my experiences:
C2 with a long axis parallel to the shortest crystal dimension, crystals were plates. Used prebent loops to fish the crystals. Personally I haven't tried to bend loops in mounted crystals as Frank does, but it sounds very useful.
bar-shaped P321 crystals with hexagonal cross-sections, these naturally "fell" into loops in the "right" orientations. Too "right" usually, because you also don't want the long axis too parallel to the rotation axis and have a large blind cone compromising completeness, 10-20º from parallel is great, here a minikappa or the bendable loop mounts are very useful.

Mark J van Raaij
Laboratorio M-4
Dpto de Estructura de Macromoleculas
Centro Nacional de Biotecnologia - CSIC
c/Darwin 3
E-28049 Madrid, Spain
tel. (+34) 91 585 4616
http://www.cnb.csic.es/~mjvanraaij



On 7 Mar 2012, at 08:44, Frank von Delft wrote:

> Yes... quite.  Thanks!
> 
> (Beam, rotation axis... how can you expect me to keep all these new-fangled inventions apart?!)
> 
> 
> 
> On 07/03/2012 07:33, VAN RAAIJ , MARK JOHAN wrote:
>> typo correction, you'll want the long axis parallel to the rotation
>> axis, not to the beam.
>> Mark
>> 
>> Quoting Frank von Delft:
>> 
>>> You probably have to tilt your crystal, so that the long axis is
>>> parallel to the beam.  We do this routinely:  cut a plastic pipette
>>> tip to have a sharp point, then push the loop where it attaches to
>>> the pin, to bend the crystal itself.
>>> 
>>> You have to identify from your diffraction whether the long axis is
>>> pointing through the face or the edge of the loop.  As it's P6,
>>> chances are it's through the face, because long-axis P6 tends to
>>> make flat hexagons which lie flush with the face.  So you have to
>>> bend so the face of the loop upwards.
>>> 
>>> You'll have to practice this first, though, so put up an empty loop.
>>>  Top tips:
>>>     * Don't breathe!  You'll blow the cryostream away.
>>>     * Bend the loop towards (rather than away from) the rim edge of
>>> the pin to which it's glued.
>>>     * Don't breathe!
>>>     * Practise practise practise.
>>> 
>>> 
>>> Another thing:  most in-house sources allow you to reduce divergence
>>> of the beam.  You lose intensity, but no matter, just expose longer.
>>>  That also improves overlap.
>>> 
>>> Cheers
>>> phx
>>> 
>>> 
>>> 
>>> On 07/03/2012 04:56, Dipankar Manna wrote:
>>>> Dear Crystallographers,
>>>> 
>>>> I am working on a protein having SG P6, the cell parameters are a=
>>>> 79, b= 79, c= 325. The crystals are forming in big size and with
>>>> very good shape. It also diffracting very well in Home source
>>>> facility both in terms of resolution and intensity. But the only
>>>> problem is the number of overlaps. Its showing much more than the
>>>> good spots. As a result the completeness is showing maximum up to
>>>> 65% even after collecting 180 degrees. I am unable to get a
>>>> complete data. I tried with reducing the oscillation angel to 0.3
>>>> degree/0.5 degree but it did not improve that much. Please give me
>>>> some suggestions.
>>>> 
>>>> Regards,
>>>> 
>>>> Dipankar
>>>> 
>>>> /Dipankar Manna/
>>>> 
>>>> */Aurigene Discovery Technologies Limited,/*
>>>> 
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>> 
>> 
>> Mark J van Raaij
>> Laboratorio M-4
>> Dpto de Estructura de Macromoléculas
>> Centro Nacional de Biotecnología - CSIC
>> c/Darwin 3, Campus Cantoblanco
>> 28049 Madrid
>> tel. 91 585 4616
>> email: [log in to unmask]
>>