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ASI178MM vs QHY5III178M as OAGuider?

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#1 Lord Beowulf

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Posted 18 April 2018 - 11:57 PM

As I go through galaxy season fighting to find a guide star with my remote OAG setup (can't rotate anything) that keeps my target framed, I'm debating upgrading from my QHY5L-II M to an IMX178 based guide camera.  That will give me roughly twice the total area (7.4 x 5 mm vs. 4.83 x 3.63 mm), but with 4x the pixel resolution.  If I can successfully marry this with the 0.5x focal reducer I have (that wouldn't reach focus on the end of the 5L-II tube) and still have enough mirror FOV in the OAG, I should be able to guide with equivalent accuracy but have about 8X the FOV!  Assuming the pixels are more sensitive to boot and I should have plenty of stars to work with.  So, anyone using one of these and have any feedback, especially if you've upgraded from a 5L-II?  Any thoughts on my chances of success?

 

Next is deciding between ZWO and QHY.  I have an original beta QHY247C, and after some firmware updates and a hardware fix they guided me through, it's been working great.  I also have a ZWO ASI178MC that I'm using for my all sky camera that I'm generally happy with, although it never worked reliably at USB 3.0 speeds, and getting driver updates to resolve the other problems it had took a while.  I'd definitely want my autoguider transferring at USB 3.0 speeds!  And no, I don't want to tear apart my all-sky camera to try to test it as a guider.  It wouldn't be a fair comparison anyway with the color sensor.  The one thing going for the QHY is the smaller form factor.  I like that better both in terms of weight and the flexibility of adjusting the length of the tube insertion.  On the other hand, ZWO is running a NEAF sale at the moment, so the ASI is currently cheaper.

 

Thoughts?

 

Thanks,

 

Beo    



#2 Konihlav

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Posted 19 April 2018 - 04:13 AM

from these two cameras you list I'd choose the third one, ASI 290MM. You may have it in two forms:

https://astronomy-im...90mm-mini-mono/

or, standard:

https://astronomy-im...b-3-0/asi290mm/

the difference is, apart of size and form factor, the USB. I have got recently the standard version of ASI290MM, but haven't used it yet in my OAG (still using MII G1-301 for my 900mm focal length).



#3 Lord Beowulf

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Posted 19 April 2018 - 06:41 AM

Hi Konihlav,

 

I'm not sure why you're recommending that camera, other than that ZWO did make a version that copies the QHY form factor.  Do you have any specifics why you think it would be better than what I'm looking at (beyond being cheaper)?  My initial attempt for an all-sky camera was with the ASI290MC, and it was a big disappointment.  In addition to the same driver problems that ZWO eventually resolved for the 178, at least at USB 2.0 speeds, there were other limitations.  The sensor is tiny, and with the 16x9 1080P form factor did not provide good coverage of a round FOV.  You're either wasting half the sensor or missing half of the image!  If your goal is for full screen 1080P video then it might be a fine camera, but I don't consider it very good for astrophotography.  At 5.61 x 3.18 mm, it's just over half the size of the 178 sensor and a third the resolution.  As an all sky camera it was a horrible choice.  Here's one of the few shots I had with that camera before I sent it back.

 

4745.jpg link31.png

 

For comparison, here's the 178MC with the stock lens.

 

4594.jpg link31.png

 

And here with the smaller (wider) lens I switched to.

 

4617.jpg link31.png

 

And here's with the current slightly slower lens for full sensor coverage. Forgive the bird poop I need to go clean off!

 

4746.jpg link31.png

 

Thanks to Michael Poelzl and his latest version of AllSkEye that allows overlaying my own image with logo, etc. I'm just about where I want to be with this.  You can see the live view here.

 

At any rate, from a resolution and FOV standpoint, the 290 isn't going to be any better than the 5L-II I already have, and I don't think it's significantly more sensitive.  QHY actually bills it as the next generation replacement for the 5L-II, so they also aren't promoting it as being significantly better (at twice the price), where they give the 178M their highest recommendation as a guide camera.

 

Thanks,

 

Beo


Edited by Lord Beowulf, 19 April 2018 - 06:51 AM.


#4 Konihlav

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Posted 19 April 2018 - 07:52 AM

Beo - you are right! the 178 is a nice 1/2" size. I have had QHY178mm before and am still using also a 1/2" size, old tech CCD G1-301. I recommended the IMX290 solely with sensitivity in mind. From the "datasheet" the sensor shall be twice as sensitive as the IMX178. And sensitivity is important for me.

 

But you are right the 178 will also do a good job there. So, sorry, for the potential confusion...



#5 Konihlav

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Posted 19 April 2018 - 07:55 AM

BTW my old OAG guidecam has 9um pixels and 1/2" size and my focal length is about 900mm. Even though it is a very old and not much sensitive CCD I never had issues with a guidestar. But that's off topic of your question on the 178. There are still guys with some of the big pixels (8.3x8.3or so) lodestar's etc.

It's nice that I focus on chip sensitivity, but it's true that with the big (much bigger pixels) you easily overcome and outperform the small pixel CMOS guidecams.



#6 rgsalinger

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Posted 19 April 2018 - 11:55 AM

There's really no point to USB 3 speeds in a guider. The guider is only sending in a roughly 32x32 pixel slice ever 2-5 seconds. That's a tiny amount of data and will arrive in milliseconds. Now, if you are doing some sort of full frame multi star guiding, it might be different but for the rest of us, USB 2 is working fine. It's also the case that most modern guiding software can accurately calculate centroids to the point that pixel size really doesn't matter. Having used several guide cameras over the years, I have not found any correlation. Recently I went from a 6 micron pixel camera to a 2.9 micron pixel camera and guiding stayed exactly the same. The only reason I changed it was to get a wider FOV with my 2.5 meter PlaneWave telescope.

Rgrds-Ross



#7 Lord Beowulf

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Posted 19 April 2018 - 08:06 PM

Hi Kohnilav,

 

What datasheet are you looking at?  I'm having trouble finding useful information, even from Sony.  They spec sensitivity in mV (for a given exposure time) rather than EMVA1288 standard quantities.  If I divide by the pixel area, and assume the voltage is a linear function of electron count, then the QE would appear to be about double on the 290 over the 178, but it's hard to tell if that's accurate or not.  The ZWO manuals only show relative QE, not absolute.  On read noise, it's a bit hard to compare given the variable gain control.  It'd be nice just to be able to compare SNR values for equivalent signals. 

 

My understanding on the 178 is that it can bin at 2x2, which should help while keeping the larger sensor size.  The alternative would be something like the 174, but that's another 25% more in cost and back to a pretty low resolution.  Ross, another reason for the 178 is that it should be a decent solution for some solar imaging, where the lower resolutions wouldn't be as versatile.  Given the cost it'd be nice to know I would have more options than just guiding with it.  As far as subframes, I can't say I've ever noticed PHD using subframes, but maybe that's camera dependent.  Beyond that (and when there are more than one visible) I've always thought that multi-star guiding would make a significant difference over seeing variation, etc.  

 

At the moment I'm definitely leaning towards ZWO simply because of the NEAF discounts (plus OPT's current sale), but that means I need to make a decision soon!

 

Thanks,

 

Beo



#8 Konihlav

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Posted 20 April 2018 - 03:16 AM

SONY recently changed URL paths, announcement: http://www.sony-semi..._en/IS/sensor0/

 

new valid URL pages:

STARVIS news and info - http://www.sony-semi...rity/index.html

PREGIUS news and info - http://www.sony-semi...stry/index.html

 

and SONY's proprietary SNR1s measurement:

http://www.sony-semi...logy/snr1s.html

 

I have to admit that since they change the numbering so frequently (last time the datasheets contains some digits value instead of mV and here the conversion factor from digits to mV could even vary per sensor) it is almost impossible to really trust these numbers and be sure this is the best you are looking for...

 

One additional link: http://www.webastro....ad.php?t=148863


Edited by Konihlav, 20 April 2018 - 04:25 AM.


#9 Lord Beowulf

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Posted 20 April 2018 - 07:38 AM

Thanks Konihlav,

 

That SNR1s measurement looks like the most important number for this application, and according to that table, the 290 is exactly twice as sensitive as the 178, so my calculation was close.  Unfortunately they don't list the 174 there, but comparing currents and the fact that it's old front-side technology, I'd say that the only real advantage it's giving is the larger pixel size.  The 178 could potentially compensate with binning,  assuming it supports it and assuming that the SNR of a binned well is better than an individual well (e.g. signal adds and noise averages).  Given I'm guiding through a C11, I'm still thinking that larger area is going to be more helpful than higher sensitivity, although I obviously want both.  

 

Now, as far as the SNR1s number, the IMX294 looks pretty nice, but it'd be hard to justify that as a guider.  Still, should make a pretty good imager otherwise.  It's basically just the 4K version of the 1080P IMX290.  It's also apparently only in color, at least as implemented so far.

 

The last link looks like it's just a summary of the data I was looking at yesterday, but it's a nice table.  Would be nice to have a English version of that!

 

Thanks,

 

Beo



#10 Lord Beowulf

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Posted 22 April 2018 - 10:21 AM

Well, I realized I was getting sidetracked comparing the 178 with the 290 instead of just comparing it with the MT9M034 sensor in the QHY5L-II.  While unfortunately there's no good data for a direct comparison of sensitivity between sensors, assuming the 178 is at least as sensitive as the QHY5L-II, then I will double (actually 2.09x) the area of my sensor and any additional sensitivity is a bonus.  On the other hand, the IMX290 is just 1.03x the area of the MT9M034 but at a wider (worse) form-factor (5.61 x 3.18 mm vs. 4.8 x 3.6 mm) , increasing the likelihood of needing to search for stars along the short axis and making my problem worse. 

 

My original question on vendor choice generally made itself obvious as well, since while it's more expensive (presumably largely due to the guide port connector used), only QHY makes the 178 in a guider form-factor and has USB 3.0.  The ZWO version would have fit ok on my OAG, but my biggest concern was in the focal distance and whether or not I'd have the necessary range of adjustment.  I guess the ZWO wouldn't be much different from the StarShoot AG I used to mount on there, but I didn't think about that before placing the order!  Still, since I'm still planning to play with the focal reducer I bought (turns out I need spacers there to make it work) I wanted as much flexibility as I could get in mounting location.

 

As far as the 174, that's just too absurdly overpriced to even consider for this application.  I'm not sure why as it doesn't seem to be in a very competitive position in terms of resolution and performance.  Yeah, it has big pixels so it's relatively sensitive, but otherwise it doesn't seem that impressive in comparison to other sensors in the lineup.

 

Beo



#11 Lord Beowulf

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Posted 29 April 2018 - 10:19 AM

I received my new QHY5III178M camera from High Point Scientific on Thursday night (they and OPT had the same sale price, but they had it in stock).  I also had to wait for a same day delivery from Amazon for a small USB 3.0 hub to add to the OTA so I could run both cameras.  That didn't arrive until 8 PM, so in was already after dark by the time I made it to the observatory, and overall it made for a late night!  

 

The camera's definitely pretty with its blue anodized finish.  

 

4752.jpg link31.png

 

 

Here's the connector end of the camera with the USB 3.0-B style connector and the non-standard LEMO connector for the guide port due to the limited space. I'd rather have a USB-B connector than a USB 3.0 micro connector and a standard RJ-11 socket for the guide port.

 

 

4753.jpg link31.png

 

I didn't get the best of focus, but here's my attempt o compare the two sensors.  You can see how much bigger the new IMX178 sensor is. The distance from the tube front appears the same, so adjusting the confocal ring on the new camera to the same distance from the front of the nosepiece had it almost perfectly focused when I put it into the OAG.

 

 

4759.jpg link31.png

 

Here it is installed.  Forgot to take the picture while I was using it, so this was after parking.  I definitely need to work on cleaning up my cables!

 

4760.jpg link31.png

 

Here's the USB hub.

 

4761.jpg link31.png

 

 

As always, there are more pictures in the gallery (use the link icon) but I'm trying to avoid the image limit per post here.

 

Thanks,

 

Beo

 


Edited by Lord Beowulf, 29 April 2018 - 10:30 AM.


#12 Lord Beowulf

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Posted 29 April 2018 - 10:26 AM

Now to the important part.  How did it perform?  For a test I ran over to M82 where I knew I had a good guide star pre-meridian, and took some shots with the 5L-II.

 

At one second exposure there's a good lone guide star. 

 

4762.jpg link31.png

 

By three seconds, that star's saturated, but nothing else is visible.

 

4763.jpg link31.png

 

At five seconds, another star starts to appear, and adjusting gamma brings it out.

 

4764.jpg link31.png

 

4765.jpg link31.png

 

At ten seconds, still nothing else.

 

4766.jpg link31.png

 

Beo



#13 Lord Beowulf

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Posted 29 April 2018 - 10:38 AM

Now, for comparison, at 1/5 second, the same bright guide star is visible.  The focus isn't perfect here, and the star profile is a bit noisy, but still, much more sensitive.

 

4767.jpg link31.png

 

At one second, that second star is visible and you can tell just how much larger the FOV is, although it's not helping much in this case.  Still, the trend holds that we're basically 5X more sensitive, even with the smaller pixel size.

 

4768.jpg link31.png

 

At two seconds, a third star starts to show.

 

4769.jpg link31.png

 

At four seconds, it should be usable too, but we're starting to get some amp glow or something and occasionally the frame comes back all noise.

 

4770.jpg link31.png

 

Now here's where we have a problem.  At five seconds, the frame is all noise and is completely unusable.  Not sure what's going on here, but time to contact QHY!

 

4771.jpg link31.png

 

Beo



#14 SkyGeek

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Posted 02 May 2018 - 05:26 PM

I'm not an expert but here is my understanding.

 

It looks like you are changing the gamma with each exposure value.  Gamma is non linear relationship between bright and dark and is different for each monitor.  Gamma correction (the slider) adjusts this relationship to get the widest possible range. The 4 second and 5 second show the Gamma slider maxed out to the right and is probably not an accurate display of the 5 second exposure.

 

After you adjust the gamma with the slider for the most accurate range between bright and dark you should leave it there for all exposure values. 

 

I think you are just blowing everything out with the max gamma value you are using.


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#15 akulapanam

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Posted 02 May 2018 - 10:03 PM

I'm not an expert but here is my understanding.

It looks like you are changing the gamma with each exposure value. Gamma is non linear relationship between bright and dark and is different for each monitor. Gamma correction (the slider) adjusts this relationship to get the widest possible range. The 4 second and 5 second show the Gamma slider maxed out to the right and is probably not an accurate display of the 5 second exposure.

After you adjust the gamma with the slider for the most accurate range between bright and dark you should leave it there for all exposure values.

I think you are just blowing everything out with the max gamma value you are using.


That is correct. He needs to leave gamma in one spot.

On ASI vs QHY it all comes down to fpn. The ASI has A LOT more than the QHY

#16 Lord Beowulf

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Posted 03 May 2018 - 12:15 PM

Hi All:

 

Thanks for the responses.  Sorry to disappoint, but the issue shown has nothing to do with the gamma setting.  The gamma was simply adjusted to give the best possible contrast of the data that was captured.  Normally I leave the gamma slider to the right to see the brightest guide star(s) against a black background, but as I increased the exposure to show multiple stars I had to turn it down to have them show on the screen at similar magnitudes, but against a grey background.  However, when reaching that last bad frame, I had to pull the gamma back to the right to see anything other than a solid white frame. 

 

I won't have clear skies for a while yet, so I can't do a star test, but I did go back and run some tests with the ambient light in the observatory and learned a bit more about what is happening, but not why it's happening.  Unfortunately the gamma slider DOES affect the saved image, so it's not possible to evaluate the camera by itself through PHD.  The issue is a bit more insidious than that as well.  I was able to take a few shots last night inside my observatory using the IR light from my monitoring cameras.  That doesn't give me the ability to evaluate star vs. background, but did teach a little more about what PHD is doing.  

 

So first off, extracting the raw dark from the dark library FITS file, the dark noise looks reasonable up to the 15 second exposure, so that shouldn't be an issue.

 

4777.jpg link31.png

 

With the slider right, a two second exposure of the IR background gives this result.

 

4779.jpg link31.png

 

Moving the slider left shifts the histogram to the right, indicating the slider acts like a typical midpoint adjustment.

 

4778.jpg link31.png

 

Thus, as indicated, when the background is getting swamped as in the 5s exposure, the slider should be to the right to pull the background down as far as it will go.

 

With the slider to the right and no dark library applied, we get this noisier histogram that's even further to the left:

 

4780.jpg link31.png

 

Now, here's where things get interesting.  Turning off the IR cameras so that I just have whatever minor background is in the observatory due to a stray LED or two, I get the following with the dark library disabled.  I think this was a 5 second exposure, but can't be positive as PHD2 doesn't appear to put that into the FITS header.

 

4781.jpg

 

Applying the dark library, however, gives a really odd behavior. 

 

4782.jpg

 

The histogram narrows, which is to be expected when subtracting a dark from dark, but the screen function shifts the entire histogram to the right so it's full white instead of black.  I don't believe the slider impacted this, but I'd have to repeat the test again tonight to be sure.  

 

Unfortunately this still doesn't answer what's happening at the 5s exposure where I have multiple saturated stars (right of the histogram) and a white background as well.  Is that real or some oddity of the screen stretch algorithm like the dark above?  The only thing I can think of that might be a real effect is that since this started out as a quick test, I didn't bother turning off the observatory cameras.  Normally that only introduces a small amount of "sky glow" when the scope is pointing up, but given how sensitive this camera is, and that it appears to be pretty sensitive to IR, that may have contributed to the 5s exposure problem.  Unfortunately I won't be able to check that until we get clear skies.

 

Now, akulapanam, first off, I have to ask, where were you when I was asking about differences between ZWO and QHY!?!!  grin.gif   I'm assuming you're referring to fixed pattern noise, in which case I'm happy if QHY is better, but I have to ask why two cameras using the same sensor would have different FPN.  About the only impact I would think the camera hardware design would have would be thermal impact of the PCB and packaging.  I wouldn't consider that FPN.  This is of course assuming that they're buying the sensors from the same manufacturer, but given these are Sony IMX178s, I wouldn't think that anyone else has a clone (yet).  Then of course there's driver functionality and any post processing they might apply, but I would be surprised if there's something there.

 

Thanks,

 

Beo

 

 

 

 



#17 Lord Beowulf

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Posted 03 May 2018 - 12:21 PM

Oh, and I forgot to mention.  The other thing that seems to point to this being something weird in PHD's gamma function is that if you look at the 5s exposure and look at the star thumbnail, it still shows a blown out circle with a black background, where the star is hardly discernible in the background noise of the stretched image.  That would SEEM to indicate that maybe the raw data still has good SNR.

 

 

4771.jpg link31.png

 

On the other hand, now that I look at this in the context of the previous tests I ran last night, I'm seeing an indication of the same "bird" shadow just above the star, which would indicate that's real background signal (unless the bird is fixed pattern noise in the sensor!!!)

 

Thanks,

 

Beo


Edited by Lord Beowulf, 03 May 2018 - 12:23 PM.


#18 akulapanam

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Posted 03 May 2018 - 08:25 PM

Hi All:

Thanks for the responses. Sorry to disappoint, but the issue shown has nothing to do with the gamma setting. The gamma was simply adjusted to give the best possible contrast of the data that was captured. Normally I leave the gamma slider to the right to see the brightest guide star(s) against a black background, but as I increased the exposure to show multiple stars I had to turn it down to have them show on the screen at similar magnitudes, but against a grey background. However, when reaching that last bad frame, I had to pull the gamma back to the right to see anything other than a solid white frame.

I won't have clear skies for a while yet, so I can't do a star test, but I did go back and run some tests with the ambient light in the observatory and learned a bit more about what is happening, but not why it's happening. Unfortunately the gamma slider DOES affect the saved image, so it's not possible to evaluate the camera by itself through PHD. The issue is a bit more insidious than that as well. I was able to take a few shots last night inside my observatory using the IR light from my monitoring cameras. That doesn't give me the ability to evaluate star vs. background, but did teach a little more about what PHD is doing.

So first off, extracting the raw dark from the dark library FITS file, the dark noise looks reasonable up to the 15 second exposure, so that shouldn't be an issue.

4777.jpg link31.png

With the slider right, a two second exposure of the IR background gives this result.

4779.jpg link31.png

Moving the slider left shifts the histogram to the right, indicating the slider acts like a typical midpoint adjustment.

4778.jpg link31.png

Thus, as indicated, when the background is getting swamped as in the 5s exposure, the slider should be to the right to pull the background down as far as it will go.

With the slider to the right and no dark library applied, we get this noisier histogram that's even further to the left:

4780.jpg link31.png

Now, here's where things get interesting. Turning off the IR cameras so that I just have whatever minor background is in the observatory due to a stray LED or two, I get the following with the dark library disabled. I think this was a 5 second exposure, but can't be positive as PHD2 doesn't appear to put that into the FITS header.

4781.jpg

Applying the dark library, however, gives a really odd behavior.

4782.jpg

The histogram narrows, which is to be expected when subtracting a dark from dark, but the screen function shifts the entire histogram to the right so it's full white instead of black. I don't believe the slider impacted this, but I'd have to repeat the test again tonight to be sure.

Unfortunately this still doesn't answer what's happening at the 5s exposure where I have multiple saturated stars (right of the histogram) and a white background as well. Is that real or some oddity of the screen stretch algorithm like the dark above? The only thing I can think of that might be a real effect is that since this started out as a quick test, I didn't bother turning off the observatory cameras. Normally that only introduces a small amount of "sky glow" when the scope is pointing up, but given how sensitive this camera is, and that it appears to be pretty sensitive to IR, that may have contributed to the 5s exposure problem. Unfortunately I won't be able to check that until we get clear skies.

Now, akulapanam, first off, I have to ask, where were you when I was asking about differences between ZWO and QHY!?!! https://www.cloudyni...efault/grin.gif I'm assuming you're referring to fixed pattern noise, in which case I'm happy if QHY is better, but I have to ask why two cameras using the same sensor would have different FPN. About the only impact I would think the camera hardware design would have would be thermal impact of the PCB and packaging. I wouldn't consider that FPN. This is of course assuming that they're buying the sensors from the same manufacturer, but given these are Sony IMX178s, I wouldn't think that anyone else has a clone (yet). Then of course there's driver functionality and any post processing they might apply, but I would be surprised if there's something there.

Thanks,

Beo


QHY inserts an anti-amp glow circuit in there build and the difference is striking. Starlight Xpress’s is even better on their new cmos line. ASI just hasn’t made the same investment
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#19 Lord Beowulf

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Posted 03 May 2018 - 11:33 PM

Well, thanks for the info and it's making me feel better about my decision, assuming the 5s problem is what I now suspect with the IR glow.  I was really close to having gone with the ASI, but at the end of the day, the form factor and the USB 3.0 interface in that form factor drove me to go with QHY.  

 

Thanks,

 

Beo



#20 Lord Beowulf

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Posted 09 May 2018 - 06:43 PM

For anyone who's interested, I summarized this information on my blog post.

 

Beo



#21 rgsalinger

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Posted 10 May 2018 - 12:38 PM

I suggest that the five second problem has to do with the gain setting in the camera. I have a couple of CMOS (sensitive) guide cameras and what the image looks like (gamma  and/or stretch constant) is highly dependent on the gain setting. Last night I was using a ZWO174 camera and I had to spend some time tuning the gain so that the stars ended up with the best possible signal to noise ratio. FWIW I also found that with that camera the higher gain settings gave me amp glow which went away with lower gain. Play around with the gain and see what happens.

 

I strongly prefer USB C simply because it's easier to insert it in the dark - there is not single "right way" as there is with USB 2/3. I don't care about the ST4 port as I'm not trying to avoid using a computer.

 

Rgrds-Ross



#22 Lord Beowulf

Lord Beowulf

    Vendor - Orion Ranch Observatory

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Posted 10 May 2018 - 10:28 PM

Hi Ross,

 

Not sure if you read through the whole thread, and there's actually more detail over the PHD2 forum, but turning the gain down does exactly what one would expect it to do and reduces the brightness of the stars.  Given the goal is to find dim stars, reducing the gain would defeat the purpose.  The only reason to turn the gain down would be if you had a guide star that was saturating at the minimum exposure and you wanted to pull it back.  Otherwise, keeping the gain high will do what I'm looking for.  

 

That said, there are two different problems identified.  The first was that for my initial tests I'd left my observatory monitoring cameras on so there was a decent amount of IR sky glow leaking in.  The second is that there's actually something weird with the dark subtraction in PHD2 that I haven't had a chance to investigate in the code yet.  Turning dark subtraction off actually gives a much better result with this camera than attempting to use dark subtraction, at least in the visual display.  When I have time to dig through the PHD code further I may find out what's really going on. 

 

As far as USB C, I'd agree as long as it's at USB 3.0 speeds.  However, the need to connect in the dark is not really an issue for me, and frankly there's not much chance of having a problem with a USB 3 B style connector even in the dark.  For USB C you still have to hit the slot at the right angle.  All it eliminates is the +/- 180 degree flip.  I'd say the jury's still out on the long term robustness of a USB C connector, but the B style connector is pretty beefy.

 

Thanks,

 

Beo




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