symmetal

You shouldn't sync in the home position because the counterweight bar is in the wrong position for viewing near the meridian. The home position is a known starting position with the weights safely at their lowest position and that's all. If you unpark the scope and tell the scope to slew to polaris (or any object near the meridian) the RA axis will turn through 90 degrees so that the bar is horizontal. This is the position the scope needs to be in when you sync. However, never sync on Polaris anyway, as unless your polar alignment is 100% accurate the RA in particular will probably be significantly out. Always sync on objects well away from the pole to align your scope pointing. This would explain your RA being 90 degrees out in Eqmod. Alan

It would reduce the total volume of 'damp' air in contact with the desiccant so the slight increase in the humidity of the desiccant as it absorbs the moisture present would be less. I tested the camera after having been outside in high humidity for 24 hours and still no ice formed at -15C. I was going to leave it two days but there is high winds of over 60mph forecast tonight so I brought the camera indoors in case the roll off shed started rolling. There may be a slight air leak in the camera which could cause the desiccant tablets to eventually saturate but as long as I keep the camera in the sealed container with a big desiccant bag when not in use I should be OK. I'll remove the sealing plug from the side of the camera while it's in the container to hopefully remove any extra moisture the tablets have accumulated when outside. This will take a long time but as things are at the moment it'll be spending most of its time in the container. Now to remove the dust spots from the sensor. I've ordered these to place in the containers and jam jars holding the desiccant tablets/sachets/bags to check their dryness. The absolute reading may not be so accurate but should indicate any changes. They cost very little anyway. Alan

Cooled to -15C and no ice, but dust spots now on sensor and front glass. Spent ages yesterday trying to clean the glass but didn't do a good enough job. Will have to open it up again to clean the sensor. Before then I'll leave the camera in the shed with humidity around 90% for a couple of days and then check whether the icing has returned. My original query as to whether it's advantageous to use the desiccant in the fridge is a bit more complicated. The reason the RH increased from 24% to 27% when cooling from 19C to 4C is because the desiccant did remove the moisture from the cooling air trying to maintain 24% but the water content of the desiccant obviously increased, therefore the slight increase in RH at 4C. Removing the cooled box from the fridge and letting it warm to room temp it stayed at 27% RH as while the air RH would decrease with an increase of temperature the desiccant was releasing it's moisure back into the air as the air was getting drier than the desiccant. To get the benefit of fridge cooling you have to remove the desiccant from the box once it's cooled and then remove the box from the fridge to let it warm back up to room temperature. The RH in the box will then decrease, halving with every 10C rise. At 20C the box RH should be around 8 to 10% This also explains why the desiccant dried fine in the airing cupboard at 37C and 24% RH. It doesn't need high temperature just an environment with a lower RH. High temperature just dries it more quickly. So a camera with saturated tablets will dry the tablets if put in a container with dry desiccant as they try to reach an equilibrium but as the access air hole plug into the camera is small it will take many weeks I expect. Worth doing if the camera isn't going to be used for a long while. Fairly common around here. Alan

I think they disassemble the camera and re-apply the sealant around the sensor chamber reading some replies on the ZWO forum. Luckily my 1600 has never had icing problems in over two years even cooled to -30C and it's spent weeks on end in high humidity on the pier outside. If it's 100% airtight there shouldn't be a problem but it's a bit hit and miss as to whether they are. If my 071 is OK after my last fiddling, I'll leave it outside for a few hours in high humidity and try again. I'm not too hopeful but may be surprised. Alan

Tried again. Ice started forming at -4C. Opened up the camera and the internal tablets were pinkish so they were setting the internal humidity and not the outside, so putting everything in the fridge was a waste of time. The camera sensor PCB is sealed from the outside air by silicone like sealant between the black vanes and the red front panel. The ribbon cable from the sensor pcb to the rear PCB passes through a slot in the red front panel which has black sealant around the ribbon cable to hopefully make it airtight. The front window panel is screwed onto the sensor panel with six screws and a large O-ring to form a seal. I suspect one of the seals is leaking so the outside air has access to the sensor chamber as the new tablets went pink so quickly. I've put all the tablets in the oven at 130C for a couple of hours and the opened camera with the sensor exposed in a sealed container with a fresh unopened bag of desiccant. Reading 24% RH at 19C in the container. The same as my airing cupboard drier so it looks like the airing cupboard does dry them well although it takes at least a week to do so. I'll put the cooled roasted tablets in the camera, seal it up and and try again. If I get icing again after a day or so then there is a leak somewhere. In that case hopefully it can go back for an exchange or repair. Alan

Camera been in fridge for about 5 hours. Temp 3.6C and RH is hardly changed at 31%. as I'd hoped. A drop of 24C and only an increase of 7% RH. Without the desiccant in the sealed container the RH would be 100% as the dew point would have been reached. I'll leave it another day in the fridge so the air in the camera can reach the same RH and then put the stopper seal in the side of the camera quickly while it's still in the fridge. The dew point in the camera should be -12C so fingers crossed no ice. When warmed to room temp the RH in the camera should drop to around 8%. Assuming no air leaks. The spanner in the works may be the tablets already inside the camera and whether they will release any held moisture back into the camera. I suppose I should have removed them and given them a blast in the oven or microwave first but wasn't sure if the fridge trick would work. I'll report back. Alan

They are left just above a tube heater in the airing cupboard and after a week the FLO sachets are a golden brown and the Pingi 250g bag is blue. I put three temp/humidity meters there (two are mechanical hair hygrometers and one electronic) and they all read 37C and between 21 and 26% relative humidity. The sealed box was then kept higher up in the cupboard at 27C. Little change in camera icing. For the last day I've kept the box in a cooler room of the house at 19C. I put the hygrometer that read 24% at 37C in the box and after an hour it reads 27% at 19C. This seems to confirm pretty much your stating that the desiccant just maintains its conditioned relative humidity. This is good as it means the box at 19C has around a 1/4 of the total free air moisture than if the box was at 37C. A rule of thumb is the RH rises by a factor of 2 for every 10C drop in temperature assuming conservation of the absolute moisture. At 27C and 25% RH (where the camera was stored for 4 days) the dew point is 6C so probably explains why the camera experienced icing . At 19C and 27%RH (where the camera currently is stored) the dew point is -1C. This is better and the ice may not form so quickly. If I stored it in the fridge at 4C and the RH stayed at say 30% the dew point drops to -12C. Woohoo! I'll try the camera in the fridge and see if the RH stays low. My current rise of only 3% RH for a temp drop of 18C suggests it will. I'll do a test with a Pingi bag in the microwave as Julian suggests then seal it with a hygrometer and see what the RH is compared to my airing cupboard heater method. I'll also test if over time a dry desiccant bag will partially dry out a 'wet' bag if they are sealed in together and whether they both then reach the same state or will the 'wet' one always stay wet until it's forcibly dried. This would save me having to open the camera again to remove the tablets to dry them. Alan

The ice is in focus so is on the sensor. The camera has a dew heater built in to warm the sensor window. It doesn't start forming (being visible) on the sensor until -2C or so I hoped being in the fridge at 4C the desiccant would still absorb it while it's in the air and before it starts condensing on the sensor. Shining a torch in the camera it's very difficult to see any ice or moisture present. It's only really visible when taking flats, or having stacked and stretched the images. Small halos around bright stars also indicate there's a problem. The desiccant works down to -20C or so when used in the freeze drying process so being in the fridge shouldn't inhibit it working. This previous thread shows the images. I started a new thread as the question was a bit different and more people might look at it. Alan

Still having icing trouble with my ASI071 after 4 days in airing cupboard in sealed container with loads of desiccant. I'm thinking would it be better putting the sealed container in the fridge at around 4C as that would make the air release more moisture, to be absorbed by the desiccant. 30% humidity at 4C contains less water than 30% humidity at 25C. When cooled to -15C there should then be less moisture to freeze on the sensor. Does that sound reasonable? Alan

This gives the wiring for the EQ6 D9 connector for the EQDirect cable. Alan

Yes, they are 5V and 3.3V 1A regulators. They are the commonly used AP1117 series of low dropout regulators. The ones you have are made by Diodes Incorporated. Here's the data sheet. Page 6 shows the markings corresponding to yours which are the SOT223-3L package version. Several manufactures make them. You don't need to use the DI manufactured ones. It's worth checking electrolytics around the ICs for shorts and any possible inductors connected to their input terminals for showing signs of overheating. It's common for the 3.3V regulator to be fed from the 5V regulator output and for the 3.3V regulator to use 6.3V electrolytics. If the 5V regulator goes short in to out the 6.3V electrolytics will also fail and possibly also go short. The NO5A marked regulator in the handset is a similar 3.3V regulator, the LM1117 series made by Texas Instruments. The handset 17-50 will be a 5V regulator, not sure of the manufacturer. Good luck. Alan

Having stacked in Astroart and quickly processed with Startools the Andromeda image does show the effects of icing. The dithering tended to break up the streaks and they appear more as coarse blotches predominantly at the top. The full size crop shows it more. The icing is also probably to blame for the halos on the bright stars. ASI071MC + RedCat51, 31 3 min subs. There is some RedCat coma on the left but not enough to worry too much about. Used uncooled flats. Camera now in food container in airing cupboard along with Lunt diagonal and stack of desiccant ready to try on the next clear night, whenever that may be. Alan

Good luck with the move Brian. I'm a mile from the North coast between Port Isaac and Tintagel. Bortle 3 or better. Away from the major towns the skies should be fine. As you say the North coast is more wild, generally having harsher weather and rougher seas compared to the South coast. I'm fairly high up at 190m so seems to attract any fog/drizzle that is around too. Alan

Another set of excellent detailed images. Alan

You must be right Allinthehead, although a very heavy stretch on the images doesn't show ice streaks like the flats. I'd have thought the ice would also act as microlenses/prisms so would also give random misshapen stars. I did change the internal tablets a month or so ago and the camera is kept indoors attached to the scope when not in use. I did use the screw on adapter with the desiccant tablets before I changed the internal tablets. The 071 doesn't come with the adapter but my 1600 did. The 071 chamber is meant to be airtight but it seems it's not. I'll try keeping the camera in a tight lid food container with a desiccant bag or sachets when not in use. Probably better to leave the adapter plug off initially to enable quicker drying. Alan

But why does it only appear when used with the flats panel. Icing like that would show up on all images wouldn't it? Alan

Had first proper use of the ASI071MC yesterday for a few hours without the moon since I bought it a few months ago and got 48 3 minute subs of M31 which looked very promising on quick stack and stretch. Tonight as it's cloudy again, as usual, I went to take the darks and flats. Used my Huion display balanced on top of the scope with two sheets of ND filter, to get exposure of 0.4s, like I do with the ASI1600 and Atik One without issues. As soon as the cooler went below 0C the flats showed streaks like icing. The cooler it got the more severe the streaks. Here's a screen grab of SGP of a complete flat at -14C and one uncooled at 6C. The histograms however do look very similar though the 'icing' peaks are a little wider. I've stretched the brightest bump as that shows the effect most. It's a colour camera, hence the three peaks. All the 'flats' were taken at 0.4s exposure. Ignore the 0.004s in the screen grabs. I just loaded the images into my desktop SGP to show the effects. The anti-dew was enabled to heat the sensor window. Flat at -15C Flat at +6C I'd already replaced the tablets in the camera. To remove the camera to look at the sensor I had to warm it back up and disconnect it as it's all screwed together on the scope. Hanging in the air I cooled it back down to -15C and the sensor looked fine with no visible icing. I let the camera look at the ground which was lit by the Huion panel and took another 0.4s exposure. It was very approximately a similar shape to the real flat but showed no 'icing' streaks at -15C. Here it is with a similar stretch to the others. Ground 'flat' at -15C Put the camera back on the scope with the flats panel. As soon as the camera was cooled below 0C the streaks appeared again like in the first picture. Can anyone explain this? Is it icing or something else. The subs I took yesterday of Andromeda at -15C show no visual evidence of icing. Alan

Some open star clusters as opposed to globular clusters can be quite large so may be more suitable to image. Alan

The moonlight increases the level of the sky background, so can be considered as light pollution, though over pretty much the full light spectrum, as opposed to urban light pollution which is generally concentrated in narrower width peaks. Any imaging object which is fainter than the sky background at that light wavelength will not be visible as the sky background will swamp it. The recogizable stars that form star clusters will, on the whole, still be brighter than the sky background so can be imaged successfully. Fainter stars may not show however. Moonlight can give rise to noticeable gradients, though these are easier to correct on images which just contain stars. The spectrum of moonlight, which follows fairly closely the light spectrum of the Sun exhibits a dip at the wavelength of Ha (656nm), which is why narrowband Ha imaging can be performed in moonlight with good results. Narrowband OIII at 501nm and SII at 672nm don't have similar dips so are more affected by moonlight. Alan

The halos and multiple diffraction spikes are unfortunately due to condensation, possibly on the main mirror. The star shapes as you say look pretty good. Very slight elongation but not enough to worry about at the moment. There is possibly slight coma on the bright corner stars but this may be just due to the condensation. In your processing you've black clipped the background so have probably lost any nebulosity which was present, though it was probably masked by the condensation artefacts anyway. Good start anyway. Alan

You could ask the seller I suppose or know someone who already has one. The one that Dave linked to does have very bright edges implying this may be where the leds are. If the individual dots were leds I would expect them to be brighter than the edges of the panel which would not need or want leds. Alan

I have an A4 and a A3 Huion LED Panel which have very even illumination. I did buy a cheap A5 one, similar looking to the one Dave posted for my RedCat 51 and the individual leds were just little perspex prisms. The leds were under the black strip on the left so the panel naturally had a noticible gradient left to right. The larger ones may use actual leds but it's best to check. Alan

It will work putting them on a radiator but it can take up to a week for them to turn yellow brown. As this doesn't work in the summer, I thought of utilising the 60W tube heater on the floor of the airing cupboard. The hot water tank had been removed and the heater does a good replacement job. I just placed a perforated aluminium place above the heater and keep the sachets and tablets on the plate. Again it takes a week to dry them and just leave them there until needed. I happened to change two sachets yesterday from my FLO eyepiece caps which are the green ones. The Zwo tablet bag is actually open in the picture. Alan

Click your user name top right and select Profile. Then click the symbol in the bottom left of your photo that's displayed next to your username to choose another one. Alan

Yes, it does depend on the camera pixel size as to whether the Powermate or Barlow with the 60mm Lunt will give extra detail. The ASI174 as used by Merlin66 with its large pixels certainly would and the ASI1600 and ASI120 with more 'medium' size pixels would also gain some. 'Glad' someone else also had them. Thought I was the only one, when using a Powermate. Alan