Tair 3 - Budget Lens

[chemistorge]

Hi All, 

 

I obtained a Tair 3 off ebay a few months ago and I finally got around to using it. Here is Andromeda (300mm, f5.6, 45x180', 40 flats and 40 darks, ASI294MC, 5 degrees, Full Moon, Bortle 6.7). I processed the image in startools and finished with camera raw in photoshop. I am not a good image processor but I don't think it is bad especially as it was full moon and I only used a IR cut filter. During processing I did have to remove violet halos around stars, maybe I need to stop down to f6.7. 

Edited August 26, 2021 by chemistorge

[alacant]

18 minutes ago, chemistorge said:

did have to remove violet halos

Hi

Lovely shot. The Russian lenses are very good, but I'd put good money on there being loads more galaxy in your image.

Maybe don't be so harsh on the development? Here is our version, also with a tair3 and StarTools.

Focus on our tair is a compromise; viewing a medium bright star on a large screen, move toward infinity until a red halo is seen around the star. Now back off until the red halo just disappears. Oh, and we find f5.6 is fine.

Cheers and HTH

Edited August 26, 2021 by alacant

[chemistorge]

@alacant thank you, I focused using a 3D Bahtnov mask, but maybe that doesn't work for this lens I will try manual focus on screen (Thank you for the tip). I am still trying to get the hang of processing, I have lots of data on various targets but struggle with processing, I find startools makes my images very noisy (usually the wipe module), So I stick with photoshop, but I am still trying to find the best work flow.

[alacant]

1 hour ago, chemistorge said:

Bahtnov mask, but maybe that doesn't work for this lens

Refractors in general I believe. Certainly our 72ed and other camera lenses. The mask will get you close, but the final tweak is best done by a human. 

1 hour ago, chemistorge said:

startools makes my images very noisy

We find the opposite. I'd say that the second development ROi in AutoDev being chosen wrongly. 

Post the stack if you like.

Cheers.

[chemistorge]

1 hour ago, alacant said:

Refractors in general I believe. Certainly our 72ed and other camera lenses. The mask will get you close, but the final tweak is best done by a human. 

We find the opposite. I'd say that the second development ROi in AutoDev being chosen wrongly. 

Post the stack if you like.

Cheers.

Here is the stack, the moon glow gradient is very prominent. Autosave.fits Thank you.

Edited August 26, 2021 by chemistorge

[alacant]

2 hours ago, chemistorge said:

moon glow gradient is very prominent

Hi

This with the latest ST v1.8.511.

Apart from wipe using synthetic bias and flats, I stuck as close to the default values as possible. It seems that maybe the flat frames are not correcting the field too well and there are vertical bands which new dark frames may help with. Both succumbed to Wipe however.

Not definitive by any means. Yours has more detail and colour, but as I thought, there is more galaxy to be had. 

HTH anyway.

 

Edited August 26, 2021 by alacant

[chemistorge]

1 hour ago, alacant said:

Hi

This with the latest ST v1.8.511.

Apart from wipe using synthetic bias and flats, I stuck as close to the default values as possible. It seems that maybe the flat frames are not correcting the field too well and there are vertical bands which new dark frames may help with. Both succumbed to Wipe however.

Not definitive by any means. Yours has more detail and colour, but as I thought, there is more galaxy to be had. 

HTH anyway.

 

Thank you, I have tried again and your result is similar to mine, although I think I need to work on star colour. I have just re check my stack and found that I used 2 min darks from my library not 3 min darks. I am going to try again on the new moon as the moon glow was pretty bad. Thank you for all your help. I am only using ST 1.7, I have just download 1.8 and going to give it ago.

Edited August 26, 2021 by chemistorge

[chemistorge]

I do like ST8, just got this result in 5 mins from old data on the Veil Nubula.

[chemistorge]

On 26/08/2021 at 17:35, alacant said:

Hi

This with the latest ST v1.8.511.

Apart from wipe using synthetic bias and flats, I stuck as close to the default values as possible. It seems that maybe the flat frames are not correcting the field too well and there are vertical bands which new dark frames may help with. Both succumbed to Wipe however.

Not definitive by any means. Yours has more detail and colour, but as I thought, there is more galaxy to be had. 

HTH anyway.

 

Hi, You must be a wizard with Startools, I find it very difficult especially the wipe module, also I still don't know how to your the autodev ROI. this is my best effort on the same data set straight out of startools (5 attempts to replicate yours). I can't workout how you get such a smooth none-blotchy image.

 

[alacant]

13 hours ago, chemistorge said:

the autodev ROI

Much better:)

You've still gone very heavy handed on the choice of ROIs though. Go easy on the contrast. That is almost certainly where your unevenness originates.

For second (an subsequent) AutoDevs, it's important to try different ROIs. Try the core only, one of the arms, a group of bright stars, a group dim stars including or not the galaxy... The possibilities are endless. Don't worry if you don't get it right first time. The beauty of st is that your data is always linear. Do your processing in any order.

In the end, at last we've a viable alternative to the ancient levels and curves approach where your data was manipulated as a series of non linear files produced as a result of isolated unrelated procedures. Of course, if you're happier with the latter and it produces better images for you, stick with it.

Cheers

 

EDIT: even if you've overdone it, there are a couple of 'rescue' things you can do:

 

But it's just as easy to wind back to an earler stage in the processing and redo it from there. your data remains linear.

 

Edited August 31, 2021 by alacant

[chemistorge]

22 hours ago, alacant said:

Much better:)

You've still gone very heavy handed on the choice of ROIs though. Go easy on the contrast. That is almost certainly where your unevenness originates.

For second (an subsequent) AutoDevs, it's important to try different ROIs. Try the core only, one of the arms, a group of bright stars, a group dim stars including or not the galaxy... The possibilities are endless. Don't worry if you don't get it right first time. The beauty of st is that your data is always linear. Do your processing in any order.

In the end, at last we've a viable alternative to the ancient levels and curves approach where your data was manipulated as a series of non linear files produced as a result of isolated unrelated procedures. Of course, if you're happier with the latter and it produces better images for you, stick with it.

Cheers

 

EDIT: even if you've overdone it, there are a couple of 'rescue' things you can do:

 

But it's just as easy to wind back to an earler stage in the processing and redo it from there. your data remains linear.

 

Ah thank you, I didn't realise you can go back, I will keep persisting, thank you for all your help.

[alacant]

1 hour ago, chemistorge said:

didn't realise you can go back

With conventional processing you can't, no. With StarTools, you most certainly can:)