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08-31-2009, 10:59 PM   #1
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Question regarding M42 Vivitar 300mm

Hello, I have an M42 Vivitar 300mm f5.5 lens that's in nice shape. I would like to use it on my K10D. I have adapters (both flanged and non-flanged - I've read the many posts on that subject). I am unsure of the proper way to meter and shoot using this lens. My Takumars have a lever that switches between auto stop-down and manual stop-down. I focus in the auto position and then meter and shoot in the manual position. The Vivitar has this same lever, but it doesn't stay in the manual mode - it only stops down momentarily when you push the lever and then pops back. So even if I could meter and use exposure lock with the lever pushed in, I would have to keep pushing the lever as I shoot or the aperature would be wide open. It doesn't appear that the Vivitar is broken, it just seems like it was designed this way. Is there any way to make it stay in manual mode?

Perhaps I doing this all wrong, even with the Takumars? Any help would be appreciated!

09-01-2009, 12:39 AM   #2
pbo
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I would assume that vivitar is a T4 lens? Sounds like it.
If so, then you are right - it was designed that way. That lens actually consists of two parts - lens itself, and the mount adapter. There's a sort of switch near the base with O<->L on it. Just push in the button and turn the switch towards the "O" side - and adapter will come out.
Then, you can open up the adapter (there are three tiny screws from the sides of the adapter) and remove all guts from it. That way lens will be permanently "stuck" in manual mode. I don't know if that's fine with you, though! If you want the auto mode, I've got nothin'...
I always did that with T4 M42 adapters since I usually shot M42 lenses this way - focus wide open (with aperture ring at wide open position), then turn the ring while counting clicks (one click - one stop for most, if not all, T4/TX lenses. Takumars, as far as I know, are half-stop per click). So, on your 300/5.5, one click from wide open will be f/8, one more - f/11, etc etc.
09-01-2009, 10:58 PM   #3
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More 300mm Vivitar questions

Thanks for the info! I don't know what a T4 is, but it is exactly as you describe so it must be one. I think what you propose will work - take the guts out of the adapter so it will always be in manual mode. That's what I was thinking about as well, but I was trying to figure out a way to just keep the pin permanently depressed. This is better.

Maybe you could answer some other questions about this lens? The aperature has two sets of F-Stop designations, green and white. With the adapter installed, only the white ones are available. What are the green ones for? And since that adapter comes off, are there others available? Such as a K-mount? Wow, that would be really cool....

Is this a decent lens? I'm thinking about bidding on a 300mm Takumar on Ebay, but if this lens is almost as good as a Takumar it's probably not worth it.
09-02-2009, 09:06 AM   #4
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I don't know how to keep it permanently depressed, since I never tried and went for the easy way M42 adapters are cheap anyways, and it's not like I'm going to use those lenses on film M42 cameras that actually use that pin.

QuoteQuote:
The aperature has two sets of F-Stop designations, green and white. With the adapter installed, only the white ones are available. What are the green ones for?
If you take a look at Canon FD lenses, you'll notice how their aperture rings are backwards That's what those green ones are for.

QuoteQuote:
And since that adapter comes off, are there others available? Such as a K-mount? Wow, that would be really cool....
Yep, K-mount, Canon FD, Nikon (with prong-like thing) etc. I have one with K-mount, but it wasn't cheap; it's also quite hard to find, and it's actually designed for a later generation TX lenses, so there are some complications when used with T4 lenses.

QuoteQuote:
Is this a decent lens? I'm thinking about bidding on a 300mm Takumar on Ebay, but if this lens is almost as good as a Takumar it's probably not worth it.
I don't know... Do you find it decent? Then it's probably decent!

09-03-2009, 11:01 PM   #5
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Would this work?

T-mount for Pentax Camera

PBO: I just happened to find this bad boy on Craigslist today. Do you think it would work to mount this lens to a K-mount. You mentioned there are "complications" when you use the TX mount with a T4 lens. Are those complications difficult to overcome?
09-03-2009, 11:55 PM   #6
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No. that does not work.

TX and T4 are related. The difference is that TX allows open aperture metering (for film SLRs, does not apply to DSLRs) and T4 does not.

The current batch of Pentax DSLRs (and likely all future models) do not allow open aperture metering for manual lenses, so you can use TX and T4 adapters interchangeably (with some modification either to the lens or to the adapter).

But the T-mount mentioned in your post is a totally different animal. It does not work with the lens in question.

I think your lens is like in the photos below (pardon the lousy white balance - it's too late in the night ). The adapter in the photos is TX-to-PK. It has been modified to work also with T4 lenses.
Attached Images
   

Last edited by SOldBear; 09-04-2009 at 12:24 AM.
09-04-2009, 08:51 PM   #7
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Thanks - that is my lens exactly. Knowing that the T-mount will not fit on this lens saved me a 60 mile roundtrip. I would still like to find a TX or T4 to K-mount adapter for this lens. If anyone has any suggestions, please let me know.

Thanks,
Dave
09-04-2009, 09:21 PM   #8
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SOldBear: I actually did the opposite - I altered the lens, and kept the adapter intact, since adapter cost a lot more than the lens (and, I didn;t like the fact that aperture went from f/22 to, say, f/2.8 wide open, then if you continue turning, you go to f/22 again )
If you look at your second picture, there are two slits that house two forks - one to the top-left, one to the top-right. If you remove the left prong of the top-right fork, PK adapter (unaltered) will work fully with this lens - for DSLRs; for older cameras - still no open-aperture metering - but that's not important for me.

daveo76: I can sell you mine for 50 bucks (no kidding, that's what it costs...)

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