Time exposures?

A

alanw89

Messages
107
Edit My Images
Yes
I've just been reading the manual for my new bronice etrsi and came across the section for time exposures and its confused me.

"The exposures are made with the time exposure lever on the lens, regardless of the setting
on the shutter speed scale. However, the lever is locked to prevent accidental movement
and must be unlocked for use.

B. Next, cock the shutter with the film winding crank and then shift
the time exposure lever to the left (looking from the body towards
the lens) which will expose a red-colored "T" on the barrel. The shutter
will stay open when the shutter release button is depressed in this
condition. The shutter is closed by shifting the time exposure lever in
the opposite direction and exposing the letter "A" once more.

A. First, cock the shutter with the film winding crank and then pull up
the time exposure lever release.

* Except for time exposures, always shift the time exposure lever so
that the letter "A" is visible on the lens barrel and keep the time exposure
lever release pushed in all the way."

I thought all you did was set the aperture on the lens and then set the shutter speed on the dial, but after reading this im confused. I might be being stupid but i cant think what a time exposure is.
 
This sounds like the 'bulb' mode? Where the shutter stays open for however long you want, like several minutes?
 
Thats what i thought but then theres a "B" on the shutter speed dial aswell.
 
B is Bulb, i.e. the exposure is as long as you hold the shutter button down for.
T is Time, i.e. the exposure starts when you open the shutter, keeps going when you let go of the shutter button, and stops when you actuate the shutter again.
 
I understand now, it was just one of those things where i though i knew how everything worked and then read that bit and thought i had it all worng.

Thanks
 
I'm still a bit confused about this?!

I was thinking of doing some long shutter stuff with my Bronica SQ-A which has this T thing on the bottom of the lens, but I still dont really understand it
 
cherryrig said:
I'm still a bit confused about this?!

I was thinking of doing some long shutter stuff with my Bronica SQ-A which has this T thing on the bottom of the lens, but I still dont really understand it
Click to expand...

As said earlier, on the 'B' setting, the shutter will stay open as long as you keep it depressed, and close when you release it. In practice of course, you'd use a cable release to avoid moving the camera during the exposure. The 'B' stands for 'Bulb' and the term originates from the earliest remote shutter releases which were air operated, and you pressed a large rubber bulb (rather like an old car horn) to fire the shutter.

On the 'T' or 'Time' setting, one press of the shutter opens it for as long as you like, and a second press closes it. The advantage of the 'T' setting is that you're not touching the camera during the exposure, so you don't need a cable release. The 'T' setting was common on older cameras, but sadly, for the most part it's dropped into misuse now.

The 'T' setting on some medium format cameras is a bit of a fudge, in that a second press of the shutter button doesn't close the shutter but it works nonetheless....

On the Mamiya RB67, you set the shutter speed to 'T' and press the shutter. You can now remove your hand from the camera and the shutter will stay open. At the end of the exposure time you have two alternative methods of closing the shutter...

(1) Turn the shutter speed ring away from the the 'T' setting and the shutter closes.

(2) Moving the shutter cocking lever by the slightest fraction closes the shutter.

I'm not familiar with your Bronica, but it could well be a similar system.
 
The Bronica system is confusing

alansw89 Having just done a quick search the ETRsi the "B" setting will control how long the shutter stays open as discribed by CT.

HOWEVER

Cherryrig the Bronica SQ-A does not have this fuctionality, IT is all done via the "pin" and "switch" on the lens.
Easiest way to do it is:
1) Wind camera on
2) Pull Pin out
3) Stick lens cap on
4) Move switch as instruction manual (http://www.tamron.com/assets/pdfs/SQ-A.pdf page 13)
5) Fire shutter, WAIT till camera settles down
6) Remove lens cap and time exposure
7) When finished replace lens cap
8) Move switch as discribed in manual
9) Wind on off you go.

It is a pain in the ass to use but it can be done, you might waste some frames till you get it right but hey ho.

Looking at CT way of doing things on the Mamiya is like the old Nikon F cameras, the earlier Bronicas don't work like that unfortunatly.
Hope that makes sence
 
cherryrig said:
O right thanks.

Think is my light meter doesn't go down in the mintues I think, so how would I know what to meter at? Just stick it on a high f number f/8 and higher?
Click to expand...

Which meter have you got?

If it is an electronic one then they can read faily low light levels, if it is one of the selenium ones "Weston Master etc" then you will be a bit stuck if you are after accurate reading.

If you have a digital camera you could also try that as a starting point, or the good old way of "guess work"

Hmm looks farily dark but still a hint of colour in the sky :thinking:

"OK I'll give it a minute"

Just make a note of the conditions, time, aperature you use and after a bit you will get good exposures. Oh and bracket as well (y)

Don't forget print film has a very wide range, slide is a bit more trickey.

But yes to your question I can waste a fair bit of film getting it right :bang: :LOL:
 
cherryrig said:
O right thanks.

Think is my light meter doesn't go down in the mintues I think, so how would I know what to meter at? Just stick it on a high f number f/8 and higher?
Click to expand...

It's all down to simple mental arithmetic once you get into these longer exposures, which is why it's important to understand the halving and doubling reciprocal relationship between the shutter speed, aperture and ISO setting.

So.... let's say you take a meter reading at 200 ISO which indicates an exposure of 1 sec at f2.8 ( 1 sec being the longest time on your meter) Armed with this information, you knows straight away that selecting an aperture of f4 will double the exposure time to 2 secs. changing the aperture to f5.6 will mean an exposure time of 4 seconds and so on - up to 32 seconds at f22.

If you want to take the shot at 100 ISO you know also that f22 would mean an exposure time of 1 min and 4 secs. 50 ISO at f22 would mean 2 mins and 8 secs.

Fairly straightforward once you have a grasp of the basics. That's the good news, but now for the bad news. With film, that reciprocal rule of the halving and doubling of aperture, shutter speed and ISO to maintain a given exposure value, breaks down with longer exposures, and is know as 'Reciprocity Failure'

What it means in practice is that each time you double the exposure time you might need to add a percentage more exposure time to take account of reciprocity failure. It varies from film to film how much compensation you'd need to make. Film manufacturers publish tables of reciprocity compensation times for their films, but you can no doubt find the same info on any film using Google. Photography isn't an exact science unfortunately, so even given all the forgoing, you'd still be well advised to bracket your exposures to be on the safe side.

Provia 100F film is quite incredible in that you can take exposures of up to 2 minutes without any consideration being needed for reciprocity failure, which is why this film is so popular for night exposures. Fuji themselves claim 2 minutes -many users would argue you can get away with longer.
 
You must log in or register to reply here.
Back
Top