The email said:
I found the attached photo in the back of another picture in an old frame. I bought it in Rozelle in Sydney, so I was a little surprised when the photographer was so close to my family home in Geelong.
I saw that J M ARNEST is in your list of Geelong and District photographers in Colac and thought you may like one of his photos, of what is most likely a local family from there. It’s such a large group for a wedding photo, probably the entire extended family. Unfortunately I have no way of knowing who they are! There is nothing at all on the back of the photo.
With Val’s permission I’m putting in on my blog in the hope that someone can identify the family featured in the photograph.
John Mond ARNEST died on 23rd April 1920 and was buried in the Colac Cemetery. He was born in St Louis, Missouri, USA. In the 1880 Census for San Fransisco he was listed as widowed, aged 37. His occupation stated “works in photograph gallery”.
In July 1881 he was living in Queensberry Street, Hotham East [now North Melbourne], when he married 17 year old Nellie Maud ST JEAN. Births of children were registered in 1884 and 1886.
In August 1898 Nelly Henriette ARNEST of Carlton:
sought a dissolution of her marriage with John Mond ARNEST, photographer, of Colac, on the grounds of desertion for three years and upwards. [ … ] The marriage took place at the office of the Registrar, Elizabeth-street, Melbourne, on 19th July, 1881. The parties lived together in elbourne and Adelaide until April, 1882, when the petitioner alleged, respondent deserted her. Communications passed between them until 1890, when ARNEST disappeared, and was believed to be dead, until it was accidentally discovered that he was living at Colac. [ … ] After questioning petition as to the reason of her delay in bringing the present proceedings, his Honor intimated that he was not satisfied, but would allow an adjournment until Monday.
Nelly was asked if she sought the dissolution because she wanted to remarry.
The decree nisi was granted, however her marriage the same year  and the births in 1884 and 1886 don’t support her claims!
Whatever the truth of the relationship, ARNEST ended up in Colac operating his photographic business from 1896 until his death in 1920. Therefore the photograph would have been taken between those years.
John left all his assets to his sister, Belle ANDREWS, who was living in San Francisco.