620 film is a Kodak version of 120 film. The only difference is the size of the hole in the end of the metal spool. I believe the 620 spool has a smaller hole. I seems to have been an effort by Kodak to force Kodak camera users to buy Kodak film.
Some cameras are able to use either size of film.

I seem to remember the colour film had an ASA (ISO) of 80. I think the B&W film was faster, probably 125. If you are shooting negative film there is probably a fair amount of latitude in the exposure that can be adjusted in printing.

620 film is a Kodak version of 120 film. The only difference is the size of the hole in the end of the metal spool. I believe the 620 spool has a smaller hole. I seems to have been an effort by Kodak to force Kodak camera users to buy Kodak film.
Some cameras are able to use either size of film.

I seem to remember the colour film had an ASA (ISO) of 80. I think the B&W film was faster, probably 125. If you are shooting negative film there is probably a fair amount of latitude in the exposure that can be adjusted in printing.

Being one of the oldies I like others I have run the whole gambit of cameras. Re' your question to 400ASA. with the Brownie, you have no control (basically) over aperture or shutter speed but it will be OK if the light reading is low (overcast), but knowing the work of a lot of processing houses you will still be pleased with the results. Kitcar

Kitcar
This is going to be fun!
Photo Tex
Further to my previose opinion to your question, what results can be attained with the Kodak Brownie?
Years ago I used to go to an international photographic exibition in Birkenhead UK with top awards. In the portrait section quite a few of us used to search out a regular photographer who year after year had a portrait hung (an achievment in itself) with the camera details "Kodak Brownie". I can't imagine he didn't have a top range camera of the day, but the challenge was the Kodak Brownie.The photograpger had an ARPS after his name, so knowing the shutter speed/ lens aperture & setting up his lighting to suit , his results were print any body would be thrilled with. So Photo Tex push that Kodak Brownie to its limits. Kitcar

Being one of the oldies I like others I have run the whole gambit of cameras. Re' your question to 400ASA. with the Brownie, you have no control (basically) over aperture or shutter speed but it will be OK if the light reading is low (overcast), but knowing the work of a lot of processing houses you will still be pleased with the results. Kitcar

Kitcar
This is going to be fun!
Photo Tex
Further to my previose opinion to your question, what results can be attained with the Kodak Brownie?
Years ago I used to go to an international photographic exibition in Birkenhead UK with top awards. In the portrait section quite a few of us used to search out a regular photographer who year after year had a portrait hung (an achievment in itself) with the camera details "Kodak Brownie". I can't imagine he didn't have a top range camera of the day, but the challenge was the Kodak Brownie.The photograpger had an ARPS after his name, so knowing the shutter speed/ lens aperture & setting up his lighting to suit , his results were print any body would be thrilled with. So Photo Tex push that Kodak Brownie to its limits. Kitcar

Mogul
Thanks for the suggestion and link. I think I will return one of the 2 400 ISO I purchased and try to get a 100 ISO. Then I will try both.
Photo Tex

Generally older films had very low ASA (ISO) ratings. I would suggest you use a film with a speed of 100 (or less if you can find one). Here is the address for a site that will show you your options:
http://www.adorama.com/catalog.tpl?op=itemlist&cat1=Film%20%26%20Darkroom&cat2=Film&cat3=Black%20%26%20White%20Film

I'd shoot the 400 and see how it turns out - probably dark (maybe not). Maybe the developing will compensate for poor exposure. Lower speed film was more common when this camera was new.

I think I have every bit of equipment Canon sells for macro photography, from the 100mm L and 180mm L primes to the 2x extender, the 1X-5X micro lens, the 90mm Tilt-Shift (it does great close-ups!), and even a ring light flash for good measure. By far the 100mm L is the one I use the most. It is just an outstanding lens, from macros to portraits to telephoto. If it's not on my camera, it's in my bag. The other gear is all wonderful, but I think most people will get the most use out of the 100mm.