Crop lens on FF ISO performance

derekkite · 03-18-2016, 06:03 AM

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Comparing the K3 to the D800E, using the whole frame there is an improvement in noise both pixel to pixel and normalized according to DXO. But as we know, we are dealing with a totally different field of view, and the photo will be different. The graph compares the iso levels, I wanted to extrapolate what happens when you crop the image.

For example, yesterday an eagle was eating a fish on a pole beside the road. The whole thing happened in the morning, light was poor. I used the truck as a blind, handheld through an open window. 1/320, iso 1280, 500mm f4.5, right on the edge of capability for the k3. Cropped down to 3114x2489 pixels, or .31 of the total available.

On the D800E, in that situation, normalized, what would happen? The chart at the bottom shows them normalized curve at % crop of the full frame sensor compared to the K3.

Here is the cropped and finished image.

---------- Post added 03-18-16 at 06:29 AM ----------

This image wouldn't be printed, it isn't good enough. I'm surprised I got anything, handheld at 1/320 from a vehicle usually ends up with a blurry mess. At 1600 iso it would have been worse, the noise was surprisingly not bad. The K3 seems to have a dramatic falloff point, and if you stay inside it is reasonable, but past it is garbage. Essentially to get to the same place with the full frame 32mp sensor I would need to crop 20% less; longer lens, be closer.

I'm not convinced that this represents what the sensor will do in the field, but it probably is reasonably close. Now what I have to do is figure out whether shots like this, which are ultimately throw away in any case with full frame or apsc are the deciding factor.

Enlightening nonetheless.

audiobomber · 03-18-2016, 09:26 PM

Originally posted by amoringello

You say "Shooting the same scene from the same position, with the same settings and lens and printing to the same size"
This is a clear indication that you do not quite understand what is happening. It is also ambiguous. What does "printing to he same mean".. Both crop and FF printed 8x10, or same pixel to print ratio? i.e. crop at 5x7 and ff at 8x10 (approx)? Lets keep terms consistent and defined. Without an understanding of some basic guidelines partial explanations become white noise.

Everyone here, including you, understands what PRINT BOTH AT THE SAME SIZE means.

Originally posted by amoringello

You cannot possibly have the same image from a FF vs Crop if you do not change some combination of the position, focal length, and/or aperture. Otherwise FF is going to contain a wider angle of view which needs to be compensated for.

I don't know where your lack of comprehension comes in. You're still sound confused on the basics.
It sounds like you're almost there, (as the second bullet point may be correct in proper cotext) but it comes across that you are still missing the most basic physics on which all of this stands.

That should not offend you, but instead simply be an indication of where you need to learn more.

I explained very specifically how to obtain the same image from FF and APS-C. Position and shutter speed cannot change. Aperture, focal length and ISO must change to produce equivalent images.

christiandre · 03-18-2016, 10:59 PM - **1 Like**

i will have my K-1 in... 16 days
l'll do some samples with both : no more disagreements after

derekkite · 03-18-2016, 11:10 PM - **1 Like**

Originally posted by christiandre

i will have my K-1 in... 16 days
l'll do some samples with both : no more disagreements after

Looking forward to seeing what comes out of it. I really enjoy watching the skilled people here master a new tool. I suspect this will be quite the challenge for most of us.

Tan68 · 03-27-2016, 07:20 AM - **1 Like**

Originally posted by 2351HD

No he is not. We are talking about cropping a picture, that is all. Apsc sensor vs FF with same lens, same settings, same distance, but cropping the FF to match.

I am only on page 4 and Mr. Beholder has just written several bullet points to make his point. I agree with him. Maybe all this will be ironed out in the next couple pages, but I will add a thought here.

I think it is easy to forget about the part of the process that involves enlarging. Even if no prints will be made, I think it is helpful to think about 'print output'. Considering a picture on a wall where the picture can be different sizes and the person looking at the picture can be either closer or farther away might aid visualization more than thinking of pictures at 75% or 33% or etc. on a monitor.

If that don't help, a trip to DOFMaster should help.
Unless my memory misfires, at this site, circles of confusion and how they relate to print size (image view size) and how these relate to ranges of /acceptable/ depth of field will be explained. Yes, DOF may be defined by the user and varies depending on how particular you want to be about sharpness...

When I think of doing a digital crop on a sensor (crop mode of K-1) and then taking that smaller area of image and 'zooming it out' to equal a larger imaging surface (back to FF size), I think of actors wearing those VR gloves in movies like Minority Report. I don't now if this visualization will be useful..?

i5_david · 04-11-2016, 10:05 AM

Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something!

Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums

Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open.
Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?!

enoeske · 04-11-2016, 10:27 AM

Originally posted by i5_david

Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something!

Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums

Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open.
Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?!

~~The 30mm Art is not available in Pentax K mount.~~

Oh, looks like it is. nm.

Last edited by enoeske; 04-11-2016 at 10:55 AM.

i5_david · 04-11-2016, 10:37 AM

http://www.amazon.de/Sigma-Objektiv-Filtergewinde-Canon-Objektivbajonett/dp/...s=sigma+30+1.4

amazon says so...

osv · 04-11-2016, 01:40 PM

Originally posted by i5_david

Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something!

Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums

Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open.
Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?!

it's clearly vignetting, as others in the thread pointed out.

that vignetting will get worse depending on how far away it's focused.

it's an interesting option, just be ready to clean up the corners or even crop to get clean corners.

03-18-2016, 09:26 PM	#122
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by amoringello You say "Shooting the same scene from the same position, with the same settings and lens and printing to the same size" This is a clear indication that you do not quite understand what is happening. It is also ambiguous. What does "printing to he same mean".. Both crop and FF printed 8x10, or same pixel to print ratio? i.e. crop at 5x7 and ff at 8x10 (approx)? Lets keep terms consistent and defined. Without an understanding of some basic guidelines partial explanations become white noise. Everyone here, including you, understands what PRINT BOTH AT THE SAME SIZE means. Originally posted by amoringello You cannot possibly have the same image from a FF vs Crop if you do not change some combination of the position, focal length, and/or aperture. Otherwise FF is going to contain a wider angle of view which needs to be compensated for. I don't know where your lack of comprehension comes in. You're still sound confused on the basics. It sounds like you're almost there, (as the second bullet point may be correct in proper cotext) but it comes across that you are still missing the most basic physics on which all of this stands. That should not offend you, but instead simply be an indication of where you need to learn more. I explained very specifically how to obtain the same image from FF and APS-C. Position and shutter speed cannot change. Aperture, focal length and ISO must change to produce equivalent images. Last edited by Ash; 03-19-2016 at 02:56 AM.

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03-18-2016, 06:03 AM	#121
derekkite Pentaxian Join Date: Sep 2011 Location: Nelson B.C. Posts: 3,782	Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. Comparing the K3 to the D800E, using the whole frame there is an improvement in noise both pixel to pixel and normalized according to DXO. But as we know, we are dealing with a totally different field of view, and the photo will be different. The graph compares the iso levels, I wanted to extrapolate what happens when you crop the image. For example, yesterday an eagle was eating a fish on a pole beside the road. The whole thing happened in the morning, light was poor. I used the truck as a blind, handheld through an open window. 1/320, iso 1280, 500mm f4.5, right on the edge of capability for the k3. Cropped down to 3114x2489 pixels, or .31 of the total available. On the D800E, in that situation, normalized, what would happen? The chart at the bottom shows them normalized curve at % crop of the full frame sensor compared to the K3. Here is the cropped and finished image. ---------- Post added 03-18-16 at 06:29 AM ---------- This image wouldn't be printed, it isn't good enough. I'm surprised I got anything, handheld at 1/320 from a vehicle usually ends up with a blurry mess. At 1600 iso it would have been worse, the noise was surprisingly not bad. The K3 seems to have a dramatic falloff point, and if you stay inside it is reasonable, but past it is garbage. Essentially to get to the same place with the full frame 32mp sensor I would need to crop 20% less; longer lens, be closer. I'm not convinced that this represents what the sensor will do in the field, but it probably is reasonably close. Now what I have to do is figure out whether shots like this, which are ultimately throw away in any case with full frame or apsc are the deciding factor. Enlightening nonetheless.

03-18-2016, 10:59 PM - 1 Like	#123
christiandre Inactive Account Join Date: Jul 2015 Posts: 157	i will have my K-1 in... 16 days l'll do some samples with both : no more disagreements after

03-18-2016, 11:10 PM - 1 Like	#124
derekkite Pentaxian Join Date: Sep 2011 Location: Nelson B.C. Posts: 3,782	Originally posted by christiandre i will have my K-1 in... 16 days l'll do some samples with both : no more disagreements after Looking forward to seeing what comes out of it. I really enjoy watching the skilled people here master a new tool. I suspect this will be quite the challenge for most of us.

03-27-2016, 07:20 AM - 1 Like	#125
Tan68 Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 501	Originally posted by 2351HD No he is not. We are talking about cropping a picture, that is all. Apsc sensor vs FF with same lens, same settings, same distance, but cropping the FF to match. I am only on page 4 and Mr. Beholder has just written several bullet points to make his point. I agree with him. Maybe all this will be ironed out in the next couple pages, but I will add a thought here. I think it is easy to forget about the part of the process that involves enlarging. Even if no prints will be made, I think it is helpful to think about 'print output'. Considering a picture on a wall where the picture can be different sizes and the person looking at the picture can be either closer or farther away might aid visualization more than thinking of pictures at 75% or 33% or etc. on a monitor. If that don't help, a trip to DOFMaster should help. Unless my memory misfires, at this site, circles of confusion and how they relate to print size (image view size) and how these relate to ranges of /acceptable/ depth of field will be explained. Yes, DOF may be defined by the user and varies depending on how particular you want to be about sharpness... When I think of doing a digital crop on a sensor (crop mode of K-1) and then taking that smaller area of image and 'zooming it out' to equal a larger imaging surface (back to FF size), I think of actors wearing those VR gloves in movies like Minority Report. I don't now if this visualization will be useful..?

04-11-2016, 10:05 AM	#126
i5_david Veteran Member Join Date: Feb 2016 Posts: 332	Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something! Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open. Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?!

04-11-2016, 10:27 AM	#127
enoeske Veteran Member Join Date: Jul 2009 Location: Surprise, Az Photos: Gallery Posts: 2,136	Originally posted by i5_david Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something! Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open. Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?! ~~The 30mm Art is not available in Pentax K mount.~~ Oh, looks like it is. nm. Last edited by enoeske; 04-11-2016 at 10:55 AM.

04-11-2016, 10:37 AM	#128
i5_david Veteran Member Join Date: Feb 2016 Posts: 332	http://www.amazon.de/Sigma-Objektiv-Filtergewinde-Canon-Objektivbajonett/dp/...s=sigma+30+1.4 amazon says so...

04-11-2016, 01:40 PM	#129
osv Veteran Member Join Date: Mar 2007 Location: So Cal Photos: Gallery Posts: 2,080	Originally posted by i5_david Hey folks, does anyone has a Sigma 30 1.4? I wonder if its right that it covers 100% circle on a FF body as this dude claims. That would be something! Canon 28mm f/1.8 vs Sigma 30mm f/1.4 (A) on Full Frame - FM Forums Scroll down in the middle. The shot shows some lenses in an electronic store. There he writes that its 5D III with Sigma 30 wide open. Oh, btw they speak of old and new version... I don't know when what lens was released but maybe someone has insight into this?! it's clearly vignetting, as others in the thread pointed out. that vignetting will get worse depending on how far away it's focused. it's an interesting option, just be ready to clean up the corners or even crop to get clean corners.