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09-24-2013, 10:35 AM   #1
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SMC Takumar 300mm/f4 on EOS 7D

Hi All,

I recently purchased a Super-Multi-Coated Takumar 300mm/ f4 on ebay.
I am waiting to receive this beautiful lens in the mail.

This lens has a M42 mount.
I plan to use this lens with a M42-EOS adapter on my Canon EOS 7D.

However, the back rear part of this lens has a pin and also has an aperture control 'lug'.
I understand the pin will be pushed in when I attach the adapter.
However, as the aperture lug is sticking out a few milli-meters out of back of the lens.
It seems like the aperture lug would not allow me to screw in the M42-EOS adapter completely.

Is there a work around this situation?
Will a M42-EOS flangeless adapter work in this case?
Will it screw up the lens if I open the lens and remove the lug?
Is there a tutorial online that shows how I can remove the lug?

I have read that I can file down the aperture lug, if I don't intend to use the lens on a Pentax camera.
I will be using this lens on a Canon EOS 7D.

Any ideas and suggestions would be greatly appreciated.

Thanks in advance - Chikkad.

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09-24-2013, 11:12 AM   #2
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The aperture flag on K-mount cameras has a problem with full frame Canon cameras. The aperture coupling on a Takumar should not interfere with the operation of a 7D. The only Takumar that I have heard of having problems with a Canon full frame is the 8-element Super Takumar 50/1.4 which has a protruding rear element.

The aperture coupling itself should not protrude further than the aperture pin. In the second picture the aperture pin appears to be depressed. The lens has an Auto/Manual switch so the aperture pin does not need to be pressed in by the adapter.

Last edited by boriscleto; 09-24-2013 at 11:18 AM.
09-24-2013, 01:11 PM - 1 Like   #3
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So you bought a Pentax lens to put on a Canon 7D?
The 7D is a crop sensor?
Why didn't you just buy a Canon lens or a Pentax K5?

Don't damage a beautiful copy of a Pentax lens, that's not cool.
09-24-2013, 01:13 PM   #4
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The lens has auto/manual switch.
You need to change to manual in order to use with canon in Av mode.

Now, to move the switch to manual, you need to press the aperture pin (at the bottom) with your nail then turn the switch.
Don't use force.

I use all my taks in 5d or 5dm2, and do not have one single canon lens in my collection.

09-24-2013, 03:54 PM   #5
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QuoteOriginally posted by hoanpham Quote
now, to move the switch to manual, you need to press the aperture pin (at the bottom) with your nail then turn the switch.
Don't use force..
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Last edited by boriscleto; 09-24-2013 at 04:06 PM.
09-24-2013, 04:04 PM   #6
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QuoteOriginally posted by LaurenOE Quote
Don't damage a beautiful copy of a Pentax lens, that's not cool.
Agreed. The lens has survived and been useful for many years. Disabling it just for one user's quirky requirements may potentially stop other people in future making use of the lens. Seems a shame. There seem plenty of old Canon lenses around on eBay a 7D user might experiment on instead.
09-24-2013, 04:29 PM   #7
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Seems like I touched a nerve here...when I said the I read things like filing down the lug or removing the lug. I don't want to do either.
I am trying to find out how I can use this beautiful glass on my DSLR, of course without damaging the mirror.
Hence, I came to this forum to ask for suggestions on how I can use it on my 7D.

I bought the Takumar based on the reviews and sample pictures I saw on the net and in this forum. It's simple economics.
And I love my gear, doesn't matter which brand it is.

Thanks boriscleto for your suggestion. I will try out your suggestion once I receive the lens in the mail.
I am still trying to understand the procedure you described.
I may have a few more questions when I have the actual lens in my hand to try out the procedure you described.
Thanks for the suggestion though.
09-24-2013, 06:39 PM   #8
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QuoteOriginally posted by chikkad Quote
Seems like I touched a nerve here...when I said the I read things like filing down the lug or removing the lug. I don't want to do either.
I am trying to find out how I can use this beautiful glass on my DSLR, of course without damaging the mirror.
Hence, I came to this forum to ask for suggestions on how I can use it on my 7D.

I bought the Takumar based on the reviews and sample pictures I saw on the net and in this forum. It's simple economics.
And I love my gear, doesn't matter which brand it is.
HA!

So you came here to learn how to destroy Pentax heirlooms?
You're worried about the mirror on a Canon?

Did you stop to check the sign on the "door"?

P E N T A X forums last time I checked.



09-25-2013, 05:56 AM   #9
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QuoteOriginally posted by LaurenOE Quote
HA!

So you came here to learn how to destroy Pentax heirlooms?
You're worried about the mirror on a Canon?

Did you stop to check the sign on the "door"?

P E N T A X forums last time I checked.
No, he came to know how to use it without damaging [Gollum voice] our precious, ouuuuur preciiiiiiiiious [Gollum voice off] takumars

As other said, there is no need to cut anything on the 7D. Just do as Boriscleto said, and it will be alright.

In fact, most lens don't need to be cut or butchered on the 5D /5DII or 5DIII : just unscrew the back part that protect the lever to unscrew it. You keep the part, and you can re-assemble it later to sell it to Pentax people
09-25-2013, 06:07 AM   #10
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QuoteOriginally posted by aurele Quote
No, he came to know how to use it without damaging [Gollum voice] our precious, ouuuuur preciiiiiiiiious [Gollum voice off] takumars

As other said, there is no need to cut anything on the 7D. Just do as Boriscleto said, and it will be alright.

In fact, most lens don't need to be cut or butchered on the 5D /5DII or 5DIII : just unscrew the back part that protect the lever to unscrew it. You keep the part, and you can re-assemble it later to sell it to Pentax people
Too funny!
He's got an exceptional copy of that lens, and I freaked that he might damage it.
There is a reason why in 2013 he can use a lens that was made in the 60-70's, and we like to keep it that way for the next Pentaxian that comes along.

At least he knows the fanaticism that exists in Pentax land.

09-25-2013, 10:08 AM   #11
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Thanks Boriscleto and aurele for your suggestions and support.

1) Looking at the picture posted by Boriscleto and the related suggestion, I am still not able to understand it completely.

2) aurele seems to agree with Boriscleto's suggestion. But also mentions something about unscrewing the back part (I guess this is if the lens is used on a Canon 5D. Please correct if I am wrong.)

I am seriously hoping I don't have to unscrew the back part or remove anything.

I am expecting to receive the lens in the mail tomorrow and I will try out your suggestions once I physically have the lens.

Cant wait to start using the lens.

Regards - chikkad.
09-25-2013, 10:52 AM   #12
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QuoteOriginally posted by chikkad Quote
I am seriously hoping I don't have to unscrew the back part or remove anything
For a 7D, you have no need to unscrew anything, only for the 5DII usually.

QuoteOriginally posted by chikkad Quote
Looking at the picture posted by Boriscleto and the related suggestion, I am still not able to understand it completely.
It will make sense when you'll have the lens in the hand.
09-27-2013, 10:13 AM   #13
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Finally - Tak in hand

Finally, today I got the lens in the mail.
Its very nice and beautiful, sturdy construction, glass and blades all look nice.
Just cant wait for the weekend to try it out on my 7D.

I have attached two marked up pictures, in which I am concerned about the "lever like" pin show in the circle.
Will this touch against any parts or the mirror in the EOS 7D?
Thats the question I had all these days.

I figured out the aperture pin, the auto/man switch and the small tiny pin which locks the auto/man switch.

I guess trying the lens on my 7D is the only way to find out i guess.

Thanks for your feedback.

Regards - chikkad
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09-27-2013, 10:58 AM   #14
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The aperture coupling is no danger to any Canon camera. Only the rear element of the Super-Takumar 50mm F/1.4 8-element will interfere with the mirror of a Canon full frame SLR. The aperture shield/lever of K-mount lenses will also interfere with the mirror of a Canon full frame slr...
09-27-2013, 01:34 PM   #15
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QuoteOriginally posted by chikkad Quote
Will this touch against any parts or the mirror in the EOS 7D?
I think you know, but may i remind you that APS-C mirror are smaller than the one of FF camera ? Hence, it won't touch
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