What are typical setting for a Grasshopper3 camera?

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What are typical setting for a Grasshopper3 camera?

Post by OTangen » Thu Apr 23, 2015 5:30 pm

Hi!

I just came home from NEACI/NEAF with a Grasshopper3 GS3-U3-28S5M. (Great event, by the way) It seems like this is the most common Grasshopper3 camera used by the solar community. I use FireCapture for acquiring the images on a Lunt 100 DS. Can someone tell me typical settings as far as gain, shutter speed and gamma is concerned.
Increasing the gain naturally gives shorter exposure time, freezing the seeing better. How much can you increase the gain without adding noise to the image?

Best regards
Oivind Tangen, 60N 10E

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Thu Apr 23, 2015 8:42 pm

Hi Oivind - lucky you!

I have the Lunt 100 SS and the Grasshopper model you mention and use FireCapture so here is my advice:

Gain: set to minimum and NEVER CHANGE IT
Gamma: set to 100 for most subjects. I sometimes drop down to 950 for CaK and White light or up as far as 1200 when capturing both disc and proms together. Some people report getting artefacts if they go above 1050 or below 950 but I sometimes work outside those limits and get good results (try 800 for dramatic disc detail).
Shutter: whatever you need to get approx 80% on the histogram. I find myself somewhere near 1-5ms for the LS100 in SS mode?

If your computer can cope, switch on 16 bit mode and capture ser files. This gives a wider dynamic range and will allow you to capture disc detail and proms in a single go rather than combining two shots taken at different exposures.

Others may give different advice but minimum gain, gamma=100 and exposure for 80% histogram is a pretty good starting point for your own experimentation.

The Grasshopper has much less noise than other cameras I own and I find that capturing 300 frames and stacking the best 20 in Autostakkert works very well.

Depending on the power of your computer, you may find that it struggles to keep up with the capture speed, especially at max resolution.
I find that the Ram Disc option in FireCapture helps - if you don't already know, it pre-allocates 'empty' frames before starting the capture sequence.

Good luck and post your results for us to admire.
.

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Re: What are typical setting for a Grasshopper3 camera?

Post by swisswalter » Fri Apr 24, 2015 4:33 am

Hi Oivind

me too I have the GH3/LUNT100 combo. I never touch gain, sits at 175. I play with gamma around 600 - 1000, for proms around 1200 and get shutter speeds around 1-20 ms
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Re: What are typical setting for a Grasshopper3 camera?

Post by OTangen » Fri Apr 24, 2015 10:09 am

Thank you for replies guys!

I will try the suggested settings and keep you posted. Here is a link to the images I took yesterday in bad seeing conditions. I hope that the details will improve when the seeing is better:

http://www.knuttangen.no/astro/index.ph ... 113721_utc

http://www.knuttangen.no/astro/index.ph ... Exposure-5

http://www.knuttangen.no/astro/index.ph ... e-5_104410

As you can see on the two last images, I included some of the imaging parameters in the filename. The gain is, as you can see way too high, according to your recommendations and I will try to lower the gain to minimum when the skies will cooperate again.

I met a few English guy at NEAF, Michael Hattey from Starlight Xpress, Gordon Haynes at Televue and people from Atik. Very few if any English were there as visitors. You should come over on time, we have a great solar star party setup on the lawn outside the exhibition with a variety of solar instruments. I have been there since 1999 almost every year and can't stop. I have got many good friends over the years.

Best regards
Oivind Tangen

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Fri Apr 24, 2015 11:31 am

Pretty good first set of images.
I have never found it necessary to move the gain from its minimum setting with any combination of scopes/filters.
Using the Quark to double stack the LS100 puts the most strain on the system but even then, the 38ms exposure allows me to get reasonable results:
LS100 Quark Grasshopper.jpg
In really poor seeing it might be worth exploring a slightly higher gain setting to get shorter exposure hence 'freezing' the seeing but I'm not convinced from my own experiments.
With my new 152mm refractor plus Quark, I'm getting sub 1ms shutter speeds which some people say will produce artefacts but........ so far it seems to work pretty well.
In my humble opinion, the Grasshopper is a fantastic camera and has done far more to improve my images than any other change of scope or filter. I'm sure that you will love it.
.

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Re: What are typical setting for a Grasshopper3 camera?

Post by clearestimage » Fri Apr 24, 2015 11:48 am

At the moment I use DMK cameras for solar capture (DMK21AU618 and 51AU02) but after reading the specs of the Grasshopper 3 I'm wondering whether I might be better off with one of those.

I did have a USB Flea3 camera but found it very difficult to find software that would work with it other than PGs own software (FlyCapture) but that had an issue with file sizes that I got fed up with.

Is it preferable to use lower (eg 12-15) frame rates or higher (60 plus)?

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Fri Apr 24, 2015 12:27 pm

That is an interesting - if rather controversial - question :lol: :roll: :lol:

Many people suggest that more frames per second (or do we mean shorter shutter speed......or both?) give you a better chance of 'freezing' the moments of good seeing.

I have used DMK21, DMK41, ZWOASI120 and now the Grasshopper for solar (Ha, white and CaK) in an area where 'good seeing' happens very rarely. My conclusions may (will) be different to those drawn by people who have the luxury of good to excellent seeing and say that 12 frames per second is plenty".

As with most things, its not a simple situation and many factors will influence your final decision.......... here are a few observations based on my experimentation which might start you off:

The Grasshopper is more sensitive and less noisy than my DMK cameras. This means that my old work-flow of capturing 1000-2000 frames and stacking the best 100 is no longer appropriate. This is just as well as the large sensor (1920x1440) and higher frame rate (approx 26fps at full res) put a real strain on my computer and the hard drive struggles to keep up with the data flow. I now capture 300 frames and stack the best 15-20 using Autostakkert. This gives a very low noise result which will take enough 'wavelets' or other form of sharpening without the image starting to break down.

I don't find the full resolution of the Grasshopper is needed for most of my work; I prefer to drop down to 1280x960 and capture at about 30fps which seems to give me pretty good results even in poor seeing.

The Grasshopper is totally free of Newton's rings - one of the major reasons for me buying one as they drove me insane with the ZWOASI120 (a pity as it is a very nice camera in most other ways). Newer CMOS cameras like the ZWOASI174MM seem to have reduced the problem to an easily manageable level although users report different experiences............ may depend on their equipment/seeing/work-flow etc. Barlows and especially Powermates seem to be the cause of most problems?

Cameras like the ZWOASI174MM give even higher frame rates for about one third the cost of the Grasshopper and they now seem to be the 'camera of choice' for many solar imagers.

Both the Grasshopper and the ZWOASI174MM work very well in the latest version of FireCapture although they will both put much greater demands on your computer than the DMK cameras. At a minimum, you will need usb3, a large and fast hard drive and a reasonably up to date cpu if you are to make the most of the technology. Some people use a solid state drive to cope with the data flow rate. I find that my hard drive can just about keep up when I ask it to capture a long series of 300 frame ser files at 1280x960 and with a 20 second gap between captures (my usual time-lapse capture routine using AutoRun in Firecapture). Size also matters as I often capture 350GB of data in a single imaging session!

Hope some of this helps :roll:
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Re: What are typical setting for a Grasshopper3 camera?

Post by KMH » Fri Apr 24, 2015 7:09 pm

Mike,

I have the same set up and am now very eager to try your advice. Maybe I've been too quick to increase gain rather than exposure with my 2.5x powermate, figuring I needed < 8 ms or so the freeze the seeing (which is typically not too good here either).

Also, if you keep 20 shots out of 300, what does that correspond to in AS2! scoring? I generally take the top 25%, however many that may be, but haven't quite convinced myself that that's optimum.

Thanks,
Kevin

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Fri Apr 24, 2015 10:58 pm

In the latest version of Autostakkert 2.1.5.7 you can specify the actual number of frames to be stacked OR the percentage.
In fact, you can enter a number in up to 4 different boxes and AS2! will produce a stack for each number specified - very useful if you want to explore the effect of different stack sizes.
When I first got the Grasshopper I continued to use the 'capture 1000, stack 100' routine that I used with my DMK cameras.
It took me several runs of AS2! using stacks of 100, 50, 30 and 20 to be convinced that not only is 20 frames enough to avoid noise BUT that in poor seeing conditions the smaller number of 'good' frames can actually produce a better result.
In really bad seeing the rule seems to be 'capture a lot of frames and only stack the very best'. I find that capturing 500 and stacking 15 will often get me something reasonable even in really poor conditions.
.

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Re: What are typical setting for a Grasshopper3 camera?

Post by OTangen » Tue Apr 28, 2015 9:27 pm

Hi Mike!

I have now tried to reduce the gain of the Grasshopper (using Firecapture) to 175. But since I am running a double stacked system the image gets way too dark for me. Using only one filter it works fine, but if I use the DS I end up with exposure times in the order of 30 ms and that's too slow to try to beat the seeing. I ended up using numbers around 275 for disk images and for very weak proms I had to go close to 1000. I will experiment with the figure to reduce the amplifier noise as much as possible.
For general interest I can mention that Lunt had a new Heat Rejection filter at NEAF (the red filter in front of the the DS unit) that takes care of the glare when stacking the two filters. It almost reduces the glare to zero. According to Bryan Stephens, chief engineer at Lunt, is reduces the pass band throughput by 40%. That is negligible for visual work and can easily be compensated for doing imaging. I bought one and it works beautifully in my scope too. I paid $ 160 for it. Definitely worth it in my opinion.

Best regards
Oivind Tangen, 60N, 10E

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Tue Apr 28, 2015 9:36 pm

Those are very long exposures Oivind - as long or longer than I need when double stacking with the Quark which surprises me. I don't think I'll be getting the LS100 DS any time soon.
It would be interesting to know what exposures other people with DS systems are getting?
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Re: What are typical setting for a Grasshopper3 camera?

Post by swisswalter » Wed Apr 29, 2015 4:25 am

grimble_cornet wrote:Those are very long exposures Oivind - as long or longer than I need when double stacking with the Quark which surprises me. I don't think I'll be getting the LS100 DS any time soon.
It would be interesting to know what exposures other people with DS systems are getting?
Hi Mike

my LUNT100/Quark combo works around 5-10 ms. Just the etalon of the Quark, TZ removed
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Wed Apr 29, 2015 9:44 am

Hehehe.......... I knew you would have it apart eventually Walter.

I remove the LS100 blocking filter and simply insert the Quark and get approx 30ms?
I had thought of trying it out WITH the LS100 blocking filter but without the first filter in the nose of the Quark but - not sure how it would work.
I assume you are using it WITH the Lunt blocking filter in place and removing both the first Quark filter and the telecentric?
.

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Re: What are typical setting for a Grasshopper3 camera?

Post by swisswalter » Thu Apr 30, 2015 4:27 am

Hi Mike

yes that's the way I worked with it. I found the best results with that combo I got are with the Quark set to the very red end
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

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Re: What are typical setting for a Grasshopper3 camera?

Post by grimble_cornet » Thu Apr 30, 2015 6:17 am

Thanks Walter - I'll give that a try.
.

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Re: What are typical setting for a Grasshopper3 camera?

Post by OTangen » Thu Apr 30, 2015 9:40 am

Hi!

Does anybody know if it is safe to remove the red ERF in front of the DS module on a Lunt100? Since I get so long exposures when double stacking I thought that I might get a brighter picture if I removed this filter. Or is it only reducing the infrared portion of the spectrum and does not affect the Ha band.

Most of all I want to have a safe setup that does not burn the camera. I never use it for visual.

Best regards
Oivind Tangen 60N, 10E

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Re: What are typical setting for a Grasshopper3 camera?

Post by Montana » Thu Apr 30, 2015 2:10 pm

I think Bob Yoesle has done this on his Coronado DS filter. You might have to ask this on the solar modification section.

Alexandra

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