DX V FX confusion

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mikew_RIP

Senior Member
Something ime trying to get my head round,will 24mp on a DX resolve more fine detail than 24mp on FX,i understand the DR,noise, ect factors but not the actual resolving power.The reason i ask is i have this 150-600 Sigma contemporary lens on a FX and cannot get the detail i used to get with the Tamron on my D7100,we are not talking about a crop from the file as i would expect the DX to hold up better than if i start cropping the FX,ime comparing full file image,dont want to put examples up as i am more interested in the scientific aspect of 24mp on either sensor rather than getting involved in lighting ect on individual images.
Or is it the Sigma lens is just not as good as the Tamron and the sensors should both be able to resolve the same detail,or am i going altogether in the wrong direction looking for a solution.
 
Marcel

Marcel

Happily retired
Staff member
Super Mod
Well to me I think it might not be the lens but the simple fact that the 7100 is without the low pass filter... I don't know if you'd get that filter removed from the 750 if it would out resolve the 7100. But if you are looking for sharpness and resolution at a long focal length, it seems to me that the DX option would turn out the best withholding the extremely expensive Nikons 600 f5.6 or longer prime lenses.
 
Scott Murray

Scott Murray

Senior Member
If it is a new lens it may take you some time to adjust to the slight differences, there are more than a few reasons why you would be losing detail etc. The only sure way would be to do tests on a tripod and try different apertures/shutter speeds to determine what may be the issue.
 
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mikew_RIP

Senior Member
Marcel said:
Well to me I think it might not be the lens but the simple fact that the 7100 is without the low pass filter... I don't know if you'd get that filter removed from the 750 if it would out resolve the 7100. But if you are looking for sharpness and resolution at a long focal length, it seems to me that the DX option would turn out the best withholding the extremely expensive Nikons 600 f5.6 or longer prime lenses.
Click to expand...

Thanks never considered the low pass filter,in fact i had forgotten that difference between them.
 
M

mikew_RIP

Senior Member
Scott Murray said:
If it is a new lens it may take you some time to adjust to the slight differences, there are more than a few reasons why you would be losing detail etc. The only sure way would be to do tests on a tripod and try different apertures/shutter speeds to determine what may be the issue.
Click to expand...

Thanks Scott,i have been changing settings and working modes to try and track down a difference between the two set ups,i didnt see any point in tripod testing as i would need it to work hand held but it is a way to see if the OS is having an adverse effect as it would be off on a tripod.
 
Horoscope Fish

Horoscope Fish

Senior Member
Marcel said:
Well to me I think it might not be the lens but the simple fact that the 7100 is without the low pass filter...
Click to expand...
Dollars to donuts that's your answer right there.

I had the OLPF removed from my D750 so I've seen first hand the difference it makes on the exact same camera.
....
 
M

mikew_RIP

Senior Member
Blacktop said:
Also to match the 24MP pixel density on the DX body , you would need over 50MPs on the FX body.
Click to expand...

So are you saying 24mp DX can record better detail than 24mp FX because ime not talking about cropping the image ime talking the same size object filling both sizes of sensor,will one show more fine detail.
 
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ryan20fun

Senior Member
mikew said:
So are you saying 24mp DX can record better detail than 24mp FX because ime not talking about cropping the image ime talking the same size object filling both sizes of sensor,will one show more fine detail.
Click to expand...
It's like looking at a movie on two screens, But one is a HD and the other is 4K.

The APS-C cameras have a lower pixel pitch therefore they have the capability to resolve finder detail(in theory).
Like playing a game at low res (640x480) and then upping the resolution (1024x268).

But the difference may not be so easy to discern on ~2M monitors without doing a proper down scalling of the images

HTH
 
Bob Blaylock

Bob Blaylock

Senior Member
mikew said:
Something ime trying to get my head round,will 24mp on a DX resolve more fine detail than 24mp on FX,i understand the DR,noise, ect factors but not the actual resolving power.The reason i ask is i have this 150-600 Sigma contemporary lens on a FX and cannot get the detail i used to get with the Tamron on my D7100,we are not talking about a crop from the file as i would expect the DX to hold up better than if i start cropping the FX,ime comparing full file image,dont want to put examples up as i am more interested in the scientific aspect of 24mp on either sensor rather than getting involved in lighting ect on individual images.
Or is it the Sigma lens is just not as good as the Tamron and the sensors should both be able to resolve the same detail,or am i going altogether in the wrong direction looking for a solution.
Click to expand...

Putting aside issues about the quality of a sensor, and the presence or absence of an optical low-pass filter, 24 megapixels of resolution is 24 megapixels of resolution.

I assume you understand about the “crop factor” of a DX sensor, and how that relates to the focal length of a lens? You seem to be comparing the performance of one 150-600mm zoom on a DX sensor to a different 150-600mm zoom on an FX sensor. Assuming the sensors to be of equivalent quality, and the optics to be of equivalent quality, the “crop factor” means that you're going to get a higher magnification on the DX sensor, which, if you're comparing similar subjects at similar ranges, is going to translate into more fine detail on the DX sensor. For the comparison to be entirely valid, you'd need a lens on the FX of approximately 1.5× the focal length of the lens you're using on the DX. For example, a 100-400mm lens on the DX would match the 150-600 on the FX, or a 225-900mm on the FX to match the 150-600 on the DX.

It may also help to realize that the difference between a 24mp DX and a 24MP FX is that the DX has the same number of pixels crammed into a smaller space; so with the same or equivalent optics, the DX gets finer detail, of a smaller angle of view.
 
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aroy

Senior Member
As the DX sensor is smaller than FX sensor, if both were 24MP, then the DX sensor would record more details per unit area of the sensor. What it means is that for same size image on the sensor (same lens same settings), say 15mm
. DX 15mm = 3750 pixels.
. FX 15mm = 2500 pixels.

So you will see more details on a DX sensor, till FX has the same pixel density as DX
. DX - 24MP, FX - 54MP
. DX - 10MP, FX - 22.5MP

So the new Canon 50MP body should have the same details as their 22MP DX.
 
M

mikew_RIP

Senior Member
Bob Blaylock said:
Putting aside issues about the quality of a sensor, and the presence or absence of an optical low-pass filter, 24 megapixels of resolution is 24 megapixels of resolution.

I assume you understand about the “crop factor” of a DX sensor, and how that relates to the focal length of a lens? You seem to be comparing the performance of one 150-600mm zoom on a DX sensor to a different 150-600mm zoom on an FX sensor. Assuming the sensors to be of equivalent quality, and the optics to be of equivalent quality, the “crop factor” means that you're going to get a higher magnification on the DX sensor, which, if you're comparing similar subjects at similar ranges, is going to translate into more fine detail on the DX sensor. For the comparison to be entirely valid, you'd need a lens on the FX of approximately 1.5× the focal length of the lens you're using on the DX. For example, a 100-400mm lens on the DX would match the 150-600 on the FX, or a 225-900mm on the FX to match the 150-600 on the DX.

It may also help to realize that the difference between a 24mp DX and a 24MP FX is that the DX has the same number of pixels crammed into a smaller space; so with the same or equivalent optics, the DX gets finer detail, of a smaller angle of view.
Click to expand...

Thanks Bob not having the D7100 any more or the Tamron 150-600 i had been going through previous files looking for the same subjects filling both sensors with out any cropping on the FX,there is more fine detail showing in the D7100 images,i have come to the conclusion the D7100 could in these circumstances resolve more detail then the D750,when you think about it if you had a D750 but wanted better fine detail in you images i imagine you would buy a D810 with more MP on the sensor.
Obviously if you start trying to get the same FOV from cropping a FX that would match a DX you can expect to get fine detail loss,when i made the decision to get another long lens i expected to have to get closer to my subjects with the D750 and eventually pick up another D7100,i think i am just seeing confirmation that i was right and need another body.
The other option for what ime seeing is obviously a possibility the Sigma lens isnt as good as the Tamron was,that final conclusion will have to wait a couple of months until i can pick up a D7100 body.
 
M

mikew_RIP

Senior Member
aroy said:
As the DX sensor is smaller than FX sensor, if both were 24MP, then the DX sensor would record more details per unit area of the sensor. What it means is that for same size image on the sensor (same lens same settings), say 15mm
. DX 15mm = 3750 pixels.
. FX 15mm = 2500 pixels.

So you will see more details on a DX sensor, till FX has the same pixel density as DX
. DX - 24MP, FX - 54MP
. DX - 10MP, FX - 22.5MP

So the new Canon 50MP body should have the same details as their 22MP DX.
Click to expand...

Thanks i was slowly one finger typing my post while you did this :D
 
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ryanwphoto

Senior Member
I have to agree, the D7100 was amazing for capturing details, with good glass of course. I had a Nikkor 17-55 2.8 on my D7100 and I could get unreal sharpness.
It was so sharp that for some portrait shots I would have to soften the image. Landscapes or details were out of this world. I now have a Sony a7 with a kit 28-70 and I can tell the difference. It is quite sharp but not like the the other setup I had.
Saving right now to buy some good glass for this new Sony 😉

Sent from my D6503 using Tapatalk
 
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