Drum Scanners: Upgrade from Howtek 4500 to Heidelberg Tango?

[onnect17]

I purchased it via B&H like a year ago. Back then the cost was $55. Now is like $70.
It's a positive copy of the USAF 1951. Comes in a slide frame. The last element of the group seven is not perfect, it's OK all the way to 10'000 dpi.

[sanking]

Interesting. I wish they said more about it. For instance, from their data I can't tell if it's flexible or not. My hi-res target is chrome on glass from Edmund Optics, and it's anything but flexible.

It is a flexible target on film. You could use it on a drum, or on a flatbed. The target comes in a snap together slide holder, easy to remove. Pretty much identical to the chrome on glass USAF 1952 targets, except it is on film and requires careful handling.

Sandy

[Peter De Smidt]

That's good to know, and it's reasonably priced!

[Grumium]

Sandy: Did you perform resolution tests with your drum scanner?

[sanking]

Sandy: Did you perform resolution tests with your drum scanner?

Yes, it was very easy to do. I just wrapped the target around the drum and fluid mounted it.

I did not do extensive testing but I made several scans of the target with the smallest aperture, 6, to see how close I could get to the theoretical maximum optical resolution. 5000 dpi was best possible, I got around 4000 dpi.

Sandy

[Grumium]

I performed a few test runs and determined a maximum resolution of about 4000 dpi for my Tango. Considering that it was marketed to up to 11000 dpi, this is on the low side. On the other hand, 4000 dpi translates to roughly 80 lpm, which is way more than most films and most lenses are able to resolve.

[Pali K]

Makes me wonder how much real dpi I am getting from Scanmate 11000 which is also rated at 11000 dpi. I have always heard great things about the tango and am surprised that it doesn't even resolve 50% of rated resolution.

Is yours properly calibrated?

[Tyler Boley]

there are many ways to create pixels.. resulting in dpi. Actual resolved detail has a lot to do with aperture as well as making big files. So resolution tests without attention to that setting, as Sandy mentioned in his, don't tell the whole story. There seems to be some confusion about controlling the Tango's aperture, I don't know about the Scanmate. Would be worth looking into.

[Grumium]

The Tango features 25 apertures that can't be directly selected by the operator but are chosen by the scanner based on the scan settings. By selecting aperture setting -5 and a resolution in the range that we are discussing it's very easy to force the scanner to use the minimum aperture size (10.0 µm). Please keep in mind that 10.0 µm translates into 50 lpm or 2540 dpi. Higher resolutions are the result of scanning overlapping areas (the Tango's stepper motor is capable of steps up to 2.3 µm!) and internal algorithms.

It's not easy to determine the maximum resolution by scanning the test target, thus the results should be taken with a grain of salt, as:
1) The Tango doesn't provide raw data, thus interpolation always takes place.
2) The transition between black and white on the test target isn't perfectly sharp (this is definitely the case for the Silverfast target).
3) The transition might not fall between two rows/lines of pixel-lines.
4) Reading the test is subjective.

@ Pali: Yes, my Tango is properly calibrated (by Karl).

[onnect17]

I don't know if Silverfast changed the source for the USAF targets but the copy I received seems fine (sharp). The only defect was in the last element of the last group (7,6) so is good all the way to 10'000 dpi. Ideally should be mounted slanted, around 5 degrees.

Here's a pic I took using the target while testing the Howtek lens.