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11-23-2009, 10:02 AM   #1
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First M42 Lenses

I'm new to Photography and purchased a Pentax K20D with a kit lens. After reading the forum and looking at some of the picture, I took the leap and purchased three M42 Super- Takumar lenses. F1.4 50mm, F2 55mm, and a F3.5 135mm. I also ordered a new Pentax adapter from the pentax store. Waiting on it to be delivered two weeks and still waiting

Could someone explain the metering for me using AV mode or the process to take a picture. I want to use these lenses with a tripod to get very sharp picture plus I want to learn how to compose pictures using these lens. I will be taking pictures of still shots and maybe cats and dogs no sports events.

Thank you all for your help this is a fun hobby.

11-23-2009, 10:15 AM   #2
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Welcome to the forums. Nice kit and a very good start with these lenses. I'd recommend you get hoods if they don't already have them. The 50mm f1.4 is one of the nicest lenses avaiable to us.

I have a bunch of M42 glass and I always shoot manual mode. So reallt it's getting used to the unique qualities of each lens. For the most part when using the green button, they meter pretty accurately at or near wide open. At middle apertures (f8 f11 etc. I find they will meter 1.5 or 2 stops underexposed but that can vary from lens to lens.

For me, it's using the histogram and chimping a shot much of the time or using the Sunny 16 rule.

Can't help you with AV mode.
11-23-2009, 11:10 AM   #3
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Aperture-preferred auto is the preferred mode for using M42 lenses on bodies (film and digital) that support Av. The procedure is simple:
  • Put body in Av mode
  • Put A/M switch on lens in the M position
  • Open lens to widest aperture
  • Focus
  • Stop down to desired shooting aperture
  • Expose
The camera will select an appropriate shutter speed based on the amount of light coming through the lens. In practice, you should still confirm the exposure by chimping the histogram. Most Pentax dSLR bodies will not meter accurately at all apertures with non-A contact glass (no "A" position on aperture ring). My experience with the K10D is:
  • 1-2 stops underexposure at f/4 and wider
  • Good or moderate overexposure at f/11 - f/5.6
  • Underexposure at f/16 and narrower in dim light (light to detector is below meter linearity)
The pattern varies on other bodies and can even be affected by whether the lens base is conductive (go figure...). The more recent bodies are supposed to have better metering with legacy glass. I spent a few minutes with a K-7 and my M 50/1.7 and was pleased to find that it metered properly. A big plus for that body in my book.

Steve
11-23-2009, 11:41 AM   #4
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QuoteOriginally posted by stevebrot Quote
<snip>
  • Put body in Av mode
  • Put A/M switch on lens in the M position
  • Open lens to widest aperture
  • Focus
  • Stop down to desired shooting aperture
  • Expose

Steve

Steve, I thought I would put the A/M switch on lens in the A position so I can use the rear dial to change the aperture, instead of turning the aperture ring on lens, not correct? Thanks...

11-23-2009, 11:52 AM   #5
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@aleonx3 - That's the process for K-mount A, F and FA series lenses.

With M42 lenses the auto setting on the lens only works with certain screw mount bodies. When you use screw mount lenses on K mount bodies you stop them down manually to the aperture you want to shoot and meter at.
11-23-2009, 12:20 PM   #6
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Congrats on making the leap into manual focus lenses. I think you are going to like them.

Just to expand on what others are saying, on M42 lenses that have the auto-M switch, make sure you have it switched to M.

Then set your camera's meter mode to M.

Then select the aperture you want to use for a shot and press the Green Button. This will give you the recommended shutter speed for the shot (and set it).

If you take a shot and like the exposure, but want to adjust the shutter- speed/aperture combination - click the AE-Lock button after the Green Button. Now by turning the dial you can adjust up and down the range of shutter speed/aperture combinations to choose the one you like.
11-23-2009, 12:34 PM   #7
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From my experience

You really need hoods, to stop not only flair but loss of contrast.

Also, I have found that many M42 lenses (on my K10D) need exposure compensation set to about +1 stop.

As for the A/M switch on the lens, and this depends on the lens and location of the switch, I find it useful if you have an aperture selected that you want to shoot, you use the A/M switch to stop the lens down after focusing. It is easier than counting aperture clicks
11-23-2009, 12:50 PM   #8
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QuoteOriginally posted by Steinback Quote
@aleonx3 - That's the process for K-mount A, F and FA series lenses.

With M42 lenses the auto setting on the lens only works with certain screw mount bodies. When you use screw mount lenses on K mount bodies you stop them down manually to the aperture you want to shoot and meter at.
Yep...what he says...

It will be obvious when you fit the adapter to the lens. The little auto-aperture pin has nothing to engage with on the body.

Steve

11-23-2009, 12:53 PM   #9
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QuoteOriginally posted by cheekygeek Quote

...Then set your camera's meter mode to M.

Then select the aperture you want to use for a shot and press the Green Button. This will give you the recommended shutter speed for the shot (and set it)...
No need for the green button. Av mode works just fine. Exposure compensation may be dialed in using the Exposure Compensation button.

Steve
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