Ad
Ad
Ad
Pages: « 1 [2]   Bottom of Page
Print
Author Topic: comparison is unfair to 4x5 Velvia  (Read 29958 times)
jrkeat
Newbie
*
Offline Offline

Posts: 8


« Reply #20 on: June 02, 2006, 07:28:06 PM »
ReplyReply

Quote
Not that it matters much, but his point, as I understand it, is that all the digital files should have been up-resed to match the highest resolution of scanned film.

Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=66989\"][{POST_SNAPBACK}][/a]

Yes, you're right I'm saying that up-resing the digial files and displaying them all at a higher resolution is an essentail part of a valid comparison.  That was the intent of my first post.

However, my claim is now somewhat stronger, based on the scans in my second post.  I believe that if a fair comparison were done (digital files up-resed, everything in focus, objects of the right size shot) that Velvia would clearly be the raw resolution winner, at least given that the Betterlight was not used in interpolation mode.  (Personally, I'd rather use the lower-noise Betterlight when possible, but studying resolution, not noise, was the core goal of the original article.)

The 24000x18000 scan (4800 dpi) in my previous post show detail that cannot possibly be seen in a 8000x6000 (1600 dpi) scan.  The numbers are clearly readable in the 4800 dpi scan.  In the 1600 dpi scan, they are only ~3.5 pixels high, and completely impossible to read.  There's no way that you can display a number like 4 or an 8 in 3.5 pixels, so there's no way the Betterlight's 8000x6000 scan/photograph could resolve the numbers.
« Last Edit: June 02, 2006, 10:05:45 PM by jrkeat » Logged
hankg
Jr. Member
**
Offline Offline

Posts: 55


WWW
« Reply #21 on: November 26, 2006, 10:44:10 AM »
ReplyReply

In the real world film destined for reproduction in print will not recieve the attention it does in a test like this. I have been to printers and seen top of the line drum scanners collecting dust while they do all thier scans on inferior flat-bed scanners because it's faster and cheaper and the operators don't have the skills anymore to operate the drum scanner properly.

In addition when the photographers final product is a transparency the art director is likely to pick the under-exposed tranny. It looks richer and more saturated under a loup but it will produce a scan that is inferior to the less dramatic looking slide that has more open less saturated shadows. Digital gives the photographer more control over the end result and allows the use of more flexible equipment, i.e., shooting fashion with a DSLR instead of a view camera.

If digital can get close in quality to analogue at one to one enlargements on your monitor in carefully performed tests you can be sure that it will be superior in most applications in the real world.

Hank Graber
www.hankgraber.com
Logged

cescx
Jr. Member
**
Offline Offline

Posts: 65


WWW
« Reply #22 on: November 26, 2006, 12:45:04 PM »
ReplyReply

friends... not itself if is because my English is very bad, or nobody has realized a very important detail.

The film have a 2 micon grain, the best digital back have a 6,4 micon pels, obioulsy, the film, is better in fine detaill resolotion. But, in the other hand, the film is "binary", only captures, per grain, black or white, one bit per grain, the conjunction of 65.000 grains equals the color resolution of 16 bits, 3 pels in digital back.... In the bill example, the detail is only BW, no gradations, only lines in black, in the case, the film is better. But in others parts of the shot, I am sure the digital is better.
Logged

Francesc Costa
neil snape
Sr. Member
****
Offline Offline

Posts: 1431


WWW
« Reply #23 on: September 29, 2007, 03:55:51 AM »
ReplyReply

Let's not forget that image repro is in every case reconstituting the original or an approximation thereof. A scanner's goal is reproduce as close as possible the original , yet as all imaging applications has its optical limitations. True resolution is going to be reduced to less than theoretical spec as diffraction , noise, optical paths, PMT condition, etc etc all play into this. I often see Aztek touting the top of the line as far superior to the Tango. Optical res is not the only part of what a scanner sees nor how it puts the image together. I'll just say that the Tango is a top quality drum scanner and it cannot be dismissed as a lesser quality scanner than any other drum scanner. Now scanner operators certainly can , but if Charlie did the scans , you can rule out this factor.

Drum scanners all have diffraction, and flare. Even though you can up the res, the optical or rather visual sharpness while pixel peeping is always lesser at the higher numbers. There is more detail resolved, yet the image is not going to look as well reconstituted on your screen , nor your print.
In very rare cases if you had a brand new scanner, drum, etc they may be better, but I will never have a chance to prove this right.

In short, scanning colour films above 3000 ppi has never shown any significant gain, in fact contrary , the results always looked less alive than the same scans at lesser res when scanning.

I do hope that 4x5 or 8x10 film is far better than digital , as I would be glad to sell my drum scanner to those who would need it for doing so.
Logged
KAP
Full Member
***
Offline Offline

Posts: 168


WWW
« Reply #24 on: October 09, 2007, 01:05:22 PM »
ReplyReply

Does any of this apply to real world photography? maybe a handfull of photographers. I'm shure there are many other factors day to day that will decide the best medium other than the scanner aperture etc. I don't see any relevance in a section of detail in a dollar bill. I would rather see detail in a tonal range or the quality of finished files of a room set or landscape. I would think the fact the betterlight takes so long to make an exposure and the need for zero vibration would have a bigger effect on resolution or weird streaking on an area day to day. I think you would need to be very niche market to base a living on the betterlight, nice to have as an option but lots of opportunity to tear ya hair out.

Kevin.
Logged
MikeMike
Full Member
***
Offline Offline

Posts: 145


WWW
« Reply #25 on: October 11, 2007, 03:38:00 PM »
ReplyReply

I think those are questions that nobody could really answer but yourself KAP. How could anybody tell you which is the best for you? the tests show the detail level and sharpness for each system and how you apply that knowledge relies on your needs.

Michael Amir
« Last Edit: October 11, 2007, 03:38:36 PM by MikeMike » Logged
timparkin
Jr. Member
**
Offline Offline

Posts: 50


« Reply #26 on: December 26, 2009, 06:45:07 AM »
ReplyReply

I think something that is being missed completely is that the dollar bill test subject plays into an area where digital excels, i.e. white light monochromatic high detal subjects with lines. Raw converters can make easy use of edge/line detection and colour interpolation in order to get an apparent resolution that equals the number of pixels in the camera.

However, a more interesting test might be a textured pattern that has areas of monochromatic colour. e.g. a textile with intense blue and red sections. This would cause real problems with the raw converter trying to interpolate data from the bayer array and would probably mean an halving of the digital camera linear resolution.

The problems caused by a lack of monochromatic colour resolution in digital cameras (and their issues with resolving textural rather than line detail) are not raised very often.

Tim Parkin
http://www.timparkin.co.uk
Logged
ErikKaffehr
Sr. Member
****
Online Online

Posts: 6926


WWW
« Reply #27 on: December 26, 2009, 09:45:03 AM »
ReplyReply

Hi,

I spent some time looking into Velvia vs. Digital. My comparison is based on 67 vs. Sony 900. That article is here:

http://83.177.178.7/ekr/index.php/photoart...-sony-alpha-900

My findings are not very clear. Essentially I have the impression that Velvia may resolve better than full frame 135 at 24.6 MP for simple high contrast subjects. Regarding color separation Velvia is truly horrible compared to the Sony, especially in the reds.

I have made some additional tests trying to use an enlarger lens on bellows to make highly enlarged macroscopic photographs of my Velvia slides, but the results I came up with were pretty similar to my best scans.

My impression is simply that 67 Velvia can not keep up with a modern DSLR, at least not with the Pentax 67 I'm using. I have made a few very nice 70x100 cm prints using my Pentax 67, so I think it is essentially OK. Would love to repeat the experiment with a Hasselblad.

But, we need to put things in perspective. On digital I take one picture, check histogram and focus on the LCD. That's it. On film I need to shot a roll of film, wait for development (around in a week where I live), scan the images try to figure out possible problems. So I essentially have one shot on digital which took me something like a minute, and about 40 shots on film with perhaps three weeks of lab time. I'm doing my own scanning on an old MF scanner which cost about 3000 USD when I bought it. Would I do drum scans of 30 images they would set me back a significant amount.

To put it short, in my view digital outperforms Velvia with ease, although there may be areas where Velvia can match digital. Add to this that digital achieves this conveniently and economically.

Now, the stuff I was doing was based on 6x7 and amateur equipment. Real photographers who are much more knowledgeable than me, like Charlie Cramer, Bill Atkinsson and Joseph Holmes seem to arrived to similar conclusions regarding MFDBs and 4x5" film, using drum scanners and having considerable expertise.

So, in short, I don't feel the comparison is unfair to Velvia

Best regards
Erik Kaffehr




Quote from: timparkin
I think something that is being missed completely is that the dollar bill test subject plays into an area where digital excels, i.e. white light monochromatic high detal subjects with lines. Raw converters can make easy use of edge/line detection and colour interpolation in order to get an apparent resolution that equals the number of pixels in the camera.

However, a more interesting test might be a textured pattern that has areas of monochromatic colour. e.g. a textile with intense blue and red sections. This would cause real problems with the raw converter trying to interpolate data from the bayer array and would probably mean an halving of the digital camera linear resolution.

The problems caused by a lack of monochromatic colour resolution in digital cameras (and their issues with resolving textural rather than line detail) are not raised very often.

Tim Parkin
http://www.timparkin.co.uk
Logged

Jonathan Wienke
Sr. Member
****
Offline Offline

Posts: 5759



WWW
« Reply #28 on: December 26, 2009, 08:37:31 PM »
ReplyReply

Quote from: michael
You can please some of the people all of the time, and all of the people some of the time, but you can't please all of the people all of the time.

With apologies to Bob Dillan.

You should actually direct your apologies to Abraham Lincoln...
Logged

timparkin
Jr. Member
**
Offline Offline

Posts: 50


« Reply #29 on: January 05, 2010, 05:26:14 PM »
ReplyReply

Quote from: ErikKaffehr
Hi,

I spent some time looking into Velvia vs. Digital. My comparison is based on 67 vs. Sony 900. That article is here:

http://83.177.178.7/ekr/index.php/photoart...-sony-alpha-900

My findings are not very clear. Essentially I have the impression that Velvia may resolve better than full frame 135 at 24.6 MP for simple high contrast subjects. Regarding color separation Velvia is truly horrible compared to the Sony, especially in the reds.

I have made some additional tests trying to use an enlarger lens on bellows to make highly enlarged macroscopic photographs of my Velvia slides, but the results I came up with were pretty similar to my best scans.

My impression is simply that 67 Velvia can not keep up with a modern DSLR, at least not with the Pentax 67 I'm using. I have made a few very nice 70x100 cm prints using my Pentax 67, so I think it is essentially OK. Would love to repeat the experiment with a Hasselblad.

But, we need to put things in perspective. On digital I take one picture, check histogram and focus on the LCD. That's it. On film I need to shot a roll of film, wait for development (around in a week where I live), scan the images try to figure out possible problems. So I essentially have one shot on digital which took me something like a minute, and about 40 shots on film with perhaps three weeks of lab time. I'm doing my own scanning on an old MF scanner which cost about 3000 USD when I bought it. Would I do drum scans of 30 images they would set me back a significant amount.

To put it short, in my view digital outperforms Velvia with ease, although there may be areas where Velvia can match digital. Add to this that digital achieves this conveniently and economically.

Now, the stuff I was doing was based on 6x7 and amateur equipment. Real photographers who are much more knowledgeable than me, like Charlie Cramer, Bill Atkinsson and Joseph Holmes seem to arrived to similar conclusions regarding MFDBs and 4x5" film, using drum scanners and having considerable expertise.

So, in short, I don't feel the comparison is unfair to Velvia

Best regards
Erik Kaffehr

Hi Erik

I think you missed part of my point (although your article is well written and perfectly valid) ... The comparison is unfair to velvia because it was a monochromatic subject with strong, linear edges - the ideal subject for a raw converter to interpolate and do edge detection on. If the subject had been a non-uniform coloured  texture (like a lot of distant landscape textures) then the resolution of the digital camera would be quartered (or the linear resolution would be halved). Then the results would start to look like a velvia transparency having a similar 'colour' resolution to a an 15mp digital SLR...

However, black/white details will resolve at the full resolution of the digital sensor, which is pretty close to a medium format transparency. however, if we say that a 24Mp is almost equivalent to 6x7 , lets say 25Mp for the sake of argument, then when we get to 100Mp we'll have the equivalent of a 4x5 transparency ... we're not quite at that point yet, and I still consider the lack of hi frequency colour response a problem for landscape photography.

There are still a large number of photographers who can't afford medium format digital backs that want the resolution, quality and control that large format brings. After all, a 4x5 transparency is at least a 100Mp disposable sensor that only costs $5!!

Tim

Tim
Logged
Jonathan Wienke
Sr. Member
****
Offline Offline

Posts: 5759



WWW
« Reply #30 on: January 05, 2010, 07:52:22 PM »
ReplyReply

Quote from: timparkin
However, black/white details will resolve at the full resolution of the digital sensor, which is pretty close to a medium format transparency. however, if we say that a 24Mp is almost equivalent to 6x7 , lets say 25Mp for the sake of argument, then when we get to 100Mp we'll have the equivalent of a 4x5 transparency ... we're not quite at that point yet, and I still consider the lack of hi frequency colour response a problem for landscape photography.

There are still a large number of photographers who can't afford medium format digital backs that want the resolution, quality and control that large format brings. After all, a 4x5 transparency is at least a 100Mp disposable sensor that only costs $5!!

Actually, you have it completely backwards. Digital's resolution is consistent between low-contrast and high-contrast detail. Film, on the other hand varies considerably. Because film's grain structure is composed of clumps of silver or dye, it takes a larger area of film surface to resolve a low-contrast edge than a high-contrast edge. It's similar to the dithering used by inkjet printers. An inkjet can render high-contrast edges like black text on white at the full resolution of the printer (say 2880 DPI), but subtle shades of color require droplets of several different colors of ink to be dithered together, and the effective resolution for subtle tones is more like 360 DPI than 2880. Film is the same way; subtle tones require the dithering of multiple clumps of dye or silver, and effective resolution is reduced considerably.

This is the reason that film trumps digital in resolution tests where high-contrast test targets are used, but in real-world comparisons, digital wins when format is equal.
Logged

Pages: « 1 [2]   Top of Page
Print
Jump to:  

Ad
Ad
Ad