SW/C exposure help

[PamelaHL]

I bought an SW/C, and I'm having trouble getting the exposure correct on it. I've had the camera and my light meters reviewed twice. I'm having to overexpose by at least two stops in order to get a decent exposure. Any tidbits or other trinkets of knowledge that would help me sort this out?

Also, I bought a Hoya 1B for it because I'm headed to the Coast. It's my first filter outside of UV and red [for IR]. How will that impact my exposure?

Thanks.
Pamela

 

[Ed Sukach]

Strange.

I cannot see a great difference in metering for the SWC (38mm Biogon Lens?) compared to a 40/ 50 mm on the 500 series.

From memory ... there should be very little effect on exposure with run-of-the-mill UV filters; it will be significant with an Infra-Red, which removes most of the light that is NOT red/ infra-red. I'm not sure about a Hoya "1B" - I think it is a trifle "stronger", filtering out more "blue"... but, again from memory - not really significant.

Are you seeing this "two-stop underexposure" with every filter and every film?

Another possibility may be in the processing... are you developing your film, or using an outside lab?

 

[Dan Fromm]

Hmm. I shoot a 38/4.5 Biogon in Copal #0 with no problems.

Its unlikely, but not impossible, that your Biogon's shutter is running fast.

I can't believe that the shutter's aperture scale is off ... But, when you set it to f/4.5 is it really wide open with no diaphragm visible?

 

[John Koehrer]

Having to realize that the SWC is like shooting LF(ind. shutters) You may have to adjust your exposure/dev procedure for that partictular shutter/film combination

 

[PamelaHL]

Having to realize that the SWC is like shooting LF(ind. shutters) You may have to adjust your exposure/dev procedure for that partictular shutter/film combination

How would I learn to make such adjustments?

 

[PamelaHL]

I am having the trouble even without a filter & yes, with every film, from 100 to 3200 speed, indoors & outdoors.

I've had the camera [which I bought from KEH in "excellent" condition] repaired by a local Hassy expert. The only thing he could find was that the 1/50 was off by 50% [which he has since repaired].

 

[Anscojohn]

Are you rating your B/W film at "normal?" Most of us find that the "true" film speed is on the order of one-half the rated ASA. That might account for one stop right there.

 

[PamelaHL]

I usually expect to overexpose B&W by one stop. This is requiring 2-3 stops. When you say half, do you mean that 3200 should be rated at 1600? I wouldn't have gone that far. So that could indeed account for it. But it is strange that I haven't had trouble with my other cameras--Yashicamat 124, Pentax 645N [but the latter has a functioning built-in meter].

 

[PHOTOTONE]

The SWC like all traditional Hasselblad cameras has the leaf shutter in the lens. If your exposures with this camera are off as compared to another camera, then the only explanation is that the shutter is running fast. You can have the shutter serviced, or you can just have it calibrated and carry around a sheet showing marked shutter speed = true shutter speed for each speed available on the lens. When I do professional work with my Hasselblads, I always shoot a polaroid first to confirm exposure. I have polaroid backs for my Hasselblads.

 

[PHOTOTONE]

If you are shooting outside, you can confirm your meters accuracy by applying the Sunny 16 rule, and seeing how much different your meter reading is.

 

[Tom Hoskinson]

Optical physics tell us that with a 38mm WA lens, you should expect about a 2 f stop light falloff at the edges of the image due to the cosine theta 4th power illumination falloff effect.

See: http://photo.net/bboard/q-and-a-fetch-msg?msg_id=004fzV

 

[Leon]

I usually expect to overexpose B&W by one stop. This is requiring 2-3 stops. When you say half, do you mean that 3200 should be rated at 1600? I wouldn't have gone that far.

Pamela ... rating 3200 film at 1600 is only over exposing by 1 stop - if you're having to at 2-3 stops, that would mean rating it at between 800 and 400 iso - right?

 

[Dan Fromm]

Optical physics tell us that with a 38mm WA lens, you should expect about a 2 f stop light falloff at the edges of the image due to the cosine theta 4th power illumination falloff effect.

See: http://photo.net/bboard/q-and-a-fetch-msg?msg_id=004fzV

Um, Tom, f/4.5 Biogons use the Slussareff effect, their falloff is cos(theta)^3. Gotta check them rules of thumb ...

Cheers,

Dan

Biogon. Ask the man who has one.

 

[Tom Hoskinson]

Um, Tom, f/4.5 Biogons use the Slussareff effect, their falloff is cos(theta)^3. Gotta check them rules of thumb ...

Cheers,

Dan

Biogon. Ask the man who has one.

Yup!

I've got a Biogon