vulpess
Active member
Due to the larger focal length, the 800 f6.3 will actually have smaller depth of field than a 600 f4. Obviously, quality of the out of focus areas remains to be seen, but subject isolation shouldn’t be an issue!
Nikon Z 800mm f6.3 PF lens announcement
- Thread starter Ivan Rothman
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fcotterill
Well-known member
For a subject at 20m on a FX sensor, calculated DoF is 26 cm for 600 f4 (41 cm @f6,3) and 23cm for 800 f6.3
for subject at 30m, DoF = 59 cm for 600 f4 (93 cm @f6,3) and 52 cm for 800 f6.3
A 600mm can magnify a 30 x 30 cm subject as a 20mm image on a FX sensor at 9.6m, compared to the 800mm at 12.8m. The ability to use this 800 f6.3 as a 1600mm f13 will be a unique advantage where and when needed - projecting a 20mm image of a 30 x 30 cm subject at 25.8m (DoF @f13 = 77 cm)
for subject at 30m, DoF = 59 cm for 600 f4 (93 cm @f6,3) and 52 cm for 800 f6.3
A 600mm can magnify a 30 x 30 cm subject as a 20mm image on a FX sensor at 9.6m, compared to the 800mm at 12.8m. The ability to use this 800 f6.3 as a 1600mm f13 will be a unique advantage where and when needed - projecting a 20mm image of a 30 x 30 cm subject at 25.8m (DoF @f13 = 77 cm)
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vulpess
Active member
Thanks for giving the numbers, @fcotterill! I was too lazy, I must admit 
DoF numbers are always a trick with longer lenses. As pointed out, the 800 F/6.3 will give you shallower DOF than the 600 f/4 - and as a side note, the 600 F/4 does the same when compared to the 400 2.8
Also, shallower DoF isn't the be-all and end-all of subject isolation. The other thing long glass does is to magnify the background more, so the OOF areas appear larger. That's another reason why subject isolation gets better as the lenses get longer (others factors play in as well of course).
In short, I have zero concerns about subject isolation with the 800 F/6/3
Also, shallower DoF isn't the be-all and end-all of subject isolation. The other thing long glass does is to magnify the background more, so the OOF areas appear larger. That's another reason why subject isolation gets better as the lenses get longer (others factors play in as well of course).
In short, I have zero concerns about subject isolation with the 800 F/6/3
I have used an 800 f5.6, and actually, for birds relatively close up I have found that getting the whole bird in focus at f5.6 is sometimes a problem due to the very shallow DOF. So I don't think that subject isolation will be a downside (for me, anyway) with the f6.3 lens.
arcticfocus
Member
As far as equivalence is concerned, an 800mm f/6.3 is equivalent to a 600mm f/4.725.
fcotterill
Well-known member
It will take a 600 f3.3 to get equal DoF to a 800 f6.3 on a FX sensor e.g. if compared at 10m
uday592
Active member
So the upcoming Z 400TC +1.4TC should not have autofocus issues with Z9 though not sure about image quality.
RoyC
Active member
For the 180-400 Nikon recommends to focus without the TC if there are and issues you may be having with a subject. Then move the TC into place, right hand does not have to change position, and take the shot.
John Navitsky
Well-known member
you’ll find a 100-400 comparison to the 180-400 on the youtube channel, “Ricci Talks”. he notes the 100-400 is about as sharp as the 180-400 with and without a TC
arcticfocus
Member
Equivalence is about making things equal or as equal as possible. Shooting a 600mm and an 800mm from the same distance isn’t doing that.
Typically, most people are gonna be closer to their subject with a 600mm, say 20 meters vs those shooting at 800mm, say 30 meters, since you can be further away from your subject to fill the frame.
Let’s say you want a half body portrait of a person (doesn’t have to be a person, could be a bird or bear, but you get the idea). At 600mm you’d be 17.50 meters away from your subject and shot at f/4 your depth of field would be 19.1 cm. At 800mm you’d have to be 23.33 meters away for the same framing and shot at f/6.3 your depth of field would be 30.0 cm. The background will obviously be more compressed on the 800mm due to the longer focal length, but the 600mm f/4 has less depth of field (more blur) and light gathering ability.
To have the equivalent depth of field, blur and light gathering capability of a 600mm f/4, you’d need an 800mm f/5.3 or a 945mm f/6.3.
fcotterill
Well-known member
How did you calculate these statistics? At 600mm f4 at 17.50 meters has a DoF of 13cm; 800mm f6.3 at 23.33 m the DoF is 21cm.
also blur and light gathering capability ?
I am not the only one who steers clear of the idea of Equivalence with respect to photographic image formats. I stick to variables that can be calculated, except Bokeh which is a subjective, an aesthetic quality of an optic. So with respect to subject distances at correct exposures, what matters out in the wild are DoF and magnification, also crop factor when relevant.
“Everyone is right, everyone is wrong,”
Equivalence Also Includes Aperture and ISO
photographylife.com
arcticfocus
Member
How did you calculate these statistics? At 600mm f4 at 17.50 meters has a DoF of 13cm; 800mm f6.3 at 23.33 m the DoF is 21cm.
also blur and light gathering capability ?
I am not the only one who steers clear of the idea of Equivalence with respect to photographic image formats. I stick to variables that can be calculated, except Bokeh which is a subjective, an aesthetic quality of an optic. So with respect to subject distances at correct exposures, what matters out in the wild are DoF and magnification, also crop factor when relevant.
“Everyone is right, everyone is wrong,”
Equivalence Also Includes Aperture and ISO
What is equivalence and why should I care?
Equivalence, at its most simple, is a way of comparing different formats (sensor sizes) on a common basis. Sounds straightforward enough, but the concept is still somewhat controversial and not always clearly understood. We thought it was about time we explained - and demonstrated - what...
m.dpreview.com
Not all things are created equal. No reason to steer clear or ignore reality/facts.
Regardless, I’m sure the 800mm f/6.3 will be an excellent lens, just not a 600mm f/4 equivalent, you’d need atleast a 800mm f/5.6 for that.
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MikePapple
Well-known member
If you can afford a $15,000 lens, you can afford to hire a porter/sherpa to carry your gear for you. You could also hire someone to take the pics for you
I agree but those are challenges with any prime lens 300 and over. I find my Think Tank “Glass Limo” bag makes it much much easier to do that. It fits perfectly with the lens hood reversed. Set up time is quick and the bag stays on my back while I shoot. That said, I am restricted to just one camera and one lens as carry on luggage on planes. Its been too long since I have been able to travel with it. Alternately I can use my 300 F2.8 G VRII with (or without) the TC 1.4. It is much lighter.
I love prime lenses. The moment I looked through at the bokeh and the subject isolation, I forgot about zoom lenses. For bird photography I don’t see the point in owning a zoom lens but having it permanently at maximum zoom.
The Z6ii seems to love the 300 as well.