4-panel wide field of Sadr region in Cygnus

[old_eyes]

This was from data taken on Pier 14 at Roboscopes. Reduced FSQ106 at 387 mm FL with an ASI 6200MM full frame mono camera. 2x 2 mosaic.

The sensor is so big that we get coma at the corners of the image using a reducer. This makes mosaics quite tricky, particularly 2 x 2 where the corners of four frames meet in the centre. You have distortions going in all directions! However, if you stand back and look at the overall effect and don't pixel-peep, you don't notice so much.

I like the way the Crescent Nebula pops out at the bottom with a Hokusai "Great Wave" breaking over it.

Image is 7d 22' by 5d 43'

 

 

[symmetal]

Great composition.  My 6200 with the FLT98 has coma effects on 2 corners but I don't feel so bad about it now if a Takahashi has similar. 😊 With mine it's considerably worse on OIII compared to other filters. Blue is much better which seems strange, unless the triplet correction happens to be worse near a particular wavelength coinciding with OIII.

As an observation, I would say the black point is set a bit high on the bottom right quadrant compared to the others which has also reduced the saturation on that panel. 🙂

It has a good 3D feel to the picture with the Crescent appearing in the foreground with the 'waves' coming towards you. 😀

Alan

[old_eyes]

The problem with the Tak is the reducer we think. At it's native 530mm FL it should be OK, but reduced to 387mm we seem to be asking too much of the reducer. The problem with full frame cameras!

I was a bit worried about the bottom right panel, but I have looked very carefully at the individual mosaics for the three filters, and there seems to be real data there, particularly in O3.

I used DNALinearFit to bring the individual panels together, and with a close inspection I can't see a shift in the background across the overlap. It also did not seem to matter which way round the sub-panels I went with DNALinearFit.

I think I am going to leave it for a while and get on with some other images. Mosaics from full-frame high-res CMOS cameras take some processing, and I don't want to go back to the start if I can avoid it 😲.

Thanks for the comments. And if you have another process for balancing panels at the mono and linear stage, I would love to hear it.

[symmetal]

Since getting the 6200 I haven't really felt the need for mosaics which was the main reason for getting it. 😊

Astro Pixel Processor is highly regarded for its mosaic capabilities though I haven't used it for mosaics myself, just for stacking. I imagine it balances the mosaic panels to match, though someone who has used it can confirm.

Alan