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Asahi Auto Takumar 2.3/35 after cleaning
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PostPosted: Fri Dec 16, 2016 5:10 pm    Post subject: Reply with quote

If you have other M42 lenses that work OK on the adapter, that points to the fault being with the Takumar. And I have no idea of how this particular Takumar is adjusted - but a lot of Takumars have two sets of three screws under the trim / name ring, slacken one set of screws and the adjustment can be made. I think it's fairly obvious which of the two sets are the adjusting screws.
The other Takumar that I've adjusted in the 50 / 4 Macro Preset lens, which has shims that need to be removed or added to to reset infinity focus. I did a topic here - http://forum.mflenses.com/takumar-50-4-macro-infinity-focus-adjustment-t69118.html that describes basically how its done. Removing such a thick shim did seem drastic - but it was right, the lens is perfect now and I use it a lot.


PostPosted: Fri Dec 16, 2016 6:39 pm    Post subject: Reply with quote

Every time I see a post about infinity focus, I wonder how many lenses are really correct. If the lens actually stops short of infinity by a small amount and you perceive it to reach infinity, will you ever know? I always want my lenses to go past infinity, allowing me to focus instead of trusting a hard stop. I have also found that most of my lenses do go past infinity on adapters without any adjustments. However, most of my shooting is close, so infinity doesn't mean much.

On another subject, is this subject lens better than the f/2 35mm? I go curious and saw on on ebay now for $299. Too high for me, but anyone with deeper pockets may be interested. The lens does have an interesting look to it. Would be nice to see images again.


PostPosted: Fri Dec 16, 2016 8:48 pm    Post subject: Reply with quote

woodrim wrote:

On another subject, is this subject lens better than the f/2 35mm?
I go curious and saw on on ebay now for $299. Too high for me, but anyone with deeper pockets may be interested. The lens does have an interesting look to it. Would be nice to see images again.


According Pentaxforums the older f/2.3 lens is slightly better than the newer F/2 lens. I am not sure if that is really true.
I have an early F/2 Super Takumar and in my last years 35mm lens test it was among the better ones. Especially when stopped down.


Last edited by tb_a on Sat Dec 17, 2016 5:57 am; edited 1 time in total


PostPosted: Fri Dec 16, 2016 8:57 pm    Post subject: Reply with quote

Kinosaur wrote:
Ha! Hi Edri, I guess it's likely it was me that beat you to it! Sorry! ...


Laugh 1 Friends


PostPosted: Sat Dec 17, 2016 5:48 am    Post subject: Reply with quote

woodrim wrote:
I go curious and saw on on ebay now for $299.


The price at auction is usually around $170-180. The $299 price is only a yearning of the seller.


PostPosted: Sat Dec 17, 2016 9:27 am    Post subject: Reply with quote

[quote="woodrim"]Every time I see a post about infinity focus, I wonder how many lenses are really correct. If the lens actually stops short of infinity by a small amount and you perceive it to reach infinity, will you ever know? I always want my lenses to go past infinity, allowing me to focus instead of trusting a hard stop. I have also found that most of my lenses do go past infinity on adapters without any adjustments. However, most of my shooting is close, so infinity doesn't mean much.

You make a good point about most lenses going past infinity on adaptors, it certainly is the case that the majority of cheaper (and expensive!) modern adaptors seem to be machined to deliberately err on the side of being too slim to ensure that infinity acheived and in some cases allowing them to be corrected by shimming if required.

I think that the old Canon 'P' adaptor I'm using is probably very accurate so I guess trying it with a cheap adaptor is worth a try.

Thanks for all the replies, I'll try to post a couple of pictures of what is seen behind the front element when I have a moment, to give an idea of what I'm faced with, and why I'm scratching my head.


PostPosted: Sat Dec 17, 2016 1:32 pm    Post subject: Reply with quote

Here are some pictures, I think!

#1



#3


#4


PostPosted: Sat Dec 17, 2016 1:48 pm    Post subject: Reply with quote

Here's another one, bit smaller this time! showing the end stop screw amongst other things
#1


PostPosted: Sat Dec 17, 2016 2:30 pm    Post subject: Reply with quote

Last one! I've removed the end stop screw for the moment and this is where the focus ring needs to be turned to to achieve infinity focus, so not miles out.

So I guess what I'm looking for is any advice on fine back focus adjustment, It feels as if the error is less than I'd expect from incorrect fitting of the helicoids
although I still suspect that is the case, there are markings showing that the lens has been taken apart in the past, and they do not line up correctly at infinity.

As you can see, the lens ring fits in one position to the outer helicoid,(no adjustment posible) and the end stop screw is on that helicoid.

Is it possible that the entire optical block can be adjusted within the helicoids? I suspect that it should not be adjusted by screwing it in or out simply because
when you look at other pictures of the same lens, the words on the front ring seem to be reliably in the same orientation, as does the position of the lens markings
ie the red dot, in relation to the rear of the lens.
#1


PostPosted: Fri May 31, 2019 11:02 am    Post subject: Reply with quote

Hi, sorry to re-open an old post but like previous members I am looking for information on how to open this lens...existing info seems very limited.

It looks as though access must be from the front. It would even be helpful to know if front element removal is done by removal of the name ring or whether the name ring is fixed to the collar at the end of the lens barrel as this seems to be a separate part to the actual barrel itself and may unscrew.... though so far unsuccessful for me!

The name ring is extremely narrow and it looks very tricky to get a friction tool onto it without risk of damaging the large and protruding front element.

Again, any info would be greatly appreciated.
Thanks


PostPosted: Fri May 31, 2019 12:15 pm    Post subject: Reply with quote

Hi Airblower

No need to apologise, I guess this is what these forums are for!

The front element does unscrew from the larger, tapered, part.

grip the tapered part (with your hand) and just unscrew the front element. Have faith, it will probably be stiff if it hasn't been opened for a while
but there are no hidden grub screws or anything. Do hold the tapered bit though, not the focus ring or any other part of the lens, hope that makes sense!


PostPosted: Fri May 31, 2019 1:37 pm    Post subject: Reply with quote

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Last edited by Blazer0ne on Tue Feb 22, 2022 5:33 pm; edited 1 time in total


PostPosted: Sat Jun 01, 2019 9:26 pm    Post subject: Reply with quote

Thank you both for the above information...extremely helpful!

Mine is quite a beaten up copy but glass is good and I didn’t pay much.

It has a problem where focus won’t fully retract to infinity setting unless the silver shutter is partial pulled back....like something is jamiing or fowling on the inside. Thought I’d risk some investigation as the shutter arrangement looks similar to that of the auto Yashinon 5cm f2 and I’ve worked successfully on a number of those.

Thank you again and I’ll try and post on my findings.


PostPosted: Tue Jun 04, 2019 12:58 am    Post subject: Reply with quote

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Last edited by Blazer0ne on Tue Feb 22, 2022 5:33 pm; edited 1 time in total


PostPosted: Fri Jun 07, 2019 9:28 pm    Post subject: Reply with quote

It has a problem where focus won’t fully retract to infinity setting unless the silver shutter is partial pulled back....like something is jamiing or fowling on the inside. Thought I’d risk some investigation as the shutter arrangement looks similar to that of the auto Yashinon 5cm f2 and I’ve worked successfully on a number of those.[/quote]


Thanks to previous replies I successfully managed to remove front element and investigate further.

I now understand what was causing the problem but I think resolving it may be trickier.

Basically the rear of the lens has a brass tab (pic1) which should sit neatly in a recess in the rear mounting (pic2)to lock it place and stop it rotating when the aperture ring or lever are turned.

When I openen the lens up these were not aligned and this was preventing the lens focusing back to infinity. It’s actually surprise it moved at all.

Anyway, this sounds simple to remedy but why I place the lens block correctly into the recess the screw holes which hold the lens block in place no longer align with those on the rear mount. Pic3 shows the two parts aligned to fit orrectly together but you will see the screw holes do not align.

#1


#2


#3



The lens looks as though it’s probably part in the past but you may notice the infinity markings have been meticulously added to the focus ring and helicoids but again I cannot get get these to align with the corresponding mark on the base whilst positioning the lens correctly so the brass tab fit in the recess.

Sounds confusing but any ideas or suggestions are welcome. The aperture works perfectly when brass tab slots into position but I can’t see anyway to adjust he position of the recess in the mounting so the the screws align or adjusting the position of the screw holes.


PostPosted: Sat Jun 08, 2019 12:44 am    Post subject: Reply with quote

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Last edited by Blazer0ne on Tue Feb 22, 2022 4:51 pm; edited 1 time in total


PostPosted: Sat Jun 08, 2019 1:34 am    Post subject: Reply with quote

airblower wrote:
...



Sounds confusing but any ideas or suggestions are welcome. The aperture works perfectly when brass tab slots into position but I can’t see anyway to adjust he position of the recess in the mounting so the the screws align or adjusting the position of the screw holes.


Helical threads have multiple starting points. Try each one.