Calibration picture sizes

[Astronix]

I have been having trouble with calibration pictures coming out in different sizes to my lights and flats.

my darks, dark flats and bias pictures come out much larger and this is stopping me from stacking them.

I am using a fully modded canon 450d and a 72ED scope.

Does anyone have any thoughts, the only thing that I have changed is the exposure time.

 

[Anthonyexmouth]

File sizes or image sizes? Are you shooting raw? 

[Daf1983]

I had this problem when using the 600d. Make sure that all your files are in the same format (ie fits or canon raw). I found when I tried to mix fits with cr2 files, they wouldn't stack because they were slightly different sizes

[Astronix]

2 hours ago, Anthonyexmouth said:

File sizes or image sizes? Are you shooting raw? 

Image sizes, I am shooting in Raw.

 

53 minutes ago, Daf1983 said:

I had this problem when using the 600d. Make sure that all your files are in the same format (ie fits or canon raw). I found when I tried to mix fits with cr2 files, they wouldn't stack because they were slightly different sizes

Thanks for the advice I will double check tonight, hoping to get out later.