Focal length vs aperture IQ

[Rjdane2]

After some testing between my 600 f4 with and without the 1.4 tc and 800 pf and todays denoise software I wonder which one really has the advantage when it comes to end result image quality. I feel like the closer you can get to your subject even if it’s a stop higher iso it’s a better image.

This post is geared toward wildlife shooting where you don’t really have the opportunity to fill your frame. I have taken the same photo locked on my tripod with the tele on and off with the 600 @ f4 and 840 @ f5.6 and even tho my iso is much higher with the tele my final cropped image is always sharper with the tele due to having to crop the 600 shot more and losing quality.

Now when comparing my 600mm f4 with 1/4 tc @840mm 5.6 to the 800mm pf at 6.3 the 800 is producing slightly sharper results with my final edited photo. So if you use your 600 with the tele the majority of the time I would suggest the 800mm being it’s so much lighter just easier to use and maneuver.

The only time I would want my 600 over the 800 is if it was dusk/dawn or in a wooded area where I could get close enough to fill the frame. Heavy crop 600 f4 vs non cropped 800 6.3 produce similar results.

I’m not expert just someone who enjoys taking wildlife photos daily in all types of scenarios and this is just some testing I did on my own. I was a d850 shooter now using a z9.

 

[bleirer]

Interesting comparison. As a side note, there is some math that gets mentioned here every now and again: Square the crop factor and then multiply that by the original ISO to get the ISO equivalent for noise. So cropping to a 2x crop factor at 2000 ISO would be as noisy as shooting at ISO 8000. So what you say about cropping makes sense in that context.

 

[NorthernFocus]

What you describe is consistent with my experience. I've really noticed it/become more convinced since I've had the 800mm 6.3. There is a point where more pixels on target trumps lower ISO. Particularly nowadays with such excellent NR software available. I've been tempted recently to post a thread like this but shied away from it rather than initiate a debate. I'm glad you did so since you have both the 600mm f4 and 800mm 6.3 to make the comparison.

Interesting comparison. As a side note, there is some math that gets mentioned here every now and again: Square the crop factor and then multiply that by the original ISO to get the ISO equivalent for noise. So cropping to a 2x crop factor at 2000 ISO would be as noisy as shooting at ISO 8000. So what you say about cropping makes sense in that context.

Bill, any idea who came up with the equation?

 

[bleirer]

What you describe is consistent with my experience. I've really noticed it/become more convinced since I've had the 800mm 6.3. There is a point where more pixels on target trumps lower ISO. Particularly nowadays with such excellent NR software available. I've been tempted recently to post a thread like this but shied away from it rather than initiate a debate. I'm glad you did so since you have both the 600mm TC and 800mm 6.3 to make the comparison.


Bill, any idea who came up with the equation?

I hope I'm remembering it correctly. I believe I've read Steve mention it a couple times. But it makes sense, the squaring because you are effectively enlarging (if you keep the same image size and viewing distance) both the width and height of the image by the crop amount and multiplying by the original ISO because whatever noise is present is also enlarged. Now I hope someone chimes in to confirm or correct.

 

[BillW]

After some testing between my 600 f4 with and without the 1.4 tc and 800 pf and todays denoise software I wonder which one really has the advantage when it comes to end result image quality. I feel like the closer you can get to your subject even if it’s a stop higher iso it’s a better image.

This post is geared toward wildlife shooting where you don’t really have the opportunity to fill your frame. I have taken the same photo locked on my tripod with the tele on and off with the 600 @ f4 and 840 @ f5.6 and even tho my iso is much higher with the tele my final cropped image is always sharper with the tele due to having to crop the 600 shot more and losing quality.

Now when comparing my 600mm f4 with 1/4 tc @840mm 5.6 to the 800mm pf at 6.3 the 800 is producing slightly sharper results with my final edited photo. So if you use your 600 with the tele the majority of the time I would suggest the 800mm being it’s so much lighter just easier to use and maneuver.

The only time I would want my 600 over the 800 is if it was dusk/dawn or in a wooded area where I could get close enough to fill the frame. Heavy crop 600 f4 vs non cropped 800 6.3 produce similar results.

I’m not expert just someone who enjoys taking wildlife photos daily in all types of scenarios and this is just some testing I did on my own. I was a d850 shooter now using a z9.

Were you testing the F mount 600 f4 or the new Z mount 600 mm f4 with built-in TC?

 

[Rjdane2]

What you describe is consistent with my experience. I've really noticed it/become more convinced since I've had the 800mm 6.3. There is a point where more pixels on target trumps lower ISO. Particularly nowadays with such excellent NR software available. I've been tempted recently to post a thread like this but shied away from it rather than initiate a debate. I'm glad you did so since you have both the 600mm TC and 800mm 6.3 to make the comparison.


Bill, any idea who came up with the equation?

I posted something similar on one of the Facebook pages I be to but it was filled with replies of people responding with no experience with the two lenses just how it’s wrong and the f4 is better. I agree with them when you can fill the frame but not when your still cropping.

 

[Rjdane2]

Were you testing the F mount 600 f4 or the new Z mount 600 mm f4 with built-in TC?

Latest version f mount. I’m pretty sure you would see similar results with the z lens once you enable the t/c.

 

[BillW]

Latest version f mount. I’m pretty sure you would see similar results with the z lens once you enable the t/c.

Brad Hill has been comparing the Z 600 f4 TC with the Z 800 mm PF. No final review/report yet. But he noted in some recent photos in his gallery of latest images that he found the Z 600 with its internal TC engaged (so 840 mm at f5.6) to be a bit sharper with a bit better bokeh than the Z 800 mm PF. He also noted that he found the AF of the Z 800 PF to be giving him somewhat more sharp images than the Z 600 mm with TC engaged when photographing fast action. I'm interested to hear more of Brad's impressions. So far, it sounds like both lenses are excellent overall with some differences -- flexibility, weight, cost, ....

 

[fcotterill]

The technical explanation gets complicated. It entails the relationships between luminance, image area and capacitance. I won't attempt it!

Here's a readable review article

Equivalence Also Includes Aperture and ISO

photographylife.com

 

[EricBowles]

What you describe is consistent with my experience. I've really noticed it/become more convinced since I've had the 800mm 6.3. There is a point where more pixels on target trumps lower ISO. Particularly nowadays with such excellent NR software available. I've been tempted recently to post a thread like this but shied away from it rather than initiate a debate. I'm glad you did so since you have both the 600mm f4 and 800mm 6.3 to make the comparison.


Bill, any idea who came up with the equation?

Bill Claff of Photonstophotos.net has calculated the Photographic Dynamic Range using both FX and DX crop of full frame cameras for a number of years. The formula is consistent with his data across a number of cameras. He typically sees about 1 stops of difference between FX and DX crops of the same camera. Using the camera crop factor - 1.5 crop for Nikon - the square of the crop factor is 2.25 - slightly more than doubling the ISO which would be one stop. Depending on the sensor and camera processing, this difference can vary from 0.9 to 1.2 stops, but the formula is a good rule of thumb. It can vary as there is noise reduction taking place at the raw level.

You don't need to limit yourself to the crop factor of the camera. The crop factor can be applied to any crop. So if you crop an image from a camera that is 8200 pixels on the wide side to 1000 pixels on that side, you are using a crop factor of 8 times. That's 64 times the original ISO equivalent - so you would need to shoot at ISO 200 to have the same noise as ISO 12,800 uncropped. Again - this is a rough calculation.

It also works in reverse. If you are downsizing an image, you are effectively reducing noise using a similar equation. So downsizing an 8000 pixel image to 1000 pixels for web use means noise is generally insignificant.

 

[Rjdane2]

Bill Claff of Photonstophotos.net has calculated the Photographic Dynamic Range using both FX and DX crop of full frame cameras for a number of years. The formula is consistent with his data across a number of cameras. He typically sees about 1 stops of difference between FX and DX crops of the same camera. Using the camera crop factor - 1.5 crop for Nikon - the square of the crop factor is 2.25 - slightly more than doubling the ISO which would be one stop. Depending on the sensor and camera processing, this difference can vary from 0.9 to 1.2 stops, but the formula is a good rule of thumb. It can vary as there is noise reduction taking place at the raw level.

You don't need to limit yourself to the crop factor of the camera. The crop factor can be applied to any crop. So if you crop an image from a camera that is 8200 pixels on the wide side to 1000 pixels on that side, you are using a crop factor of 8 times. That's 64 times the original ISO equivalent - so you would need to shoot at ISO 200 to have the same noise as ISO 12,800 uncropped. Again - this is a rough calculation.

It also works in reverse. If you are downsizing an image, you are effectively reducing noise using a similar equation. So downsizing an 8000 pixel image to 1000 pixels for web use means noise is generally insignificant.

I’m gonna have to reread that a few times lol