Super Takumar 200 asterism test.

[MattJenko]

I decided to make a go of fixing the infinity focus issue with my Super Takumar 200mm lens after being disappointed on holiday and then seeing Louise's excellent efforts with her lens.

I managed to move the focus ring and allow those last few mms of travel, so I can now get focus. The image below is a test tonight using 20 x 60secs at F5.6 with no calibration frames. I noticed some coma in the corners and also wondered what processing people use to emphasize asterisms against a big star field?

Cheers

Matt

[kalasinman]

Hi Matt. Interested as I just bought a Pentax 200mm. What body is the SMC made for? What adapter are you using? Would not focus issues and coma be indicitive of an improper backfocus? Just asking.-Jack

BTW the picture has potential, I'll be excited to try mine which is a 6x7 version.

[steppenwolf]

I have deliberately overcooked this a little to highlight the effect but Star Spikes Pro by Noel Carboni will emphasize asterism stars for you:-

[Knight of Clear Skies]

Using the internal aperture blades as you have done can help the naked-eye visible stars stand out, such as this 35mm shot of Cassiopeia.

...but they are still difficult to spot against the busy background. In this version I've used curves to bring the mid-range down, which helps a bit:

I like star spikes for this kind of shot as it helps to tie-in the image with what can be seen visually, but I'm going to experiment with using step-down rings as a front aperture mask for closer shots.

The 200mm Takumar is a nice lens but as you say there is a little coma in the corners at f5.6. Have you tried the focussing on a star a third of a way across the frame?

[MattJenko]

Thanks all. I forgot about the focus on the third way process, I was so ecstatic I managed to get focus at all! I quite like the spikes in these shots as well.

The Takumar lens I have is an M42 screw lens for older Pentax systems. I think this particular lens is around 40+ years old. I am using a low profile M42/EOS adaptor, but it could not quite get infinity focus, so I unscrewed the focus ring and turned it to allow the last couple of mm required, so now I can go through infinity focus.

Steve, that looks much better, I'll give Photoshop a go, as I was trying to get things done in PixInsight.

[Thalestris24]

Thanks all. I forgot about the focus on the third way process, I was so ecstatic I managed to get focus at all! I quite like the spikes in these shots as well.

The Takumar lens I have is an M42 screw lens for older Pentax systems. I think this particular lens is around 40+ years old. I am using a low profile M42/EOS adaptor, but it could not quite get infinity focus, so I unscrewed the focus ring and turned it to allow the last couple of mm required, so now I can go through infinity focus.

Steve, that looks much better, I'll give Photoshop a go, as I was trying to get things done in PixInsight.

Hi Matt

Looks like the same lens as mine - 'vintage'!  One can always crop a bit to get rid of any edge field curvature...  Stars can be like trees in a forest can't they, but as Steve did above, emphasizing the coloured ones helps, I think I only wish I had darker skies to help pick up the fainter stars. There was talk of a partial street lighting plan for here in Glasgow but I've not noticed any changes yet. I live in hope!

Louise

[Ruud]

The coat hanger!

I'll never forget how I discovered it with my binoculars. The next day, when I tried to find it again, I stumbled upon the Dumbbell nebula. I was twelve. I've been hooked on astronomy ever since.

Thank you Matt, for the beautiful images and stirring up that memory. 

[Pompey Monkey]

CR399!

I also "independently" discovered this cracking little asterism when I was a child.

[Knight of Clear Skies]

The Takumar lens I have is an M42 screw lens for older Pentax systems. I think this particular lens is around 40+ years old. I am using a low profile M42/EOS adaptor, but it could not quite get infinity focus, so I unscrewed the focus ring and turned it to allow the last couple of mm required, so now I can go through infinity focus.

They are nice lenses, the Super-Takumars are late 60s vintage while the SMC Takumars are early-to-mid 70s I believe. I got this on the Orion Nebula using a 200mm SMC.