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08-14-2021, 06:57 AM   #1
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Is the focus on the Takumar SMC 50 mm THAT soft?!

Hi to all! I bought a used Pentax Asahi Spotmatic a few years ago and it came with the Takumar SMC 50 mm 1.4, I just bought a Canon 90D and thought... hey why not try the Taku on it! The image is really beautiful but I'm unable to get the focus right... so I looked on YT and someone said that the Takumar was a "soft" lens... my question is... is it THAT soft?! I'm used to recent Canon lenses and movie making so... maybe it's just that I'm not used to this "softness"... or is there a problem with the lens?

Thank you so much for your help! (and here's my cat...) It's really the sharpest I could do. So problem or normal Taku?!

eazykamikaze

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08-14-2021, 07:08 AM   #2
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Something is up with the lens I'd say, if you've done your best at trying to get focus.
08-14-2021, 07:19 AM   #3
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You won't get much depth of field at f1.4, of course, but the centre should be much sharper than we see in your samples. Is there any evidence the lens has been apart? I agree with HarisF1 that it's a lens issue. The adapter shouldn't be causing this.
08-14-2021, 07:26 AM   #4
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QuoteOriginally posted by Elroy Jetson Quote
You won't get much depth of field at f1.4, of course, but the centre should be much sharper than we see in your samples. Is there any evidence the lens has been apart? I agree with HarisF1 that it's a lens issue. The adapter shouldn't be causing this.
Thanks to you both... yeah I promise, this is the sharpest I don't even think I was all open... maybe more f4, to be sure... I'll try looking with the viewfinder maybe... but I think it's the lens... is this a "repair" thing or it's a "get another one used" thing?

Thanks!

08-14-2021, 07:52 AM   #5
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This far away tree in the viewfinder and in the screen is SHARP and CLEAR and this is the result... so yeah, that's what I don't understand, the when I take the picture it's perfectly sharp, but the result is way off... any ideas what could do this?!

Thanks again!
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08-14-2021, 08:41 AM   #6
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I would hazard a guess someone has had that lens apart and not reassembled it correctly. Nothing is sharp in that image

If you shine a torch through the lens is there signs of fungus or major dust ?
08-14-2021, 09:37 AM - 1 Like   #7
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Yeah, something isn't right with lens. A back or front focus with the camera would have something sharper than the other.

Here is a shot with my SMC Takumar 50/1.4




08-14-2021, 10:13 AM - 1 Like   #8
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QuoteOriginally posted by pschlute Quote
I would hazard a guess someone has had that lens apart and not reassembled it correctly. Nothing is sharp in that image

If you shine a torch through the lens is there signs of fungus or major dust ?
Hello Peter,
what I do not understand is that OP states that in the viewfinder it looks sharp but the result is not. Could it be that the diopter setting of the camera's viewfinder is at fault? I am able have an unsharp scene in the viewfinder if the diopter correction is wrong, but does it work the other way round as well. If I am a little off with the diopter I can get a sharp scene if the manual lens corrects the wrong setting of the diopter when I am focusing or was I just dreaming I did that?
If the lens was wrongly assembled I would or should not get a sharp scene in the viewfinder I reckon, but I may be wrong there.

Last edited by AfterPentax Mark II; 08-14-2021 at 11:42 AM. Reason: typo
08-14-2021, 11:23 AM - 2 Likes   #9
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QuoteOriginally posted by AfterPentax Mark II Quote
If the lens was wrongly assembled I would or should not get a sharp scenen in the viewfinder I reckon
Depends how good your eyes are

You make a valid point, but simply looking at the pictures posted the lens has issues in my opinion.
08-14-2021, 12:04 PM - 1 Like   #10
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I have the 8-element Super-Takumar 50 f/1.4, and it would be criminal to call it soft. Even though the later ones have a change to the optical design, I don’t think anyone accuses them of being soft (but certainly very think DoF wide open). Please direct us to the YouTuber who has made these allegations so the Pentax Army can be sent after them

More constructively, then Google machine suggests that the 90D has focus peaking. I would try focusing using that rather than the OVF to assess focus and sharpness. I do concur with others that this particular lens copy appears to have issues, perhaps from a botched repair (or modification attempt), but I always thing that live view focus peaking is extremely useful for focusing these older lenses, especially at wide apertures. (For your tests, I’d say to stop down to f/4 or thereabouts and then focus in live view with focus peaking.)
08-14-2021, 03:02 PM - 1 Like   #11
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The 90D having 32 MP can be quite demanding on image sharpness but no that image should not be that soft.

Silly question perhaps but have you tried focusing in Liveview with maximum magnification on a static item (i.e. doesn't move)? I'm assuming you are not relying on what the 90D viewfinder is saying is focus as this could be misleading with a manual lens.
Also I'm assuming you have a good adapter that allows infinity focus - can confirm if this is a factor by trying shots focused on far and near objects.

Otherwise its probably a defect with the lens (likely someone has taken it apart as these lenses are unlikely to do this on their own given their very robust construction).
08-17-2021, 02:05 PM - 1 Like   #12
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The question of whether to replace or repair is a matter of your confidence in being able to get the lens apart, address the issue, and get it together again. If you don't have a lot of money invested it might not be a bad idea to attempt repair yourself, but I'd guess most people (even enthusiastic Pentaxians) would prefer the comfort of skilled hands doing the job. The idea of a screwdriver chewing a scar across a piece of glass can be traumatic.
08-17-2021, 09:02 PM - 1 Like   #13
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I assume that you - having used a Spotmatic - set the 'man/auto' switch {the slide switch at the "12 o'clock" position in the photos below} to show 'man'/'m' {to hide 'auto'/'a'}???
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08-17-2021, 09:10 PM   #14
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This looks a lot like lenses I've had where someone reversed an element.
08-17-2021, 10:09 PM - 1 Like   #15
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Have you thought about checking the lens adapter?

The distance from the back of EVERY Pentax lens to the sensor should be 45.46mm. The distance of 44.00mm exists from the front of an EOS lens mount to the sensor. The adapter should be 1.46mm thick. A bumped, dropped, or poorly made adapter could cause this problem.

Look at your adapter. Make sure it is not bent or warped and the flange is a millimeter and a half thick. If there is glass in your adapter, you have the wrong adapter.

I've had a copy of your lens and used it a lot. Something is wrong.
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