Super-Multi-Coated Takumar 3.5/24 Lens-Flares

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

hi,

some weeks ago i bought a Super Multi-Coated Tak 3.5/24 and i was very happy about it!

now i took the first shots on my eos30 (film). i do a lot of bulb exposures an there (and also on "normal" shots) i had to see annoying lens flares. my tamron-zoom (28-200) produced no such flares in shooting the same situations. ok, it wasn't sharp at all, and i hated it for that, but whats the matter with this tak?

what is wrong? unfortunately i have no dslr and no scanner, so that i cannot show you test shots.

but what could be the reason in your experience? is there something wrong with the coating? i didn't us a filter, so that cannot be the reason. could dust (between the glasses) be the reason? there's just a tiny little bit.

thanks alot for your help,
supahmario.

scsambrook · Expire: 2011-11-18

Supahmario - is the flare patches of light, internal reflections, or an overall "veiling" problem where the whole frame looks to be lacking contrast ?

SMC lenses are not immune to flare - it may still happen, even though it is less than with a non-SMC of the same design. Very wide angle lenses suffer more than longer lengths, and lens hoods are of much less use with them.

Look carefully into the lens from front to rear, holding the lens to a bright artificial light source, and look for any sign of "misting" inside. That probably has the worst effect in causing veiling flare. It can be hard to see except when looking in the way I have suggested. Dust would only do the same if there was a LOT of it, which is unlikely. The Pentax lenses are quite well sealed as a rule. But misting can happen through changes in temperature and humidity, condensation may form and evaporate, but progressively leave behind a surface layer which gets worse with time.

Sorry not be more helpful, but it is difficult without actually seeing the results you are getting. I hope you can get it fixed.

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

thanks alot sam,

i will try to scan some results at work (there we got a scanner).

the overall contrast is fine, so that i dont think that it is a "veiling" problem. i allways use lens hoods. for that lens i use the original lens hood.

is it difficult to open the lens for cleaning? it seems so, because at the front there are no slots for setting a special tool to. some weeks ago i saw a introduction for taking apart a 1.4/50er tak. i will have a look at it.

so lets see my scanned test shots. thanks for your help so far.
supahmario.

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

i am not celebrating easter, so i took a short trip to my office.

i scanned in 300dpi directly from the cheap 9x15cm drugstore prints. the results are bad, but good enough for showing you the flares.

here i could say: "ok. shooting directly into the sun i cannot expect that there are no flares" but i cannot say so, 'caus i am a perfectionist! flares can be nice, but just when i want them to be there!!!

this is a bulb exposure. and it's very interessting, 'caus there seem to be two different types of flares. the ones going out directly from the street light and the ones that are like slight clone-lights above the original lights. ok, and then there is this object at the top of the roof. but everybody knows that this is an UFO.

here you can see also the clone-lights. here they are positioned to right of the original. this could lead me to the assumption that something is decentred within the lens. what do you think? but would there be something decentred, it would have an affect to the sharpness. but there are noch problems with sharpness. (you just can divine it, looking at these scans)

here one more example for the flares directly going out from the lights.

do you think, that this are two different flare-problems or is it the same task just looking different?

all shots (except the first) are shot with f11 to f16. with lens hood and without any filters.

by the way, pictures 2 to 4 are taken at the new "o2-arena" in berlin. it's an ugly building, caus it don't fits to the surrounding. but for itself it can look nice i think.

scsambrook · Expire: 2011-11-18

Hi Supahmario,

I don't think you actually have a problem with this lens, please do not worry any more - those images look good to me! Nice pictures and the lens behaving just as we should expect. Perhaps use some lens cleaning fluid and proper lens cleaning tissues on the front and rear surfaces to make sure they are absolutely clean, but otherwise I think you have nothing to worry about. Wide angle lenses do give results like this - and many are by no means as good as this one. The "star" effects round points of light are a characteristic and not a fault, and the internal reflections in the first picture are also quite typical of such wide angle lenses. Don't forget that the design is from the 1960s, almost half a century ago.

It's good to strive for perfection, and good to be really critical, and you are to be commended for identifying these particular aspects of the lens's "misbehaviour" ! But honestly, that lens looks good and I would be happy to have it if you decide to throw it away - !!!

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

but i wonder... the bulb exposure shoots i took with my tamron af 28-200 aspherical had never flares like this. against the sun, YES. but on normal street lights within the picture, NO! and i ever hab a bad (simple coating) skylightfilter an that zoom-lens.

can the difference in flares be so strong between 28mm and 24mm focal length? i will test it!

and NO! i will never throw away this beautyfull lens! perhaps i will find out that other lenses are better for my bulb exposures, but i love the contrast and color of the taks!

the star effects where not the flares i meant. i know these effects and they are one reason i love shooting bulb exposures! i meant the aperture ghosting going out from the lights. they seem to be the same as on picture 1. but what about the clone lights on the other pictures?

do not missunderstand me. i dont want to query your explinations. i just want to understand better.

scsambrook · Expire: 2011-11-18

Hello Supahmario ! Good to find someone really getting down to understanding what makes things happen - but I'm not sure if my expertise is great enough to explain just what is happening with your 24mm lens.

I feel the explanation for these effects must lie in the design of the lens. I think we see two sorts of effects: the "flares" radiating from light points, which are something like extended spokes of a wheel, and then what you very sensibly call "clones" of the lights themselves. Both are typical of what can happen when strong point-light sources are in the field of view - that they don't happen with your other lens is very likely because of its different optical construction and more modern coatings. You are right to say that if there were a decentration problem other faults would be apparent.

So, not much scientific explanation for you here, I'm afraid. Perhaps other forum contibutors with greater optical knowledge can shed more light on it.
My belief is that your 24mm is okay, in that it is working in the same way that it did when it was new.