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Forum: Pentax K-1 03-14-2017, 08:38 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
I think that matches closely with what I said in post 32, Vincent: :)

So if you're not just resizing, you're also doing some sort of postprocessing that includes downsampling, in poor light conditions you'd expect to see about a stop's difference between your K-5 and K-1. Alright, it destroys details too, but the idea is that details aren't random, noise is, and so to a point, averaging is desirable.

You can see from my night concert shot above, I think it was worth my money to chase that marginal improvement.


Just in this thread, Mee and BarryE seemed a little underwhelmed by the K-1 vs APS-C images they've taken at good light levels, and Rupert thought even at poor levels.

Expectations must be understood by looking at the RAW files and their SNR and Dynamic Ranges, which is DxOMark's Screen tab.

Biz-engineer found the pics hard to tell apart at ISO 400 ... these pics, like all JPEGs, have certainly been downsampled. See if you think one is twice is good as another!

K-1 vs K3, which is which - PentaxForums.com

And even at ISO 6400, you can see if that's also true in the famous Imaging Resource RAW files:

The superiority of FF over APS-c re: Depth of Field - Page 12 - PentaxForums.com
Forum: Pentax K-1 03-13-2017, 08:37 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
But that is what you want in your workflow, @Gimbal

Listen to Barry and the others.

You will resize not downsample as you go through all your postprocessing steps. You don't want any downsampling until the last possible step, because it causes deterioration of the image.

The golden rule is to get the cleanest, best, biggest RAW file manageable (that is what DxOMark's Screen Tab measurements are about) then do the least damage to it in output.

This is not a hard idea. :)
Forum: Pentax K-1 03-13-2017, 08:28 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Of course, @leekil

You can read here about the problems inherent to Resampling. It's an art.

http://designer-info.com/Writing/image_resample.htm
Forum: Pentax K-1 03-09-2017, 03:51 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Best not to mistake those two for each other, Peter. :)

They don't have the same pixel sizes ... more are crammed into the K-3's sensor.

As a result, their RAW performance is different ... the K-5 has consistently between 2-3 dB better SNR ratio than the K-3, even though it's an older camera.

The reason we mentioned the K-5 is that it shares the K-1's pixels.
Forum: Pentax K-1 03-09-2017, 03:42 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Well, you're quite wrong again, Gimbal ....

"When changing the size of an image in Photoshop, there's really two ways to go about it. You can either resize the image, or you can resample it. A lot of people use the terms resizing and resampling as if they mean the same thing, but they don't. There's an important difference between the two."

That's from here ... Image Resizing vs Resampling In Photoshop Explained

Adobe even post a video about this from Lynda.com ... Understanding Resize vs. Resample
Forum: Pentax K-1 03-09-2017, 03:00 AM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
A resize cannot effect noise, Barry. You are simply dropping three out of every four pixels, for example, no matter what they are, leaving the fourth intact. If every tenth pixel was noise, it still is in the output.

Downsampling is required to reduce that ratio. There you are replacing all four pixels with a single averaged value.

That is why skin textures become plastic when pushing the noise reduction slider. You are averaging out the details you want to keep.

The lesson? Go for the cleanest possible image with the best performing sensor in the first place, instead of relying on post processing.
Forum: Pentax K-1 03-09-2017, 02:13 AM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Sure, it speeds up when you convert it, Mee. I have so many screwdrive lenses I'm used to the noise. It's got such terrific IQ I don't mind using it in crop mode on the K-1 at all:

Forum: Pentax K-1 03-09-2017, 01:57 AM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Well, sizing doesn't have anything to do with it, Rondec, because the noise and dynamic range are the same whether they're from the cropped portion of a frame or outside it. A RAW file is a RAW file, and the pixels don't know where they are on the sensor.

As for resolution, if the output device is, say, 150 dpi, if you resize there is no difference in a 5x7 print or a computer monitor.

You would need to go to A3 to see an effect.

If you resize down to 8Mp, there is no change in noise or dynamic range, either. That's impossible.

There are folks around here who are uncomfortable with postprocessing. But to the rest of us, that's part and parcel of photography.

So if you're not just resizing, you're also doing some sort of postprocessing that includes downsampling, in poor light conditions you'd expect to see about a stop's difference between your K-5 and K-1. Alright, it destroys details too, but the idea is that details aren't random, noise is, and so to a point, averaging is desirable.

You can see from my night concert shot above, I think it was worth my money to chase that marginal improvement. And you obviously feel the same about your very delicate landscapes. If there's anyone we should crowdsource a 645Z for, it's you, Vincent! :)
Forum: Pentax K-1 03-07-2017, 10:10 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Well, only the first tab has the whole sensor's data, Gimbal. That's what a Signal to Noise ratio is about, and it's what DxO tested.

The second tab has no data that DxO measured. It is not real world, so let's dispose of that notion.

It is a guess on what you might see in the JPEG, using only the number of pixels that could be downsampled, not the sensor size at all. I can show you the formula used if you like. :)
Forum: Pentax K-1 03-07-2017, 10:05 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
I agree on 'horses for courses', BE.

For tele work, the K-1 comes with a built-in fifty percent penalty for reach. You can spend a lot on FF lenses just to get that back.

In good light, your comparison showed it will be very difficult to tell images taken with the K-3 and K-1 apart, but I do quite a bit of night shooting, and concerts also where the shutter speed has to remain high. The K-1's extra pixels can help me trade off ISO in making the final JPG.

I'll pay for the one stop difference in this kind of photography, I can understand others who won't.

Latin American musicians, K-1, Sigma 35mm Art:

Forum: Pentax K-1 03-06-2017, 09:48 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
I have two of them, Biz-engineer, but you raise a very good question. I remember you posting nearly identical shots of IIRC a K-1/450mm and K-5/300mm combo. You should link back to it, it was very interesting. :)

I still prefer my APS-C bodies for macro and sports/wildlife for the reach, BTW. You're an excellent bird photographer and know that what counts is laying down the maximum number of pixels on the target from where you're shooting. Your D FA 150-450 works on either your K-3 or K-1, and in fact, the K-3 uses the best part of that lens - the middle.

My 24Mps Sony FF doesn't give me any more resolution than your K-3, but each pixel is bigger. My 36Mps K-1 doesn't give any better noise or dynamic range than Mee's K-5 II, but there's another 20Mp to downsample the JPEGs from.

It's a lot of money to pay for about a one stop advantage, isn't it? :lol:

I put the Nikon D800 stats above, but anyone who wants to compare the K-5 vs the K-1 can repeat the exercise here:

https://www.dxomark.com/Cameras/Compare/Side-by-side/Pentax-K-1-versus-Penta...IIs___1075_830
Forum: Pentax K-1 03-06-2017, 08:55 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
Yep.

The SNR 18% for this APS-C camera and a FF one like the K-1 or Nikon D810 using the same sensor wafer is practically identical.

You can do the following:


Go to Pentax K-5 II vs Nikon D800


Click on Measurements


Click on SNR 18%


Click on Screen


Repeat for Dynamic Range, Tonal Range, Color Sensitivity


For fun, click on ISO Sensitivity
Forum: Pentax K-1 03-06-2017, 07:46 PM  
Was I expecting too much?
Posted By clackers
Replies: 56
Views: 5,448
The pixel sizes are the same, and the Signal-to-Noise ratio of the RAW files will be almost the same. Many don't understand this. :)

The improvement you will have to do in post-processing your JPEGs. The K-1 will have more pixels to downsample.
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