[MegaPower]

To the best of my knowledge, the rear element of the 8 element does not protrude further than the usual 7 element 50/1.4. It is just the protective rim that is bigger on the 7 element, so that the element is less exposed.
That being said, the 8 element grabs its high prices mainly because of it being a collector's item. Multi coating really makes a difference here, and I believe the coating on the 8 element is rather primitive by comparison (I've owned Super Takumars and I know that is the case with most of them).

not correct.
the rear element of 8-element protrude more than than S-M-C takumar (same as all 7-element)


(7-element on top, 8-element below, words are wrong)


On my canon 5D, mirror hitting rear element is worse in the case of 8-element.

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Last edited by MegaPower; 03-09-2013 at 07:58 PM.

[MegaPower]

K30 + S-M-C takumar 50/1.4


Canon 5D + ST 50/1.4 (8-elem)

[stevebrot]

not correct.
the rear element of 8-element protrude more than than S-M-C takumar (same as all 7-element)


On my canon 5D, mirror hitting rear element is worse in the case of 8-element.

Your photo seems to show the contrary. The absolute intrusion (measured from the mount face) of the 8-element looks to be a millimeter or so less than the S-M-C. As for mirror incompatibility, there is a "surgical" fix for that


Steve

[rubender]

To the best of my knowledge, the rear element of the 8 element does not protrude further than the usual 7 element 50/1.4. It is just the protective rim that is bigger on the 7 element, so that the element is less exposed.
That being said, the 8 element grabs its high prices mainly because of it being a collector's item. Multi coating really makes a difference here, and I believe the coating on the 8 element is rather primitive by comparison (I've owned Super Takumars and I know that is the case with most of them).

I understand that its price is higher because it's a rare version, but for what I read in this forum and others everybody who owned the 8 elements and 7 elements (ST or SMC) liked much better the 8 element version than the 7 element, even keeping in mind that the SMC has 8 blades instead of 6. I might get a SMC copy from ebay but right now I can not spare 150-200 USD for a duplicate lens, I really want to buy the Volna-9 2.8 macro, I don't have a macro lens and I read pretty good things and I love how russian lenses look.

[rubender]

K30 + S-M-C takumar 50/1.4


Canon 5D + ST 50/1.4 (8-elem)

Thanks for the samples pics of both lenses. Which one do you like better on your 5D? I knoe that the 8 elements flares more but that's not an issue for me (as long as I can controlled the flare not like the sensor reflection issue I'm having).

[rubender]

not correct.
the rear element of 8-element protrude more than than S-M-C takumar (same as all 7-element)


On my canon 5D, mirror hitting rear element is worse in the case of 8-element.

I believe you are right in the info you wrote but in the pic you posted your mark lenses wrong, the one on top is the 7 element SMC (red mark next to 4 is on the left, says MANUAL and AUTO) and the one below is the 8 elements (red mark on the right side of 4, and says M and A). You're right either way.

[rubender]

Talking about coatings...Did you guys have any issues with yellowing? I know that 7 elements version, SMC and Super Multi Coated have thorium in their coating and that might provoke yellowing.

I was checking prices for 50mm SMC takumars in eBay and a few sellers said that they "UV treated the lens for yellow", is there a process (besides exposing the lens to sunlight for days) to treat the yellowing?

[stevebrot]

Talking about coatings...Did you guys have any issues with yellowing? I know that 7 elements version, SMC and Super Multi Coated have thorium in their coating and that might provoke yellowing.

The thorium is in the glass not the coatings and was added to change the refractive index. There is some discussion as to what actually turns yellow. There are users here that have stated that it is the coatings that turn in reaction to the radiation. I have seen convincing reports on the Web that indicates that glass itself is discolored. For years, it was my opinion that the yellowing was the balsam cement used in grouped elements (have my doubts now). Regardless of the cause, the lens can be bleached by exposure to sunlight or another source of UV light.


Steve

[stevebrot]

Well, I was able to check this out on my K10D and you can add the Auto Rikenon 55/1.4 to the list of lenses that make the bright spot. With the Rikenon on that camera the spot is golden, but definitely there in the very center at f/16 when shooting in VERY strong direct light. I tried it with my Jupiter-9 85/2 (also has a huge rear element), but no spot for the Jup'. While both lenses have large rear elements, the Rikenon's appears almost flat while the Jup's has a definite cap.


Steve

[rubender]

Well, I was able to check this out on my K10D and you can add the Auto Rikenon 55/1.4 to the list of lenses that make the bright spot. With the Rikenon on that camera the spot is golden, but definitely there in the very center at f/16 when shooting in VERY strong direct light. I tried it with my Jupiter-9 85/2 (also has a huge rear element), but no spot for the Jup'. While both lenses have large rear elements, the Rikenon's appears almost flat while the Jup's has a definite cap.


Steve

Both lenses (RIkenon and ST) look very similar built wise, maybe they share design/coating and that's why they produce the bright spot... or not.

Thanks,
Ruben

[rhodopsin]

That looks exactly the same as the infamous blue spot on the Tamron 90 2.5 macro, which is a superb lens in every respect except this blue spot. Which as Steve says, is most likely a reflection of the sensor on the flat rear element.
With my Tamron I can see it in the viewfinder as it occurs and changing position so the flare through the lens doesn't reflect gets rid of the blue spot. I didn't finda hood a great deal of help - some help but not enough to get rid of it. I experimented with different hoods and apertures with the camera on a tripod.

Latest info on SP 90 "spot", from somebody who talked with Tamron employee at a trade show, is the rear compensator group of elements is uncoated (thus the reflections), that the lens is designed for low contrast lighting at high magnifications. I suspect other lenses that exhibit these spots have uncoated elements.

The thorium is in the glass not the coatings and was added to change the refractive index. There is some discussion as to what actually turns yellow. There are users here that have stated that it is the coatings that turn in reaction to the radiation. I have seen convincing reports on the Web that indicates that glass itself is discolored. For years, it was my opinion that the yellowing was the balsam cement used in grouped elements (have my doubts now). Regardless of the cause, the lens can be bleached by exposure to sunlight or another source of UV light.

Thorium doped glass is well known, however, Gerjan van Osten says, in "The Ultimate Asahi Pentax Screw Mount Guide" (1999), there is thorium in one of the coatings. Since Mr. van Osten had access to Asahi Pentax personnel and documentation, I tend to believe him.

[rubender]

I just realized that the iris of my ST moves (like 1mm) when I pull focus, I haven't noticed it while shooting but I was checking the lens for dust earlier today and I realized it moves, and it fiels like something moves inside, just a tiny bit but it feels weird. That isn't right, right?

I made a video of it:

password: test

I know it might look like an optical illusion but when you have the lens in your hands you actually feel something moving inside the lens(very subtle). Just double checking if that is normal (doesn't happen in my MF Nikon lenses) or I'm just getting too paranoid after finding the blue spot.

Thanks

[MegaPower]

Your photo seems to show the contrary. The absolute intrusion (measured from the mount face) of the 8-element looks to be a millimeter or so less than the S-M-C. As for mirror incompatibility, there is a "surgical" fix for that


Steve

I drawn a line on the paper which is the flange mount.
And the mirror in my 5D is absolute a good tool to measure the rear element > sensor distance.

[stevebrot]

Both lenses (RIkenon and ST) look very similar built wise, maybe they share design/coating and that's why they produce the bright spot... or not.

Thanks,
Ruben

They look similar build-wise because that type of build was the standard of the day. (My Rikenon dates to about 1970). Put the two lenses side-by-side and the difference is obvious, at least in relation to size. The Rikenon is much larger and heavier. Beyond that, almost all Japanese fast 50s are derived from the Zeiss Planar and share very similar optical design. Coating technology was probably similar as well. As a result, it would not surprise me if 50mm f/1.4 lenses from most makers would have similar issues.


Steve

[stevebrot]

I drawn a line on the paper which is the flange mount.
And the mirror in my 5D is absolute a good tool to measure the rear element > sensor distance.

I noticed the line. As noted above, you mis-labeled the lenses.


Steve