Comparison - Epson Flatbed Scans With Glass vs. Without Glass

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Flatbed scanner users have always wondered how much detriment is caused by
the piece of glass found in the optical path of flatbed scanners when
scanning their film. There have been many statements made about this but I
had never seen any postings of actual comparison images. I had been
contemplating experimenting to see how much of a gain could be obtained by
removing the glass. Other projects took precedence and I also wasn't real
excited about dismantling my scanner, so the project had been "on the
backburner." A friend, Ian S. (name hidden to protect the innocent!),
recently emailed me and said he had removed the glass on his Epson flatbed
scanner. Ian does incredible panoramic work and found glassless scanning
added benefit for his particular workflow (including sharpening, etc.) and
encouraged me to give it a try. I have no doubt it is a good solution for
him. His panoramic scans are gorgeous. For my workflow, I did not feel the
benefit was worth the effort. I can see a very slight increase in resolution
(e.g. the fins in the color image), but nothing like I had hoped to achieve.

I thought others might like to see the results, so links are provided below.
Both images were shot using a 35 mm Nikon F3 HP on a tripod with either a
Nikon 24 mm 2.8 AFD or a 50 mm 1.4 AIS. The color image was shot on Kodak
E100S and the b/w image on Tmax 100 developed in Xtol. The film images are
tack sharp when printed in the "fume room." I used my Epson 3200 with the
original Epson holders for these scans (my 4870 isn't out of warranty yet!).
FWIW, Ian sent me a comparison scan made on his modified 4870 and the
"level" of benefit appeared about the same to us both. I did not manipulate
these scans (including resampling) before uploading. EpsonScan was used
without any adjustments to the software, so that is why the scans look a bit
flat and show the scratches. The custom cut "plate" that I created to
replace the glass bed retained all the characteristics to provide correct
scanner startup calibration. Both of the "before" and "after" scans produced
nearly identical histograms/black points/middle points/white points.

Full image used for the color scan comparison:

http://www.photo.net/photodb/photo?photo_id=3111674

Crop of color scans comparing with and without glass:

http://www.photo.net/photodb/photo?photo_id=3111679&size=lg

Full image used for the black and white negative comparison:

http://www.photo.net/photodb/photo?photo_id=3111581

Crop of black and white scans comparing with and without glass:

http://www.photo.net/photodb/photo?photo_id=3111670&size=lg


Doug
---
Doug's "MF Film Holder" for batch scanning "strips" of 120/220 medium format
film:
http://home.earthlink.net/~dougfisher/holder/mainintro.html







..
 
- wrote:
....
I thought others might like to see the results, so links are provided below.
Both images were shot using a 35 mm Nikon F3 HP on a tripod with either a
Nikon 24 mm 2.8 AFD or a 50 mm 1.4 AIS. The color image was shot on Kodak
E100S and the b/w image on Tmax 100 developed in Xtol. The film images are
tack sharp when printed in the "fume room." I used my Epson 3200 with the
original Epson holders for these scans (my 4870 isn't out of warranty yet!).
Click to expand...
....

Doug,

Very interesting work. It looks to me as though there is more shadow
detail in the glassless scans. Perhaps just looking at histograms of
cropped shadow areas might be worth doing.

Steve
 
....
I had been
contemplating experimenting to see how much of a gain could be obtained by
removing the glass. ....
The custom cut "plate" that I created to
replace the glass bed retained all the characteristics to provide correct
scanner startup calibration. Both of the "before" and "after" scans produced
nearly identical histograms/black points/middle points/white points.
Click to expand...

Thanks very much for that! It's always very interesting to read
lateral approaches to scanning!

From personal experience, I can immediately see at least two major
benefits to glassless scanning, perhaps much more important than the
small reduction in gain the glass may be causing:

1. Even with regular care and cleaning, scratches and stubborn dirt
("fog") inevitably accumulate on the glass over time.

2. Newton's rings on glossy photos caused by the contact with the
glass.

On the minus side, I guess, the scanner is now wide open to marauding
dust particles intent on doing damage.

A few questions:

What is your "plate" made of?

How did you affix it to the scanner so that its bottom side is in the
same "sweet focus spot" as the top of the glass? I found that lifting
glossy photos even a fraction of a mm with a cardboard frame caused
more loss of gain than, I imagine, glass could ever do.

Finally, how do you attach the photo to the bottom of the plate? In
the above case of Newton's rings, I used double sided tape to affix
the photo to a piece of thick Plexiglas so it's flat and the cardboard
frame lifts it evenly. But I was unhappy with that because it's very
difficult "unsticking" the photo without damaging it.

Oh, one more ;o) How do you handle different thickness of photographs?
Presumably - if the plate is fixed - the distance between photo
surface and the scanning elements will differ depending on the
thickness of photo paper. And, as described above, that distance seems
to have a considerable influence on gain.

Don.
 
Perhaps just looking at histograms of cropped shadow areas might be worth
I uploaded moderate file sizes in the hopes anyone should be able to right
click on the image file to download the files in unaltered format to the
their own computer. Then you can manipulate them any way you want so that
you can see if there is any real benefit to your particular workflow.

Doug
 
2. Newton's rings on glossy photos caused by the contact with the
glass.
Click to expand...

Well, you really can't do photos without the glass :). If I would have gone
ahead and decided to produce a retrofit kit for sale, I might have included
a drop-in glass piece to add this functionality but then you would
basically have been back to the same performance as with a regular scanner
(in terms of reflective scanning).
On the minus side, I guess, the scanner is now wide open to marauding
dust particles intent on doing damage.
Click to expand...

This is something I worried about. I would have definitely kept the scanner
covered in plastic when not in use. Two things to remember though. The
cases on these scanners are not sealed and have plenty of vent holes so dust
is always getting in anyway. At least the scanner optics "park" back up
under the case when not in use. You are right though, there is an increased
risk. Keep a can of compressed air around! If the optical resolution gains
had been substantial, I think the cleaning hassles would have been worth it.
What is your "plate" made of?
Click to expand...

The same class of plastics I use for my holders. Nothing exotic.

In regard to your other questions about photos, this experiment was just for
film scanning. These scanners really do a good job with photo's already in
my opinion. The plate is designed to allow you to use the Epson film
holders or my holder pretty much as if you were using the glass, but of
course without anything in the area where film is scanned.

Doug
 
Well, you really can't do photos without the glass :).
Click to expand...

Actually, you could if you attached the photo to the plate with double
sided tape. In other words, the photo would "hang" from the plate with
its back stuck to it.

As I mentioned last time I do something similar in order to have the
photo "float" above the glass in order to avoid Newton's rings.
Removing the glass completely would have been the next step.
This is something I worried about. I would have definitely kept the scanner
covered in plastic when not in use. Two things to remember though. The
cases on these scanners are not sealed and have plenty of vent holes so dust
is always getting in anyway.
Click to expand...

Indeed! As my - almost weekly - cleaning of *both* sides of the glass
confirms!
At least the scanner optics "park" back up
under the case when not in use.
Click to expand...

That's very true and why I dared to open the scanner in order to clean
the underside of the glass.
In regard to your other questions about photos, this experiment was just for
film scanning.
Click to expand...

Oh, OK, I misunderstood.

I see how you would not want anything between the film and the glass.
It would be like scanning slides in glass mounts.

Nevertheless, interesting idea that, to remove the scanner glass!

Don.
 
Don said:
Actually, you could if you attached the photo to the plate with double
sided tape. In other words, the photo would "hang" from the plate with
its back stuck to it.

As I mentioned last time I do something similar in order to have the
photo "float" above the glass in order to avoid Newton's rings.
Removing the glass completely would have been the next step.




Indeed! As my - almost weekly - cleaning of *both* sides of the glass
confirms!




That's very true and why I dared to open the scanner in order to clean
the underside of the glass.




Oh, OK, I misunderstood.

I see how you would not want anything between the film and the glass.
It would be like scanning slides in glass mounts.

Nevertheless, interesting idea that, to remove the scanner glass!

Don.
Click to expand...
Speaking of scanner glass...is it difficult to remove the glass on the
Epsom 4870 Photo for underneath cleaning? I called Epson and they told
me to take it to a professional repair shop. But I routinely clean the
under side of my Microtek E6 glass with no problem.
Thanks,
Frank
 
Speaking of scanner glass...is it difficult to remove the glass on the
Epsom 4870 Photo for underneath cleaning? I called Epson and they told me
to take it to a professional repair shop. But I routinely clean the under
side of my Microtek E6 glass with no problem.
Click to expand...

Definitely do it yourself and save your money. You will do a better job
because you actually care. Also, you won't risk damaging the unit during
shipping.

There is a .pdf file which does a great job of explaining how to open your
scanner up for cleaning and it is found in the files section for the Epson
2450/3200 Users Group http://groups.yahoo.com/group/epson3200/ as well as
the Epson 4870/4990 Users Groups at Yahoo Groups. Go slow and work in a
well lit area with lots of table space. It will take you 25 minutes the
first time and 10 minutes thereafter.

Doug
 
- said:
Definitely do it yourself and save your money. You will do a better job
because you actually care. Also, you won't risk damaging the unit during
shipping.

There is a .pdf file which does a great job of explaining how to open your
scanner up for cleaning and it is found in the files section for the Epson
2450/3200 Users Group http://groups.yahoo.com/group/epson3200/ as well as
the Epson 4870/4990 Users Groups at Yahoo Groups. Go slow and work in a
well lit area with lots of table space. It will take you 25 minutes the
first time and 10 minutes thereafter.

Doug
Click to expand...
Got it! Thanks Doug.
Frank
 
- said:
Definitely do it yourself and save your money. You will do a better job
because you actually care. Also, you won't risk damaging the unit during
shipping.

There is a .pdf file which does a great job of explaining how to open your
scanner up for cleaning and it is found in the files section for the Epson
2450/3200 Users Group http://groups.yahoo.com/group/epson3200/ as well as
the Epson 4870/4990 Users Groups at Yahoo Groups. Go slow and work in a
well lit area with lots of table space. It will take you 25 minutes the
first time and 10 minutes thereafter.

Doug
Click to expand...
BTW, is there a pdf specifically for the 4780?
THX
Frank
 
BTW, is there a pdf specifically for the 4780?

No, but since they are so similar the procedure should be the same. One
thing I did find on my 3200 was that it had a better connector for the power
button cable. Read the .pdf and you will know about this cable.

Doug
 
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