220 Roll film

Joe,<br><br>Thanks for the picture.<br>As mentioned before, that's not how the Hasselblad magazines space their frames though. They do "make use of the knowledge about this [the way in which the diameter of the take up spool determines the length of film that is transported per revolution of it], turned into cams or gearings that set the always changing number of revolutions the take up spool will make when advancing the film."<br><br>I'm sorry that a 'fellow Photonetter' thought he should disagree and make a show out of his ignorance about that, only to finally repeat the same info.<br>But that's life, i guess ;-)

Alan

 

The films (120 and 220) are the same thickness.220 is just twice as long and will give you 12 or 24; or 16 vs 32.

 

No special processing labs required

Q.G., Hasselblad magazines have no knowledge of the diameter of film on the take up

spool other than the default settings inherent in the design. If you put a 120 roll of film

in a 220 back then the back does not know the difference. That is all I am saying. It is

relevant because the orginal poster asked about using 120 film in a 220 back - your

response to that querry (that " there indeed is a direct link between the fact that the

increasing take up spool diameter determines the length of film that is transported each

time it is rotated") is therefore misleading.

 

If anyone here is following an agenda it is you and your rather immature put downs. Read

the question.

 

Oh yes, and a little humility on your part would be most welcome. You are just one voice

on photo.net and you are in none to pass judgement about anyone else here.

There is an ISO specification for the diameters of the 120 and 220 spools. Hasselbald backs assume that the spool is of the proper size and in spec with the ISO (formally ANSI & DIN) specification.

 

What QG stated is correct. A simple test will prove it.

 

I missloaded an A24 back (there are TWO start lines on the Kodak 220 backing papers!). Spacing was all messed up. The next roll I loaded correctly, frame spacing was fine.

A comment on Joe's picture of the Mamiya 645 insert. When the Mamiya 645 was first introduced it caused a bit of stir by yeilding only 15 exposures of 2.25 x 1 5/8 inch frames instead of 16. The reason was that the Mamiya engineers could not design a 16 frame insert that would accuratly place the 16 frames on film (cost?). The pressure roller in Joe's picture works well enough IF you reduce the frame count from 16 to 15. I remember reading reviews of the camera addessing this verry issue. The ISO spec still calls for 16 exp 6x4.5 cm per roll of 120 film.

 

Note that the the Hasselbald A16 backs are engineered to place 16 frames on a a 120 roll per the ISO spec. The Mamiya 645 inserts can not do this.

 

I do have and use a Mamiya 645 and am please with the extra space per frame that you get when you place 15 framse on a 120 roll. I'd like to get 11 frames spread out on 120 film instead of 12.

Antonio, Q.G.'s original answer to the query correctly describes the situation. The film

spacing DOES depend on the diameter of the take-up spool, even though there is no

mechanism to sense it. No need to take my word for it. Wrap a few layers of gaffer tape

around an empty spool, cut a slit for the "tongue" of the backing paper, and load some

cheap film. Take 12 exposures and see how the spacing comes out compared to a roll

exposed in the usual fashion. If you want to do it really cheaply, don't even bother

developing the film, just remove the back after winding each time, pull the dark slide and

trace the outline of the magazine window. The only thing that will have changed is the

diameter of the take-up spool (including the film), so if the results are different, it clearly

does depend on that (assuming a properly functioning magazine).

 

The OP asked if not having the backing paper made a difference. It does, and Q.G. not

only said that, but gave an explanation of why it makes a difference (and correctly pointed

out some places where it does not, in a Hasselblad, unlike some other MF cameras).

Carefully reviewing his statements before your "it would be more honest to admit you got

it wrong" statement, the only place where I see any possibility of error is the assertion that

cameras and film backs make use of the properties of the changing diameter of the take-

up spool to do the spacing; one could also design a camera or back that operated by

sensing the length of film that had gone past the gate, by using sprocket holes, or a roller

turned by the passage of the film, for example. For cameras such as the Hasselblad, his

statement is correct; for a camera using another method it wouldn't be, but I do believe

the original poster was talking about Hasselblad given his third question.

 

I haven't bothered to read every thread you've posted on in an attempt to find out why you

appear to get in arguments with Q.G. so often. Without taking sides, I'll simply suggest

that both of you might do well to remember the saying "Never argue with a fool, onlookers

might not be able to tell the difference!"

<i>Antonio, Q.G.'s original answer to the query correctly describes the situation. The film

spacing DOES depend on the diameter of the take-up spool, even though there is no

mechanism to sense it.<i>

<p>

Bill, yes, but my point was that it is not a direct relationship, i.e. take up spool diamter x

= frame spacing y.

<P>

If there were a direct relationship then frame spacing would be correct with 120 film.

<p>

I believed this to be important to point out because the OP asked about using120 film in

a 220 film.

"I haven't bothered to read every thread you've posted on in an attempt to find out why

you appear to get in arguments with Q.G. so often. Without taking sides, I'll simply

suggest that both of you might do well to remember the saying "Never argue with a fool,

onlookers might not be able to tell the difference!"</i>

<p>

Bill, Q.G. seems to be following me around photo.net for some reason and arguing

against me for hte sake of it. I have no idea why he is doing this and have asked him to

stop. The moderator (Josh) has informed me that he will have a word with him and I have

agreed to no answer him in future.

"Bill, yes, but my point was that it is not a direct relationship, i.e. take up spool diamter x

= frame spacing y."

 

Antonio, the relationship is a bit more complicated: the amount of film taken up is a

function of the diameter of the take-up spool prior to film advance, the thickness of the

film (plus backing paper, if any), and the count on the magazine (in other words, which

frame the mechanism "thinks" it is on, which determines how many rotations of the take-

up spool occur). Those three variables will determine the distance the film travels, and

after subtracting out the size of the frame, you'll have the spacing at that point.