Testing Rokinon Lens - Please Help Me!

Okay - I am on my third copy, and this is the closest I have gotten to a good copy - I think. I am probably driving myself nuts... then I thought "Why not ask for help?"

So, for those of you used to a Rokinon 14 2.8, or others that just want to help, please let me know what you think of this copy. There are two full size JPEGs - one 15 seconds and one 30 seconds. Seems that the stars are more stretched in the corners (especially upper left) in the 30 second shot. Is this too much, or am I too picky?

Thanks in advance for your help! I have been lurking in this Forum, and finally decided to try Astroimaging. Fighting to get a solid result and would love advice.

Thanks!

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Keltab wrote in post #17961151
Okay - I am on my third copy, and this is the closest I have gotten to a good copy - I think. I am probably driving myself nuts... then I thought "Why not ask for help?"

So, for those of you used to a Rokinon 14 2.8, or others that just want to help, please let me know what you think of this copy. There are two full size JPEGs - one 15 seconds and one 30 seconds. Seems that the stars are more stretched in the corners (especially upper left) in the 30 second shot. Is this too much, or am I too picky?

Thanks in advance for your help! I have been lurking in this Forum, and finally decided to try Astroimaging. Fighting to get a solid result and would love advice.

Thanks!

Hosted photo: posted by Keltab in
./showthread.php?p=179​61151&i=i229475981
forum: Astronomy & Celestial Talk

Hosted photo: posted by Keltab in
./showthread.php?p=179​61151&i=i28193252
forum: Astronomy & Celestial Talk

Seems you are clearly describing star-tracing.
Hope you do realize that earth is not stationary and length of tracing grows with time, and farthest away form earth's either poles.

The golden rule is "Rule of 600" that some OCD users call it 500, to be more ridged. What you need to know is that if you divide your lens that magic number, say 600 (I suffer no OCD), by the focal length or your lens (In mm) you get the maximum shutter speed that you should not see a star tracing.
In your case:
600/14=42 sec.
But still it depends on which side of sky you look at. I assume that left upper corner is the farthest away from North of your location (That is your right side of image).

Anyways if this is not adequate, leave a link to your original size image so that we can see the detail as well. The reduced size for web images, hosted by site are not adequate to see the detail. All I see as such is a good image with spot stars and a typical full frame sensor vignette.

Yeah, I use the 500 rule

My Samyang (aka Rokinon) 14mm f2.8 will give me about 30 seconds before trailing is noticeable ( on my 5D3 FF camera)
even tho 500 / 14mm = 35 sec. This leads me to think that even the 500 Rule is a bit generous (600 would be just waaaayyy out there )


Dave

My corners usually look better at 25 seconds than they do at 30. The 500 rule is a good practice, but like every other scenario in photography it's about compromise.

wilmslowastro.com has some great calculators that can help. I find 14mm on full frame needs careful planing and pointing to avoid crossing to large an area in declination and probably more like 10 sec max. at 0 dec.

Niteclicks wrote in post #17961884
wilmslowastro.com has some great calculators that can help. I find 14mm on full frame needs careful planing and pointing to avoid crossing to large an area in declination and probably more like 10 sec max. at 0 dec.

You mean THIS LINK?

Way too complicated for me to even to try, what to say about remembering
Nevertheless a good referral site to bookmark. TFS.

Thanks for the responses folks! I appreciate the help and guidance. I tried 15 seconds (second pic above) and the stars seem sharper. So maybe I'll stick with that and see.

Samsen - as for the full file, do you mean RAW or JPEG? I tried doing a link to my Zen site but couldn't embed it correctly.

Keltab wrote in post #17962338
Thanks for the responses folks! I appreciate the help and guidance. I tried 15 seconds (second pic above) and the stars seem sharper. So maybe I'll stick with that and see.

Samsen - as for the full file, do you mean RAW or JPEG? I tried doing a link to my Zen site but couldn't embed it correctly.

No as long as it is clear to be star trailing, due to long exposure, its all fine and no need for original. You know how to go around it and enjoy your gem lens.

Also once you felt more comfortable with wide field astrophotography, the next step that will zoom you a light year ahead, in terms of result, is to buy a sky tracker. Simply there is no other tool that can advance your IQ and end result to that extend, by allowing you to take much much longer time image (Acquisition of those precious but scanty photos) with much lower ISO, and if you are looking for the Wow factor, I just told you the secret.
For now practice at high ISO (Anything north of 1600) that make you happy, and yields least startrail and when ready to step up, send the words and will tell you more about tracker that should best suit you.

Dark, clear night to all.

High ISO is a TOTAL myth, FYI. Also, the rule of 600 or 500 is a bunch of crap as well.

I think everyone in this thread would do themselves a big favor by reading through this:

http://www.clarkvision​.com/articles/nightsca​pes/

It's long and full of a lot of technical detail, but it WILL take your astrophotography to another level and it will educate you on a lot of very common misconceptions about this hobby. If I could go back to the beginning of my adventure into this field and start with any form of online tutorial/guide/educati​on I wish pretty much every day I would have started with the Roger Clark one, it's by far the most comprehensive and accurate one on the internet that I've found. There's a lot of crap out there, tons of bad advice and advice that's based on misconceptions and bad "science" if you will, I spent a couple years following some of it. The amount I've grown personally, as an astrophotographer, over the last year since I've been following the Clark guide and expanding my technical understanding of the field has been astounding. The month or so I've found myself combining ideas and guides from Clark and Lonelyspeck to improve my visual appealing factor, I still start with first creating the most accurate image possible and then start adding a little here and there in terms of color, saturation, MINOR white balance adjustments, contrast, etc.

pdxbenedetti wrote in post #17962709
High ISO is a TOTAL myth, FYI. Also, the rule of 600 or 500 is a bunch of crap as well.

I think everyone in this thread would do themselves a big favor by reading through this:

http://www.clarkvision​.com/articles/nightsca​pes/

It's long and full of a lot of technical detail, but it WILL take your astrophotography to another level and it will educate you on a lot of very common misconceptions about this hobby. If I could go back to the beginning of my adventure into this field and start with any form of online tutorial/guide/educati​on I wish pretty much every day I would have started with the Roger Clark one, it's by far the most comprehensive and accurate one on the internet that I've found. There's a lot of crap out there, tons of bad advice and advice that's based on misconceptions and bad "science" if you will, I spent a couple years following some of it. The amount I've grown personally, as an astrophotographer, over the last year since I've been following the Clark guide and expanding my technical understanding of the field has been astounding. The month or so I've found myself combining ideas and guides from Clark and Lonelyspeck to improve my visual appealing factor, I still start with first creating the most accurate image possible and then start adding a little here and there in terms of color, saturation, MINOR white balance adjustments, contrast, etc.

LOL... Respectfully!

samsen wrote in post #17962915
LOL... Respectfully!

Yep I agree , I'm too old to spend a couple years going back through time and relearning a new process . Anything you read on the internet today is out dated by tomorrow . Technology has ruined our lives as we once knew it . Just like baseball . in 10 more years 80% of the players in America will be oriental from Asian countries . I was watching the Rangers and Seattle play last night and they told that the pitcher was the 20th oriental hire for pro baseball and the 3rd one for Seattle . The American generation now days is not interested in playing pro sports so Orientals will take over .

Celestron wrote in post #17963040
Yep I agree , I'm too old to spend a couple years going back through time and relearning a new process . Anything you read on the internet today is out dated by tomorrow . Technology has ruined our lives as we once knew it . Just like baseball . in 10 more years 80% of the players in America will be oriental from Asian countries . I was watching the Rangers and Seattle play last night and they told that the pitcher was the 20th oriental hire for pro baseball and the 3rd one for Seattle . The American generation now days is not interested in playing pro sports so Orientals will take over .

Fair enough, but I would highly recommend a person just entering this field or someone who is looking to improve their imaging to give it a read. It really is a game changer and if you want to be improving your "skill" at a hobby like this you should do all you can, read all the resources available, and understand what the technology/software/pr​ocessing can do for your imaging. Like I said, I wish I could go back in time and START with this resource, just knowing how much my own imaging technique has evolved in the last year since finding this makes me wonder where I would be if I had discovered this earlier. Maybe following bad advice and learning from it was part of the process of what made me get better, who knows.

Celestron wrote in post #17963040
Yep I agree , I'm too old to spend a couple years going back through time and relearning a new process . Anything you read on the internet today is out dated by tomorrow . Technology has ruined our lives as we once knew it . Just like baseball . in 10 more years 80% of the players in America will be oriental from Asian countries . I was watching the Rangers and Seattle play last night and they told that the pitcher was the 20th oriental hire for pro baseball and the 3rd one for Seattle . The American generation now days is not interested in playing pro sports so Orientals will take over .

Off topic but; You are absolutely right Ron.
I am from a city that has provided "George Brett" to MLB also before that in 60s provides a full member Water polo team to Olympics but I really don't see that enthusiasm toward professional game player development anymore (May be except providing those beautiful cheerleaders to Lakers).
But then after recent wide opening of the Cuba's doors (even with Castro's not coming to airport or forgetting to allow a shoulder tap from his counterpart), there will be a great influx of Cuban players, who were preparing themselves at best & dreaming for ages, into American professional baseball for years to come.
So I can surly say Oriental's dominance in American baseball will not occur in at a decade, if not longer, unless in the very very very rare event that Trump can actually build his free wall.

pdxbenedetti wrote in post #17963081
Fair enough, but I would highly recommend a person just entering this field or someone who is looking to improve their imaging to give it a read. It really is a game changer and if you want to be improving your "skill" at a hobby like this you should do all you can, read all the resources available, and understand what the technology/software/pr​ocessing can do for your imaging. Like I said, I wish I could go back in time and START with this resource, just knowing how much my own imaging technique has evolved in the last year since finding this makes me wonder where I would be if I had discovered this earlier. Maybe following bad advice and learning from it was part of the process of what made me get better, who knows.

a little extreme in your comments, me thinks

he has some interesting info, but nothing that would make me change my ways of doing things !
his ISO info is already broadly known by anyone who has been imaging the sky for more than a year or so

I also noted his ISO tests were on cameras known for their poor ISO performance .... So I take what he said with a grain of salt,
when comparing to some of the newer cameras and their better sensors


Dave

Davenn wrote in post #17965635
a little extreme in your comments, me thinks

he has some interesting info, but nothing that would make me change my ways of doing things !
his ISO info is already broadly known by anyone who has been imaging the sky for more than a year or so

I also noted his ISO tests were on cameras known for their poor ISO performance .... So I take what he said with a grain of salt,
when comparing to some of the newer cameras and their better sensors

Dave

Not sure how my comment was extreme, just my thought process when it comes to how I've evolved over the last several years in astrophotography.

His ISO tests were done on cameras he had available to him at the time he did them, which was several years ago. There are newer cameras and better sensors, but the physics and application of ISO has not changed. ISO is still a POST-SENSOR modification of signal, it is purely digital and has nothing to do with sensor sensitivity. The same thing happens now as it did 5+ years ago when you raise your ISO beyond the "ISOless" point of any digital camera (and most DSLR's these days are ISOless at some point, usually around 800-1600 ISO), you clip the highlights and significantly reduce dynamic range. In the case of astrophotography the highlights are stars, when you clip them they become white and you lose color information. Most stars in the sky are not white (or even blue, but the white balance argument is a whole other ball of wax), the vast majority, as measured by the ESA/NASA Tycho 2 star catalog, are yellow/orange/red. You are literally degrading image quality by shooting at a high ISO and because most cameras are now ISOless there is absolutely zero reason to do so. Shooting at the point your sensor becomes ISOless is the way to preserve maximum amount of data and image quality, this misconception of having to shoot at ridiculous ISO's of 3200, 6400, 24k+, needs to stop. There are lots of articles now talking about this across the internet, you probably won't bother taking the time to search them out and read, but I urge anyone just getting into this hobby (reading this thread) to google "ISOless DSLR" and learn a very important concept that affects your astrophotography image quality.

And Roger knows plenty when it comes to the ISO arguments, even with new cameras, he helped compile and collate this website (which everyone should be using when deciding on what camera to use for astro imaging):

http://www.sensorgen.i​nfo/