Graflex.org Forum Index Graflex.org
Get help with your Graflex questions here
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

recommend lens for close up portraiture
Goto page Previous  1, 2, 3, 4  Next
 
Post new topic   Reply to topic    Graflex.org Forum Index -> Lenses Help
View previous topic :: View next topic  
Author Message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Mon May 14, 2012 2:50 am    Post subject: Reply with quote

The Crown Graphic has 12.5 inches bellows draw. 1 inch = 25.4 millimeters. 12.5*25.4=317.5. The Crown Graphic has 317.5 mm bellows draw. Any lens that you want to use on your Crown must focus at the subject distance you want 317.5mm or less.

The further from the film plane a lens is the more exposure you have to add to get a correct exposure. A lens at its marked focal length (infinity)from the film plane requires no exposure compensation. As a lens moves forward from its infinity position it require an increase of exposure to get proper exposure as light falls off. As the lens is moved forward from infinity it will focus on a closer distance. At some point a large change in film to lens distance will be encountered. The close marked focus distance is a point before this increase. The exposure compensation needed is usually less than 1/6 stop. Exposure differences of 1/3 stop can just be seen in a conventional wet print.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Mon May 14, 2012 3:07 am    Post subject: Reply with quote

Take the 180mm lens:
1/3 stop exposure increase occurs at 240mm from the film plane.
1/s2=1/180-1/1000 for a subject at 1 meter.
1/s2=0.0055555555555555555555555555555556-.001
1/s2=0.0045555555555555555555555555555556
s2=219.51219512195121951219512195122
So a 180mm lens focused at 1 meter will require 220mm (approximately) bellows draw and 1/4 stop more exposure.

Take a 210mm lens:
1/3 stop exposure increase occurs at 280mm bellows extension approximately. So for a 210mm lens focused at 1 meter,
1/s2=1/210-1/1000
1/s2=0.0047619047619047619047619047619048-.001
1/s2=0.0037619047619047619047619047619048
s2=265.82278481012658227848101265823
requires 266 mm bellows extension and a touch more than 1/4 stop exposure extension.

Windows calculator in scientific mode makes it easy.

To use large format cameras you must think. Over thinking makes it harder than it actually is.

came close to getting dumped but this s l o w machine showed all typed text highlighted before the next key was pressed which prevented another wipe out.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Mon May 14, 2012 3:26 am    Post subject: Reply with quote

Search engine of your choice, keyword : depth of field calculator . Not all will include medium format or large format.

Use the focal length of the lens you use, for the format you you are using,
and make a table for hyperfocal lengths for the lens f stops and/or a depth of field table for each f stop starting at lets say 1 meter and for each meter up to 15 to 20 meters then zone focus by approximating the subject distance and selecting the aperture that will put that distance in focus and control exposure with the shutter speed.

Also using a 150mm to 210mm at 1 meter will have a significant magnification factor that may make your portrait an 'eyes and nose" shot instead of a full face one.

The Rangefinder operation range is 20 to 30 mm. Measure the rail travel of your camera from infinity to the end of rangefinder actuator movement. That will be the limit of rangefinder focusing. Closer focusing will have to be done on the ground glass or by a custom made scale.

A 152mm lens is the longest focal length that will RF focus at 1 meter provided that the RF actuator has 30mm of travel.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
MonkeyBrain



Joined: 05 Nov 2011
Posts: 49

PostPosted: Mon May 14, 2012 11:39 am    Post subject: Reply with quote

Hey, thanks for all the calculations. I'm not using a PC so I dont even know if I'd have been able to do them my self (though my mac's calculator may also have scientific mode..who knows).

Anyway, in amongst all that information, there was one little bit of info that probably renders half this thread a waste of time for all involved (sorry...). I guess you just assumed nobody would be so stupid as to overlook this detail, but in fact some people are, and here I am as living, breathing proof. The info in question is this:

45PSS wrote:

That will be the limit of rangefinder focusing. Closer focusing will have to be done on the ground glass or by a custom made scale.


What an idiot. It just never occurred to me that the rangefinder would be more limited than the lens. But, as you rightly point out, it is...very much more limited.

And so, as I've just discovered by looking through the ground glass, my lens will actually allow me to focus waaaaaay closer than I previously thought possible. In fact, much closer than I'm likely to ever want to shoot. It's the rangefinder that can't keep up. But as I hate ground glass viewfinders (and they are anyway totally impractical for fast hand-held work) I had never bothered to even look through the thing beyond checking it was intact when I first bought the camera.

Stupid, stupid, stupid.

Anyway, a whole encyclopedia-full of useful information in your posts, so I'm glad they didnt all get wiped by the poor internet connection.

This was also particularly helpful: "Any LF lens can focus on an object .1mm in front of the lens if the lens is far enough from the film plane."

though if you'd told me this earlier I wouldnt have had to harass you with quite so many stupid questions afterwards

anyway, my lens is fine, and it sounds like any lens I'm likely to buy is gonna be fine for my purposes too...its just the rangefinder that sucks...

So, sending this thread off in a slightly different direction now: can anything be done to increase the rangefinder's limit of focusing?


I was aware of the exposure compensation necessary when extending bellows beyond a certain point (though I think I was perhaps only aware of this because you pointed it out to me previously), but it doesnt concern me too much tbh as I usually pull a "fujiroid" test or two before shooting, so any problems with exposure will make themselves apparent at that stage. And I shoot neg film anyway, which is extremely forgiving...
Back to top
View user's profile Send private message
1banjo



Joined: 16 Nov 2008
Posts: 478
Location: kansas

PostPosted: Mon May 14, 2012 5:45 pm    Post subject: Reply with quote

will a rangerfinder only has so much travel !!
it looks like on a topfinder thats only 22mm to 25mm
a super graphic its 30mm
to make a rangerfinder to go from say 1' to INF. it would need to be 3 X
as big!! so just thank how much biger that would make you camera
you ask why ?? the closer you get the more your rail has to travel to get it in focus where as INF. to 50' may only be 2mm of travel but 10' to 6' is 5mm of travel AND 6' DOWN to 1' is 70mm of travel!!!!

NOW you don't beleave me just try it!!
as I just did!!
with my Raptar 135mm topfinder Crown

OH yes exposure compensation 1 f stop more at 270mm that is
if you are useing a 135mm lens
what ever lens that your useing you take the FL x 2 = 1 F stop more exposure !! {{135 x 2 = 270}}
Calumet usto have a exposure compensation ruler
Back to top
View user's profile Send private message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Mon May 14, 2012 9:33 pm    Post subject: Reply with quote

Quote:
can anything be done to increase the rangefinder's limit of focusing?


My Super Speed will focus at about 30 inches with no cam installed, the same as a cam the height of the tube the cam fits into.
25.4*30=762 mm, 7.62 cm, .762 m

Test your Crown and see what it will do. Due to the limited cam movement and extended rail movement to focus lens closely you may have to recalibrate the rf for a closer distance and limit yourself to a 1 meter to 5 or 10 meter range.

---------
I use fCalc version 1.14 which may run only on windows. There is a newer version that works on line and with mac.
Depending on the calculation you plug in the focal length, focused distance, format up to 4x5, or the f number and it displays the other information. You should be able to use the Angle of View tab or Magnification tab to find values for a known lens/distance that gives you the image you want then plug in other focal lengths and distances to find something close or equivalent to your desired image.

--------
--------

The XP Pro (slower) machine has the hot keys issue with this site.
The XP Home (faster) machine rarely exhibits a hot key response.
Both are service pack 3 and up to date.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
MonkeyBrain



Joined: 05 Nov 2011
Posts: 49

PostPosted: Mon May 14, 2012 9:41 pm    Post subject: Reply with quote

yeah that all makes sense. though I dont need to focus as close as 1', but still, I can see that having the rangefinder even twice as big might not be very practical.

this sucks, and I really dont see any way round the problem


edit - 45PSS, seems you posted while I was replying to Banjo...

so, to put it in idiot's terminology: by removing the cam altogether I might find I can shoot the close up portraits I desire, but totally lose the ability to shoot landscapes?

actually, I wouldnt totally lose the ability to shoot landscapes would I? I'd just have to use the GG to focus, which for landscapes really isnt so much of an inconvenience

hmmm, I'm going to have to think seriously about this. It might well be a compromise I can live with, but will need to think long and hard before f'ing up my RF calibration.

at least I have some kind of option open to me anyway, thanks, thats good news

another edit - looking at fCalc now

and yet another - doing away with the cam would not only allow me to focus closer, but also save me having to search for the correct cams for any new lenses I purchase...looking more and more appealing as a solution
Back to top
View user's profile Send private message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Mon May 14, 2012 11:01 pm    Post subject: Reply with quote

Eliminating the cam only shows what the close limit of the rangefinder is. With no cam you have to ground glass focus.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
MonkeyBrain



Joined: 05 Nov 2011
Posts: 49

PostPosted: Tue May 15, 2012 8:13 am    Post subject: Reply with quote

ah, i see...I thought that seemed all rather too easy.

so what's the point of removing the cam then?
Back to top
View user's profile Send private message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Tue May 15, 2012 7:01 pm    Post subject: Reply with quote

Quote:
so what's the point of removing the cam then?


Place a tape measure across the long side of the table with the beginning measurement mark away from you and an object to be focused on next to the beginning of the tape measure. With cam removed from the RF site the test object in the RF's view window from the opposite end of the table and move toward the object. When it considers in the RF's view window stop and look where the film plane is on the tape measure. This is the closest focus distance the RF is capable of.

T a p e_ m e a s u r e_ b e g i n n i n g _ m a r k →|
↑ start at up arrow with camera level to →|
When RF indicates in focus with no cam read tape measure at front edge of ground glass.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
MonkeyBrain



Joined: 05 Nov 2011
Posts: 49

PostPosted: Tue May 15, 2012 9:37 pm    Post subject: Reply with quote

ok thanks, i follow that, but knowing the limit of my rangefinder...what next?

recalibration?
Back to top
View user's profile Send private message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Tue May 15, 2012 11:16 pm    Post subject: Reply with quote

Can I focus a lens 1 meter from the subject?
Yes, if it will focus that close within the bellows limit of the camera.

Can I Range Finder focus it at 1 meter?
Unknown. Find the closest focusing distance the Range Finder is capable of.

How do I adjust or modify the Range Finder to focus lens X at 1 meter?
Unknown. Insufficient information supplied.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
1banjo



Joined: 16 Nov 2008
Posts: 478
Location: kansas

PostPosted: Wed May 16, 2012 12:22 am    Post subject: Reply with quote

OK with my topfinder Crown

with a Ektar 127mm cam 127mm P4
back from the end of the bed {{to the lens standard frame on th rail}}


INF. back """""" 117mm
10' back 111mm
8' back 108mm
3' useing the rangefinder
3' 96mm

@ 34" the rangefinder does no langer work
Back to top
View user's profile Send private message
MonkeyBrain



Joined: 05 Nov 2011
Posts: 49

PostPosted: Wed May 16, 2012 12:17 pm    Post subject: Reply with quote

I havent tested the RF minus cam, but, with the cam still in, the focus limit of my RF is worse than yours Banjo, its more like 4'. It seems we are talkign about the same camera (top RF crown) so I assume this difference is due to the cam for my 135mm lens.

though, as I got someone else to calibrate it for me, I dont know what is actually involved in calibration or how much choice the person calibrating has to how they calibrate. is there only one correctly calibrated position, or is there actually a wide choice of positions the cam/RF/etc can be put in and still be correctly calibrated?

by which i mean, could I recalibrate, moving the closest possible RF focusing distance nearer (say 34", like yours) without ruining my ability to focus at infinity, or is there only one correct calibration position for this lens/cam and therefore I'm stuck with 4' unless I choose to go the "focus on infinity only using the GG" route?

eventually I'll follow your suggestion 45PSS and pull the cam out, but for now I dont want to go messing around in there and potentially cause problems for my otherwise perfectly functional camera...
Back to top
View user's profile Send private message
45PSS



Joined: 28 Sep 2001
Posts: 3216
Location: Mid Peninsula, Ca.

PostPosted: Wed May 16, 2012 6:54 pm    Post subject: Reply with quote

4' sounds about right for a 135. There is only one calibration point, infinity.
http://www.southbristolviews.com/pics/Graphic/manual-pdf/TRFService.pdf
Covers the Top Rangefinder only;
http://www.southbristolviews.com/pics/Graphic/manual-pdf/servicemanual.pdf
Covers the complete camera.

Read through the rangefinder section.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    Graflex.org Forum Index -> Lenses Help All times are GMT
Goto page Previous  1, 2, 3, 4  Next
Page 3 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group