Is the QHY5Lll better for guiding than QHY5llHi

[Guest]

Hi all,

I ask the question in the title because I want a good mono guide cam, I was going to get the QHY5ll with the larger sensor and larger pixels for guiding but I see now that the QHY5Lll has a 2x2 binning option which means it's pixels for guiding can be 7.5 microns square instead of 3.75, as opposed to the 5.2 square of the QHY5ll, so would the "L" version be a better buy now even though the sensor will always be smaller, but with the new binning option and the higher QE.

Regards

MM

[Guest]

Hi all,

I ask the question in the title because I want a good mono guide cam, I was going to get the QHY5ll with the larger sensor and larger pixels for guiding but I see now that the QHY5Lll has a 2x2 binning option which means it's pixels for guiding can be 7.5 microns square instead of 3.75, as opposed to the 5.2 square of the QHY5ll, so would the "L" version be a better buy now even though the sensor will always be smaller, but with the new binning option and the higher QE.

Regards

MM

Ignore the Hi at the end of the title I got ahead of myself...lol

[lensman57]

Hi all,

I ask the question in the title because I want a good mono guide cam, I was going to get the QHY5ll with the larger sensor and larger pixels for guiding but I see now that the QHY5Lll has a 2x2 binning option which means it's pixels for guiding can be 7.5 microns square instead of 3.75, as opposed to the 5.2 square of the QHY5ll, so would the "L" version be a better buy now even though the sensor will always be smaller, but with the new binning option and the higher QE.

Regards

MM

I guide with an ASI 120 MM which has the same sensor as the QHY5LII but with much better drivers. It works very well with my guide cameras of 50~80mm . Alternatively there is the choice of supersensitive but expensive Starlight Xpress Lodestar or the QHY IMGOH ( even more expensive) which uses the same sensor but has active cooling and the usual QHY driver problems.

A.G

[Guest]

I guide with an ASI 120 MM which has the same sensor as the QHY5LII but with much better drivers. It works very well with my guide cameras of 50~80mm . Alternatively there is the choice of supersensitive but expensive Starlight Xpress Lodestar or the QHY IMGOH ( even more expensive) which uses the same sensor but has active cooling and the usual QHY driver problems.

A.G

Thanks for that

But does not really address the question

MM

[Guest]

We'll I am amazed with all the combined knowledge on here that no one has an answer for me...............

[lensman57]

Thanks for that

But does not really address the question

MM

I don't have either of cameras but the sensor in the QHY5LII has a QE of about 74, the one in the QHY 5 was only about 50% so yes it is more sensitive and that is you want when guiding.

A.G

[Guest]

But the sensor is a lot smaller so won't that counteract the sensitivity, and by binning the other camera won't that make that more sensitive?

Regards

MM

Sent from my iPad using Tapatalk

[lensman57]

But the sensor is a lot smaller so won't that counteract the sensitivity, and by binning the other camera won't that make that more sensitive?

Regards

MM

Sent from my iPad using Tapatalk

Size of the sensor has nothing to do with sensitivity, you might be confusing this with sensor dimension as there is school of thought that says the larger the sensor dimension the larger the "full well depth" of the sensor. This argument is not relevant to guidingand applies to a degree to DSO imaging using cooled CCDs with exposures in to tens of minutes  per sub frame and the effect on the Dynamic Range. A larger sensor ie 1/2" format is preferable to 1/3" format if the sensor sensitivity is the same. In the case of QHY5 LII the extra 20% of sensitivity is so huge that there is no contest but this does not mean that QHY5 II is not suitable for guiding, quite a lot of people use this camera and the larger sensor does give you a wider FOV to find a suitable guide star . The QHY5LII also has a very limited ability to do some DSO imaging of the brighter targets too. Whichever camera you opt for make sure that you get the mono version if it is for guiding.

Regards,

A.G

[LouisJB]

Not sure about your original question, but my first adventure into guiding has been with the QHY5L-II colour and an ST80 and it's worked well so far.

I got this as it works out quite cheap i.e. it can be both a colour webcam for planets and a guider camera with inbuilt ST-4 port for guiding, in a reasonably priced unit. It picks up guiding stars pretty easily, even seen some galaxies on screen during guiding in PHD. I tend to use around 1s exposure time, adjusting either way if stars are saturated or dim, but generally is seems fine without much adjustment.

The field of view is quite small but the sensitivity means there's nearly always several stars available for guiding, no matter when you're pointing. Well I've not failed to find guide stars or guide so far. Most of the problems I've had are unrelated, like forgetting to recalibrate after slewing, clouds etc. This is my first setup, so can't compare with other previous models or alternative cameras and I've not got extensive experience in imaging, but thought I'd say compared to various horror stories I've read about with guiding, it seemed a pretty cheap, easy and relatively reliable way to guide and cost effective too.

[Scott]

Can't help with a comparison only ever owned the qhy5-II. It works a treat and I've never had a problem finding a star to guide on and thats with a 50mm finder scope. I'd imagine (though I don't know for certain) that the 2x2 binning option would be more useful when planetary imaging. There is also the option of getting a 0.5 fr for guide cameras.

http://www.altairastro.com/product.php?productid=16483&cat=108&page=1

hope this helps

[Guest]

Size of the sensor has nothing to do with sensitivity, you might be confusing this with sensor dimension as there is school of thought that says the larger the sensor dimension the larger the "full well depth" of the sensor. This argument is not relevant to guidingand applies to a degree to DSO imaging using cooled CCDs with exposures in to tens of minutes  per sub frame and the effect on the Dynamic Range. A larger sensor ie 1/2" format is preferable to 1/3" format if the sensor sensitivity is the same. In the case of QHY5 LII the extra 20% of sensitivity is so huge that there is no contest but this does not mean that QHY5 II is not suitable for guiding, quite a lot of people use this camera and the larger sensor does give you a wider FOV to find a suitable guide star . The QHY5LII also has a very limited ability to do some DSO imaging of the brighter targets too. Whichever camera you opt for make sure that you get the mono version if it is for guiding.

Regards,

A.G

So would the QHY5ll in 2x2 bin mode be more sensitive than the other camera in normal un binned mode?

[lensman57]

So would the QHY5ll in 2x2 bin mode be more sensitive than the other camera in normal un binned mode?

You do not need to bin the camera, as far as I understand binning is for focusing and imaging not guiding. with a short FL scope such as an ED80 a 50mm finder guider is more than adequate and at F3.4 is super fast and bright, there is no need to bin the camera. You may try it if you wish though and see if it makes a difference to your guiding. I have not had any problem finding guide stars using a 50 mm finder scope and the ASI, in fact due to its sensitivity I usually have to bring the gain down to a very low level otherwise I get the dreaded "STar Saturated" message in PHD guiding. As for your ST80 you would still be able to use either camera for guiding.

Regards,

A.G

[Guest]

You do not need to bin the camera, as far as I understand binning is for focusing and imaging not guiding. with a short FL scope such as an ED80 a 50mm finder guider is more than adequate and at F3.4 is super fast and bright, there is no need to bin the camera. You may try it if you wish though and see if it makes a difference to your guiding. I have not had any problem finding guide stars using a 50 mm finder scope and the ASI, in fact due to its sensitivity I usually have to bring the gain down to a very low level otherwise I get the dreaded "STar Saturated" message in PHD guiding. As for your ST80 you would still be able to use either camera for guiding.

Regards,

A.G

So what about when I want to guide through my 8" SCT @1260mm f6.3, and image through the 80 scope? I wondered whether binning would be useful then as I was under the impression that guide camera have larger pixels, so binning the QHY5Lll the pixels would be 7.5 microns square, much better I thought for guiding at longer focal lengths

This is new to me so sorry for all the questions, but I really need to choose the right camera for my set up

MM

[lensman57]

So what about when I want to guide through my 8" SCT @1260mm f6.3, and image through the 80 scope? I wondered whether binning would be useful then as I was under the impression that guide camera have larger pixels, so binning the QHY5Lll the pixels would be 7.5 microns square, much better I thought for guiding at longer focal lengths

This is new to me so sorry for all the questions, but I really need to choose the right camera for my set up

MM

With all due respect even seasoned imagers with access to astronomical quality instruments would run a mile at the thought of guiding with an SCT. There is no way that unless your mount is of the mega box brands that you'd be able yo guide with such a long focal length as there is not enough  accuracy in the mounts motors and gears to cope with such small corrections needed for guiding. The other way around maybe a possibility but only after gaining a lot of experince . A 50 mm finder guider is good for guiding up to 750~1000mm of FL and the ST 80 should cope with anything beyond. I would forget about guiding through an SCT for now. If you have to guide through an SCT then the only viable options are 1) an OAG with  loedstar guide camera  and 2) either a FLI or an SBIG CCD with onboard guide chip, but hold on to something before you look at the price of these. OAG is relatively affordable but there are problems such as occassional lack of guide star, crucial spacing of the FF/FR to the guide camera chip and getting the guide camera and the imaging chip parfocal. Most of us humble soles have enough trouble getting our guiding right using a 50 or 60 mm guider with an FL of 180~200 mm let alone 1200mm of FL. Sorry to be the beare of bad news.

A.G

[Scott]

This might be a very helpful thread for you. it's got loads of useful information...well worth a read

[Guest]

This might be a very helpful thread for you. it's got loads of useful information...well worth a read

Where's the thread???

[Guest]

With all due respect even seasoned imagers with access to astronomical quality instruments would run a mile at the thought of guiding with an SCT. There is no way that unless your mount is of the mega box brands that you'd be able yo guide with such a long focal length as there is not enough  accuracy in the mounts motors and gears to cope with such small corrections needed for guiding. The other way around maybe a possibility but only after gaining a lot of experince . A 50 mm finder guider is good for guiding up to 750~1000mm of FL and the ST 80 should cope with anything beyond. I would forget about guiding through an SCT for now. If you have to guide through an SCT then the only viable options are 1) an OAG with  loedstar guide camera  and 2) either a FLI or an SBIG CCD with onboard guide chip, but hold on to something before you look at the price of these. OAG is relatively affordable but there are problems such as occassional lack of guide star, crucial spacing of the FF/FR to the guide camera chip and getting the guide camera and the imaging chip parfocal. Most of us humble soles have enough trouble getting our guiding right using a 50 or 60 mm guider with an FL of 180~200 mm let alone 1200mm of FL. Sorry to be the beare of bad news.

A.G

We'll I have gotten 17 min subs ( for test purposes) guiding my SCT with the 80mm, so it's not that difficult, but I know it would be very very hard the other way around, so it would be best to guide my 80mm with the 50mm finder then?

MM

[lensman57]

We'll I have gotten 17 min subs ( for test purposes) guiding my SCT with the 80mm, so it's not that difficult, but I know it would be very very hard the other way around, so it would be best to guide my 80mm with the 50mm finder then?

MM

I would say so.

Regards,

A.G

[SnakeyJ]

I read a very interesting thread and debate on CN comparing the QHY5L-IIM and Loadstar for sensitivity, not quite the answer to the OP, but well worth a read nevertheless - http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5969048/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1

I've used mine with both Ascom drivers under PHD and the native qhy driver in PHD2 beta and had no problems with either, but then only guiding HEQ5 Pro at 900-1000mm with a piggybacked 70mm guidescope.

[Scott]

Where's the thread???

sorry

http://stargazerslounge.com/topic/188777-phd-guiding-basic-use-and-troubleshooting/

[Guest]

So what calibration step size in PHD would you use for this camera with pixels only 3.75 microns in size, I currently use 750 ms For my DSI with pixels of around 6x4 microns, so I guess I will have to reduce this for a much smaller pixel, is that correct.

Also the min motion movement in PHD would also need to change I guess as I use 0.15 but 0.15 of the larger pixel is a lot more movement than on the smaller pixel, so what would that need to change to, my guess would be around 0.45 ....any thoughts appreciated

MM