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Sigma Art 105mm F1.4 Full Frame Sample

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16 replies to this topic

#1 Jerry Lodriguss

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Posted 15 August 2019 - 02:30 AM

Check out the corners at 100% and decide if you can live with them at f/1.4... cool.gif

 

Cassiopeia Full-Frame 8-Bit TIFF on Google Drive 57mb File 

 

Sigma Art 105mm f/1.4 working at f/1.4

  • 150 x 15 seconds (37.5 minutes total exposure)
  • ISO 100
  • Mag 18 skies
  • Mount: Unguided iOptron CEMP25P
  • ASCOM Dither every 10 frames via BackYardEOS

 

Camera

  • Canon 6D (stock, unmodified)
  • Sensor: 35.8mm x 23.9mm, 5472 x 3648 pixels, each 6.5 microns
  • Overlay: Nikon APS-C (because Nikon at 1.5 is a wider FOV than Canon's 1.6x crop factor)

Field of View and Image Scale

  • Canon 6D: 19.90 x 13.35 degrees,  Image scale: 13.1454"/px
  • Nikon D5300:  13.12 x 8.77 degrees, Image scale: 7.90932"/px

 

Processing: DeepSkyStacker

  • 151 Raw light files calibrated with 64 flats and 64 bias
  • Use Camera WB
  • No Cosmetic repairs
  • Kappa-Sigma Average combine (2.50/5)
  • Adaptive Heterogeneity-Directed (AHD) Interpolation
  • Per Channel Background Calibration
  • RGB Channels Align
  • 2x Drizzle then downsample back to original size

Processing:  Photoshop

  • Assign sRGB color space
  • Non-linear curve
  • Sky background neutralized
  • Sky background flattened with GradientExTerminator
  • Levels stretch
  • Star colors enhanced
  • Black point adjusted
  • No lens correction profiles used at all 

What do y'all think?

 

Pretty good right? grin.gif


Edited by Jerry Lodriguss, 15 August 2019 - 03:09 AM.

  • Jim Waters, james7ca, sharkmelley and 4 others like this

#2 rockstarbill

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Posted 15 August 2019 - 02:42 AM

CA - no.

 

Stars otherwise - fine.



#3 sharkmelley

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Posted 15 August 2019 - 03:27 AM

Wow, that really is the ultimate test and it's a very impressive result for a lens used wide open - especially at f/1.4 !

 

Stretching the image further (as you will want to do for imaging faint dust and nebulosity) you can see the stars towards the corners beginning to turn into crosses and develop blue "wings".  But I could certainly live with that for f/1.4

 

Mark


Edited by sharkmelley, 15 August 2019 - 03:27 AM.


#4 calypsob

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Posted 15 August 2019 - 08:03 AM

That is outstanding for F1.4

 

There is a slight reflective halo on the bright star in the center and on FF it seems the top left bottom left and top right have astigmatism, but the lower left is perfect for some reason.

Honestly though I could live with that little amount of astigmatism if it meant I could shoot f1.4

And on APS-C, stars are corrected perfect to the edges.

 

CA seems pretty well controlled IMO, even if yous saturated the heck out of this it could easily be dialed back to nothing in camera raw.  Definitely a killer lens.


Edited by calypsob, 15 August 2019 - 08:04 AM.


#5 AtmosFearIC

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Posted 15 August 2019 - 08:21 AM

That's pretty amazing performance wide open, probably some of the best I've seen.



#6 2ghouls

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Posted 15 August 2019 - 10:43 AM

Very nice, and thanks for posting this sample. I plan to rent the lens at the end of the month to see if I like it enough to purchase.

 

How did you mount it? Did you use the included arca-swiss foot?


Edited by 2ghouls, 15 August 2019 - 10:43 AM.


#7 kingjamez

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Posted 15 August 2019 - 10:56 AM

Looks very useable at F/1.4 with an APS-C sensor, and probably very good with a full frame sensor at F/2. Impressive.

 

-Jim



#8 Jerry Lodriguss

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Posted 15 August 2019 - 03:03 PM

Very nice, and thanks for posting this sample. I plan to rent the lens at the end of the month to see if I like it enough to purchase.

 

How did you mount it? Did you use the included arca-swiss foot?

I thought about it using the arca-swiss foot, but I just don't trust the female clamp part because the one I have is made in China and I'm not risking a $1,600 lens on a $15 Chinese part, so I put it on a short Vixen dovetail into an ADM Vixen female clamp.

 

If I had had a really good arca-swiss clamp, I probably would have used it.

 

Jerry


Edited by Jerry Lodriguss, 15 August 2019 - 03:04 PM.


#9 Jerry Lodriguss

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Posted 15 August 2019 - 03:10 PM

That is outstanding for F1.4

 

There is a slight reflective halo on the bright star in the center and on FF it seems the top left bottom left and top right have astigmatism, but the lower left is perfect for some reason.

Honestly though I could live with that little amount of astigmatism if it meant I could shoot f1.4

And on APS-C, stars are corrected perfect to the edges.

 

CA seems pretty well controlled IMO, even if yous saturated the heck out of this it could easily be dialed back to nothing in camera raw.  Definitely a killer lens.

Yes, it does have uneven corners. These lenses seem prone to that. I guess the tolerances of that much glass being perfectly collimated and aligned at f/1.4 is hard to attain. But I can live with what it is.

 

It does have reflections on bright stars that you have to deal with if you push the frame really hard to reveal faint stuff.

 

Jerry



#10 Coconuts

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Posted 15 August 2019 - 04:31 PM

I must be missing something... there seem to be far fewer stars than I would expect with a 75 mm aperture and 37.5 minutes of exposure.  I can't recognize Cassiopeia.  What am I doing wrong?

 

The stars look pretty good, but there is a bright one in the upper right with distinct oblique sagittal spherical aberration and astigmatism.  So it might be worth stopping "all the way down" to f/2.0.  I am still waiting as some gear trickles in, but hope to get some images with this lens soon.  The tripod mount ring is solid, and allow easy full rotation for framing.  the base of the foot is quite flat, so I have simply bolted it to a Vixen dovetail.

 

All the best,

 

Kevin



#11 Jerry Lodriguss

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Posted 15 August 2019 - 06:09 PM

I must be missing something... there seem to be far fewer stars than I would expect with a 75 mm aperture and 37.5 minutes of exposure.  I can't recognize Cassiopeia.  What am I doing wrong?

Hi Kevin,

 

Maybe you don't know your constellations?  Just kidding. lol.gif

 

You're probably just used to seeing enhanced images pushed for deepsky objects where bright stars get enormous.

 

This is the way stars are recorded with a DSLR. It happened with film too, that's why Akira Fuji used to use a fog filter, and why I use softare so you can see the bright stars in wide fields... see:

 

Gamma Persei.

 

Jerry


Edited by Jerry Lodriguss, 15 August 2019 - 06:11 PM.


#12 maxmir

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Posted 17 August 2019 - 08:47 AM

That's a keeper !  What a nice lens.

I have a 50mm Sigma. Not near as good until you stop down to F3-4.

 

Max



#13 gunny01

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Posted 17 August 2019 - 09:33 AM

  Jerry,

 

  I'm curious as to whether you have tried the sigma f1.4 in 20 and 24mm?    Is one any better for astigmatism/coma over the other?  Thanks for any insights. 



#14 Jerry Lodriguss

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Posted 17 August 2019 - 04:12 PM

 I'm curious as to whether you have tried the sigma f1.4 in 20 and 24mm?    Is one any better for astigmatism/coma over the other?  Thanks for any insights. 

No, sorry I have not tried those. 

 

Unfortunately I don't have an unlimited budget. :-)

 

Jerry



#15 dugpatrick

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Posted 18 August 2019 - 08:58 AM

Perhaps Sigma (and others) should give/loan lenses to you for astro testing. :-)

Your images will certainly sell the product.  I just picked up a Sigma 135, and these things are not cheap!

 

Doug

 

Unfortunately I don't have an unlimited budget. :-)

 

Jerry



#16 Coconuts

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Posted 18 August 2019 - 03:19 PM

gunny01: Both the Sigma Art 20 mm and 24 mm have corner issues.  Their 40 mm f/1.4 is amazing, though.  Here is a look at the three:

 

https://www.lenstip...._and_bokeh.html

https://www.lenstip...._and_bokeh.html

https://www.lenstip...._and_bokeh.html

 

All the best,

 

Kevin



#17 gunny01

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Posted 19 August 2019 - 06:46 AM

  Excellent articles Kevin.  The reason I asked for this information is that I have the 20mm f1.4 Sigma and I imaged the MW for the first time a few weeks ago.  Sure enough, what these articles describe is what I was seeing with my image. I was not sure of myself on these issues and I didn't want to shoot my mouth off without more information.

Maybe I should post the image?

 

  The lens has been good for indoor work though.  Outdoors it can show great distortion on the edges of an image.  Thought about trading it in, but it has done well for video.  Thanks.


Edited by gunny01, 19 August 2019 - 06:47 AM.



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