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01-01-2007, 04:53 AM   #1
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Two apature rings?

I have a very old Tak 300mm f 1:6.3 lens. It has two apature rings on the front of the lens. Why are there two, and how the heck do you use them? There is a red dot in front of the first ring. I assume that sets the apature for that ring, but what is the other one for?

Any help on this will be appreciated.

Thanks,

01-01-2007, 06:06 AM   #2
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Good morning Ken, and Happy New Year.

What you have is an old Preset Aperture lens.

The lens has no auto aperture at all. This was a way to focus and compose at full aperture, and then set the camera to shooting aperture without taking your eye from the view finder.

If you hold the lens with the front element toward you and manipulate each ring in turn, you will see one ring does nothing. This is the preset ring. The other ring actuates the aperture.

The way it works is you set the Preset ring to the aperture setting you want to use, leave the other wide open. compose and focus the shot. Close the other ring until it stops and you will set the aperture to what you set the Preset ring to. Don't forget to hit AE-L/green button AFTER you stop down to set proper exposure.

Hope this helps
-Alan
01-01-2007, 06:58 AM   #3
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Good morning and happy New year to you Alan! Thanks. I tried it yesterday and thought if I set both rings to the same setting I'd be OK. Now I understand why I was having a hard time focusing. I paid $50 for it and am amazed at how sharp it is.

Regards,
01-01-2007, 07:31 AM   #4
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QuoteOriginally posted by roscot Quote
Good morning Ken, and Happy New Year.

Don't forget to hit AE-L/green button AFTER you stop down to set proper exposure.

Hope this helps
-Alan
no, you don't need to do this. what you do is use Av mode, set the preset ring to the ap you want to use, compose the shot and immediately close the other ap ring down. it will stop where you have set the preset ap. at this point the cam is reading the amount of actual light coming into the cam. release shutter.. there is no need to press the AE-L button because the cam is already reading the light. as long as you are in Av mode.

01-01-2007, 08:26 AM   #5
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Thanks Roy,
I'll try this next time out.
Regards,
01-01-2007, 07:42 PM   #6
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i was out shooting my tak 500mm f4.5 this morn. i have to use this method with it. i don't have a preset aperture ring but i've gotten pretty good at setting the ap by habit.
01-02-2007, 12:30 AM   #7
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Guys, just to satisfy my curiosity, what is the advantages in having a lens like regken's? More in the lines as to why was a lens built like that? Thanks.
01-02-2007, 02:27 AM   #8
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Why it was built like that:when 35 mm cameras were all with separate viewfinder only, diaphragm closed as you turned the ring around.
When reflex were introduced, the problem of darkening of reflex viewfinder arisen. The first solution introduced was preset aperture, like in the lens of this topic. Then, automatic diaphragm was invented, where a small lever act as a simulator of diaphragm, allowing the correct reading of exposure at full aperture, while it actually closes only at the moment of shooting.

The advantage is that if you accept the sloweness of use, you can have (on selected lenses) good or excellent quality for very little money.

01-02-2007, 03:23 AM   #9
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Morning Alvin,

The lens was built at a time when there was no auto aperture control (early '60s). Auto aperture in this sense meaning the ability to stay wide open to focus, and only stop down when you trip the shutter. Prior to auto aperture, you would have to manually set the aperture when you were ready to shoot then open it again to compose and focus your next shot. The preset feature just allowed you set the aperture without having to take your eye from the view finder.

-Alan
01-02-2007, 09:40 PM   #10
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Thanks guys!
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