[3dem] FEI LowDose over-exposing film?
LLORCA BLANCO, OSCAR ANTONIO
ollorca at cib.csic.es
Tue May 15 04:48:34 PDT 2012
by the way....in our hands, film with the emulsion on the wrong side appeared completely transparent after development, as not being exposed.
Spanish National Research Council
Quoting "LLORCA BLANCO, OSCAR ANTONIO":
> Dear Gabe
> We encountered a similar problem with the emulsion on the WRONG side
> of SO-163 film. These were batches we bought in 2010 (we are not
> using film now because we use a CMOS).
> We made some extensive testing and we found out that the film on the
> wrong side appeared only in some pictures within the same package.
> Sometimes just 10-20 pictures out of a 100, other times 50 out of a
> 100. We tried to track the lot number of those films showing the
> problem without success. The only answer from the supplier was to
> send us new film.
> I hope it helps.
> Oscar Llorca
> Spanish National Research Council
> Madrid, Spain
> Quoting Gabriel Lander:
>> Thanks to everyone for your responses,
>> John Rubinstein brought up an issue that had not crossed our minds -
>> as it turns out, some (but not all) of the films in our batches of
>> SO-163 have the emulsion on the WRONG side relative to the notch.
>> With the emulsion side down, the backscattered electrons from the
>> metal film holders are resulting in this over-exposed appearance.
>> We are using film purchased from Ted Pella in late 2010/early 2011.
>> If anyone else has noticed this issue and remembers what batches of
>> film had this problem, please let me know.
>> There are two ways to test if the emulsion is on the correct side:
>> One way is to try scratching off the emulsion with a razor after it's
>> been developed. It should scratch off easily and be clear underneath
>> if you are scratching the emulsion side.
>> The other way (this is how we plan on checking that each film is
>> emulsion side up when loading plates in the future) is to gently
>> slide a gloved finger along a corner of the film. The plastic side
>> will squeak, while the emulsion side does not.
>> Thanks for the advice John,
>> -gabe & greg
>> On May 14, 2012, at 3:46 PM, Wim Hagen wrote:
>>> On May 14, 2012, at 10:55 PM, Gabriel Lander wrote:
>>>> We are encountering a serious issue collecting film using our Titan
>>>> (not Krios) with the Tecnai low dose kit. Certain images appear to
>>>> be severely over-exposed, while others appear to be normal, high
>>>> quality, low-dose exposures. Here are two examples of images
>>>> collected during the same session, from the same cartridge of film,
>>>> one right after another.
>>>> The top image is of good quality, exhibits Thon rings to around 5Å,
>>>> while the one below it has no discernible Thon rings, and is
>>>> overall much darker in appearance. We can only assume that this is
>>>> due to overexposure of the film to the beam, but not to the extent
>>>> that we see obvious radiation damage to the sample (no bubbling).
>>>> We've monitored the blanker during the exposures, and according to
>>>> all the readouts in the Tecnai software it is working properly. The
>>>> film is inserted into the microscope and waits for 10 seconds
>>>> before exposing the film. Multiple users are having this issue.
>>>> Also, we never seem to have this problem when collecting CCD images.
>>>> If anyone has ever experienced this issue or has any insights into
>>>> what is happening, we would be most appreciative.
>>>> - Gabe Lander & Greg Alushin, Nogales
>>>> 3dem mailing list
>>>> 3dem at ncmir.ucsd.edu
>> 3dem mailing list
>> 3dem at ncmir.ucsd.edu
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