Hasselblad Lens DOF "Preview" switch - Open or Closed when exposing film?

HI all,

First, please excuse me if I get the terminology wrong, I'm new to shooting my Hassy. I have a 510CM and have been collecting lenses...50mm, 80mm and 150mm.

Each of these has a switch/lever that when you push it one way, it will close down the aperture to allow you to see through the viewfinder, what the DOF will look like....when light is low, this makes it hard to see the image.

I lower light, I often set the switch to open the blades up fully so I can better see to compose and focus.

My question is....when you are ready to expose the film, should you have the switch set so that the aperture is what it is set to (ie you set aperture to f/11, you can see the blades in the lens closed to f/11)....or should you set the switch to where you can see the blades fully opened?

Or...does it matter...with it expose the film properly based on your lens settings regardless of which way the switch is set?

For the life of me, I've not been able to find anywhere on the internet so far that gives me an answer on this one.

Thank you in advance,

cayenne

Yes, the lens should be fully open when exposing. It will stop down automatically to the correct aperture and immediately reopen.

It really does not matter. When you take a picture, the following process takes place:
1. shutter closes
2. film magazine cover flaps open
3. aperture closes to the desired f/stop
4. shutter opens and closes,
5. cover flaps close

If the DOF preview switch is "closed", the aperture will already be closed during step #3 but the rest of the process is unaffected. The aperture is in the same state as where it would be if the switch were open. The exposure will be identical in both cases.

The position of the DOF preview switch matters if you use a metered prism. Those assume that the aperture is fully open to make a measurement. If the preview switch is "closed" you will get a wrong reading.

Hope the above is clear if not please let me know.

etn said:

It really does not matter. When you take a picture, the following process takes place:
1. shutter closes
2. film magazine cover flaps open
3. aperture closes to the desired f/stop
4. shutter opens and closes,
5. cover flaps close

If the DOF preview switch is "closed", the aperture will already be closed during step #3 but the rest of the process is unaffected. The aperture is in the same state as where it would be if the switch were open. The exposure will be identical in both cases.

The position of the DOF preview switch matters if you use a metered prism. Those assume that the aperture is fully open to make a measurement. If the preview switch is "closed" you will get a wrong reading.

Hope the above is clear if not please let me know.

Click to expand...

Ok thank you!!!

I was hoping it would expose right with the switch in either position.

I pretty much can have in my head what the DOF will look like for a given f-stop....so, I think likely from now on, I'll just leave the switch open so it is easier to focus!!


With my aging eyes, I need all the help I can get!!

Thank you both for the replies and advice!!

I love learning something new every day!!

C

That feature - being able to view and compose at maximum aperture and then have the lens stop down to the set aperture automatically at the time of exposure - was an important new feature when it was introduced. Different manufacturers referred to it in slightly different terms. I prefer the name "open aperture viewing and metering".
I can remember when that feature was highlighted in magazine ads!

cayenne said:

With my aging eyes, I need all the help I can get!!

Thank you both for the replies and advice!!

I love learning something new every day!!

C

Click to expand...

You're entirely welcome
Re: the aging eyes, I realized that a prism helps a lot. (I have a PME45 and it is a joy to use... less of a joy to carry though.)
And learning something new is what keeps us young - the eyes can age, the brain stays young (and in my case, according to my girlfriend, even childish )

etn said:

You're entirely welcome
Re: the aging eyes, I realized that a prism helps a lot. (I have a PME45 and it is a joy to use... less of a joy to carry though.)
And learning something new is what keeps us young - the eyes can age, the brain stays young (and in my case, according to my girlfriend, even childish )

Click to expand...

LOL, I hear you on the eyes, and childish....I'll likely never grow up, at least...that's my goal!!


I ended up getting a prism finder for mine too, I can't remember the model number, but I opted to get the one that was a bit more modern, but no light meter...I was going for keeping my Hassy kit purely mechanical.

I'm trying to train myself for Sunny 16's when forgetting my meter, otherwise I try to carry my sekonic with me.

I have been eyeballing a kickstarter micro meter that is so small it might work being stuck perm. on the Hassy (with some kind of hot shoe adapter maybe?) or my GSW690 III)....it appears to get good reviews, and I may pre-order one to see how well it works:

https://www.reveni-labs.com

HTH,

cayenne

etn said:

It really does not matter. When you take a picture, the following process takes place:
1. shutter closes
2. film magazine cover flaps open
3. aperture closes to the desired f/stop
4. shutter opens and closes,
5. cover flaps close

If the DOF preview switch is "closed", the aperture will already be closed during step #3 but the rest of the process is unaffected. The aperture is in the same state as where it would be if the switch were open. The exposure will be identical in both cases.

The position of the DOF preview switch matters if you use a metered prism. Those assume that the aperture is fully open to make a measurement. If the preview switch is "closed" you will get a wrong reading.

Hope the above is clear if not please let me know.

Click to expand...

+1

MattKing said:

That feature - being able to view and compose at maximum aperture and then have the lens stop down to the set aperture automatically at the time of exposure - was an important new feature when it was introduced. Different manufacturers referred to it in slightly different terms. I prefer the name "open aperture viewing and metering".
I can remember when that feature was highlighted in magazine ads!

Click to expand...

I believe my Graflex Super D does the same thing.

Making a habit of viewing your shots, before exposure, in whatever format you choose, is, IMO, a very natural and useful thing and will result in training your 'eye' to better recognize the potential of a scene more quickly and in an assured manner.

Even using a len's own rangefinder does no substitute for a good peak through the closed appiture, in aiding in fluid compositions, again, in my opinion.