There is no Macromia alleghaniensis in this checklist http://www.njodes.com/checklists/Camden.pdf. Is that OK?

It appears it may be a Camden County record. You could try submitting it to Odonata Central. You have to register at the site first, but it is easy to do. Bear in mind records sometimes get vetted as unconfirmed due to a lack of sufficient diagnostic photographs. But it's worth a shot. Compare the submitted record of alleghaniensis from New Jersey to your photo.

I don't. It was on high branch (and I'm short!) and I only could take picture from this angle...

I'm not sure that you can rule out Macromia alleghaniensis from just this view. M. i. georgina has half-length antehumeral stripes, which alleghaniensis should essentially lack. Georgia also averages more yellow, with larger abdominal spots, but differs in some of the fine details. The keel on the middle tibia of the male is 14-20% of total length on alleghaniensis and 25-50% on georgina (Dunkle 2000). The small size of the abdominal spotting and the interrupted band on S2 makes me lean more towards an Allegheny, but almost all of the diagnostic marks you would need to confirm without capture require a lateral view. I'll mull this over and check back.