Extension/exposure guide for 4x5?
PhotoCamel: Your friendly photo community, with free discussion forums, digital photography reviews, photo sharing, galleries, downloads, blogs, photography contests, and prizes.
 

Go Back   PhotoCamel - Your Friendly Photography Forum > Cameras and Lenses > Medium and Large Format

Reply
 
LinkBack Thread Tools Display Modes
Old 12-24-2008   #1
Guanaco
 
Vedauwoo's Avatar
 
Location: Boulder, Colorado
Posts: 436
CamelKarma: 5692
Editing OK?: Ask First
Constructive Critique?: Yes
Default Extension/exposure guide for 4x5?

Anyone know where I can d/l or buy one of those little rulers for measuring the extension of my 4x5 rail to compensate for exposure falloff?

The only tool I have is the little art work dealie that you line up with the grid...and it just ain't cutting it with this magnifying glass lens....lol

__________________
Members don't see ads in threads. Register for your free account today and become a member of PhotoCamel to open up the site's many benefits and features.
__________________
[Canon 50D][17-85 f/4-5.6 EF-S]
[Bronica ETRS][50mm f/2.8][75mm f/2.8]
[Mamiya RB67][50mm f/4.5][90mm f/3.8][140mm f/4.5 Macro][Ext. Tube #2][150mm SF-C f/4][250mm f/4.5]
[Minolta X-700][16mm f/2.8 Fisheye][50mm f/1.4]


flickr
Vedauwoo is offline   Reply With Quote
Old 12-24-2008   #2
PhotoCamel Supporter DONATED
Photocamel Master
 
verdesardog's Avatar
 
Location: Arizona
Posts: 7,312
CamelKarma: 3249515
Editing OK?: Yes
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

I thought that the graphlex cameras had a scale on the rail
__________________
Michael

COMMENTS, CRITIQUES ALWAYS WELCOME

IMAGINE ALL THE PEOPLE LIVING LIFE IN PEACE
verdesardog is offline   Reply With Quote
Old 12-24-2008   #3
Guanaco
 
Vedauwoo's Avatar
 
Location: Boulder, Colorado
Posts: 436
CamelKarma: 5692
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Quote:
Originally Posted by verdesardog View Post
I thought that the graphlex cameras had a scale on the rail
Mine's an old Calumet (I think....has a red "C" insignia) rail style....so no guides for me.....I used to have a little ruler...but I cannot find it to save my life!

Now that I do this research...it appears some of it is dependand on the FL of the lens....considering mine is a bare magnifying glass, this might be tricky....lol

Thank Krishna for Trial and Error!
__________________
[Canon 50D][17-85 f/4-5.6 EF-S]
[Bronica ETRS][50mm f/2.8][75mm f/2.8]
[Mamiya RB67][50mm f/4.5][90mm f/3.8][140mm f/4.5 Macro][Ext. Tube #2][150mm SF-C f/4][250mm f/4.5]
[Minolta X-700][16mm f/2.8 Fisheye][50mm f/1.4]


flickr
Vedauwoo is offline   Reply With Quote
Old 12-24-2008   #4
Guanaco
 
Vedauwoo's Avatar
 
Location: Boulder, Colorado
Posts: 436
CamelKarma: 5692
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Ok...just found this....does this math seem right...would it work?

"
You mean for bellows extension? It's easy -- no charts required.
Convert your lens's focal length in inches to fstops: for instance, a 210mm lens is 8", so think "f8". When focusing on something close, look at your bellows extension. Let's say, for example, 11" from the lensboard to the groundglass (I carry a small tape measure, but a guess is probably close enough). Convert that 11" measurement to "f11". The difference between f8, the focal length, and f11, the extension you need to use, is one f-stop. So, give one more stop of exposure to compensate for the longer bellows draw.
Similarly, 16" of extension would be "f16", warranting 2 stops more exposure. If you can get within a half stop you're fine, so there's no need to go crazy. It works with any lens where you convert the focal length to inches: a 120mm is 5 inches, a 150 6 inches, and so forth. If you want to do the math, the multiplier between full stops is the square root of 2, or about 1.4 (close enough): 8 times 1.4 is roughly 11, and so forth. Stick with fstops, it's simpler.
This is a simple, reliable and repeatable way to get it Close Enough For Photography."
__________________
[Canon 50D][17-85 f/4-5.6 EF-S]
[Bronica ETRS][50mm f/2.8][75mm f/2.8]
[Mamiya RB67][50mm f/4.5][90mm f/3.8][140mm f/4.5 Macro][Ext. Tube #2][150mm SF-C f/4][250mm f/4.5]
[Minolta X-700][16mm f/2.8 Fisheye][50mm f/1.4]


flickr
Vedauwoo is offline   Reply With Quote
Old 12-26-2008   #5
Photocamel Master
 
Brooks's Avatar
 
Location: Tampa, Florida
Posts: 5,670
CamelKarma: 2943091
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

That would be the way to figure bellows factor IF you knew the focal length of your lens.

To find the focal length of your lens, focus the camera on infinity and measure the distance from the film plane to the lens board (ideally the focal point of the lens but the lensboard is close enough). That measurement is the actual focal length of your lens.

No need to convert to inches if you're using, for example, a lens with a focal length of 210mm. Add a decimal point and think of that lens as f/21. If you do that and use mm for your focal length then use mm when you measure the bellows length. If you do convert your focal length from mm to inches then use inches to measure and compare the bellows lengths.
__________________
Adventure Before Dementia!

"To them, the bike is just garage clutter. To us, it's a loaded Beretta, a half-million in cash, and a forged passport under the floorboards." - Dan Walsh

" Enjoy every sandwich!"

Every single camera and all of the lenses that I've ever owned.
Brooks is offline   Reply With Quote
Old 12-28-2008   #6
Vicuna
 
Posts: 154
CamelKarma: 19298
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Brooks, that will give you "approximately" the f.l. of the lens, it gives you the back focus. To get the actual f.l. make a mark where infintiy is in focus, then focus 1:1, the difference will be the focal length of the lens. Telephoto type lenses have far shorter back focus than a conventional lens, and some wide angle designs have significantly more back focus than the f.l.
epatsellis is offline   Reply With Quote
Old 01-03-2009   #7
Guanaco
 
C Webb's Avatar
 
Location: Canon City, Colorado
Posts: 414
CamelKarma: 1385
Editing OK?: Ask first
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Check the internet for "Bellows Factor" information. There are several "do it your self" devices on line that you print out and put together your self. You place a circle or square in your composition, focus on it with your camera. With the little ruler
type scale you also downloaded, you measure the circle or square on the ground glass. The bellows factor can be read directly from the measurement.

www.salzgeber.at/disc/index.html
C Webb

Last edited by C Webb; 01-03-2009 at 02:09 AM.. Reason: to add an address
C Webb is offline   Reply With Quote
Old 08-08-2010   #8
F1 Camel
 
Location: Los Angeles, CA
Posts: 2,757
CamelKarma: 104888
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

You can order those scales from Calumet or Zone V.
kgphoto is offline   Reply With Quote
Old 08-09-2010   #9
Guanaco
 
Location: Brentwood, MD
Posts: 381
CamelKarma: 15
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Try the quick disk. It is the link posted by C Webb above.

QuickDisc Home Page

Last edited by SensorDust; 08-09-2010 at 08:23 PM.. Reason: Already posted
SensorDust is offline   Reply With Quote
Old 08-09-2010   #10
F1 Camel
 
Location: Los Angeles, CA
Posts: 2,757
CamelKarma: 104888
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Extension/exposure guide for 4x5?

Neat idea. I will try it.


__________________
Members don't see ads in threads. Register for your free account today and become a member of PhotoCamel to open up the site's many benefits and features.
kgphoto is offline   Reply With Quote
Reply

« PhotoCamel - Your Friendly Photography Forum > Cameras and Lenses > Medium and Large Format »


Share this topic:

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
first timer with 4x5 belch_queen Medium and Large Format 22 02-04-2016 04:11 PM
4x5 film shot in Architecture Latinbob Film Camera 3 03-17-2008 10:18 PM
4x5 aspect ratio files AJW390 Image Editing 3 08-12-2007 06:34 PM