

The point was that what you're talking about is pixel size, not sensor size, and there are trade offs. The 5DS is a FF camera with the same pixel size as the 7DII, and the 7DII does not offer any comparative reach advantage.

Consider the PowerShot SX60 HS, which gives you 1365mm of 'full frame reach' with only a 250mm lens.

 

[gpolly]

Sorry, i thought the discussion also was referring to sensor size.

I am not a fan of the 5Ds, either model. I can only see it used as a studio camera or landscape. tripod use almost required for razor sharp pics.

The 5ds and the 7d2 bodies are not design for the same use. technology aside on pixel size, these is almost no reason I would consider using one camera or another in a similar situation or even compare them. the 5ds would fail terribly in high speed sports situations. the 7ds would fail in studio or architectural shots in comparison to the 5ds, esp with ultra wide lens.

 

[Loswr]

I am not a fan of the 5Ds, either model. I can only see it used as a studio camera or landscape. tripod use almost required for razor sharp pics.

The 5ds and the 7d2 bodies are not design for the same use. technology aside on pixel size, these is almost no reason I would consider using one camera or another in a similar situation or even compare them. the 5ds would fail terribly in high speed sports situations. the 7ds would fail in studio or architectural shots in comparison to the 5ds, esp with ultra wide lens.

Art Morris – renowned bird photographer and former Canon Explorer of Light (before he switched to Nikon then back to Canon – doesn't do much studio or landscape photography, but is an expert in avian photography particularly birds in flight. He now prefers the 5Ds R. That's a far cry from 'failing terribly'.

 

[gpolly]

Wow that is a surprise. I have not heard much success with those bodies with shots like that. that is really good to hear. I have heard a lot of gripping on softness with those bodies. I want to upgrade the 5dm2....just sitting on the fence with that.

to be honest it took my a year to learn the new auto focus on the 7dm2 before i starting to get 90% hits on focus. out of the box i only got about 20%, was not very happy at first. really like that thing now.