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Everything posted by Gina
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Eyebolt arrived today and I've been out to the observatory and fitted it. Seemed too short at first but I managed to get a couple of threads engaged without a washer and tightened the nut until the eye was at the right level for the pin. Now about three-quarters of the threads nut in the nut are engaged with the bolt. May be enough. There is a nice clearance between the pin and the eye and it clears. This is adding no extra to the force needed to open the roof. There is a bit of binding of the roof on the top of the SE corner post so I shall have to shave that a bit.
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Back to the "Economy" version... I have found RPi GPIO lines for PWM0 and PWM1 which I assume will drive two small server motors using a 1K resistor to protect the RPi. Then I went on to see if I could find out how to drive servos via PWM with INDI and drew a blank. I'm sure this is quite simple but Google couldn't find it. @RadekK maybe you have the answer as an INDI expert, please. Now I'll go back to the WiFi problem...
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Not actually raining this morning though overcast and damp. Been out searching for that front lens element but nothing! Even searched the pond, though I guess my hand moving the water might move the lens away from my hand. I could only search for a couple of minutes as the water was very cold. The reason for bothering to search is that I think there's a small chance that the lens element may be undamaged - just popped out as the damage to the lens casing barely reaches where the lens element was.
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The weather forecast is certainly not promising for the next 5 days - rain, rain and more rain. This is one of those times I'm hoping they're wrong!
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Having said I can only afford the "Economy" version, I'm thinking I'm not going to be satisfied with second best but I'll test what I've got. I might buy one of the used Fujinon DF1.4HB-L1 fisheye lenses though there might be a more suitable lens. I might go for the ASI 178MC camera rather than the ASI 385MC for it's larger sensor (assuming the DF1.4HB-L1 lens). I already have the mono version that I could try pro tem.
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Here's a daytime image but clouds are not best for assessing focus that will have to wait for a clear night sky. This is with an exposure of 64µs and the aperture control around half way. I have adjusted the focus by hand with the rig pointing out of the window. I can see the chromatic distortion around the edge of the image that I remember with this lens. Stars show as separate RGB pixels around the edge. This didn't happen with the other lens but they are several hundred pounds new and even £65 used. Being an OAP I have to go with the "Economy" version! ?
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Seems the RPi can handle servo motors alright just using PWM and I see no reason why I can't write an INDI driver to control it (or rather modify one I've already got). These servo motors look suitable :- MoPei 2Pcs MG996R Servo Metal Gear Digital Servo for Helicopter JR RC Car Boat Motos I might be able to use one for focussing too.
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Here's a photo of the Fujinon zoom lens. I would like to control two functions - focus and aperture. I can sort out the mechanics to drive the focus pin with a stepper motor but the aperture would only need two positions I think - fully open and about half closed. I guess a stepper motor could be used for this but under conditions of power loss the actual position can become uncertain. Another possibility may be a servo motor but the "9g micro servers" I've tried in the past have been very unreliable so I would need to find something better. I shall also need to check if I can control one of these with the Raspberry Pi and INDI driver. I'll have a read of my Raspberry Pi handbooks.
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No. Nothing is ever final with me! ? At least until they take me off feet first!
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I doubt these lenses have a short enough focal length to cover the whole sky.
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A top end ASC for nighttime might employ a Fujinon DF1.4HB-L1 fisheye lens and ASI 385MC-Cool with provision for taking the air supply through an air duct from inside the observatory. The "Cool" version of these cameras adds another £300 to the cost - overall, not much change from £800 depending the cost of other parts.
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So much for my "Ultimate" ASC. More like "Economy" now!! With a totally different design.
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R.I.P. "Gina's Ultimate All Sky Camera"
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I see two options for an ASC for nighttime use - a moderate priced one with the Fujinon zoom lens and ASI 120MC-S or a high priced version with the Fujinon DF1.4HB-L1 fisheye lens and ASI 385MC. I was using a similar setup with the ASI 185MC, now superseded. The higher priced rig would cost well over £400 and I can't afford that (unless I were to sell astro gear). A disadvantage of the ASI 120 is that the minimum exposure is 64µs whereas the more expensive camera are 32µs which is just workable for daylight. However, the zoom lens has a crude aperture control with just two leaves forming a diamond aperture when not fully open. It also closes completely. So overall, it seems the zoom lens is the one to go for ATM. If my finances improve I might go for the high cost setup later.
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Yes. Or I could solder wires onto the pins. Or it might just see if it's alright with just a USB plug as it's working at present on the table.
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Some good news - the ASI 120MC-S camera works ? The bare pins on the USB3 port are making contact with a USB2 plug.
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I've dug out my Fujinon zoom lens which is a 1/3" lens rather than the Fujinon DF1.4HB-L1 1/2" lens and easily covers the whole sky. The problem with it is poor resolution near the edge of the image. I'll try it - the ASI 120 is lower resolution than the ASI 178 I tried it with before.
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Looks interesting though I'm rather surprised if a 1.55mm lens gives 180° sky coverage with the ASI 120 when my 1.4mm lens didn't quite. I like that it has focussing though. The ASC image above was with the ASI 185MC camera which has a bigger image sensor.
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Focal length is too long - they don't cover the whole sky. I have the 150° lens already - came with the ASI 120MC-S camera. I have a good clear site and apart from N-NW have views mostly down to horizontal.
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Yes indeed. I won't call anything "Ultimate" or "Final" ever again!!! Needing a whole new "group thinking" on this I have passed it over to the main discussion forum DIY Astronomer.
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Following on from my Blog - Gina's Ultimate All Sky Camera - and the catastrophe in which the lens and USB port of the ASI120MC-S camera were destroyed, I now need to rethink the whole ASC. The lens is/was the Fujinon fisheye 1.4mm FL f1.8. This is an excellent model of lens though with a problem of no provision for focussing other than unscrewing the mounting a bit. There is also no aperture control. I've done some searching for fisheye lenses and some cost hundreds of pounds. A replacement for the Fujinon would cost £65. I can see why commercial ASCs cost so much. Hence I'm open for any suggestions, please.
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I now need to think about how I proceed. I have missed my ASC since I haven't had one working so I don't want to give up on it but it seems calling this version "Ultimate" was a mistake.
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Been searching the ground all around where the rig fell and haven't found anything. The lens element has totally vanished. It could be in the pond I guess but I'm not dredging that!
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The cheapest I can find a replacement lens is £65 ?