Focussing Screen for all lenses on Wista DXgreenspun.com : LUSENET : Large format photography : One Thread
I just began using a 90mm lens on my Wista DX and have discovered the dreaded 'hot-spot'. I am using the original combined ground glass/fresnel as supplied with my camera and actually like it a lot with my 150mm and 240mm lenses as I can easily compose without the focussing cloth in most situations.
I looked through the archives for info on better focussing screens but am still puzzled. Is there anyone here with *first hand* experience in upgrading from the Wista GG/Fresnel to a better screen for general purpose use? BTW, I want one screen for my three lenses 90/150/240.
Thanks for any help.
-- Richard Ross (firstname.lastname@example.org), March 20, 2001
You need to learn how to focus. And why don't you use a darkcloth? There is a way to focus on GG and many ways not to. James
-- james (James_mickelson@hotmail.com), March 20, 2001.
Please, I am only interested in experienced comparisons between the Wista supplied GG/Fresnel and other GG options (e.g. plain GG, Bill Maxwells, Boss screen etc...). Sorry for not being so specific in my question!
-- Richard Ross (email@example.com), March 20, 2001.
Richard, try the Ebony wide angle fresnel its superb. Said not to be useable on lenses beyond 90mm but I've used it with my 135 and its still suberb, very even and bright. You should still be able to use it with your Wista GG. Good luck,
-- Trevor Crone (firstname.lastname@example.org), March 21, 2001.
The Maxwell standard fresnel for 4 x 5 should work very well with all of these focal lengths. He recommends it down to a 75 mm. I've used it with a 240 mm f9 and it works very well. I've used it with 75 mm (6cm x 9cm format so not a perfect comparison) and it works well with an f5.6 but is a bit dark for me with an f6.8. My experience indicates it should work well with all the focal lengths you've listed.
-- Howard Slavitt (email@example.com), March 21, 2001.
I use a Maxwell screen on my Wista SP with lenses ranging from 90 to 300mm and have found that it provides a noticable improvement over the stock Wista gg/fresnel. However, if you are using lenses wider that 75mm or so, you may have to acquire a dedicated screen for use with those focal lengths. Give Bill a call and he will steer you in the right direction for your particular setup. Good luck in your search.
-- Matt Long (firstname.lastname@example.org), March 21, 2001.
The hot spot is lens related and not a function of the ground glass. you reduce the hot spot with a center filter. You focus properly with a viewing aid like a dark cloth and a quality loupe.
-- Bob Salomon (email@example.com), March 21, 2001.
the Wista GG are notorious, I have immediatly replaced mine when I bought a VX (metal field) because it was far below my requirements. The fact is that they have(at least on the metal fields) a GG made of a integrated Mat and fresnel(coarse) surface, it works well but only if you are positioned exactly at the center of it and never try to use a loupe! However, fresnel lens improve the hotspot which appear on the ground glass but cause the image being made of minute dots(the GG) and concetric lines (The fresnel), if you use a loupe you will enhance both and therefore see nothing clearly because you are using the loupe.
The Hot spot on a Negative or Positive is of couse a function of the wideangle but obviously isn't what you are talking about (Bob' s suggestion of using a centerfilter applies to this, but you don't want to focus using a centerfilter which takes 1 to 2 stops away!).
I advice the use of Bosscreen (don't even get payed from them to do so!!!!). I guess Beattie and Maxwell's are similar but I have a soft spot(not a hot one) for this Ground Glass. It has been formerly discussed on the forum, you will find the threads on it. Good Luck.
-- Andrea Milano (firstname.lastname@example.org), March 22, 2001.