Resolution concern?

[reg]

I have often wondered what the purpose of a digital back is for. Care for a short explaination? Thanks.

They're built to be used mostly on the back of medium and large format cameras. Dynamic range is higher, and they don't suffer noise on long exposures nearly as bad. Digi backs can shoot exposures up to an hour at about 70-80 degrees before the pixels start getting funky. And, of course, if you find something cool in a detail of your 40MP picture, you can always crop it down to an 8x10.

 

[RyanLilly]

I Know Alfred loves that chart recently, but Its all about viewing distance. You cannot even see an entire 20x30 print from 15 inches, you have to step back quite a bit to view the whole picture, therefore 300dpi is quite unnecessary, I have made great 8x10 and 11x14" prints with 4MP and they looked great even from arms length. So don't get caught up in the MP hype, really any current body can produce reasonably large prints at high quality.

 

[Bifurcator]

There's another aspect that is important to me at least and that I think you've all overlooked here. Cropping, and BG scrolling. With todays HD cams recording 4k frames a 21mp digital back is still too small sometimes. Also just like rapid fire exposure is a useful technique so can be giga-pixel sensor or sensor arrays. Just point your camera in a general direction and go home. Once on your machine you have 100's or great "pictures" to choose from by selecting and cropping.

For me I can never get enough pixels! The threshold between shooting 200 shots with an 8mp cam and being able to capture most or many of those in just a few 8gp shots just hasn't arrived yet is all.

On that topic I think it will go in a different direction myself. I think they'll figure out how to combine vector, fractal, and light-field technologies in such a way that HDR will seem poor and retarded and at truly scalable resolutions limited only by the glass you're shooting though - and at a wider spectrum than the 400 to 700 visible light we seem to be stuck in now. Some may be very surprised at how much detail is present in higher frequencies that image sensors have no trouble recording.

Kind of a long ramble just to say I want more than 21mp just because of the cropping thing... Sorry. :blulsh2:

 

[Bifurcator]

:thumbup:, but to an extent

None if this matters if you cant take sharp pictures anyways:er:

You've hit either on purpose or by accident, on a very interesting relationship between pixel resolution, apparent resolution, and scale. Meaning that actually if someone can't (or didn't by mistake or whatever) take a sharply focused image then it is exactly pixel resolution that will save his or her day.

Try it. Take a slightly out of focus picture and then either scale it in PS or print it at passport image size. Super sharp right? The same would apply for an A4 print. At 8MP there's not much room for error if you want to print to an A4. If it was 24mp you could get away with being slightly out of focus. If it were 8GP likely focus would not matter much at all - as long as you were in the general ballpark. Do I hear 8 terapixels? Anyone?

 

[Garbz]

The problem of course is that that beyond 10 megapixels you'd be hard pressed finding a 35mm lens that can resolve the sensor resolution.

 

[Bifurcator]

YAY for medium and large formats! Hehehe

But all seriousness aside what do you mean exactly? I thought we were still along ways away from that even at 24MP? I don't really know as I haven't looked at that - but only cuz I thought I didn't need to for awhile yet.

Are the 12MP cameras out in abundance interpolating or something? Or the 21mp Canon for that mater?

 

[Ben-71]

There was a mistake in my previous post. I was both tired
and pre-occupied by something else, sorry about that.

Here it is, corrected:

bisp21 ​

My goal is to take great landscape pictures and blow them up in to
huge printed canvas framed images and also takes some pictures
of my daughter that I can blow up pretty big and gallery wrap.
I am thinking I want to blow them up to 60 inches and will be using
a 300dpi printer for the canvas. What do you think? Will it look ok
using a Nikon D80 10.2 megapixel?​

​

That's easy to test and see for yourself:

You may take a pic with fine detail, a portrait for instance.
Enlarge a section of the eye (eyelashes included, for fine detail) to,
say 8x10", keeping the enlargement proportion similar to that of your
end goal.
Print it on the same material of your end goal. That's how your large
print would look like. See how it looks from a distance.​

Approximately –​

According to Alred .D's chart, there should be 300ppi for a 7" print.
(1") 25.4mm : 300ppi = 0.085mm dot size.​

Going from 7" to 60" print is a linear magnification of ~X8.6
0.085mm x 8.6 = 0.73mm dot size ​

Assuming an enlargement of (40" x 60") 100cm x 150cm,
the area is: 100 x 150 = 15,000 sq.cm​

D300:
15,000 (sq.cm) : 12,300,000 (effective pixels) = 0.00122 sq. cm per pixel
Dot size is a 0.035 x 0.035 cm square = 0.35 x 0.35 mm​

D80:
15,000sq.cm : 10,000,000 (effective pixels) = 0.0015 sq. cm per pixel
Dot size is a 0.039 x 0.039 cm square = 0.39 x 0.39 mm square​

Both are quite smaller than 0.73mm.​

300dpi printer:
25.4mm : 300dpi = 0.08mm
In this case, the 300dpi printer dots are smaller than the camera resolution.​

From 2.25 meters, I could notice 1mm gradation on a ruler (black on white).
I couldn't count them, they looked somewhat blurred, but I could perceive that
there're details, and my eyesight isn't 6x6.​

Therefore, the 0.73mm dot size seems to me to be a bit too large, but the
0.39mm dots may be acceptable for what you want.

I suggest trying a test enlargement, using RAW and the sharpest
lens you can lay your hands on, and see if it suits you.​

(And, draw a "do not cross this line" on the floor, 2.25 meters from
the prints )

 

[Garbz]

But all seriousness aside what do you mean exactly?

Well high-res sensors are still good since slightly unsharp photos look much better than upscaled low-res photos. But the problem is a sharpness of 35mm lenses. There's a finite amount of resolution you can get out of a lens due to diffraction, and 2 or 3 stops from wide open many quality lenses have already managed to hit that point.

Photozone actually use 10mpx cameras to measure the LW/PH resolution figures of lenses by shooting a resolution target and measuring the result. Now in reality it's not a top idea, but it does work well enough to give you a general idea how cheap / prosumer lenses perform.

For instance their graph clearly shows that the Nikon 50mm f/1.8 is shocking under f/4, and by shocking I mean you could probably see the sharpness wane even on an old 4-5mpx body. Some lenses however like the Carl Zeiss Planar 50mm f/1.4 T show an almost flat response up to the point where diffraction causes it to lose sharpness. I'm inclined to believe this lens outperforms the 10mpx sensor of the D200 they used but then for $1000 for a 50mm f/1.4 with no autofocus you want to hope so. There's other lenses that do this too but you can guarantee they all have a signature Red ring or Gold ring on the front depending on the company.

As the sensor gets larger though the effects of diffraction diminish, and if you look at something like the 40mpx medium format sensors their photodetectors are much larger than those on our APS sensors so you end up with 40megapixels a much nicer image, a lens that utilises it, despite the actual "resolution" of the lens not being much greater, just light is spread across a larger area.

I really don't see much point in the new flagship Canons and their ludicrously high-res sensors for this reason. I'm not sure the glass is available (currently) to utilise them.

 

[sonny.]

OK. Let's whip out the megapixel printchart again. Here's your answer, bisp:

Those figures pertain to 'true photo quality', which is 300dpi viewed at 15" distance (normal reading distance). If the viewing distance is greater you need less dpi.

These charts that determine "true photo quality" are made by people with as inflated a head as you.

True photo quality is in the eye of the viewer.

dead poets society anyone?

 

[reg]

dead poets society anyone?

you don't view a billboard from 15" away. Therefore, you can't use 300dpi at 15" for a billboard-size photo. It says that on the chart, but some in the thread aren't compensating for that.

Thanks for playing, next time comment on something you know.

 

[Bifurcator]

Well high-res sensors are still good since slightly unsharp photos look much better than upscaled low-res photos. But the problem is a sharpness of 35mm lenses. There's a finite amount of resolution you can get out of a lens due to diffraction, and 2 or 3 stops from wide open many quality lenses have already managed to hit that point.

Photozone actually use 10mpx cameras to measure the LW/PH resolution figures of lenses by shooting a resolution target and measuring the result. Now in reality it's not a top idea, but it does work well enough to give you a general idea how cheap / prosumer lenses perform.

For instance their graph clearly shows that the Nikon 50mm f/1.8 is shocking under f/4, and by shocking I mean you could probably see the sharpness wane even on an old 4-5mpx body. Some lenses however like the Carl Zeiss Planar 50mm f/1.4 T show an almost flat response up to the point where diffraction causes it to lose sharpness. I'm inclined to believe this lens outperforms the 10mpx sensor of the D200 they used but then for $1000 for a 50mm f/1.4 with no autofocus you want to hope so. There's other lenses that do this too but you can guarantee they all have a signature Red ring or Gold ring on the front depending on the company.

As the sensor gets larger though the effects of diffraction diminish, and if you look at something like the 40mpx medium format sensors their photodetectors are much larger than those on our APS sensors so you end up with 40megapixels a much nicer image, a lens that utilises it, despite the actual "resolution" of the lens not being much greater, just light is spread across a larger area.

I really don't see much point in the new flagship Canons and their ludicrously high-res sensors for this reason. I'm not sure the glass is available (currently) to utilise them.

Wow! And we're already there at just 10mp? That sucks! I thought for sure we had till at least 80 or 100mp. The RAW crop comparisons I looked at between the D3 and the 21mp Canon didn't seem to suggest that although I wasn't really looking for it either. I don't doubt you. I'm just disappointed that the optical resolving powers of the typical $200 f2 20 through 80 FFL lenses are all eaten up at 10 or so megapixels. Really, that sucks man!

So, the fast ride is over then. Now it's all about features and better sensitivity, higher bit depths, maybe we'll start seeing light-field technology showing up. Hmm, now I'm eager to see what the D4 or D5 have to offer. I have some engineer friends at Nikon (though on the microscope side) I wonder if they'll let me pick their brains over a beer or two? Muahahahaaaa :evil:.

 

[Garbz]

Well for many practical purposes we are, but just like the topic of resolution itself it depends on the printing, viewing distance, and some key ones are aperture and sensor size.

My example above with the D200 suggests that APS sensors are limited but by all means because diffraction is dependant on sensor size it is actually possible a lens performs a bit differently on 35mm. So while the cheapy 50mm f/1.8 may be sharpest at f/4 on the D200, on the D3 it may actually be sharper at f/5.6.

Plus I mentioned that there are still outperforming lenses out there. The only time I've ever seen a D3 it had that lust worthy 14-24 f/2.8 N lens on it. The photozone review gave identical resolution figures at all apertures which is a warning light for me that the sensor is maxed out using this lens. I doubt the review of the D3 had the ever wonderful 18-200mm on it

We still have a bit to go but I doubt we'd ever realistically need to battle medium format type megapixels on a 35mm frame. I was pleased to see Nikon announce the 12mpx D300 and 12mpx D3 on the same day and that they didn't crank 18mpx on their full frame camera. So maybe the race is over. If you do get a chance to talk to them I'd be very interested in their opinions.

The race won't be over for the consumers though, megapixels is the only number they understand and unfortunately it sells cameras regardless of how crap a 10mm wide lens is. My dad's Olympus P&S's lens isn't even capable of outperforming the 4mpx sensor it has

 

[AndrewG]

Good quality lenses are far more important than getting fixated on pixel counts.

 

[JimmyO]

And having extra pixels wont make up for a misfocused shot.

 

[Bifurcator]

Depending of course on how out of focus and how many mega pixels we're talking about.