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Setup: 1000mm F/5 newtonian orion deluxe 50mm guidescope asi120mm-mini guide cam asi533mc pro ASIair Mini AVX mount My current guidescope gives a total guiding accuracy of around 1-2 arcseconds, which is okay, but enough for my liking; sometimes I have to delete some of my subs because the stars get a little deformed. I would like a guiding accuracy of at least a constant 0.5 arcseconds or smaller. And my guidescope also gets dew; I tried to stop that by putting foam around the place where the objective glass is, hoping that it somehow keeps the glass warm, but that didn't work; when I get dew on there, my guiding gets worse, between 3-4 arcseconds total guiding accuracy, and my most of my subs are junk when that happens. So I'm thinking of both upgrading the guidescope to something like an Orion ST80, or one of the Astronomics doublets, and getting a dew heater. One thing that I'm wondering about is how I'm gonna attach another guidescope to this strange shoe/mounting thing: (zoom in)  Or I can get an OAG, but then I wonder whether my stock focuser would be able to hold up my oag + guidecam + main cam and still not have tilt issues. Moreover, I don't use a coma corrector; can I still use an oag without a coma corrector? How do I simultaneously focus the guidecam on the oag, and the main cam? |
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When I upgraded my wide field scope to the Askar FR400 I started using my WO Z61 for a guidescope on my RC8 and noticed an immediate difference in guiding accuracy from the iOptrom iGuider that is built into my GEM45. This essentially tripled my guiding focal length. Without using my .65 reducer I am still probably not at the guide scope to OTA focal length ratio that most people prefer, but like I said, it made a huge difference. I did try an OAG with no success. Have not revisited since upgrading my focuser and learning to properly collimate my scope, but I don't want to mess with my current success. Oh yeah. I just looked up the Orion deluxe 50mm. Focal length is 162mm. I have always been told your guide scope should be at least 1/3 of your imaging focal length. And yes, I dewstrap everything, including guidescopes. |
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Hey I do not know the specifics about whether or not your focuser would be able to carry the extra weight of an OAG, that being said, it’s not super heavy. If you go with an OAG, you have several options. I have the ZWO OAG-L and the regular OAG with an added Helical focuser on. The latter was bought due to backfocus constraints in my imagetrain. You could also take a look at the PegasusAstro Indigo OAG - very slim design. You can without any issues use an OAG with a Comacorrector. I am currently doing exactly that. To get the focus right, your guidecam sensor needs to be exactly as far from the middle of the prism in the OAG as the sensor in your regular camera is from the prism. If you have a helical focuser, you could extend it half-way and drop you guidecam in there, and then do all the measurements to make sure you are within +/- 1mm from your focus, and then easily use the helical focuser to dial it in perfectly. If you choose to go with an OAG, you should definitely consider upgrading your guidecam to either an ASI220 or the ASI174. The latter has the biggest sensor and gather most light, as I understand it. I have the 120 and the 220 and I only use the 220 for my OAG. I can use the 120 with my regular guidescope when necessary. Look also for some of James Lambs youtube videos on OAG. They are really good. |
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I would like a guiding accuracy of at least a constant 0.5 arcseconds or smaller. Prepare to spend a lot more money on the mount, for starters. And then some... |
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andrea tasselli:I would like a guiding accuracy of at least a constant 0.5 arcseconds or smaller. Hahaha, true. Just prepare to spend a lot of money on anything and everything astrophoto 🤣 Whenever you pull on one end, money disappear on the other end 🤷♂️😃 |
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andrea tasselli:I would like a guiding accuracy of at least a constant 0.5 arcseconds or smaller. But that can't be difficult, with my mount, right? One or two times I was able to get 0.6 arcseconds guiding accuracy for like 10 or 20 seconds, but 10 or 20 seconds is obviously not long enough. How about a constant 1 arcsecond? That's fine for me. Can you guess for me, so I know whether an OAG is worth it, how good will my guiding get if I get a ZWO OAG and pair it with my 120mm mini? I mean, if I do a very precise PA, and there's no wind. |
1.51
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I used an AVX for a couple of years. I have always said it was the cheapest mount capable of "decent" guidance, but 0.8 to 1.0 is about as good as it gets. Starting with the cheapest modifications: 1. Focus your guidescope for each target. 2. Good polar alignment and balance , but keep the AVX pushing. DO NOT let it get ahead of the scope. The AVX can wiggle back and forth on the cogs if you let it. Your guidance pulses should all be PUSHING. 3. Shoot shorter subs. It only takes one of those AVX wiggles to ruin a 5 minute sub. You probably do not have a flexture problem, so an OAG will not help. The sweet-spot for your mount is probably about 120 to 300 seconds or less. With a CMOS camera that is plenty of time time for most targets. CS David Redwine |
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David Redwine: How do I keep the AVX pushing? I'm still a beginner when it comes to autoguiding, sorry if I sound dumb. |
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| And which dew heater for a 50mm guidescope? I want it powered by one of the ASIair's power out ports. |
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1.51
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Release the RA axis clamp and adjust the counterbalance so that the scope moves in the opposite direction of your target. This makes the mount "push" the scope. Do the same for the Dec axis. It may take a significant mis-balance to dampen the AVX oscillations. Do each axis separately. I can't help with the heater, sorry. CS David |
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Maybe tune up your avx to reduce backlash/better gear mesh? how long is your guide exposure? i’m guessing it’s the mount and not the guide scope. |
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| A dew heater would eliminate the dew problem. Any should work, you'd just need a cable that converts DC to RCA to use it with the ASIAIR. One problem you could have with that, is that I don't think you can modulate power with the ASIAIR Mini, so it'll be at full power all the time. Not really a huge issue though since it's for a guide scope. Beefier mount would certainly help. I would do something equivalent with an EQ6R Pro, I'm not really that familiar with other brands models, so I can't really recommend any alternatives. An OAG could certainly help if you can fit it in there, but if you go that route I would also upgrade to the next model up guiding camera, I think it's the 290mm mini. |
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Sean Mc: 1 second |
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| If I put a 2x barlow in the guidescope, will that make my guiding more precise? |
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| Maybe I should just get the ZWO OAG with helical focuser? Maybe that will give me the best guiding? I already have all the adapters to make that work for me, and I think I wouldn't need a dew heater. |
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Sean Mc: The gear train of the AVX is a bit fragile if you get the gears too tight , so go easy if you go this rout. I learned that lesson the hard way. The good news is that replacement parts are easy to find and not very expensive. CS David |
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| Also check to make sure your mount is level. Being off level will give it a lot of work to do, and I’m reading that the AVX doesn’t really like to have a payload over 12-15lbs for photography ¯\_(ツ)_/¯ |
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| Ditch the AVX, get something a little better, I'd suggest an EQ6R at minimum. You're probably not going to see much better performance from that mount. Improving your sampling isn't going to do much. I've had some nights as low as 0.2 on my EQ6s, and averaging around 0.4" rms most nights. It's a solid performer with a proven track record. |
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Brian Puhl: 0.2" is unbelievable; it must work like a dream! Imagine imaging galaxies with that type of guiding  Wish I had gotten an EQ6R, instead of the AVX, but I was too dumb at the time to know any difference between the two.I don't think I can ditch it. It's already strapped to a JMI dolly. I might ditch the newt instead, but I want to go after galaxies... Or, I had an idea, I could get a smaller newt that is more dedicated for astrophotography. Getting a smaller Newt and an OAG would help me in my guiding performance, right? My secondary mirror is too small and my focuser is way too cheap, and my spider vanes are way too flimsy anyway; I don't even get the normal cross shape in my diffraction spikes, neither do I see enough color in my stars, and my star cores don't even look right; moreover, my setup is so heavy and big that it nearly falls on my face when I try to take it down a step that goes to my backyard; if I didn't have enough muscle, I think I would be crushed long ago... |
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I might ditch the newt instead, but I want to go after galaxies... I think I missed that part, running an 8" newt. If you wanted to truly keep the mount.... I would suggest going to a smaller frac like the Meade Quad 70mm, or the newer version, the Orion 70mm Quad. They're very sharp scopes for their size. On top of that, they're light weight and won't succumb to the wind. I had one and I kinda regret parting with it. Sampling with your camera would put it at 2.2 arc seconds per pixel, which means you can have horrible guiding, up to 1.8" and it will still look sharp. It was so nice to never care about the wind or seeing conditions. It just worked. My honest suggestion would still be to upgrade the mount though. The mount is the most critical piece to success in astro. With the backlash that AVX probably has, you'll have issues with anything bigger than the Meade Quad.... I have two EQ6s and even on their worst days, they're still perfect with my Esprit 100s. |
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Brian Puhl:I might ditch the newt instead, but I want to go after galaxies... I'll stay with the mount. How about an FRA400 or an 80PHQ? How long do you think my exposures can be, for maximum sharpness, for those two? |
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I'll stay with the mount. I can't say for sure without looking at your actual mount performance. I've never had to reject subs for guiding performance. Proper sampling, seeing, wind, all play a performance factor in your guiding. You should aim for a guiding performance of 75% of your image scale or less. If your image scale is 2.0 arc second per pixel, then no worse than 1.5 guiding. Also, don't use RMS as the only indication of performance, because if your guiding spikes outside your image scale, you will have elongated stars, regardless of RMS |
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Don’t put a barlow in your guide scope. The more stars the better. I really don’t think the guide setup is the problem, I think it’s your combination of mount and scope. Now, just out of curiousity, i was having issues with my am5 and narrowed it down to the rubber feet being too squishy and allowing the whole setup to oscillate. I replaced the rubber feet with the spikes and my guiding got WAY better. |
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I did some things and my guiding accuracy is now a constant 0.6", and even down to 0.55" and some spikes up to 1.0", but no more than that, and I can do 180 sec subs with no problem (currently doing 60x180 seconds on the Pinwheel galaxy) 1. I rebalanced both RA and DEC; they were both out of balance, and I haven't tried the keep-pushing technique yet. 2. I built a dew shield for my guidescope out of cardboard and duct tape and it's working perfectly 3. I took a good bit of time trying to do my most precise PA ever, which was 4" on both axis. And although this is irrelevant to my guiding performance, I must say what an upgrade this was for my telescope: 4. You know how they make those primary mirror ring masks against abnormal star flaring, because of the mirror clips? Well, I made one of those, but for the telescope's front end, out of foam, and It works so nicely! I took a 60 second photo of Betelgeuse also, and I'll post it on my gallery. I guess my mount and scope combo is alright after all; I seem to have fixed my own problems without paying a cent for anything; all the foam and cardboard would have otherwise been thrown in the trash. EDIT: I guess my only problem now is the setup's weight |
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| I also recollimated my scope with a laser, and refocused with a bahtinov mask and my stars are looking nice so far. |
