C11 CAK Images on different days, New, added 16 Oct images

[yltansg]

The Setup for 15 Oct 19 sesssion:


It was another cloudy day and I have to pump up the gain to maximum and exposure to 9msec

15Oct19
Acquisition Length in mS: 24235
Mean FPS : 82.52528
Exposure in µS : 9000
Gain : 24000
Gamma : 2.30999994277954


12Oct19
Acquisition Length in mS: 39212
Mean FPS : 50.97929
Exposure in µS : 4878
Gain : 22179
Gamma : 3.40000009536743


Same setup, different seeing condition and 2 very different CAK images. I think the image taken on 12 Oct is of higher resolution than that taken on 15 Oct. What do you think?

Alfred

[Montana]

Wow! these are fantastic well done picture number 1 is very nice indeed

Alexandra

[MAURITS]

Very nice images Alfred.

[yltansg]

Thanks Alexandra and Maurits.

Alfred

[yltansg]

We can see that the first image is more "grainy" while the second is more "cloudy". I wonder which is more representative of the condition in the lower chromosphere.

Alfred

[marktownley]

Nice images Alfred! You're very ambitious with that large aperture and the seeing.

[yltansg]

Nice images Alfred! You're very ambitious with that large aperture and the seeing.

Thanks Mark. Hope to continue experimentation with different etalons/wedges etc to get best performance.

Alfred

[MapleRidge]

Hi Alfred...

Both images are impressive, but I wouldn't have expected as much different in the overall appearance if only the date/seeing condition was changed between them. Still, very good images

Brian

[Merlin66]

Alfred,
Very nice....
What. Camera and software were you using?

[yltansg]

Thanks Merlin and Brian.

Merlin - I used a Basler Ace Aca1920-155um BW USB3 camera. Used AS!3 for stacking and imPPG for initial processing
and minimum adjustments in PS.

Alfre

[yltansg]

Thanks Merlin and Brian.

Merlin - I used a Basler Ace Aca1920-155um BW USB3 camera. Used AS!3 for stacking and imPPG for initial processing
and minimum adjustments in PS.

Alfred

[yltansg]

Another very cloudy day with average seeing. I managed to record 8 videos during gaps in the clouds. The setup is the same:
C11 with full aperture ARIES D-ERF + Lunt CAK wedge + X2 barlow + Basler Acer Aca1920-155um camera.

The first imaging window was at at 9:36am local time, I captured this image:


At 9:49 am, the seeing condition became very bad. Focusing was impossible and there was poor contrast


Then I reduced the aperture to 230mm.


and caught this image at 10:04am at 230mm

Seeing makes a big difference and stepping the aperture stop to 230mm helps.
Views are welcomed.

Alfred

[Montana]

Wow!! I have never seen seeing like your first image well done.

The contrast is much better on the 23cm one though, even if the seeing was bad.

Alexandra

[yltansg]

Nice images, Alfred, especially the first one. Impressive with a 11" SCT. Maybe you went "lucky" with your SCT being a little undercorrected. But you will most likely never get a sharp picture with the SCT whatever the seeing in this wavelength particularly at high mag.
The spherochromatism inherent in the Schmidt plate will prevent sharp pictures at high mag and you will end up with somewhat mushy ones like the second and third picture. And of course it's getting even worse when seeing deteriorates. It's not my intention to decrease your enthusiasm but it's just the facts. But I really love your enthusiasm.

Dear langleif,

Thank you for the pointers. I am glad that my C11 was a little undercorrected I will be trying different size aperture stops (I have a few ready). I will also try different CAK filters. It is all part of my learning process.

Alfred

[yltansg]

Wow!! I have never seen seeing like your first image well done.

The contrast is much better on the 23cm one though, even if the seeing was bad.

Alexandra

Hi Alexandra,

I will try to see if I can produce another image like the first one with the full aperture and try with 24cm to take advantage of the better contrast. Looking forward to see your CAK images with the C11.

Alfred

[yltansg]

Wow!! I have never seen seeing like your first image well done.

The contrast is much better on the 23cm one though, even if the seeing was bad.

Alexandra

Hi Alexandra,

I will try to see if I can produce another image like the first one with the full aperture and try with 24cm to take advantage of the better contrast. Looking forward to see your CAK images with the C11.

Alfred

[marktownley]

Nice images Alfred! You're very ambitious with that large aperture and the seeing.

Thanks Mark. Hope to continue experimentation with different etalons/wedges etc to get best performance.

Alfred

I honestly think that short of your seeing being better the C11 is too big for the conditions you have (in this image run). While stopping down is going in the right direction with poor seeing, the increase in the percentage area of central obstruction gets higher the more that is stopped down and so does the image contrast. There comes a point where using a smaller aperture refractor (with it's higher contrast) will give better results than a similar but larger aperture SCT.

Don't take this as criticism of your images Alfred, it's just my thoughts on a bigger picture of large aperture CaK imaging

[yltansg]

I honestly think that short of your seeing being better the C11 is too big for the conditions you have (in this image run). While stopping down is going in the right direction with poor seeing, the increase in the percentage area of central obstruction gets higher the more that is stopped down and so does the image contrast. There comes a point where using a smaller aperture refractor (with it's higher contrast) will give better results than a similar but larger aperture SCT.

Don't take this as criticism of your images Alfred, it's just my thoughts on a bigger picture of large aperture CaK imaging

Thank you Mark and everyone for sharing your wealth of knowledge in this forum. There are many things that I do not know and it is great learning from and with one another.

Mark, your comments have benefited me in my learning, never taken as criticism. I also welcome criticism and I hope that I have the wisdom to see the gems and learn from them as well.

Cheers.

Alfred