September 30, 2014, 02:07:28 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - jrista

Pages: 1 ... 90 91 [92] 93 94 ... 315
1366
EOS Bodies / Re: More Sensor Technology Talk [CR1]
« on: May 05, 2014, 01:20:46 PM »
Very dangerous, jrista, very dangerous. Astrophotography is like boating - you start out with a $300.00 (slow) toy kayak, you end up wanting an America Cup yacht. I am at the toy kayak stage, and likely to stay there. A combination of living in the center of a "white" zone (central city to the rest of you), having a day job, no longer having the ability to easily adapt to swing schedules, and living in an often cloudy location (St. Louis MO) make serious application to astrophotography difficult. I can learn a bit at our local astronomy park, 45 minutes away in an "orange-soon-to-be-red" zone. High quality darkness is about 2.5 to 3 hours away at minimum.

I know a lot of imagers who shoot under red and white zones. Have you ever looked into a Light Pollution Reduction/Suppression filter? There are a number of them. I'm in a yellow zone myself, but I still use the Astronomik CLS filter myself (I prefer shooting nebula, if you shoot galaxies, lp filters are a mixed bag). You could also look into doing Narrow Band imaging...with NB, you block out a ton of light except the one (or three) very narrow bands your interested in. You need longer exposures, but NB works extremely well under red and white zones, and I've seen some stellar work from people in some of the most heavily populated places in the eastern half of America.

Hats off to you for taking on PixInsight.

PI isn't so bad once you get used to it. It has a funky way of doing things until you learn why...then you realize how incredibly awesome it is. ;) I also recommend it if you image under light polluted skies. It's DBE or Dynamic Background Extraction script can help you extract light pollution from your background skies and flatten it, and can do so if you use LPR filters or not.

I am still drinking the Sigma DP#M koolaid because the color subtlety is very suitable for landscape, and the camera weighs ~300 grams including an aluminum L bracket/grip and can be well supported by a 1600 gram tripod/head/QR kit. Pop some extra batteries, filters, and "nodal" slide in my pocket, and I have a great fast-hiking compatible landscape kit.

For those who understand what Sigma Foveon cameras offer, I say more power to 'em! There is no question the color fidelity is extremely high with Foveon sensors. The light weight is also pretty nice for when you gotta hike to your vistas. That's one of the reasons I like the idea of an A7r for landscape photography...but the camera overall is just...not general purpose enough to justify the cost.

1367
Landscape / Re: hide and seek with the moon
« on: May 05, 2014, 12:15:39 PM »
Ok, I'm sticking to the sticker shock theory ;D. I see what you mean about the non-periodic error that would be an problem. I'll keep looking at my options. This is a very expensive habit hobby >.<.

You have no idea how expensive. :P I have some fairly big aspirations. Just check out the prices on these pieces of equipment:

10Micron GM2000HPS UP
PlaneWave 20" CDK
FLI ProLine PL16803 Mono CCD

That's a semi-pro setup. It's what will allow me to get magazine-quality results, assuming I can find appropriately dark skies and some land to build an observatory under. Those pieces of gear are also on the lower-midrange end of the "high end" market....there are even better mounts, larger telescopes, and even better imagers that cost three to five times more.

So yeah, ridiculously expensive, if you get really really serious. :P

1368
Landscape / Re: hide and seek with the moon
« on: May 05, 2014, 11:58:03 AM »
Yay! more data! Hmm your view on Celestron greatly differs from those at the local astronomy club  :-\. They tend to hold the Advanced VX and CGEM mounts to a pretty high standard. I think it's sticker shock, photographers have already come to terms with $1k tripods and $2k+ lenses. The astronomers in the club haven't quite crossed that bridge yet ;).

Celestron equipment has a very strong religious following. I was hooked on getting a CGEM DX until I started researching, asking questions. Turns out that the CGEM and CGEM DX both have a flawed gearbox that causes what is called the 8/3 error, a non-periodic, non-integer error that is extremely difficult to guide out. I spent over two solid months researching mounts. In the grand scheme of things, my "real" mount will ultimately be the 10Micron GM2000HPS UP, a $24,000 mount which uses in-mount sky modeling and absolute encoding to allow for 20 minutes unguided exposures, and can hold up to 132lb of instrument capacity. :P

In my travels around internet forums during my research, though, I found one very glaring fact: Pretty much NO ONE, EVER, complains about the Orion Atlas or EQ6 mounts. They have about as pristine a reputation as I have ever seen. They are very well loved mounts. This is in great contrast to the fact that you can find dozens, if not hundreds, of complaint threads about the CGEM mounts on astronomy forums all over the net. Mostly about gearbox issues, but not solely. Some Celestron fans and objective mount reviewers will tell you the complaints are not warranted, and perhaps not...but that does not change the fact that the CGEM mounts are widely complained about buy a LOT of people. Statistically, that has to indicate some fundamental issue.

Personally, I LOVE Celestron OTAs. Their EdgeHD scopes are amazing, although they do suffer a bit from the standard SCT problems. If you want an excellent large-aperture OTA, an EdgeHD is definitely a worth while investment. Just...put it on an Atlas, instead of a CGEM. :P

The scope according to the website is about 12lb (I threw it on a scale and it's about right). The 23lb you see includes the metal case it comes with. I know it doesn't change the P2P error, but in terms of load, 120ED + 5D should be ok on the AVX?

If the weight is only 12lb, then it should be OK. I'm not sure what imager your using, if it's a DSLR that could add another pound or so. The guiding setup will add another pound or so, plus don't forget to count the weight of the various cables that you'll need to control everything (cable from the camera to laptop, cable from the guidecam to the mount, cable from the guidecam to laptop, cable from mount to laptop). You might also have additional weight from an extra vixen dovetail and telescope rings (to mount the guidescope to the telescope), which also adds a couple of pounds. Even assuming the scope is 12lb, 50% capacity is only 15lb, and all these accessories are going to put you over that limit.

The AVX is generally not considered a great mount for doing astrophotography. It's great for visual observing, but you have to understand the tolerances involved in astrophotography...if your tracking is off by arcSECONDS, your going to have problems. The AVX is the rock-bottom mount you could possibly get for AP, and it really is insufficient. That assumes that you never, ever plan to use a larger scope in the future...if you do, the $1000 on the AVX is just a waste, as you'll need a larger mount for a larger scope in the future anyway. (You will also quickly find that you'll want a longer scope, much longer, for doing anything other than nebula wide field shots...so something like the 8" EdgeHD or 8" AT8RC, both very cost effective OTAs that produce superb results, would work on an Atlas, they definitely would not work on an AVX.) You would be surprised how much better the Atlas/EQ6 is. Some astrophotographers have loaded it up with 30, 35 pounds of weight and been able to image fine...you would never be able to do that with an AVX.

The price of the Atlas is $1500, so it's $700 more than the AVX. I know that sounds like a lot...but I honestly cannot stress enough how important the mount is for astrophotography. The difference between what is acceptable for visual observing (which is probably what most of your local astronomy club members are doing), and what is acceptable for astrophotography is quite large. You can deal with stars and nebula and planets bouncing around a bit for visual work...even the smallest amount of that is completely unacceptable for astrophotography. If you don't eventually plan on getting a really large OTA that weighs over 50lb, then the Orion Atlas or SkyWatcher EQ6 would probably be the only mount you would ever need...buy it once, never need to replace it or buy a bigger one. The same is not true of the AVX. Your already pushing it's capabilities with your ProED 120.

I guess the cost difference of 900 vs 1500 is peanuts compared to everything else >.<

It really is. The mount is the centerpiece. If your mount isn't up to snuff, then it really doesn't matter what your mounting onto it...your already screwed. :P Big thing to keep in mind, visual is very different, in terms of requirements and what's acceptable, from astrophotography. Local astronomy clubs tend to be based on visual observing, and less on astrophotography, so their advice is likely to be a bit biased.

1369
Animal Kingdom / Re: Show your Bird Portraits
« on: May 05, 2014, 11:50:48 AM »
Long-billed Dowitcher

The Cottonwood Creek area is really starting to heat up. A number of duck species are still hanging around, at this point I suspect for the whole summer. The shorebirds are starting to show up in larger numbers as well. One of my favorites is the Dowitcher, the long-billed dowitcher to be specific. They are one of the more colorful shorebirds, with colorful golden-fringed back feathers and buffy breats, and beautiful streaks around their faces.

Managed to capture a few shots of a trio of dowitchers just at sunset. My vantage point allowed the fresh new greens of spring and the old dried browns of last years growth to produce colorful OOF reflections and blurs, which nicely complimented and contrasted with the bird's own colors.

Long-billed Dowitcher
Cottonwood Creek Wetland
Colorado

Canon EOS 7D
Canon EF 600mm f/4 L II
Gitzo GT3532LS + Jobu Pro 2






1370
Animal Kingdom / Re: Show your Bird Portraits
« on: May 05, 2014, 11:45:54 AM »
Maiaibing, LOVE the color in those shots! So rich!

Radagast, phenomenal detail! Such a beautiful bird.

1371
EOS Bodies / Re: More Sensor Technology Talk [CR1]
« on: May 05, 2014, 11:32:36 AM »
Glancing at his gear wish list, it looks like he's more into action than astro. An A7R is 2500 less in the budget (camera + EF adapter). Personally I would love one for portrait and landscape work, but I can not justify the expense. I suspect I'd get more use from that tamron 150-600 and a new tripod.

So, while I'd like an A7r for my landscape photography, it is actually one of the worst possible choices for astrophotography. I do landscapes sometimes, wildlife and birds most of the time, and astrophotography every time there is a clear night.


I was looking at the A7R with adapter for landscapes, but then I read on Thom Hogan's site that Sony uses lossy compression on their RAWs (unless I misread him), and you can't switch it off!

Why would they do that?   :( :(

On that basis, it may have amazing DR but then it surely will just smudge out some of the detail for err, actually I'm not sure for what benefit...

Hmm, I hadn't heard of that. If they do, it's foolish, and you really no longer have a RAW image. I am a bit skeptical of that...it doesn't seem logical, but who knows.

Had a look at that astro link - it's a whole new language there  :) If I understood correctly, then it's a 2000mm lens? And optically is it better than your 600mm lens with a 1.4x and 2.x attached? Just curious as to the benefits. Thanks.

Reflecting light tends to produce superior spots at the sensor plane in comparison to refracting light. Reflecting light can warp star diffraction spots due to coma and astigmatism, but that's about it. Refracting light, on the other hand, suffers from all forms of optical aberrations...which also includes chromatic aberrations, spherical aberration, etc. The RC, or Ritchey-Chretien, telescope design is one of the more superior designs. It's the same design used in all the major earth-bound telescopes...the huge ones, up to 10 meters in size. It tends to produce superior results, although it does suffer from some coma and astigmatism in the corners.

There is a better telescope design than even the RC, called a CDK or Corrected Dall-Kirkham. The CDK uses a mirror and built in corrector to get one of the best spot shapes, center to corner, of any telescope design I've ever seen. PlaneWave makes CDK scopes, but they are pretty pricey. From what I've read and seen, a CDK is about the best telescope design in the world today.

As good as my lens is, and it is very good with a very flat field corner to corner, it is no RC and certainly no CDK. If I throw on teleconverters, that gets me more focal length (which is not necessarily the best thing...a LOT of nebula are even larger than I can fit in my field with the 600mm, let alone a 2000mm scope), but  it also increases the optical aberrations. For galaxies, clusters, and getting close up on parts of nebula, a longer, better scope like the Astro-Tech 10" RC is better. The larger aperture, ten inches vs. six inches, also means I can resolve smaller magnitude stars, galaxies, and other details. Most scopes work with focal reducers, so while it is 2000mm natively, I can use a 0.63x reducer to make it an f/5 1260mm telescope. That is relatively fast with a moderately wide field. For planetary work, I can also throw on a 2x or 3x barlow lens, and get a 400mm f/16 or 6000mm f/24 scope, which is much better for planetary imaging (f-ratio doesn't usually matter for planetary, as you image planets by taking videos with thousands of frames for anywhere from a couple minutes to as long as a half hour...then filter, register, and stack the best frames of the video, which is basically performing a superresolution integration...that eliminates blurring from seeing, and effectively allows you to image well beyond the diffraction limit.)

1372
Landscape / Re: hide and seek with the moon
« on: May 05, 2014, 11:16:12 AM »
Thanks for the pointers. I already ordered the reducer/field flattener that goes with this scope.  I think that should help the vignetting I'm seeing right now with my 2" to 1.25" adapter + t-mount adapter + t-mount to EOS adapter.

Reducers/flatteners definitely help with corner performance. They do reduce focal length, though...so, if you have an f/7.5 scope, and use a 0.85x reducer, your going to end up with a 765mm scope. Wider scopes are great for nebula and imaging larger regions of the sky, they are a lot harder to use for galaxies, clusters, planetary work, etc. For those, you want something much longer, at least 1600mm, and for planetary, it's really best to have as much focal length as you can muster (regardless of the f-ratio...3000mm, 5000mm, even 9000mm is best for planetary work.)

I'm looking to get the Celestron Advanced VX mount to go with this. Any thoughts on that? Any accessories I should also pick up in one shipment? I heard the GPS unit is nifty, as is a polar axis scope. Anything else I should look into?

Celestron is not really my first choice for mounts. They make some excellent scopes, and are they only source of hyperstar capable scopes, but their mounts are generally a bit wanting, and you pretty much always have to go to Celestron for any support. The EQ5/EQ6 range of mounts are actually better mounts, and the support community for them is truly vast. The Orion Sirius is an EQ5 type mount, where as the Orion Atlas is an EQ6 type mount. The Sirius is a step above the Celestron AVX, but closer to it in price. The Atlas is one of the most popular and best supported lower end mounts in the world. It's $1400, vs. the $1000 for the Sirius, but it is really the lowest entry mount you probably want to go with for astrophotography.

Mounts like the AVX are just too low end to really do a good job for astrophotography. Mount capacity is a critical factor, as is the intrinsic periodic error. The AVX has a max capacity of 30lb, and it's periodic error (PE) is around 30-50" peak-to-peak (P2P). The Orion Atlas, on the other hand, has a capacity of 40lb and a (PE) of around 15" P2P. The periodic error is what is going to determine the minimum size of your stars as you track across the sky for long exposures. At 30" or more, the AVX is just not going to handle exposures of more than about a minute or so without really good guiding. The Atlas can handle unguided exposures of a few minutes, and is easier to guide than the AVX.

Capacity is the next most important point. It's best not to load up a mount with more than about half it's capacity if you are doing astrophotography, unless your using a real high end mount. At 30lb, your 23lb scope is already over 2/3rds the weight capacity, where as it is barely over half for the Atlas. At 2/3rds capacity (and even more, once you throw on a camera, and even more once you throw on a guide scope and guide camera, which are really going to be essential for tight stars with any lower end mount), the AVX is going to be extremely difficult to control and guide out errors for. For the size and weight of your scope, especially with a camera and guider setup, you want a mount that is at the very least capable of handling 40lb. A mount capable of handling 60lb would be best...but that gets you into the territory of midrange mounts, which cost around $2500-3500.

So, I very highly recommend the Orion Atlas. It's a very capable mount, with a phenomenal support community. It also works with EQMOD, which is a full open source, free total replacement software driver package that lets you ditch the hand controller and control your mount entirely from a laptop (once you really get into imaging, you'll learn you also need computer control software, such as BackyardEOS if your using a Canon DSLR for imaging, PHD2 for guiding, etc.) EQMOD is more capable and more flexible than the SynScan hand controller that comes with EQ5/EQ6 type mounts. The use of EQMOD also opens up the door for improving the Atlas, which is another somewhat unique feature...there is a hypertuning mod available (which cleans up the mount and gets rid of manufacturing crap left behind in the gears, which makes the PE worse, and regreases everything with high quality synthetic grease), as well as a number of belt and worm mods. Belt and worm mods can eliminate gears, reduce backlash issues, and otherwise greatly improve the performance of your mount to midrange levels for far less cost. (NOTE: To use EQMOD, you will need to get an EQDIR cable. They are about $45, but a standard USB to Serial cable costs almost that much anyway, so it is a very worth while investment.)

You really can't go wrong with the Orion Atlas (or any other EQ6 mount, like the SkyWatcher EQ6 SynScan, which is basically the same thing, just different seller.) Either way, the Atlas/EQ6 is a much better fit given that your scope already weighs 23lb, and that you are guaranteed to need to do guiding. You can pick up the Orion 50mm mini guidescope and SSAG guider for relatively cheap, and the weight of that setup is about as small as you can get for guiding. Without guiding, even with an Atlas, the 15" p2p periodic error is going to kill your chances for doing exposures longer than a couple minutes. Average seeing is 2-3", average star size is 1.5-1.8"...without guiding, your stars will eventually be around 10-15" in size...far too large.

1373
Landscape / Re: hide and seek with the moon
« on: May 05, 2014, 02:06:54 AM »
After mulling about for a bit, I finally decided to bite the bullet and get a telescope. After much thinking and searching I decided to get a Sky-Watcher ProED 120mm Doublet APO Refractor. I saw it as a poor man's EF 800mm. Sure, it doesn't have AF, or sharpest of corners... but, I now have a 900mm lens ;D.

I have only started this new part of my habit hobby. There's no equatorial mount... no GOTO tracker... they'll (likely) appear in due time. I just got the scope last Thursday and am struggling with the Astrophotographer's curse, 30 days and 30 nights of rain (living in the Pacific NW isn't helping). Today was the first night I had any opportunity and for a 5 minute window, I had a break in the clouds!

I present to you a "moonscape". Image taken with a Canon EF 2x Tele + EOS 5D3 mounted on a Arca-Swiss Z1 + Gitzo 2541 at 1/320 sec & ISO 6400.  The photo has been touched up but uncropped in Lightroom 5.

For the seasoned astrophotographers lurking around, any advice? I know the ISO is a tad high for this, but I didn't have a lot of time and had to make sure I got the shot in less than 5 photos.

First, congrats on the purchase. Good to see others getting into astrophotography. :) Once you get an equatorial mount, a very wide new world will open up to you. Just make sure you get s good mount...they are the most important piece of any astrophotographers kit.

As for advice...best bit is to definitely use a lower ISO. I pretty much always use ISO 100 or 200 for the moon. It moves, but not fast enough that a 1/4 second exposure will cause blurring. You REALLY want the DR that a lower ISO offers when shooting the moon...it's an exceptionally high DR subject.

I have lots more advice to offer...but I'll let you settle in first. ;P

1374
Animal Kingdom / Re: Show your Bird Portraits
« on: May 04, 2014, 10:37:44 PM »
Great shots, everyone! Some really good work is showing up on here these days. Alan, love that last shot with the Greenfinch...the way his head is cocked is great!

Click, thanks! I like that first Killdeer shot, too. Hopefully I'll be able to get some better ones as spring rolls on...those were my first shorebird shots of the year, and killdeer...well, sometimes they kinda make you wanna kill a deer...just because you gotta kill something...with their antics. :P

1375
Software & Accessories / Re: Gimbal Head: Wimberley Vs Jobu
« on: May 04, 2014, 10:35:38 PM »
Thanks jrista.
I saw some youtube clips about Jobu II, I'm impressed. The price is slightly more than Wimberley II, therefore, I settled with Wimberley II. This is my 1st gimbal head, so far, I like the feel of wimberley II.

I'm putting extra money toward decent tripod instead ;)

There is really very little difference between the Jobu 2 and Wimberley II. Someone mentioned the Wimberley didn't have ball bearings. I guess that might be one of the reasons I ended up choosing the Jobu 2 (it is WICKED SMOOTH), but I don't really think it matters all that much in the end. The Wimberley felt just as solid to me...the main reason I got the Jobu Pro 2 was because it was on sale on Amazon, and I had a bunch of amazon points to throw at it (I actually got it really cheap). It's really hard to go wrong with either of them.

1376
Software & Accessories / Re: Microfibre Cloths for Lens Cleaning
« on: May 04, 2014, 06:13:26 PM »
The point about the lens cap is key!! Also, if you can avoid it...never put a,kens cap in your pocket...that is just a transfer nightmare.

1377
F*ck focus peaking and all that video-style sh*t. All I want is a kick-butt, precise and fast af system. To hell with manual focus rings. I am done with that since the 1970s.

I want an oculus rift grade evf instead of those laggard mickey mouse vga evfs. Along with a good af-system with af fields all over the place all the way out to the corners.

 ???

1378
Software & Accessories / Re: Microfibre Cloths for Lens Cleaning
« on: May 04, 2014, 03:54:43 PM »
Seriously, it's just not that big of a deal.  If I shot thousand dollar pictures for million dollar clients in an expensive studio I would be more fastidious I guess but when you're outdoors in dust, dirt, sweat, etc then what's the point?

I guess I think of it exactly the opposite. If your shooting thousand dollar pictures for million dollar clients in an expensive, CLEAN studio, you probably don't have all that much dust and grime to worry about in the first place.

Out in the field, where there is dust, dirt, sweat, and other crap, you have to be that much more careful to avoid scratching your lens when you clean it. I wouldn't ever even remotely dream of using a napkin to clean my lens...those things are incredibly rough with nasty scratchy fibers. Just because you get dust on your lens more often doesn't mean you should trash your lens. As much as there are demonstrations on the net that show how you can still use a scratched up or even cracked lens, those defects DO impact image quality.

Just because your studio is the big, bad, dirty outdoors world doesn't mean you should not be diligent about keeping your gear clean and in pristine condition. If for no other reason than to preserve resale value.

1379
EOS Bodies / Re: New Sensor Technology Coming From Canon? [CR1]
« on: May 04, 2014, 03:02:34 PM »
Why do the etchings always have to go in the same direction?
I guess it's how are they cut out? what do they use, a saw  ;D

Well, there is no specific reason why they couldn't etch some additional sensors in the perpendicular direction, but it would be costly. The way sensor fabrication works is by etching the silicon with extreme UV light via a template. The template is oriented in a single direction. The wafer is moved underneath the light beam so that multiple sensors can be etched. Etching of a single sensor is a multi-step process, with various steps involving masking, etching, dissolution of masks, more etching, doping and layering of new materials, masking, etching, etc. This stuff has to be precise to the level of a few nanometers at most, so it is entirely automated. Rotating the wafer to etch additional sensors in a different direction introduces a source of error that could hurt yield.

Fascinating, must be very impressive to watch, though I guess not actually viewable. Thanks for the enlightenment!

Regards

As far as I know the systems used to fabricate silicon devices are not sealed. The wavers are open and accessible in most of the pictures I've seen. These things have to be done in sealed clean rooms where not even one speck of dust exists (as one speck of dust on a wafer means whatever is etched in that area of the wafer is useless). If you could find a way to get into a cleanroom at Canon, you could probably watch sensor fabrication in action. It isn't a particularly fast process, from what I understand, though.

1380
EOS Bodies / Re: New Full Frame Camera in 2014? [CR1]
« on: May 04, 2014, 02:59:26 PM »
What about a 4D? It's just a matter of time :)

No then all the Physicists would get confused they might think it were referring to advanced hypothetical spacial relationships beyond the current acknowledged 3 Dimensions...  :-*

Why do you think they went from 1D and then straight to 5D?
Bypassing 2D, 3D and 4D... then 7D.... whoops we missed the 6D so lets fill that space too...
I don't think they would ever do a 2D, 3D or 4D... simply because its a pun waiting to happen...

The number 4 in Japan is an unlucky number, same as with the number 9. I generally would not expect to see any products with those numbers from Japanese companies...but then Nikon went and made the D4...so you never know. :P

I think the 2D and 3D are definitely puns waiting to happen, or at the very least confusing names for a DSLR that is very likely to have video capabilities. The 3D just sounds too much like a camera capable of taking three-dimensional video.

I'd kind of like to see a 4D though...something above the 5D line in specs, but not as costly as the 1D line.

Pages: 1 ... 90 91 [92] 93 94 ... 315