DPL users/owners of Howtek/Aztek scanners

[onnect17]

For DIY. The alignment tools used for the Howtek 6500/7500 are the same for the Howtek HR8000/Aztek Premier. Similar procedure too.
To be honest, I initially did not put too much on the alignment thinking it was less critical than scanners with focused illuminators, like the 4000/4500. However, it's a must to check it if scanning at 8000 dpi, ie using the 3 microns aperture. Otherwise the noise could be considerable.

[thanvandang]

An update regarding the optical system tests.
thank for sharing

[onnect17]

Found an HR8000 so I can do a full comparison with the Premier, but first I have to finish some handyman kind of projects around the house.

[onnect17]

Got a chance to start looking inside the HR8000. Same motherboard, same SMU card, power supply. Identical optical box.

The only difference I found so far is the type of bearing in the tailstock. The HR8000 uses a more appropriate "angular contact", similar to the one used in the 6500/7500.

[onnect17]

Quick question for the HR8000 owners. Testing the scanner it shows is capable of resolving 8000 dpi just fine. However I read in a presentation in Aztek's website that the scanner is limited to a little over 4000 dpi. What am I missing?

Here's the link to the presentation (see slide #22):
http://aztek.com/Scanner%20Compariso...iles/frame.htm

[onnect17]

In case somebody needs the numbers for the head stock bearings in the HR8000 or Premier.

MRC 5304-CFF/H501
or
SKF 5304 A-2Z/C3

[John Harvey]

[QUOTE=onnect17;1247471]Quick question for the HR8000 owners. Testing the scanner it shows is capable of resolving 8000 dpi just fine. However I read in a presentation in Aztek's website that the scanner is limited to a little over 4000 dpi. What am I missing?

Pay no attention to that presentation. It will do 8000 SPI and will resolve down to 8000 DPI with the 3 micron aperture. I doubt you would ever need it. I use the 6.4 through 19.1 for most scans depending on the grain and what I want to do with it. Not many lens/film combinations will ever give you much more than 4000DPI resolving power anyway.

JH

[onnect17]

Thanks John. I feel better now. I thought I missed something.

I have some TechPan and Panatomic film than can get there. But you are right, not many film/lens combinations are capable of resolving that high.

Besides, after examine the aperture wheel under the microscope the 3 microns aperture is more like a 4 and not exactly square shaped.

[sanking]

Thanks John. I feel better now. I thought I missed something.

I have some TechPan and Panatomic film than can get there. But you are right, not many film/lens combinations are capable of resolving that high.

Besides, after examine the aperture wheel under the microscope the 3 microns aperture is more like a 4 and not exactly square shaped.

Armando,

With a few B&W films and very high quality 35mm and medium format equipment you may get to 8000 dpi. I have a friend who could do this with Ortho Spur and a Leica M7 and Leitz glass. I could get 5000-6000 dpi with Mamiya 7 and the 43mm, 50mm and 80mm lenses, but never 8000 dpi.

BTW, if I can get 5000 dpi with my 7500 could I assume that the alignment is OK?

Sandy

[onnect17]

Sandy,
The answer, IMHO, is yes and no.

The optical boxes of the 4xxx/7xxx scanners are better built than the 8000 dpi scanners so I would not worry too much for internal alignment problems, although it does not hurt checking for it. Ideally the center of the image projected should be targeting the aperture with not more than +/- 1 mm. Take a look at this image of the target using the scanner lens. The pitch in the digital camera used is 7.8 microns.



If the offset is 2 mm or more then color aberrations start to become significant. You could still can get the 5000 dpi in the individual color channels but the resolution should be lower if you convert the image to monochrome using all the colors. In fact, the difference in the numbers could be an indication of the condition of the internal alignment.

That's inside the optical box. The alignment in the external optical path will impact the noise level, contrast, focusing quality, etc.