finding best sharpness

[Iivan]

Hello,
I have made my own negative holder using a plastic cutting board and a couple nylon screws. The height is now infinitelly adjustable. What is in your opinion the best way to determine the height for best sharpness? I have tried putting a plastic card with small numbers in to the holder but could not get the numbers sharp. With a negative I get improvement but it is difficult to know whether the negative is really sharp.

[LSI_Ketelhohn]

Dear Iivan,

In our online shop we offer the USAF resolution target which would be suited for that task.
You could use it to measure the achieved resolution (and therefor sharpness) at different hights.

Kind regards,
Arne Ketelhohn.

[Iivan]

Hello!
Thank you for your answer but is this target really suitable for negative holder? My holder is for plain 35 mm film strips. Why the instructions for fhe USAF-target state that you should scan the target with best optical resolution when that is the thing you want to measure with the target? What is the best resolution for v700?

[LSI_Ketelhohn]

Dear Iivan,

you can also measure using the 35mm filmholder.
But you would need to open the USAF slide to put the film inside into the holder.
The measurement can be done in positive mode for better readability.
That would give you the resolution where you can still separate distinct details.

Kind regards,
Arne Ketelhohn.