Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: rogerxnz on September 06, 2012, 06:17:58 pm
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My "interesting" question is, if you photograph the same object from the same distance with the same camera and lens using, first, a 60MP and, then, an 80MP back and, then, zoom in to 100% view, is the object displayed larger on one back than the other, or the same size?
In other words, is it easier to check focus on one of the backs than the other?
Thinking about the options is doing my head in!
What I reason is: the sensor size of each back is the approx the same and the pixel density of the LCD is also the same. But the same object would be made up with more pixels on the 80 back and, thus, if each sensor pixel was mapped to one LCD pixel, the object would be displayed larger by 33% on the 80's LCD.
If that is true, checking focus on the 80 should be 33% easier than on the 60.
Does anyone know the answer?
Roger
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The size increase is not 33%.
Don't look at MP count. Resolution is a linear function.
Horizontal pixel count is more relevant.
8984 vs 10328 is a difference of 15%.
Not significant enough to make a difference when it comes to focus checking.
On both back 100% zoom is more than you need to focus check.
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That's an interesting question, however I think it's the same size with either camera. I briefly shot with a 180 and a 160 side by side and I don't remember the 100% view being any larger.
I believe you are looking at a much smaller file than the actual raw file as it would take a huge amount of time to process up a 180 file on the actual camera. I would think that the same applies to a 20mp 35mm and 36mp 35mm camera and
I know those two view are the same.
I am sure some of the dealer reps out there can answer for sure.
Of course the 100% view of a tiff created from the 80mp file will be larger than the same shot with a 60mp back.
Paul
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... If that is true, checking focus on the 80 should be 33% easier than on the 60...
Short answer: not true.
Medium answer: object will be displayed larger, but only by 15%
Long answer: Both backs have displays approximately 742 x 558 px. Given that files are 10,328 x 7760 px and 8,984 x 6,732 respectively, it means that, at 100%, 80 back will display 7% of the image, and 60 back 8% of the image
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Applause...
Short answer: not true.
Medium answer: object will be displayed larger, but only by 15%
Long answer: Both backs have displays approximately 742 x 558 px. Given that files are 10,328 x 7760 px and 8,984 x 6,732 respectively, it means that, at 100%, 80 back will display 7% of the image, and 60 back 8% of the image
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Few sporadic thoughts here at the end of the day:
- Yes the subject will be larger when viewed at 100% on an 80mp back compared to a 60mp back. As pointed out by Fred the linear size increase will be 15% while the area on the LCD will be 33% larger.
- It is noticeably harder* to focus an 80mp back than a 60mp back through an optical viewfinder. This is because the optical magnification of the viewfinder remains the same while the smallest detail the back is able to resolve is tinier.
- judging sharpness on an LCD at 100% is equally easy for any resolution back. This is because regardless of the resolution you are looking at the pixels captured by the back; either they are soft at 100% or they are sharp at 100%. A digital system cannot capture more detail than the pixels it uses to record them - so when you're viewing the pixels at 100% you're judging the maximum level of sharpness that system can achieve.
- if you are very slightly soft on an 80mp back you may still have captured more real world detail than a 60mp back which was completely sharp. So "sharp" should not be defined ONLY by whether the LCD 100% image is pixel-sharp.
You can do an experiment to show the real-world experience of viewing the same scene at 100% taken by two different resolution systems by simply taking a raw file from any camera you own and processing it at full resolution and e.g. 50% resolution and opening both in Photoshop at 100%. What you'll notice is that any slightly soft areas in the higher resolution image as-viewed-at-100% are hidden/unnoticeable in the 50% resolution image. This would of course overstate the difference between 60mp and 80mp but would make it easier to understand the real world implications of the theories presented above.
Pure resolution is not the only difference between the 60mp and 80mp sensors. Specifically comparing the IQ160 and IQ180 many forum members have noted better color and better tonal gradations. There are also back-specific limitations such as the inability to use Schneider's symmetrical-design wide angles (e.g. the 28XL and 35XL) with the IQ180 with any movements. The IQ180 also does max of two minutes instead of the IQ160's one minute exposures and has a minimum ISO of 35 rather than 50 (slightly better for blurring water and doing long exposures, slightly worse for hand holding).
In general both backs will capture a tremendous amount of detail and make very good very large prints. If you need ultra-detail for crazy sized prints I'd suggest stitching more than one frame on the back of a tech camera, which can easily catapult a "just 60mp" back into the 150+mp category (just make sure you have a good computer, lots of ram, and plenty of coffee or scotch for the processing).
*I define this by my own personal experience as well as the vast majority of our clients who have used both for a significant period of time - coupled with an understanding of the basic physics involved.
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I stand corrected. It's interesting I just didn't notice any difference and I usually catch those things. Just getting old I guess.
Paul
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Roger,
If you look at similar images from both backs on your monitor at 100% and see a difference in size and detail, then that is the difference you will also see on the backs' LCDs
Simples...
Yair