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05-10-2009, 08:29 PM   #1
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Difference between M 50mm f/2.0 and M 50mm f/1.4

I picked up an old school Pentax M 50mm f/2.0 today to use with my k100D. This is my first prime lens and I have to say that I really like it. I originally went to pick up a Pentax Spotmatic II with a Pentax M 50mm f/1.4 on it, but it turned out to be a M42 screw type lens. I went ahead and grabbed the k-mount for $35, but I still have the opportunity to grab the Spotmatic with the screw mount lens for $55. Would it be worth my time to go and grab the screw mount lens and find an adapter?? Do you guys/gals think it would be that big of a difference?? I'm still pretty new to the photography game so I'm just not sure my uneducated eyes would notice a difference.

Suggestions?

05-11-2009, 01:15 AM   #2
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QuoteOriginally posted by mr tibbs Quote
but I still have the opportunity to grab the Spotmatic with the screw mount lens for $55. Would it be worth my time to go and grab the screw mount lens and find an adapter??
Yes, yes, yes, yes.

Oh, and yes. If you can get a Takumar 50/1.4 and a Spotmatic for $55 it is worth your time.

As to whether you should use pentax-M or M42 Takumars. Note that both have limitations. An M lens will be open aperture on a digital body, the only time the lens is stopped down to the aperture ring value is when you press the green button and when you take a shot. This means that you have to use it in M mode, and take the exposure with the green button. An M42 lens can be put in M mode (hence it will be stopped down as you turn the aperture ring) which means that you can use Av mode. However, (depending on which camera you have) there will be some inaccuracy, the workaround is to short the mount contacts with some foil. M lenses tend to be smaller and lighter than Takumars.

My opinion is that M lenses have no advantage over M42 Takumars, neither has auto-exposure. So given the choice of an M50/2 and a Takumar 50/1.4 I would have taken the Takumar. And at $55 you would have had a bargain.

Richard
05-11-2009, 07:44 AM   #3
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I see, I did not realize that the M42 had contacts that could be delt with. Are the M42 adapters widely available?
05-11-2009, 05:43 PM   #4
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QuoteOriginally posted by mr tibbs Quote
I see, I did not realize that the M42 had contacts that could be delt with. Are the M42 adapters widely available?
Yes, plenty on ebay and various other places.

05-11-2009, 05:56 PM   #5
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I strongly urge that you get the original Pentax M42 adapter as it will allow you to focus to infinity (it allows the lens to sit flush with the camera body). It's also the easiest to install and remove, but costs more than the next two adapters below.

The chinese adapters are also useful, but won't let you focus to infinity and can get stuck on your camera.

The Bower M42 adapter is like the Pentax and they come with a key to remove it. Unfortunately, mine got stuck on my K200d and required a few extra seconds fiddling with a screwdriver to get it loose.
05-12-2009, 04:34 AM   #6
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QuoteOriginally posted by mr tibbs Quote
I see, I did not realize that the M42 had contacts that could be delt with. Are the M42 adapters widely available?
No, M42 lenses don't have contacts, I wasn't beuing clear. You need to short the contacts on the body to get accurate metering with an M42 lens and Av.

But you don't have to do that. I shoot mostly with M42 lenses and I use M mode and the green button (which does meter accurately on my K100D).

M42 adapters are widely available. The original pentax adapter is the best because it fits the mount perfectly (no jiggly attachments), it allows you to have infinity focus and it won't get jammed in the camera. There are third party adapters that are worth using, but they fall down in some aspect - you lose infinity focus, or they are loose, or the retaining spring can get stuck in the camera (the last two have happened to me). IMO the Kood adapter works well as long as you remove the spring (the spring got jammed in my camera and it took me a while to get the adapter out - after removing the spring the adapter works fine, and in some cases better than the original Pentax adapter).

Richard
05-12-2009, 08:32 AM   #7
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You guys are making me think long and hard about going back and getting the M42 50mm f/1.4. Does anyone have a link to the actual Pentax adapter ring? I'm just wondering how much extra it will be. Also, are there any other M42 lesnes that are worth getting? I would hate to buy an adapter just for one lens.

And for the record this fully manual stuff does not bother me at all. In fact I think it is making me a better photographer because I am forced to know how everything works. I do wish I had the meter to judge my light better, but so far I am just shooting a few test pics and looking at my histogram to see where I am. Is there a better way?

And thanks for all of the help!! It's nice to have a place to go and get some answers.

05-12-2009, 09:12 AM   #8
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QuoteOriginally posted by mr tibbs Quote
Does anyone have a link to the actual Pentax adapter ring? I'm just wondering how much extra it will be. Also, are there any other M42 lesnes that are worth getting? I would hate to buy an adapter just for one lens.
Here it is on the Pentax web store.

PentaxWebstore Mount Adapter B (35mm Screwmount to Bayonet)

They show up on eBay from time to time, but some of the eBay ones say they're "original" and they're not. Some of the third party ones get stuck in cameras more, or are at least a little trickier to get out.

As for other lenses--there are hundreds of screwmounts worth getting! Not only the takumars (which are beautiful and wonderful to use). Check out the M42 club threads and Carl Zeiss Jena lenses too.

There are deals to be found, but some are also quite expensive, depending on how rare they are. (50's are the most common lenses, but don't get me wrong, that 50 1.4 is very nice!)

But if you're cool with the whole manual thing, you're going to have fun with them.
05-12-2009, 09:16 AM   #9
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Thank you much! I just might have to go try and snag that this afternoon.
05-12-2009, 06:21 PM   #10
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Well, I just happen to be in the neighborhood today so I broke down and bought the Spotmatic II with the Takumar 50mm f/1.4. Now as soon as I get an adapter I can try this lens out. Thanks for all of the help so far! If this works out I'm betting I will be in the market for more M42 lenses!!
05-12-2009, 06:27 PM   #11
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I am getting an OEM adapter, too. Amazingly, they are more expensive on Ebay than from Pentax. ?????????????????.

For a common M series lens like a 50 / 1.4, I would just get the K mount lens. I see them often for not much more than the OEM adapter. Even Ebay lets them get away cheap if you watch and jump on a bid at the right time. Weekday mornings are usually good. Look at the non-profit and thrift auctions, you can get a handful of cools lenses in an old kit. Look closely for the "1.4".

I swore off M42 lenses until I came across one I could not possibly POSSIBLY find in K mount. 1000mm F8.

Last edited by jocko_nc; 05-12-2009 at 06:33 PM.
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