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RichS · Posted: Sun Oct 21, 2001 4:27 am Post subject:

After finally receiving my lenses, I jumped outside for some Polaroid test shots. What a surprise when the 90mm Raptar got the front focusing rails in the bottom of the pic. Didn't notice that on the GG. And I haven't seen this mentioned anywhere?

Would dropping the front work since the infinity focus is behind the rail hinges? I know I would have to bring it back up for any close focusing, but for most pics the range should be okay.

Does this also mean that a 90mm is the widest I can use on a Speed? Although I understand that infinity focus may not be achievable at all with a wider lens, but I thought I've read that some folks have use 75's? How would you get the rails out of the way? Maybe this should be mentioned in the faq?

Rich...

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

You've answered your own question. Yes dropping the rails will get them out of the way of the 90 as well as a 75mm. A 65mm won't focus beyond a few feet, but I'm pretty sure a 75 will go.

Just to be contrary, B&L made an 88mm, but you'll be hard pressed to see any difference between this and your 90

_________________
"In order to invent, you need a good imagination and a lot of junk" Thomas Edison

RichS · Posted: Mon Oct 22, 2001 3:20 am Post subject:

Ahh, thank you. I wish I had seen the rails in the GG

I'll know next time.
And it's good to know that a 75 might work. That's the lens I really wanted when I bought the 90. But seeing the 90 work, I'm happy with it...
I almost bought a B&L 88 and I've seen what was supposed to be a B&L 83. Had I seen that first, I would have grabbed it before the 90. But again, I'm happy.

I'll just have to wait for my second 4x5 (non Speed, maybe full view) to do really wide shots. But that will be a while unfortunately... Such suffering

Rich...

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

I'd bet my speed and a mountain of flash bulbs that the 83 B&L was an 88 with some black pain on the last 8, either that or it was a case of bifocal confusion.

If you are really interested in wide, then when you start to look for a full view, get a bag bellows or you'll either not be able to focus or you won't be able to move/shift the lens, and there's nothing worse than a photogrpaher that just paid $1200 for a 75mm biogon and then finds out he can't shift it because his bellows are racked closed.

RichS · Posted: Tue Oct 23, 2001 8:20 pm Post subject:

Dan Fromm · Joined: 14 May 2001 Posts: 2134 Location: New Jersey

RichS · Posted: Wed Oct 24, 2001 1:38 am Post subject:

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

The speed of the lens is determined by the design/formula of the lens which determines how much the lens will cover at infinity.

There are exceptions but my rule of thumb for when I go bottom feeding on ebay is If the lens is f4.5 then the focal lenght is equal to its image circle. In other words it takes a 165mm-ish tessar to cover 4x5,

As the speed of the lens drops, the coverage increases. So While a 6" f 4.5 lens will barely cover 4x5 Most 6" 6.3 lenses (typically a protar) will cover with room to spare

a 6" f6.8 dagor will cover 5x7 wide open and 6x8 stopped down

And while I don't expect this will excite you B&L made a 5.5" f18 extreme wide angle that cover 6x8 wide open and 10x12 stopped down.

There was a guy trying to sell a 75mm f1.9 oscillo raptar lenses as extreme wide angle for 4x5 that "they just don't know how to make this fast wide angle lenses anymore"

The truth is at infinity this lens won't cover 6x9cm!

_________________
"In order to invent, you need a good imagination and a lot of junk" Thomas Edison

RichS · Posted: Wed Oct 24, 2001 7:03 pm Post subject:

Thanks for that info. Now I know why the larger format (2 1/4, 4x5) lenses have smaller stops. I always wondered since I've use the C330. Although on the 330 there's the maximum width problem with the two lenses hitting each other. But I never related it to the size of the diaphram and the coverage.

Does this also mean that the circle of coverage gets larger if you stop the lens down? That would help a lot with movements if so.
--> Just reread your post to absorb it a bit more and realized you already answerd my question... Thanks!

I can see that LF will be a hobby unto itself

[ This Message was edited by: RichS on 2001-10-24 12:05 ]