Need help working out how many MP after crop

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mike
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#1
Cant get my head around this so please help me.

I now have two basic systems, a Panasonic m4/3 G80 with 16mp, a Nikon Z50 with 20.9mp, i much prefer the Nikon.

The question is, on the G80 i use the 100-400 ( fov 200-800) if i put a 100-400 on the Nikon i get a fov = 150-600, now if i take an imaginary crop of m4/3 from the Nikon i think this would give me the same FOV as the G80 using a 100-400.

How many MP would i have in that cropped area, i know there are more things involved but as a starting point i would like to know the pixel count in this cropped area.

Hope i have made the question clear.

Thanks
 
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mikew
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mike
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#5
Of course it isn't quite that simple as the aspect ratio is different... (I assume the Nikon is 3:2).
Yes i appreciate other things come into play but an idea of pixel count is a starting point, most of the time i would be cropping any way so not even using the full m4/3 imaginary crop, its normal for me to have to crop the G80 a lot as i dont have the mobility to get closer to subjects and naturally a lot of images would be using the full DX sensor.
 
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Andrew
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#7
Actually, it's quite an interesting question for me too as I run multiple systems. I'd like to know how this is worked out please.

For example, I have my Nikon Z7, which has 45.4 mp in FF (8256x5504), and if I shoot in DX mode, this reduces to 19.5 mp (or 5408 x 3600) both at a 3:2 ratio.

My Micro Four thirds bodies, shooting in the same 3:2 ratio, net me 17.9 mp (or 5184 x 3456).

So If I was for instance shooting the Z7 in DX mode with my AF-P 70-300 (in FF terms a reach of 450mm- and currently my longest Nikon lens), and then shot the same on my say, EM1X in 3:2 (so 17.9mp) using my 300 F4 (so in FF terms a reach of 600mm), how many MP in the Z7 DX image would i have left to crop it to the same file of view as the EM1X ? Furthermore, what would be the actual sensor crop size on the Z7 to achieve that (my thoughts are it wouldn't' be much larger (if any) than a M4/3 sensor ?

Like Mike, my brain just won't let me get my head around this, and I've never had both camera types with me a the same time to take equivalent shots. Just wanted to know if there was a formula ?
 
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mikew
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mike
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#9
Actually, it's quite an interesting question for me too as I run multiple systems. I'd like to know how this is worked out please.

For example, I have my Nikon Z7, which has 45.4 mp in FF (8256x5504), and if I shoot in DX mode, this reduces to 19.5 mp (or 5408 x 3600) both at a 3:2 ratio.

My Micro Four thirds bodies, shooting in the same 3:2 ratio, net me 17.9 mp (or 5184 x 3456).

So If I was for instance shooting the Z7 in DX mode with my AF-P 70-300 (in FF terms a reach of 450mm- and currently my longest Nikon lens), and then shot the same on my say, EM1X in 3:2 (so 17.9mp) using my 300 F4 (so in FF terms a reach of 600mm), how many MP in the Z7 DX image would i have left to crop it to the same file of view as the EM1X 80? Furthermore, what would be the actual sensor crop size on the Z7 to achieve that (my thoughts are it wouldn't' be much larger (if any) than a M4/3 sensor ?

Like Mike, my brain just won't let me get my head around this, and I've never had both camera types with me a the same time to take equivalent shots. Just wanted to know if there was a formula ?
If someone gives you all the details not just the basic answer like I wanted you could get a headache ;)
 
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Terry
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#10
I thought this was a political question

The Tories have already cropped their moderate MP's
And the Labor cropped their right of center MP's
Unfortunately they have both still got a full compliment of MP

However you get no more useful details out of any of them.
 
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6,639
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Ned
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#11
Actually, it's quite an interesting question for me too as I run multiple systems. I'd like to know how this is worked out please.

For example, I have my Nikon Z7, which has 45.4 mp in FF (8256x5504), and if I shoot in DX mode, this reduces to 19.5 mp (or 5408 x 3600) both at a 3:2 ratio.

My Micro Four thirds bodies, shooting in the same 3:2 ratio, net me 17.9 mp (or 5184 x 3456).

So If I was for instance shooting the Z7 in DX mode with my AF-P 70-300 (in FF terms a reach of 450mm- and currently my longest Nikon lens), and then shot the same on my say, EM1X in 3:2 (so 17.9mp) using my 300 F4 (so in FF terms a reach of 600mm), how many MP in the Z7 DX image would i have left to crop it to the same file of view as the EM1X ? Furthermore, what would be the actual sensor crop size on the Z7 to achieve that (my thoughts are it wouldn't' be much larger (if any) than a M4/3 sensor ?

Like Mike, my brain just won't let me get my head around this, and I've never had both camera types with me a the same time to take equivalent shots. Just wanted to know if there was a formula ?

I would just use crop factors, they’re remarkably useful at this kind of thing. 600mm is 25% more than 450mm in FF so 19.5/0.75 (i.e. minus 25%) is 14.5MP on the Nikon Vs 17.9 on the Oly - nothing real in it.

Something to consider is the lens, each lens can sustain a certain amount of magnification through it (people talk of sharpness being lens limited) and so cropping into it might not gain a sharper photo even with more MP, especially in the above scenario.
 
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