Q&A For Digital Photography Page 2
The Digital Camera Raw Vs. JPEG Choice Is Poorly Understood
Q. I hear many professionals say that the only way to get professional-quality photographs is to shoot raw. But I've also heard professionals say that you can get great professional-quality photos shooting JPEG. JPEG has some very obvious advantages in smaller file size and in the workflow process. What do you think?
A. First of all, your assumption about file size today is
not accurate. If you compare a full-resolution JPEG using the Finest quality
setting to a raw file from any current prosumer or pro camera you may be surprised
to find the JPEG is no smaller and sometimes a larger file. The reason is that
the raw format of all of the leading companies involves the use of proprietary,
The issue between raw and JPEG in terms of quality is not that there are significant differences in the physical attributes of the information between a full resolution, Finest quality JPEG and raw. The difference is the camera automatically adjusts color, brightness, and saturation by on-board internal processing in JPEG mode and outputs 24-bit image data that should not be subjected to very much color correction editing because data will be lost; while raw is all of the information captured by the sensor at the sensor's full, high bit depth. No color correction is done by the camera in raw format, so that function is left to the photographer to apply on a custom image by image basis. In other words, raw provides full control by the photographer of how the image should look, and JPEG does not.
Some Choices Between Printers Are Functional Choices, Not Which Is
Q. You wrote two excellent articles in Shutterbug about ink jet printers--one about the Epson Stylus Photo R800 in the August 2004 issue and one about the Canon i9900 Photo Printer in the October 2004 issue.
I am an advanced amateur photographer who is just getting ready to get involved in digital darkroom work and I was intrigued by your articles, but I am having trouble trying to decide which of these printers would be best for me. Do you have any suggestions as to how I should decide?
A. Thank you for the kind remarks about my articles. I can
understand having some difficulties choosing between the printers I reported
on because both do a superb job of reproducing photographic images in prints.
So a choice must really be made on factors other than print quality. One factor
might be whether you would be satisfied with prints that are letter size--or
would you require making larger prints, as the maximum width of the Epson R800
is 8.5" (letter size) and the width of the Canon i9900 is 13". Another
factor is print life. If you want your prints to remain true to color for generations,
then the pigment ink Epson utilizes in the R800 provides considerably longer
print life than the dye inks that are used by the Canon i9900.
Other than these two differences of size and print longevity the printers should both provide satisfying performance and utility. I hope I have been able to help your decision making.
Is Your Computer's CD Drive Up To Every Challenge?
Q. I recently offered to make some prints for a friend. She burned several files to a CD and mailed them to me. To my surprise when I opened them they had, for want of a better description, short lines about a pixel high and 10-50 pixels in length. These lines were alternately light and dark shades, scattered throughout all the files. These lines print, by the way.
I printed the files for her and pointed the lines out. When I returned the disc to her she reported she does not see the lines on her system nor on the system of another acquaintance. So at my request she returned the disc to me. Lo and behold I still see them on my system, but not on my wife's.
What are these lines? Why do they only appear on my system? Are they on the disc? I've never seen anything like it before and have no other difficulties with my system.
Note: Screen shots were included with the reader's e-mail clearly illustrating the problem artifacts.
A. Thanks for providing all of the details and screen shots
describing the problem you are having. First of all, consider an image file
is a matrix of square pixels and that your computer "reads" the
data the same way you read a page of type--text left to right one line
at a time. If you are reading under artificial light and the power connection
to the light is partially shorting out so the light flickers a bit, as you scan
the page line by line, letter by letter, you might miss some words or parts
Being that the files on the disc can be read cleanly by some computers other than your own, then I would look to your CD drive as the likely source of the problem. And if your CD drive reads other discs OK, then it may be the CD-R from your friend has a weaker "image," which is very possible because a CD-R is recorded in a very thin layer of dye, and different brands and types do vary one from another. Also, a few fibers of lint may have gotten into your CD drive and attached to the head (reader). This could intermittently get in the way of the laser beam reader. This would yield skips of garbled data that would record like the lines that are in the images you sent.
From the information you provided, what I described seems to me the most likely cause of the problem, but it could be something else with a similar effect, like an electrical connection that is intermittently weak. But I would suggest that the CD is OK if it can be read by other computers, and that the most likely culprit is your CD drive. And it could be as simple as some fine dust in the drive.
Copying Slides With A Digital SLR
Q. In the January 2005 issue of Shutterbug, Roger W. Hicks makes reference to a slide copier carrier for his Nikon D70 ("Studio Update" article on pages 104 and 106). My father, who has 15,000+ slides, would purchase the D70 tomorrow if he could locate this slide copier carrier. He presently uses an attachment made by Nikon for his Coolpix 5400. Is there a slide copier carrier that works with the D70, and which lens is needed?
A. I really have no idea which brand slide copier attachment Roger Hicks referred to. However, as far as being able to copy slides with a digital SLR it is really no different than with a film SLR and about any of the same slide copier attachments should be adaptable. Using a slide copier attachment usually functions best and most effectively with a macro lens if it is the type that attaches to the adapter screw ring of a lens. Some slide copiers, however, have been available that have their own lens built-in. I would suggest inquiring as to what is available in slide copier accessories from at least a couple of our advertisers: B&H and Adorama. And of course check out the Nikon website (www.nikonusa.com) to see if a Nikon slide copier is available.
Avoid Losing Image Information Data
Q. I'm using Photoshop CS on a Windows XP operating system. When a raw image file that has been created in 16-bit color, saved in a TIFF file format, and then converted to 8-bit color is saved/closed and then reopened/converted back to 16 bit, does it gain back the 8-bit color information, or is that permanently lost? The only reason for converting to 8 bit is to save file space, but if it results in any permanent loss I will leave it at 16 bit.
A. No, I am afraid once a 48-bit image file is reduced to
24-bit RGB color all of the data that would not fit in 24-bit color space is
discarded and cannot be recovered. It is always a good idea if you have originals
in 48-bit color depth to archive them as such on permanent media like a CD so
you always have access to the full body of information for future use. These
days memory space, especially CDs, is really cheap, even the archival gold/gold
CD-R discs. So what savings are you really talking about?