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05-05-2010, 02:14 PM   #1
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How to shoot with manual lenses

Hi.
I'm just starting to get into the (D)SLR world. Also I've got hold of my dad's old M50 f1.7 and M200 f4.... Both manual focus and with no A setting for aperture
I've managed a couple of good photos, but generally they come out with a rather "interesting" exposure... I know the "green button function" wich sets the shutterspeed according to chosen aperture.
However: Especially I have problems when using (built in) flash, as even in manual mode I can't get the shutterspeed faster than 1/180s Don't see why.... The "green button function" doesn't seem to take flash into account, and when min. shutterspeed is 1/180 pictures get awfuly overexposed.
Could anyone please try to explain how to get it right?


In advance: Thank you for your help, it's badly needed

05-05-2010, 02:31 PM - 1 Like   #2
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With M manual lenses, the flash will always fire at full power... And it will also arbitrarily choose 1/180 (being the fastest shutter speed it can achieve).

Now, in manual mode without flash, the green button should give you an accurate reading.
Could you explain more in detail what you do?
05-05-2010, 02:38 PM   #3
bfo
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Well.
With the aforementioned settings (flash+1/180)=very over exposed. Thats the problem basically....
And I have no Idea how to correct it, as 1/180 is the fastest shutterspeed available.
And I don't get why 1/180 is the fastest shutterspeed available either.
I have an external flash. Will it fire at full power if set to PTTL/TTL?
Anayway, it has a low/min setting. Maybe that will help?
05-05-2010, 03:05 PM   #4
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I think some of the confusion lies (lays?) when the term M lenses is used. Many newbies to this think this refers to manual lenses in general, and not Pentax M series.

05-05-2010, 03:07 PM   #5
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QuoteOriginally posted by bfo Quote
Well.
With the aforementioned settings (flash+1/180)=very over exposed. Thats the problem basically....
And I have no Idea how to correct it, as 1/180 is the fastest shutterspeed available.
And I don't get why 1/180 is the fastest shutterspeed available either.
I have an external flash. Will it fire at full power if set to PTTL/TTL?
Anayway, it has a low/min setting. Maybe that will help?
aperture and ISO settings, please?
05-05-2010, 03:17 PM   #6
bfo
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QuoteOriginally posted by Ira Quote
I think some of the confusion lies (lays?) when the term M lenses is used. Many newbies to this think this refers to manual lenses in general, and not Pentax M series.
It's Pentax M-series.
05-05-2010, 03:22 PM   #7
bfo
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QuoteOriginally posted by Ira Quote
aperture and ISO settings, please?

Aperture: According to what I want my photo to express (DOF). General problem: Need to stop down not to overexpose.
ISO: As low as possible (100).

Problem is: I can't get the shutterspeed below 1/180....
05-05-2010, 03:33 PM   #8
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What camera?

05-05-2010, 03:38 PM   #9
bfo
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QuoteOriginally posted by Ira Quote
What camera?

As in signature

K-7
05-05-2010, 03:39 PM   #10
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The reason why 180 is your fastest shutter speed relates to how quickly your mirror pops up and down exposing the sensor, plus whatever other technical sensor thingies happen, and the duration of flash needed to properly expose:

In the old days of film and focal plane shutters, 1/60 max shutter speed was the norm for flash. If you shot at 125 (which you could in the good old manual days), the shutter moved and exposed the film too quickly for the duration of the flash--and half the image would be black, every time.

Although we tend to look at a flash burst as a lightning fast burst of light, it isn't. It fires, and takes time to reach your subject. With a shutter speed too fast, you're stopping your lighting before the full frame/sensor is exposed.

This is kind of a kindergarten way of explaining it, because that's the only way I know how to.

Last edited by Ira; 05-05-2010 at 03:51 PM.
05-05-2010, 03:43 PM   #11
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Basically, with all manual lenses, you're going to shoot in manual mode, at 180 (or slower). You have no choice as to aperture, because it's all based on the flash's guide number, because the flash will always fire at full power.

You have to calculate the ONE correct aperture for that based on the flash's guide number.
05-05-2010, 03:51 PM - 1 Like   #12
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One more thing:

I have sitting in a box 5 or so perfectly good-for-nothing automatic flashes when it comes to DSLR. They're fine for film.

On these flashes, you simply turn a dial to the ISO you're shooting at, and it tells you what F stop to set the camera at between let's say 2 and 16 feet. (The dial doesn't actually do anything. It just tells you what aperture to use.)

The flashes themselves have a sensor/hole which reads the ambient light, and adjusts the output of flash for proper exposure.

But these old flashes can fry the circuitry of DSLRs.

As man left the tarpits and stood upright, more intelligent cameras were developed that communicated THROUGH THE LENS to determine proper exposure, as opposed to what the flash eye was seeing, which could be pointed at a totally different place.

Your DSLR is five steps up from this, which is why it doesn't know what to do with these old stupid lenses.

And don't feel bad, because my old lenses are stupid too.
05-05-2010, 03:52 PM   #13
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QuoteOriginally posted by Ira Quote
It fires, and takes time to reach your subject. With a shutter speed too fast, you're stopping your lighting before the full frame/sensor is exposed.
I think I get the general Idea. But according to my calculations light travels approx. 1140 miles in 1/180s. So a somewhat fatser shutterspeed should be possible

But there are probably a few more factors to take into account witch basically "fall into"/supports your explanation.

Thank you for an informative and swift reply! Guess I'll have to practice more with then M-lenses.
05-05-2010, 04:12 PM   #14
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Light travels at 300,000 kilometres per second or 186,000 miles per second, but in a flash unit, it's not a direct path. It's bounced, plus diffused, plus bounced again. Plus the delay in getting the information to the flash in time for the exposure to happen.

I gave you my idiots explanation for it, because that's all I am. I'm sure more qualified people will come along to explain it better.

And by the way:

There are film lenses and cameras, mostly rangefinders, which use leaf shutter. This type of lens system exposes the film plane all at once, and you can use any shutter speed you want.

But don't ask me how the hell it does it.

Idiot here, remember?
05-05-2010, 06:15 PM - 1 Like   #15
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QuoteOriginally posted by bfo Quote
Well.
With the aforementioned settings (flash+1/180)=very over exposed. Thats the problem basically....
Exposure in flash photography has almost nothing to do with shutter speed, since the duration of the flash itself is *much* shorter than the shutter speed. The way you get dark exposure is by stopping down the lens. Google the term "flash guide number formula" for descriptions of how one calculates what aperture to use for any given distance to subject. You'll see shutter speed doesn't enter into it.

This is only necessary when using manual lenses, since these cause the flash to fire full power. With modern lenses, the camera can control the flash output, allowing you to get correct exposures at any aperture (within reason).

QuoteQuote:
And I don't get why 1/180 is the fastest shutterspeed available either.
Google the phrase "flash sync speed" for an explanation of why cameras have a maximum shutter speed that can be used with flash.

QuoteQuote:
Anayway, it has a low/min setting. Maybe that will help?
It will, as that will lower the guide number you'll plug into the guide number formula, allowing to shoot with a larger aperture if you so desire.
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