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

[faustino]

Sorry for it, but I have question that may again raise the crop vs. full frame discussion.


I own a 500mm f4ii and I am wandering which would be the best setup if I need additional reach among the two options, crop vs. full frame:


CF: attaching to the lens a 7dii
FF: attaching to the lens a 2xiii and a 1dxii (a setup equivalent to a 700 f5.6 lens)


I know that the full frame option gives a setup equivalent to a 700mm f5.6 lens on a 20mp sensor, while the crop option will give a setup equivalent to an 800mm f6.4 lens on a 20mp sensor (somewhat different).


Apart from the difference in the equivalent focal distance and aperture, is there any major advantage of one setup vs. the other?


The question is not theoretical for me. I will later this year buy a 1dxii, and I was thinking to buy also a 7dii to be almost permanently attached to the 500mmf4ii, except from when I need less reach, when I would use the 1dxii.


Thank you very much for your recommendations!

 

[Loswr]

FF: attaching to the lens a 2xiii and a 1dxii (a setup equivalent to a 700 f5.6 lens)

I know that the full frame option gives a setup equivalent to a 700mm f5.6 lens on a 20mp sensor,

Please clarify - 500mm + 1.4x = 700mm f/5.6, 500mm + 2x = 1000mm f/8.

With the 1D X II, I'd choose the 500 + 2x since you'll retain full AF capabilities at f/8, and have more reach and better IQ.

 

[faustino]

Thank you Neuro; anyhow, the question I would like to solve is a little bit different.


1000mm would be too much reach, 700 or 800 is in the range that I would like to shoot at.


I am not saying that the crop setup is better (I moved to full frame for a reason years ago). I tend to believe that it will be more or less equivalent:


My understanding is that the crop will have a little bit more "equivalent focal length" (800 vs. 700) but less "equivalent aperture" (6.4 vs. 5.6). Apart from that, the autofocus on the 7d should work somewhat better, because it will get more intensity of light on the sensors (f4.0 vs. f5.6); but maybe it will work worse because the 1dxii has a such better autofocus that will beat the 7d even getting less intense light (but I doubt about this).


Apart from the above consideration, is there anything that I should add to the comparison to make a correct choice?


My choice will be whether to buy a 7dii for the only usage of attaching it to the 500mm or not.


The advantage would be to have the setup In the range of 700-800mm f5.6-f6.4 (equivalent parameters) without needing to pull out the 1dxii.


Another advantage should be (but I am not sure) that the autofocus of the 500+7d should perform better that that of the 500+1.4+1dx. Do you believe is this conjecture correct?

 

[j-nord]

You want to know which is better and why:

500mm f4 ii + 7Dii = 800f6.4
vs
500mm f4 ii + 1.4xiii + 1Dxii = 700f5.6

Does this sum up your question? What are you shooting?

I don't have experience with this hardware but I imagine the 7Dii combo would focus slightly faster since it doesn't have the 1.4xiii. If you shoot low/poor lighting conditions the 1Dxii will produce better images. The 7Dii will allow you to shoot at f4 but the blur/bokeh/aperture will be similar to f6.4 equivalent (but you are using a longer equivalent focal length). If you'd have to crop more with the 1Dxii combo then, the 7Dii combo will get more pixels on the subject.

 

[TeT]

FF: attaching to the lens a 2xiii and a 1dxii (a setup equivalent to a 700 f5.6 lens)

I know that the full frame option gives a setup equivalent to a 700mm f5.6 lens on a 20mp sensor,

Please clarify - 500mm + 1.4x = 700mm f/5.6, 500mm + 2x = 1000mm f/8.

With the 1D X II, I'd choose the 500 + 2x since you'll retain full AF capabilities at f/8, and have more reach and better IQ.

yOu think the 1dxII can pull out better IQ at 2X ? Granted we are looking for fleas on a giraffe to find a difference... but that would be impressive.


THe 1000mm itself would be enough to choose the 2X and at 1.4X the IQ nod is even more in the 1DXii corner...

 

[Loswr]

I don't think you'll see any difference in AF performance between f/4 and f/5.6, unless you're shooting in near-dark conditions. I suspect the native 1D X II AF will be better than the 7DII, and that adding the 1.4xIII with the 1D X II will put it in equal footing with the bare lens on the 7DII (1-series bodies focus faster, the TC will slow it down).

I have no doubt the 1D X II + 1.4x will deliver better overall IQ than the 7DII.

 

[Skatol]

Please forgive my ignorance but the crop aperture vs. full frame aperture numbers do not make sense to me.
F/5.6 is f/5.6 regardless of the sensor size. DOF is determined by aperture and distance to subject. If the goal is to shoot from the same distance then DOF will be the same on each setup. The crop sensor will have less area around the subject hence the "crop".

As to the original question, I would prefer the 1DX option for the F/8 capability on all points and spot metering linked to any AF point.

The plus for the 7D is having more pixels on target providing more detail.

 

[Mikehit]

There are so many aspects to the term 'better'....image quality, sensor quality, AF capability, ISO capability etc etc

If the 1dx2 is feasible I would go for that and the 7d2 would not get a look-in. Why? For so many reasons - superior AF is one but mainly because the because all batteries are not created equal and the battery in the 1dx will drive the AF mechanism in the lens much better.
From everything I have read and seen. I would go so far as to say that the 1dx+1.4tc when cropped will beat the 7d2 plus 1.4tc. I live in Manchester UK (latitude above Vancouver) and the 7D2 has its limitations - I would love the low light capabilities of the 1dx.

I have followed comments from 2 people quite closely over the last couple of years: Arash Hazeghi who shoots with a 1dx and Art Morris who until recently shot with a 7D2 - the latter says he prefers the 1dx but for him the bulk and weight of the 1dx are impractical. So really it all comes down to what compromises you are willing to make.
I think the 7D2 would be an excellent second body but given the choice for me it would be idx without question.

 

[Mikehit]

Please forgive my ignorance but the crop aperture vs. full frame aperture numbers do not make sense to me.
F/5.6 is f/5.6 regardless of the sensor size. DOF is determined by aperture and distance to subject.

If you are shooting birds, the chances are you will end up cropping whether using APS-C or FF body. In this case the image of the bird is the same size on the sensor and what you are saying is totally true because the ratio of image size to final viewing size will be the same.
If, however, you are shooting (for example) large mammals and getting a frame-filling image means wither using a different lens or changing the distance to the subject then the APS-C will have a deeper DOF.
This is where the discussions get so fraught

 

[Skatol]

Please forgive my ignorance but the crop aperture vs. full frame aperture numbers do not make sense to me.
F/5.6 is f/5.6 regardless of the sensor size. DOF is determined by aperture and distance to subject.

If you are shooting birds, the chances are you will end up cropping whether using APS-C or FF body. In this case the image of the bird is the same size on the sensor and what you are saying is totally true because the ratio of image size to final viewing size will be the same.
If, however, you are shooting (for example) large mammals and getting a frame-filling image means wither using a different lens or changing the distance to the subject then the APS-C will have a deeper DOF.
This is where the discussions get so fraught

This is how I understand it. It seems some confuse the matter assuming the framing is identical. In this case DOF will change because you have to be physically further from your subject with a crop sensor to obtain the same framing. This however does not change the aperture value.

 

[faustino]

Thank your for the additional comments, the points on the autofocus are very interesting:

I imagine the 7Dii combo would focus slightly faster since it doesn't have the 1.4xiii.

I suspect the native 1D X II AF will be better than the 7DII, and that adding the 1.4xIII with the 1D X II will put it in equal footing with the bare lens on the 7DII (1-series bodies focus faster, the TC will slow it down).

If I decide to buy also the 7d I will try to find a way to test the difference in performance and post the results.

 

[faustino]

You want to know which is better and why:

500mm f4 ii + 7Dii = 800f6.4
vs
500mm f4 ii + 1.4xiii + 1Dxii = 700f5.6

Does this sum up your question? What are you shooting?

Yes, it is exactly my question.


I will shoot bird in flight and small running mammals. My settings for shutter speed will force to stay in the range of ISO 3200 at those apertures (f4) on the 7d, so I will not want to further reduce the aperture below f4 on crop or f5.6 on full frame (because I would need to raise the ISO further or reduce shutter speed); also the focal length will be at the maximum for me to be able to follow the subject, above that range I would struggle too much in trying to find the subject (I experienced with the 5dm3 that I am using currently with all combinations - bare lens, 1.4x, 2.0x).

 

[faustino]

the crop aperture vs. full frame aperture numbers do not make sense to me.
F/5.6 is f/5.6 regardless of the sensor size.

It is true that f numbers and focal length remains the same whatever the sensor size is, I fully agree and will never state the contrary of that simple truth.

Anyhow, it is also true that there is a perfect theoretical equivalence between the following two:
a 500mm f4 lens projecting light on a 20mp 1.6 crop sensor set at 3200 ISO
and a 800mm f5.6 lens projecting light on a 20mp full frame lens set at 8192 ISO (theoretical iso setting, I know)


I would get everything equal: same noise, same pixels on subject, identical depth of field, identical perspective, same apparent reach... identical image.


What I am not sure is wether that theoretical equivalence holds in practice or not. And, if it does't hold true, I struggle in understanding why it is the case. And if it is true, I would find myself writing that the 800mm+1dx is like the 500mm+7d, which I understand is a quite puzzling statement
Thanks again for any clarification you can provide.

 

[bdunbar79]

This discussion always gets confused. Even if you don't move, the DOF is different. Suppose I have a 7D2 with a 400mm lens and shoot a subject at 50m at f/4. If all I do is change to a 1Dx, and don't change anything else, and keep it at f/4, the DOF values will be different because to get to the SAME output size, the smaller sensor has to undergo a larger enlargement ratio than the FF sensor. From a light-gathering perspective (pun intended) yes, f/4 is f/4. But from a DOF perspective, it is not even when the ONLY thing you change is sensor size.

 

[AlanF]

There are so many aspects to the term 'better'....image quality, sensor quality, AF capability, ISO capability etc etc

If the 1dx2 is feasible I would go for that and the 7d2 would not get a look-in. Why? For so many reasons - superior AF is one but mainly because the because all batteries are not created equal and the battery in the 1dx will drive the AF mechanism in the lens much better.
From everything I have read and seen. I would go so far as to say that the 1dx+1.4tc when cropped will beat the 7d2 plus 1.4tc. I live in Manchester UK (latitude above Vancouver) and the 7D2 has its limitations - I would love the low light capabilities of the 1dx.

I have followed comments from 2 people quite closely over the last couple of years: Arash Hazeghi who shoots with a 1dx and Art Morris who until recently shot with a 7D2 - the latter says he prefers the 1dx but for him the bulk and weight of the 1dx are impractical. So really it all comes down to what compromises you are willing to make.
I think the 7D2 would be an excellent second body but given the choice for me it would be idx without question.

Art Morris has gone over to the 5DS R, and I have followed the great man. If you don't want blisteringly fast frame rate (Art Morris doesn't, and neither do I), the 5DS R is the best bird photography machine, combining better resolution than the 7DII with all the advantages of field of view of FF.

 

[faustino]

Art Morris has gone over to the 5DS R, and I have followed the great man. If you don't want blisteringly fast frame rate (Art Morris doesn't, and neither do I), the 5DS R is the best bird photography machine, combining better resolution than the 7DII with all the advantages of field of view of FF.

Excellent point, I agree. You have the field of view to more easily follow the subject and still retain the same resolution on the subject that you would get with a modern crop sensor. The advantage of the 1dxii remains on frame rate (as you stated), and maybe on autofocus speed - because perhaps the 1dx provides more power to the lens motor (I would really like to have an answer on this point).


At high iso perhaps the crop from 1dx sensor will be better that the crop from the 5ds - because few large pixels behave better than many small pixels at high ISO.

 

[bdunbar79]

the crop aperture vs. full frame aperture numbers do not make sense to me.
F/5.6 is f/5.6 regardless of the sensor size.

It is true that f numbers and focal length remains the same whatever the sensor size is, I fully agree and will never state the contrary of that simple truth.

Anyhow, it is also true that there is a perfect theoretical equivalence between the following two:
a 500mm f4 lens projecting light on a 20mp 1.6 crop sensor set at 3200 ISOand a 800mm f5.6 lens projecting light on a 20mp full frame lens set at 8192 ISO (theoretical iso setting, I know)


I would get everything equal: same noise, same pixels on subject, identical depth of field, identical perspective, same apparent reach... identical image.


What I am not sure is wether that theoretical equivalence holds in practice or not. And, if it does't hold true, I struggle in understanding why it is the case. And if it is true, I would find myself writing that the 800mm+1dx is like the 500mm+7d, which I understand is a quite puzzling statement Thanks again for any clarification you can provide.

The 1Dx/800mm combo in your scenario would be sharper than the 7D2/500mm combo, ASSUMING everything else is equal, including noise, lens performance, all that, and you know that because you said that. But in my "perfect" example, even if I fill the frame with each, the FF image will be sharper. The reason is that to get to a final output size, let's just say 8x10, the image from the crop sensor has to undergo a 1.6x FF enlargement ratio to get there. In other words, the FF is enlarged less than the crop to get to any viewing size. But, we get into problems when say, the 500 f/4 II L is used and is likely a better performer than the 800 f/5.6L so any gain/loss is made up for with the lens quality. It's not very clear-cut.

 

[dak723]

If possible, when the time comes, rent the 7D and compare. Theory is entertaining. Actual photos will be clearer.

 

[bluenoser1993]

This discussion always gets confused. Even if you don't move, the DOF is different. Suppose I have a 7D2 with a 400mm lens and shoot a subject at 50m at f/4. If all I do is change to a 1Dx, and don't change anything else, and keep it at f/4, the DOF values will be different because to get to the SAME output size, the smaller sensor has to undergo a larger enlargement ratio than the FF sensor. From a light-gathering perspective (pun intended) yes, f/4 is f/4. But from a DOF perspective, it is not even when the ONLY thing you change is sensor size.

Ummm... Your example confuses me more. Crop is known for greater DOF, but your example states a higher enlargement ratio for the crop, which to my understanding would reduce DOF due to loss of sharpness during the enlarging.

In any case, I find the whole example misleading, because if you are happy with the framing of the 400mm and 7D2, then the 1DX will have to be cropped and enlarged to the very same enlargement ratio because the content in the image will be the very same size on both sensors at 400mm and equal distance to target.

 

[bdunbar79]

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.