[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. 


Oscar Llorca 
Spanish National Research Council 


> 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.
> Best
> Oscar
> Oscar Llorca
> Spanish National Research Council
> Madrid, Spain
> http://www.cib.csic.es/en/grupo.php?idgrupo=47
> 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.
>>>> http://www.ocf.berkeley.edu/~glander/pic/img001_FFTs.jpg
>>>> 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
>>>> Lab_______________________________________________
>>>> 3dem mailing list
>>>> 3dem at ncmir.ucsd.edu
>>>> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem
>> _______________________________________________
>> 3dem mailing list
>> 3dem at ncmir.ucsd.edu
>> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mail.ncmir.ucsd.edu/mailman/private/3dem/attachments/20120515/cfe7f137/attachment.html

More information about the 3dem mailing list