Old 50mm (yet another) battle

[rotatux]

Hi, a few days ago I posted a 135mm battle. Now here's another one at 50mm.

Same kind of procedure, except here 2 different subjects were chosen, which could make a comparison difficult, but both are star-rich fields.

Both 20s subs at 3200 iso with E-PL6 on Nexstar SLT, 22x for one, 26x for the other, and darks.

First is Perseus double-cluster + Heart & Soul nebulas with MD-Rokkor 50mm/1.7 at F/2.8. Second is Cygnus region around Deneb and Sadr with OM-Zuiko 50mm/1.8 at F/2.8.

What do you think ?

The Zuiko shows good colors but a very big and entering coma. The Rokkor has less good colors but much less coma. I also like the handling (ergonomics) of the Rokkor more, but I just wonder if the coma of the Zuiko would go away at F/4. I tried to search references on astrobin but it's difficult to tell if cropping occurred or not to mask its coma.

[happy-kat]

The first has red CA the second blue CA. I'd test again but at f4 on the same target. I like the second image more I feel it shows more and the stars are cleaner (where no CA). Is this coma after already cropping the image?

[Alien 13]

I kind of agree with happy kat, from my own experiences with my radioactive 50 mm takumar the results with astro imaging are not good and easily bettered by my 50 mm Canon f/1.8 STM or even the kit lens, having said that the old lens is brilliant for video shooting. 

Alan

[happy-kat]

Which takumar do you have mine is much better than the kit lens it's the f2 or f2.2 one. When I turn the pc on I'll go pixel peeping.

[Alien 13]

Just now, happy-kat said:

Which takumar do you have mine is much better than the kit lens it's the f2 or f2.2 one. When I turn the pc on I'll go pixel peeping.

Its the 50mm f/1.4, the radioactivity has turned some of the lens elements slightly yellow but it is still my favorite video lens for that special look..

Alan

[happy-kat]

Not the same lens a mine but I'll still go look I used it for comet lovejoy.

[rotatux]

1 hour ago, happy-kat said:

Is this coma after already cropping the image?

No all images are uncropped unscaled.

1 hour ago, Alien 13 said:

50 mm takumar the results with astro imaging are not good and easily bettered by my 50 mm Canon f/1.8 STM or even the kit lens

Sure but the fast modern primes come with a high price. For the price of a Panasonic 25/1.7 or Sigma 60/2.8 I can have at least 5 if not 10 "good old" lenses.

Initially I got into the old lens market because no money for modern lenses, plus they are generally too much closed on focal ratio. For example it's almost impossible to focus manually with my kit zooms 14-42/3.5-5.6 or 40-150/4-5.6. Meanwhile it's quite easy to find open primes within old lenses. However I come to realize that most if not all old lenses suffer from annoying aberrations, and modern optics formulas are much better (though often still debatable IMO).

Coming Christmas may help but until then, still trying to find proof of the good old lens.

[Alien 13]

18 minutes ago, rotatux said:

No all images are uncropped unscaled.

Sure but the fast modern primes come with a high price. For the price of a Panasonic 25/1.7 or Sigma 60/2.8 I can have at least 5 if not 10 "good old" lenses.

Initially I got into the old lens market because no money for modern lenses, plus they are generally too much closed on focal ratio. For example it's almost impossible to focus manually with my kit zooms 14-42/3.5-5.6 or 40-150/4-5.6. Meanwhile it's quite easy to find open primes within old lenses. However I come to realize that most if not all old lenses suffer from annoying aberrations, and modern optics formulas are much better (though often still debatable IMO).

Coming Christmas may help but until then, still trying to find proof of the good old lens.

I couldn't agree more, there are some great old lenses out there but feel that the biggest improvements with modern computer aided design and coatings is far greater with the short focal lengths, as an example the current Samyang 14 mm would have been physically impossible to even make years ago. The big plus for me with old lenses is the focus ring feel and sensitivity which is why I still use them but the STM and USM on modern lenses is not far behind.

Alan

P.S. as well as the 50mm Takumar I have a 200 mm f/3.5 Vivitar and a 135 mm f/3.5 Olympus Zuiko.

[happy-kat]

My new stm or is it usm 85mm f1.8 has more CA then my old 50mm circa 1964 even stopped down. The big plus for me is the ease of focus on manual. 

[happy-kat]

I've just found the post with a single frame 180 second image with my takumar 50mm at f2.8 and there's no particularly evident comma or CA evident on the stars shown it includes the pilades. (It may even have been wide open)

[Alien 13]

9 minutes ago, happy-kat said:

I've just found the post with a single frame 180 second image with my takumar 50mm at f2.8 and there's no particularly evident comma or CA evident on the stars shown it includes the pilades.

There are several versions of the 50mm Takumar mine is an early radioactive one the later SMC versions are less so and had better correction but did loose some of the magic in the images. There was a 55mm f/2 version that was very good I believe.

Alan

[happy-kat]

I keep it in the garage it might be the 55mm one it is f2 (I think) it is circa 1964 and is 'hot' and a tad yellow. It isn't the coated one from memory.

[happy-kat]

Yey I got outside so took a couple test shots for you with my vintage lens, paid approx £27 including P&P.

Super Takumar 55mm f2 (circa 1964 and one of those 'hot' lenses so is somewhat yellow that I have't yet bothered to clear)

I have a stepdown ring on with a 2" Baader neodymium filter as I have my share of light pollution. Camera on static mount is pointing towards the West and the star I focused on was around where the thirds intersect though looking at the image is is much further out that bright star on the left but anyway seems to have been OK to use. The star is Sadr (the jury is out on that as I have't yet matched up where I thought I was pointing) though the camera was at a weird orientation, but it was clear and I got outside for a bit.

The first shot is wide open f2 at 3.2 seconds exposure at ISO 3200, shows some CA particularly blue but corners appear quite good. Both jpegs straight from camera.

The second is same everything but stopped down to f2.8 and the blue CA has now gone (there is tiny bit of red CA (unless those are actually orange/red stars)).

The lens stops from f2, f2.4, f2.8, f3.4, f4 though I tend to just use f2.8.

[rotatux]

Weather seems as difficult as here, judging from clouds ;-)

Sad you could not track and try longer exposure... However even at F/2.8 I can spot cross-shaped stars at edges and corners, which IIRC means astigmatism. The brightest stars are elongated too, meaning some coma. It could be more clear with a higher exposure. Also remember CA in my tests appeared more easily in long subs or with more stretching, since its intensity is quite low relative to star's peak brightness.

FWIW I'm afraid it confirms the difficulty to find a good wide-field lens. But I must also say this Takumar seems to perform way better than my Helios-44M 58mm/2, which I also have some shots at 3.2s in my gallery, showing huge coma.

[happy-kat]

I have 30 second images but it was using my manual barn door and my tracking was a little jittery. If I find a none jittery image I will add it here.

[happy-kat]

This is 48 lights, 31 bias and 31 flats. 30 second exposures. I did not filter out the cloudy or jittery ones so this is warts and all.

Copped the artifacts out but a minor crop just heavier at the bottom. Binned 50% and stretched.

This is probably as good as it gets for my manual hand tracking. 30 second single exposure straight from camera.