04-18-2019 05:19 PM
“Sounds like a hint to learn more about image stacking to me.
“I have dabbled with photographing the night sky using a Rokinon 14mm T3.1 with surprising good results for the shooting conditions. There have been many complaints about the "photo" version of the lens. Over time, I have bought three of the T3.1 cinema lenses, and they have all been fine. I have not tried the newer Rokinon lenses, which communicate with the camera body, but are still manual focus.”
My mentor is one of those individuals who makes the best of his camera and peripheral equipment to get stunning photos: I have seen the photos he’d just taken and dowloaded onto his computer for review: he rarely, if ever, uses Lightroom or Adobe to alter or correct them. Of the 6 or 7 professionals I associate with, I’d say that he gets the most out of his camera and puts the group of us to shame. Steep learning curve stuff for me.
I just found a Rokinon 14mm T3.1 cine lens in a Las Vegas two days ago, and purchased it on your recommendation after trying it on my 6D Mk II. I’m driving to the California coast this afternoon to take some photos of the Milky Way, and to photograph the moon as it sets behind a lighthouse on the coast. That’s a great suggestion and I appreciate you offering it.
04-18-2019 07:31 PM
I have a Losmandy G-11 equatorial mount for 5-hour exposures, and a small Sky Watcher mount/tripod for shorter durations.
The 500 rule is a good start, but using it when utilizing the Canon EF 24mm f/1.4L II USM for 20 seconds causes the stars to appear oblong: I use 17 seconds and tweak the ISO.
Hi Chris. The G11 is a fantastic mount (just make sure it's accurately polar aligned). If your G11 has the Gemini 2, there is a Polar Allign Correction (PAC) mode (Scott Losmandy has a YouTube explaining how to use it. Just go to YouTube -- there's a Losmandy YouTube channel). I use a G11 ... and a GM8 ... and a StarLapse (I really like their mounts).
The "500 Rule" is meant for full-frame camera sensors (roughly 36mm x 24mm). The 500 rule should be valid for your full-frame bodies. For crop-frame bodies (APS-C at 1.6x crop-factor or APS-H at 1.3x crop factor) you would want to divide 500 by the crop factor. E.g. if using a 7D body then you'd use 500 ÷ 1.6 = 312.5 ... and then divide the lens focal length into that for the number of seconds (e.g. with a 24mm lens it's about 13 seconds).
The more liberal rule was the "600 Rule" ... but on close inspection some people find a slight amount of elongation (hence the "500 rule" to be a bit more conservative and most people are happy with that). I'm wondering what camera you were using when you said you needed to cut the exposure time to 17 seconds.
I use a QHY "PoleMaster" to achieve highly accurate polar alignments (within a few arc-seconds of the true pole). Equatorial mounts can use "modeling" to work out factors such as "cone error" or even moderate inaccurate polar alignment issues and creating a "model" (really only recommended for permanent observatories. If you setup/take-down the mount each time you use it then a model is a waste of time) will only help you achieve more accurate "go-to's" but will not do anything for tracking accuracy. With plate-solving software (astrometry.net and similar), the solving will give you ultra-precise go-to's and the rest is all about mount quality, balance (a slight imbalance where the "east" side of your mount is just a tiny bit heavier will help reduce "float" in the worm/spur gear backlash) and above all ... an accurate polar-alignment. The PoleMaster camera aligns the "mount" -- not the "scope". SharpCap also has a polar alignment feature ... but the field of view of a camera through a telescope is usually narrower than 5° -- so it needs a better initial estimated alignment to use it.
04-19-2019 04:23 AM
04-23-2019 06:59 AM - edited 04-23-2019 06:59 AM
I use the EF 16-35mm f/2.8L II USM, and love it. If it is not as sharp near the edges and corners, then I have not noticed it. I have ot really looked for it, either. I have noticed that it does seem to have a focus plane that is curved, with the camera at the center of a sphere or cylinder.
I like the lens. I cannot help but wonder if the soft edges and corners that people are observing are a side effect of lens correction.
04-25-2019 05:36 AM - edited 04-25-2019 05:41 AM
I purchased the Samyang 14mm 2.8 for MWP. 1st time was bad, due to user error and not understanding infinity on a lens doesn't necessarily mean in focus, 2nd time was much better. I've recently added the Tamron 15-30mm 2.8 but have yet to take it back out to the desert for a go.