[3dem] FEI LowDose over-exposing film?

LLORCA BLANCO, OSCAR ANTONIO ollorca at cib.csic.es
Tue May 15 01:01:35 PDT 2012

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.
>>> 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
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