Hi Kmack,
One interesting question among several, is wether the cassette has any and which influence over the issue of frame spacing.
Hi Ian (Jocko)
I hope you will have a nice day today.
Hi Samuel (Alternatve)
Overall I would say DVD is a nice seller, with privileged access to stuff other sellers don't have, yet the main issue is how the specific cameras in his shelf are working, the 4a or the 4am. A good way to know is asking his opinion about which one he would choose among those you are looking for. Now, in general and beforehand I would not pick a 4a manufactured later than 1969. And those before, are harder to find. In case DVD terms his 4am as "mint" it means the camera has not been used ever and there are good chances you will get a soft winding one.
As for the viewfinder, it is quite a controversial issue. Following Ian's wisdom in another thread, I would start from the question wether you wear glasses or not. The viewfinder lens exterior of the 4am is rounded and bigger, but the surrounding metal ring is a professional glass scratcher. If you don't wear glasses then no problem at all.
With the 4am you will have a yellow patch a bit more dark, just a bit, but a darker surrounding viewing as well. The opposite with the 4a, and I repeat it is just a bit. This bit is to be judged, if to split hairs, in favour of night picture taking, making the 4a a bit preferable. Although no problem with the 4am.
And yes, no doubt the classic look of the 4a has its appeal.
Finally, I would repeat, it may be a good idea to ask Mr Davidenko (DVD) to handle both models, fidle a bit with them and give his opinion, thus obliging him somehow.
Now, remember as well that here in Jerusalem I may be held as a mini kiev authority, but at RFF there are many many people whose advice I have been continuously asking and I am their pupil. I hope they emerge regarding your question.
Cheers,
Ruben