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Sony Prime Lenses
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Sep 11, 2021 13:59:55   #
dennis2146 Loc: Eastern Idaho
 
wireloose wrote:
Keep in mind the wider angle also allows for longer exposures without putting the ISO into the stratosphere. Something like the 14/2.8 Rokinon is a popular option at a reasonable price, lots of used ones out there.


Forgive me for asking but I cannot understand how a wider angle lens allows for longer exposures. Doesn't the f stop allow for longer exposures rather than the focal length of the lens?

Dennis

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Sep 11, 2021 14:01:13   #
dennis2146 Loc: Eastern Idaho
 
MDI Mainer wrote:
Who hand holds astro photography???????


The Rock.

Sorry, I couldn't resist.

Dennis

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Sep 11, 2021 14:43:57   #
ewabik6
 
The sigma 16mm 1.4 works great on my Sony a6000. It is not stabilized but that has not been an issue, although I only take pics, no video. I’ve attached a recent pic of the Milky Way I took using the Sigma 16mm.



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Sep 11, 2021 15:07:40   #
wiz302pa Loc: Henderson, NV
 
Very nice. What settings did you use, any post processing?

Getting late in the season, but hope to do this either in Utah next week or Death Valley soon. Using PhotoPills app. Lots of fun.

I am very please with the Sigma 16 - lives up to the reviews.

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Sep 11, 2021 17:25:42   #
SuperflyTNT Loc: Manassas VA
 
dennis2146 wrote:
Forgive me for asking but I cannot understand how a wider angle lens allows for longer exposures. Doesn't the f stop allow for longer exposures rather than the focal length of the lens?

Dennis


He means longer astrophotograhy exposures without star trails if you’re not using a star tracker.

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Sep 11, 2021 20:13:49   #
woodyH
 
Sony 20mm f1.8 on the crop sensor is already effectively the view of a 30mm lens on FF. Wouldn't you be turning off any form of stabilization, IBIS or ILIS, and working on a tripod, at least for star points and star trails. Perhaps you would like the Samyang or Laowe lenses, manual tho they may be, in the low teen FL.

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Sep 11, 2021 20:21:46   #
woodyH
 
Wider f/stops (meaning f/1.4 is wider than f/2) allows for shorter exposure times for the same kind of image. Shorter FL means the image dot travels less distance on the FP for the same period of time, meaning a longer exposure is possible, thus the image records more light, before the dot becomes a streak.

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Sep 11, 2021 20:28:08   #
ewabik6
 
Thank you! I shot this wide open at 1.4, 13 seconds, ISO 1600. A bit of post processing adjusting overall exposure along with whites, highlights, shadows and blacks; also some dehaze. PhotoPills is a very useful app! I agree, the Sigma lives up to its reputation! Good luck with your plans for this fall!

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Sep 11, 2021 20:52:31   #
MDI Mainer
 
bnsf wrote:
Well, if the Sony A6600 is an a mount camera you could always look at the Minolta lenses that would would great for this camera and they would be cheap enough for you.


The A6600 is the current top-of-the-line APS-C sensor e-mount offering from Sony, so the Minolta lenses would need an adapter.

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Sep 11, 2021 20:53:59   #
MDI Mainer
 
dennis2146 wrote:
The Rock.

Sorry, I couldn't resist.

Dennis



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Sep 11, 2021 23:07:04   #
wmurnahan Loc: Bloomington IN
 
Waltman wrote:
I’m looking to buy a prime lens for my Sony A6300 for astro photography. Low aperture and around 35mm. Any suggestions. Should I stick with Sony or sigma and does sigma support lens stabilization? Thanks, Walt.


I love my Rokinon 14 for astro on my Sony but I usually use it on my FF a7ii.

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Sep 12, 2021 03:53:12   #
dennis2146 Loc: Eastern Idaho
 
SuperflyTNT wrote:
He means longer astrophotograhy exposures without star trails if you’re not using a star tracker.


I understand that reasoning and of course completely agree. The longer the exposure takes to capture the scene the longer the star trails become due to the excess time. But that is only related to the f stop ability of the lens and still has nothing to do with focal length that I am aware of. If I had a 105mm f1.5 lens it should do as well, exposure only, as a 12mm f1.5 lens shouldn't it. I do understand the 105 would not be a good lens for astrophotography such as the Milky Way since it would not have a wide enough angle to capture as much of the scene wanted.

Am I correct in my thinking or am I missing something?

Dennis

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Sep 12, 2021 04:26:17   #
SuperflyTNT Loc: Manassas VA
 
dennis2146 wrote:
I understand that reasoning and of course completely agree. The longer the exposure takes to capture the scene the longer the star trails become due to the excess time. But that is only related to the f stop ability of the lens and still has nothing to do with focal length that I am aware of. If I had a 105mm f1.5 lens it should do as well, exposure only, as a 12mm f1.5 lens shouldn't it. I do understand the 105 would not be a good lens for astrophotography such as the Milky Way since it would not have a wide enough angle to capture as much of the scene wanted.

Am I correct in my thinking or am I missing something?

Dennis
I understand that reasoning and of course complete... (show quote)


No, the aperture determines how much light you can capture during the exposure but focal length is what determines how long before you start seeing star trails. The general guideline is called the 500 rule. Multiply your focal length by the crop factor and then divide 500 by the result and it’ll give you the max shutter speed you can use without star trails. So if you were shooting a 20mm lens on a full frame it’s simply 500/20=25 seconds. On a crop sensor it would be 500/(20*1.5)=16.7 seconds.

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Sep 12, 2021 04:32:55   #
dennis2146 Loc: Eastern Idaho
 
SuperflyTNT wrote:
No, the aperture determines how much light you can capture during the exposure but focal length is what determines how long before you start seeing star trails. The general guideline is called the 500 rule. Multiply your focal length by the crop factor and then divide 500 by the result and it’ll give you the max shutter speed you can use without star trails. So if you were shooting a 20mm lens on a full frame it’s simply 500/20=25 seconds. On a crop sensor it would be 500/(20*1.5)=16.7 seconds.
No, the aperture determines how much light you can... (show quote)


Thanks. I will keep that in mind. I appreciate your explanation.

Dennis

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Sep 14, 2021 15:20:38   #
topcat Loc: Alameda, CA
 
Try this one...

7artisans Photoelectric 25mm f/1.8 Lens for Sony E .... https://www.bhphotovideo.com/c/product/1387951-REG/7artisans_photoelectric_7a25f18bkse_25mm_f1_8_aps_c_for.html/reviews

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