The Choice Between .5 mm and 1 mm Base Heights
(Does NOT apply to V7xx and V8xx Series, Microtek or Agfa Holders!)

Many, but not all, scanners will benefit from a holder whose height can be varied from the standard 1 mm height of the OEM Epson® holders.

From the information that has been sent to me by my testers and information posted on the internet by other people, it seems that when a scanner's optimum film suspension height does actually vary from the standard 1 mm, the variation most often results in the need to raise a holder versus lowering it.

Why don't we sell just all of the holders with a .5 mm base height?

It is all about offering you choice as well as a product which will best meet your needs and workflow style.  When the film channels are made from .5 mm material, the edges of the film channel have extra flex when used with T-locks (T--locks are now optional on single channel film holders) compared to the 1 mm version (alternatively, flex is not normally an issue when an ANR Insert is used).  This is not a big issue as long as additional special attention is paid when inserting the T-Locks into the film holder.  (See the "see how it is used" page for the variable height holders.)  If a scanner does not have an optimum film suspension height in the .5 mm to 1 mm range, then there is no advantage to the .5 mm base height version.  Therefore, it makes sense to order the version with a 1 mm base height whose film channels will have less tendency to flex (again, most likely not a problem when using an ANR Insert).  Additionally, the additional .5 mm of suspension height with the 1 mm base height version will lessen the chances of the film coming in contact with the glass.  Therefore, Newton Rings are less likely.

How can you be more confident which holder version is best for your specific scanner?

You can carefully shim each corner of your OEM Epson holder as well as the edges next to the film channel with shims cut from thin sheet material such as a plastic report cover, thin file folder or even a thin business card.  Then make a test scan. It may be necessary to add a few layers of shims before you see a noticeable improvement.  If the shimmed test scan is sharper than the pre-shimmed scan, you are getting an indication that your holder probably needs to be raised (as opposed to being lowered below 1 mm).  This would indicate that the 1 mm base height version of the holder would be the best choice.

The .5 mm version uses thinner materials and the thinner materials require special care when inserting the T-locks so that the T-locks do not get pushed in too far.  See the variable height adjustment instructions for more information: variable height instructions.

Ultimately, selecting the correct base height has to be your responsibility and decision.  Please take the time to do some testing before you order.  If you cannot decide, please remember you can always:

1. Order a fixed height version of the single or dual channel MF Holder models.  These match the 1 mm suspension height of the Epson® OEM holders.
    
2. Order a 1 mm base height version of either variable height holder model and retract the set screws if necessary.  When you do this, the holder is by default right at a 1 mm film suspension height and functionally be the same as a fixed height holder.  That means it would perform as though you had bought a fixed height version of that MF Holder model.
    

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