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Understanding STF-8300M & STT-8300M

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#126 jerryyyyy

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Posted 18 March 2013 - 11:21 AM

Guys,

Any experiences with SBIG Adaptive Optics? Pricy but they have a system for the STT8300M:

https://www.sbig.com...e-optics/ao-8t/

Has been suggested to me as a way of significantly improving guiding. My skys are basically lousy and I can just watch the guide star scintillate in the image, even with 3x3 binning.

Given what I paid for this camera, this is a 10-5% add on.

#127 AstroGabe

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Posted 18 March 2013 - 11:29 AM

I'm considering this addition too, but mainly to improve guiding on my ATLAS mount. I have yet to experiment w/ the ccd on my 9.25 Edge, but think the 2350mm fl and weight might be too much for the mount to take for good guiding. So I'm interested also in what other people have to say about the AO-8 and STT combination.

Gabe

#128 pfile

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Posted 18 March 2013 - 03:27 PM

jerryyyyy, i have the STT-8300M, FW8-STT and AO-8. i bought the AO-8 in an attempt to compensate for the performance of my G11 but as you can see from my .sig i am now using a mach1gto.

i'm sure this is user error, but i've found that no matter how good my polar alignment is, the AO is reaching it's tilt/tip limits in 4-6 minutes. this means that the guiding software has to 'bump' the star back with the mount's guiding controls.

if your subexposure length is longer than the AO's period, then all your subs will have streaked star lines on them. with a narrowband filter this was not as big of a problem for me (though in the integrated result below you can see the stars have weird shapes). with LRGB filters it's definitely a spoiled sub.

one piece of advice i got was to really crank up the mount's guide rate so that the time to bump back is minimized. i have not tried that yet - the mach1gto tracks so smoothly that i've just turned off the AO-8 and am autoguiding the traditional way for the time being.

here's a horsehead taken with an AT10RC, STT-8300M + 5nm astrodon, and the AO-8. you can see the artifacts on the bright stars.

Posted Image

#129 jerryyyyy

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Posted 18 March 2013 - 05:38 PM

I'm considering this addition too, but mainly to improve guiding on my ATLAS mount. I have yet to experiment w/ the ccd on my 9.25 Edge, but think the 2350mm fl and weight might be too much for the mount to take for good guiding. So I'm interested also in what other people have to say about the AO-8 and STT combination.

Gabe


Nothing is easy. :tonofbricks:

Interested to hear about the weight worry. I think you may be OK. I just added my Nikon D800 to my set-up to get some wide angle shots and it guides no worse. This must add 5 lbs, but I can still ballance it well.

I am using the Celestron FR to get my 2032 down to 1360, but you get a lot of distortions in the periphery and need to crop them out. Also there is an unpleasant "horseshoe" that appears around bright stars in the periphery... often cannot crop it out.

Between a rock and a hard place. I think I have tweaked my Atlas with the help of a friend to get the work gear working well... this is easier than it sounds as the adjustment is kinda hidden unless you have someone draw you a map.

BTW I was thinking about getting something bigger than the C8.. maybe will not help much in my efforts.

#130 jerryyyyy

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Posted 18 March 2013 - 05:41 PM

jerryyyyy, i have the STT-8300M, FW8-STT and AO-8. i bought the AO-8 in an attempt to compensate for the performance of my G11 but as you can see from my .sig i am now using a mach1gto.

i'm sure this is user error, but i've found that no matter how good my polar alignment is, the AO is reaching it's tilt/tip limits in 4-6 minutes. this means that the guiding software has to 'bump' the star back with the mount's guiding controls.

if your subexposure length is longer than the AO's period, then all your subs will have streaked star lines on them. with a narrowband filter this was not as big of a problem for me (though in the integrated result below you can see the stars have weird shapes). with LRGB filters it's definitely a spoiled sub.

one piece of advice i got was to really crank up the mount's guide rate so that the time to bump back is minimized. i have not tried that yet - the mach1gto tracks so smoothly that i've just turned off the AO-8 and am autoguiding the traditional way for the time being.

here's a horsehead taken with an AT10RC, STT-8300M + 5nm astrodon, and the AO-8. you can see the artifacts on the bright stars.

Posted Image


Have you asked the guys at SBIG about how to get around this. They think about this a lot. Maybe they have better ideas. Guess this will not help....

#131 Hilmi

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Posted 19 March 2013 - 01:33 AM

It could be an issue of focal length too high for the G11 to cope with.

#132 pfile

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Posted 19 March 2013 - 01:36 AM

the image above was taken with the mach1gto. the issue is that the polar alignment is not good enough, and the AO-8 reaches it's limits too fast. this would happen with any mount. my point though is that my polar alignment was pretty good by my standards (20 min+ drift alignment) and yet it's not good enough for the AO-8 and long exposures.


my particular G11 is not compatible with long focal lengths, that is for sure. with some work i'm sure it could work okay but i didn't really want to become a G11 mechanic. i just want to image.

#133 Hilmi

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Posted 19 March 2013 - 01:41 AM

As an experiment try drift wligning using pempro then imaging with the AO unit. I am curious how that would work. Should that fail, drop me a message if you want to sell your AO8 T

#134 pfile

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Posted 19 March 2013 - 02:09 AM

i've already done that experiment. same issue, and this is on a target with a reasonably high declination.

i think my problem is i have the older mach1gto and when you loosen the azimuth plate in order to adjust it, the altitude gets messed up. so i can only get my PA so close. i should probably upgrade the AZ plate to the new one which solves this problem.

i had the idea to try guiding the mount with my external guidescope, and then also guide with the AO. the theory being that the guidescope would keep the mount pointed in the right place. but due to differential flexure, eventually the two guiders would drift apart, the AO would lose the star, and then it would all be over. i can't tell PhD to bump the mount.

i guess i will still try this to see if we're talking about hours worth of imaging or just minutes.

#135 MattThomas

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Posted 19 March 2013 - 10:44 AM

Requiring the guiding to bump the mount during an AO exposure should not normally cause the defect in your image.

The mount bump is really no different than a normal guide correction. Usually the AO is able to guide away any variations in star position even during the mount bump.

What may have happened in your image is that you let the AO get to its maximum travel before the mount bump occurred. Instead, you should limit the AO to 50% or less of its maximum travel to let the mount bumps happen more often. This will allow the AO to continue to correct through the mount movement and should give you much better results.

You never want to rely on the AO only to do your corrections unless you have a near perfect alignment (as you've experienced). You really need to optimize your system so everything is working together as intended.

I hope this helps.

#136 pfile

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Posted 19 March 2013 - 11:08 AM

matt even at 50% (which is the default) the amount of travel back to 0% is very noticeable at 2000mm.

if the guide star is dim and the guide exposure is long, it can take several seconds for the AO to return the guidestar to the center of the guide crosshairs. that's ample time for a double image, or for a streak to be noticable, etc. depending on the filter in use and how bright the stars are in the FOV.

again, i never cranked up my mount guide rate. but still with long guide exposures i'm not sure how this can be avoided.

#137 MattThomas

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Posted 19 March 2013 - 01:46 PM

It doesn't need to bring the AO back to center in order to get a good star image. As long as the AO is running fast enough to track the star (whatever the deflection) you will get a good image.

If the tracker exposure is slow - which would cause the AO to run slow and you have a fast perturbation that the AO cannot track out, then you are going to have an issue.

What I usually experience is that the AO will track the star, slowly deflecting off center (remember that even though the AO is off center, the stars are still kept on the same location on the CCD). When it reaches the limit, the mount is bumped which causes the AO to come back near center - but usually not exactly center, especially if the mount bump aggressiveness is set low. During the mount move, the AO is still tracking the star keeping it centered on the CCD - which continues until the mount needs to bump again.

Hope this helps.

#138 Mike7Mak

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Posted 19 March 2013 - 02:04 PM

if the guide star is dim and the guide exposure is long, it can take several seconds for the AO to return the guidestar to the center of the guide crosshairs. that's ample time for a double image, or for a streak to be noticable, etc. depending on the filter in use and how bright the stars are in the FOV.

Don't long guide exposures defeat the purpose of AO? I thought the point was sub-second exposures for rapid tip-tilt corrections. It seems to me if you drive the AO with long exposures it can't possibly provide any better guiding than a regular guide camera. It's gonna reveal the error that accumulates during the exposure, just without the added lag time of moving the mount. Hence the double exposure effect instead of egg-shaped stars.

#139 pfile

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Posted 19 March 2013 - 03:57 PM

this may just be a peculiarity of equinox image. it's bumping back to 0% and i'm not sure that's configurable. also, it's not making small bumps and letting the AO correct. it makes one huge bump and then the AO has to catch up. maxim could be different; i've never tried it.

> Don't long guide exposures defeat the purpose of AO?

yes and no, if you are hoping to make up for atmospheric effects then yes i suppose. but in the end, in theory, you should get superior guiding from the AO since the mass it has to move is much, much less than the entire OTA. because of this it's probably a lot less likely to under- and over- shoot.

my good images with the AO are definitely better than without.

#140 korborh

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Posted 19 March 2013 - 08:36 PM

my good images with the AO are definitely better than without.


Were the ones without AO taken using OAG? With a mount like Mach1 you really should not need AO for that OTA to get tight round stars. Unless the OAG/calibration has some issue.

#141 jaddbd

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Posted 19 March 2013 - 09:31 PM

but i didn't really want to become a G11 mechanic.


:lol: I'm sorry but for me that is the line of the day. As a long time previous owner of one I think I qualified as "certified" (in more ways than one). Kidding aside I actually had good luck with mine but a AT10RC at F8 became too much for the old horse.

Sorry to get off topic,

John D

#142 pfile

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Posted 19 March 2013 - 09:38 PM

yes FW8G-STT OAG. the stars are pretty tight either way, but it just looks a tad better with the AO. i don't have FWHM measurements. i'm talking about 30 minute Ha exposures here.

#143 pfile

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Posted 19 March 2013 - 10:21 PM

but i didn't really want to become a G11 mechanic.


:lol: I'm sorry but for me that is the line of the day. As a long time previous owner of one I think I qualified as "certified" (in more ways than one). Kidding aside I actually had good luck with mine but a AT10RC at F8 became too much for the old horse.

Sorry to get off topic,

John D


we aim to please (so please aim) :tonofbricks:

actually now that i have another mount i feel less worried about working on the G11. i didn't want to be in a situation where i screwed up the worm alignment/position and then could not get it back... and then had no mount.

at some point i have to put it on the tripod and replace the worm (scott sent me a new one...)

#144 jerryyyyy

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Posted 20 March 2013 - 12:11 AM

After all this interesting discussion, I took a good look at my last images with my Atlas and the FR on the C8 and I do not think there is much I can do to improve the guiding.. stars are nice and round. I think I need to take the FR off and see how well it guides without that distortion creating tool...

#145 jerryyyyy

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Posted 24 March 2013 - 12:51 PM

PS, have moved up (or down) to -30C and happy with results. I am still working on a lot of technical issues, but this is one 10m frame.

Attached Files



#146 mmalik

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Posted 05 April 2013 - 03:29 AM

SBIG makes only Kodak. They invested lot of time and effort into learning how to handle these beasts. SONY is completely different level. They would have to invest significant amount of manpower costs, lot of time and really lot of money, to investigate how to use/handle signals of Sony chips. Also, Sony is a company hard to deal with, hard to do business with. Their chips are also very expensive so the margin/gain/net income from such cameras is low. On the other side, Kodak is, made in USA (tradition), you get complete and full documentation and maybe sometimes even support (though not perfect). So you get all this from Kodak, but the truth is, the chips are obsolete, nowadays... that's just how it is, the fact.


Atik seems to be well diversified in their chip offerings, I see no reason why SBIG shouldn’t or couldn’t? Given Kodak is getting old, I would say it will be well advised for SBIG to invest in and introduce Sony into the mix. I get it…; ‘Sony’ may be ‘tiny’, the chip that is, but the ‘tiny’ is newer at least and will make for a lighter/slimmer/cheaper/agile camera/s for SBIG among the long line-up of heavier/heftier/expensive Kodak cameras.


While 8300 may be the bread and butter of SBIG, my pet peeve is that it is pricey and heavy, especially if one factors in the filter wheel and other accessories. That’s NOT to say well tested and reputable 8300 has to go away; it can hold the fort for however long it can. I think time has come for relatively cheaper/lighter yet high performing cameras & even lighter filter wheels which could be sold in even larger quantities to reap bigger profits.


Talking of ‘tiny’ Sony, is there or will Sony make anything bigger than their highly touted ICX694? Shouldn’t Kodak be renewing their older looking chip line-up; maybe come up with a NEWER equivalent of ICX694 but in a larger size? Will they?


References:
Truesense Imaging (Kodak)...
EXview HAD CCD II (Sony)...


While we are on the subject, following is Atik diversity at a glance:

ICX=Sony
KA*=Kodak


EDIT: Old Atik chart removed...


With the release of Atik 490EX, a fresh look at the ATIK, encompassing KAF-8300; SONY remains 'tiny' with ICX814, regardless:

Posted Image

Posted Image

#147 mmalik

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Posted 09 May 2013 - 01:12 AM

@jerryyyyy... They also have to worry about how what they do affects that crazy complex filter wheel.


There has been talk about 8300M driver issues and 'Self-Guiding Filter Wheel' concerns lately [in other, link1..., link2... and in this thread as well]. Was wondering if someone, possibly SBIG, could sum up what's going on especially in the context of their latest offering STT-8300M and 'FW8-STT Self-Guiding Filter Wheel' as it relates to such issues and concerns; technical/driver level details will be appreciated as to where things stand. Thanks in advance. Regards

#148 MattThomas

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Posted 09 May 2013 - 10:30 AM

There has been talk about 8300M driver issues and 'Self-Guiding Filter Wheel' concerns lately [in other, link1..., link2... and in this thread as well]. Was wondering if someone, possibly SBIG, could sum up what's going on especially in the context of their latest offering STT-8300M and 'FW8-STT Self-Guiding Filter Wheel' as it relates to such issues and concerns; technical/driver level details will be appreciated as to where things stand. Thanks in advance. Regards


One of your links was not a driver issue - but turned out to be a software configuration issue with MaxIm.

We did upgrade to a new version of the Microsoft developer tools recently and this caused a lot of problems - but those are resolved now.

There was also a problem recently discovered with MaxIm/DL when using the AO with the STT. The problem was a result of MaxIm/DL terminating all of the exposures 0.2 to 0.5 seconds early. This caused a problem in the camera firmware that resulted in a black bar on the top of the image. This has been fixed via a firmware update - although until MaxIm releases an update the exposures will still be terminated early by an indeterminate amount of time.

I hope this helps.

#149 mmalik

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Posted 09 May 2013 - 06:49 PM

Thanks Matt!

#150 SubJimbo

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Posted 19 May 2013 - 04:07 AM

Hey guys!

Long time reader, first time poster.

I need some advice. I have been reading extensively about a CCD for my setup.

I have a CGEM Mount with 11" OTA and an Orion 80mm Guidescope. I also have a NexGuide Autoguider (which I will sell, its not very good @ my sky site at all, I want something to connect to my laptop.)

I love the look & review on the SX Lodestar, but then I am looking at the self guiding filter wheel on the STT-8300 package...

Because of the 2800mm FL of my scope, would I be better off the with the Guiding filter wheel, or another guider to use my 80mm scope with?






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