ㄧ直有個小疑問，為何我的OM4觀景窗比Om10還要暗？能透過換對焦屏改善嗎？！

您好: 問題在OM4測光方式
OM4須提供光路給下方點測光

謝謝版主回應！這是不是說還是OM1 or OM3機械式的比較亮?

OM2SP OM3 OM4 OM4Ti OM3Ti 皆有點測光
反光鏡架構都是有中央半透光讓光路經副鏡反射測光

對焦屏
http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/accessory/screens/index.htm

http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/accessory/screens/index1.htm

很多單反的測光都在軍艦部，量度鏡頭投影在對焦屏的成象。好處是不用搞副反光鏡，不會損失光線。但不同對焦屏會影響測光(有為DSLR換過對焦屏的同好都曉得)

OM的做法是在軍艦部有測光(供參考用)，同時在反光鏡箱底部有OTF感應器。理論上換對焦屏只會影響參考用的指針，對實際曝光沒有影響。
圖中紅線部分是反光板升起後的事。
但是……SP的反光板是這樣的：

在曝光之前就已經有OTF，用的是副反光板。

引文:

是否只有第一代OM-2是這樣？觀景窗2顆CdS、反光鏡室1顆SPD,沒有副反光鏡、觀景窗亮度不影響.

採用副反的順序是OM4→OM3→OM2SP（OM3/4底定之後倒回頭更新OM2提供一個平價選擇）,其實用舊款當平價版本的idea也不錯,表示機型設計一路走來都很踏實,產品歷久彌新

記得米谷先生在OM4上市之後的訪談中有提到,他設計的每一款機身都還有生產,意思應是永不過時吧.... 不過之後整個OM系列都沒了

OM4發表時, OM1n & OM2n 是繼續量產
如果廣義來說 (M1 OM1 OM1MD OM1n) (OM2 OM2n) 各歸為一個系列

更換對焦屏不會影響OM4測光
但是不同對焦屏中央區域標示範圍可能讓你肉眼判斷點測光誤解
http://www.alanwood.net/photography/olympus/focusing-screens.html#fs24


還有還有一個重點
2-X對焦屏現在拍賣是天價

OLYMPUS OM拿來擺OTF測光元件的位置,後來的AF SLR/DSLR拿來放對焦感測元件,這應該是為何後來就沒有繼續使用OTF的原因了吧.
不過到了無反光鏡時代,感光元件輸出的訊號直接拿來判讀,而OLYMPUS的LIVE MODE B快門應該也算是OTF還魂了吧?

引文:

可以殺肉拿OM-40(美版OMPC)的對焦屏充當2-13對焦屏

我確認OM-40對焦屏可以殺肉可給OM-4T使用，
因為OM-40不是OM專業機可更換的對焦屏，所以要特別注意兩件事：

1.裝卸OM-40對焦屏時，要小心注意，以免刮傷對焦屏。因為OM-40沒設計可以拆卸，所以比較難拆，我就不小心刮傷。

2.要注意對焦屏有無裝反。因為OM-40沒設計可以拆卸，所以比較沒有突邊防止方向裝反。我拍了一捲正片，總覺得觀景窗裡面霧霧地，後來拿去請教相機維修，老闆說對焦屏裝反了



引文:

[轉]My Experience - Focusing Screen

http://www.accura.com.hk/OM/fc.htm

Two new fine and bright focusing screens (2-13 and 2-4) original for the OM3Ti are available for sales separately, which can also be used at OM3, 4 and 4Ti. You can purchase them from camera shop or directly at OM camera service center. I have bought three pieces for my OM4Ti and 2n, it require some rework on the tweezer holding tab in order to fit on the 2n. With this new FS the meter on the OM2n does not indicate proper exposure value, but it will not affect auto exposure accuracy.

Although the new focusing screens are very bright, but when I use it in my OM4Ti with 300mm/F4.5 and 85-250mm/F5 lens, I found some vignetting. Some other telephoto lens may also have this problem. Anyway, as a whole the new screens are very nice.

Recently I got a OM-4 from a professional photogarpher, he had a EOS screen modified and installed on the camera. It is a "EC-C" screen, although it is not as bright as the OM 2-series screen, but it works better with wide angle lenses, as the OM are too fine, focusing is very difficult with wide angle at the matted area. Now I have my OM-4 and 4Ti installed with this screen. (19-May-99)

Things do change very fast, I found the "EC-C" screen does not work well with my new favourite Zuiko zoom - the 35-70mm F3.6, it is very hard to focus. In the pass I rare use zoom, with the large aperture Zuikos, I have no problem to focus even down to 21mm. I found the Minolta 7000i/8000i focusing screen work better with smaller aperture zooms. So I bought 2 Minolta "7L" (with grid) from US. This focusing screen does not need any rework to put into OMs but the height of this screen is a little bit less then the OM, you have to place it at the center of the FS holder otherwise either top or bottom edge of the FS will be shown on the viewfinder. The Minolta is not as bright and fine as the "EC-C", but it is still very good and it balance well with different lens except for telephotos that down to very small aperture (< F8).

(Updated on: 22-Aug-99)