Yes, the 90mm will be very similar to a 28mm on 35mm. Not exact because the aspect ratios are not the same but close enough for a rule of thumb.
All the modern film holders are pretty well identical as far as quality and any of them are fine. The ones that are different are the later Riteways which have a locking feature. Some people do not like them for whatever reason. For one thing, the dark slide handles are larger and different and mean that the holders won't fit into a quart ziplock. Many, probably most, of us keep our film holders in ziplock bags when loaded and not in use, to keep out dust. Personally, I like the locking Riteways and use them. I keep sets of them together in a gallon ziplock. The lock release is a button on the holder that has to be depressed to remove the slide. When the film holder is inserted, the camera back depresses the button and the dark slide removes easily. It does not work with some Linhof cameras (and probably the MPP clones as well) - some say all Linhofs but I know that's not true because I have a Technika III and they work perfectly with my camera.
I'd really say to just pick up whatever you find. You probably won't need a lot of holders, at least at first. I had eight and just bought three more. That means I can carry 22 sheets of film, which for me is a lot of shooting in 4x5.
One thing that those who haven't tried it yet may not have thought of is the need to be very careful about dust. 120 film is dust free from the factory until it unspools in the camera. 35mm is dust free AND passes through a felt light trap just before exposure. But with 4x5 you have to take it out of the box and load it yourself into the holder then insert the dark slide. If any dust gets on the film it will result in a white, not black, spot on the negative, which will then print black on the print. These are much harder to deal with than white spots that can just be spotted out. There are a couple of ways you can approach them if you have a negative you otherwise really like: you can try spotting the negative so that the area prints white and can then be spotted down in the usual manner. If you are not VERY careful this results in a HUGE white spot on the print. The other approach is to use a very fine brush and bleach the spot on the print. It might be possible to bleach it back "just enough" but in practice that's so difficult the easiest thing to do is bleach it back too much then spot it - a PITA at best. So the best approach is to avoid dust in the first place! Thus, the keeping holders in zip locks. Those who have to load in changing bags or tents will usually have a lot more trouble with this than those of us who load in darkrooms. Everyone works out their own approach to avoiding it. I rarely have any dust problems but I go to a lot of trouble including an air cleaner in the darkroom, canned air for the holders, and even loading in long sleeve shirts to keep my "Chewbacca-like" arms covered and less likely to get a hair on the film.
For a dark cloth you can use a black tee shirt. One end goes over your head and the other over the camera. It's cheap, available everywhere, and very light. I just got a BTZS hood which is very nice but certainly costs more than a black tee shirt. Before that I used what some call the "horse blanket" because that's pretty much what it is, a big heavy cloth, white on one side and black on the other, in my case with weights sewn in the corners. It weighs nearly as much as my camera and is big even folded. The BTZS is much nicer to use and easier to carrry, but the "horse blanket" can also be thrown on the ground for a place to sit, or the white side can be used as a reflector for a portrait. In normal use the black goes inside to keep it dark and the white outside to reflect the sun and heat. The BTZS is similar except the outside is a sort of metallic silver.
If you don't have a loupe you will probably want one. Some people focus with just their eyes or reading glasses, but either those people are as critical of precise focus as I am, or else they see REALLY well. I'm nearsighted and have excellent close vision if I take my glasses off and get very close (6" for my left eye, about 9" for my right) but when I drop my 8x loupe on the ground glass I see that sometimes I get the focus right without it and sometimes I'm off. The loupe needn't be expensive. I use the common $10 or so 8x Agfa - I think it's still sold as Agfa. You're just trying to judge best focus, not display the image through the loupe.
Last edited by Roger Cole; 10-06-2011 at 04:44 PM. Click to view previous post history.