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Btw above graphs were taken from here: https://www.dxomark.com/Lenses/Canon/Canon-EF-50mm-F18-STM-mounted-on-Canon-EOS-760D---Measurements__1011

Is that corner of the frame or whole image? Take a look at this review: https://www.youtube.com/watch?v=PoFsXaXKetI Also take a look at this: sharpness at F/4 vs sharpness at F/5.6 That lens is best used at about F/5.6 (as noted in video above)

I think that total cost of basic motorization of EQ5 - meaning just RA stepper + belt and pulleys, arduino and stepper driver will cost less than 50e There is some soldering required and some programming - but I think you can find many examples online. Look at these links for example: http://www.buolxloud.com/?page_id=178 https://www.cloudynights.com/topic/636559-building-a-diy-motorized-control-for-a-skywatcher-eq5-mount/ Best thing with this is that it can be upgraded later - you can reuse Arduino and stepper motor and add another stepper and turn it into GOTO + guiding platform down the line

How good are you with DIY projects? You can easily turn regular EQ5 into motorized EQ5 with addition of stepper motor and arduino based controller. Depending on how complex you want that to be - you can end up with full goto + guiding capability. Check this out: https://onstep.groups.io/g/main/wiki That will be more than enough to get you going with DSLR+Lens or even DSLR + smaller scope.

It was probably that and the way they separated mold from concrete. In any case, I decided to go with steel pier, but all of that is going to wait for spring next year.

Oh, this is bino discussion Disregard my post above - I thought we are talking about scopes. Don't know much about binos.

Depends on use case scenario I think you have something mixed there. Let's first get our term straight. APO is currently used to usually denote triplet lens. It means apochromatic performance - or "color free" performance, and in reality - only good triplet lens provides true apochromatic operation in each use case scenario. ED/SD is doublet scope - one that has good color correction due to exotic types of glass used. ED/SD doublet is in essence achromatic scope - except for used exotic glass types that help eliminate most of chromatic aberration. Some of ED/SD doublets are apochromatic as far as visual use. Where they fall short is photographic use as cameras tend to be more sensitive to wavelengths that cause CA issues - deep red and violet (long and short wavelengths). If you plan on using scope for visual only and for low power - then go with ED/SD doublet and faster one - like 100mm F/6 model, or 100mm F/7 model with FPL-51. These still have some chromatic aberration left - but you won't be able to see it unless you look at bright planets at high power (not something that you'll do if I understand correctly). If you want good all round scope - for both DSO and planets - get FPL-53 doublet with a bit more focal length - like F/8-F/9. Like any doublet - slower the scope less chromatic aberration will be visible. If you want all around scope for visual and photo, or you want color free faster scope that is also capable of planetary views - go with F/6-F/7 APO triplet. Triplets cool slower than doublets and that is one of the reasons why people prefer doublets for visual.

Best bang-for-buck in APS-C size would be second hand DSLR body. Even new - mirrorless type APS-C camera will be comparable in price with smaller sensor dedicated astronomy camera. https://www.amazon.co.uk/Canon-M200-EF-M-15-45mm-3-5-6-3/dp/B07YBP7S77 That is £400 - which is cheaper than 1" ASI183mc https://www.firstlightoptics.com/zwo-cameras/zwo-asi-183mc-usb-3-colour-camera.html at £520 and in same range as say ASI485mc (but with x4 larger sensor)

I have ES82 6.7mm, ES82 11mm, ES62 5.5mm. To me - with my scopes these are all good. Not every scope / every eyepiece combination works though. For example - both 5.5mm and 6.7mm are too much for my F/13 4" Maksutov. For that one I wish I had 8.8mm ES82, or maybe 9mm ES62. With F/10 4" refractor - all are good, but 5.5mm will depend on seeing on particular night. With F/6 8" newtonian - 11mm is really not planetary EP and I would use it barlowed. Other two are excellent. If you want really good planetary eyepieces with plenty of eye relief then either look at Vixen SLV line if you can tolerate narrow field of view. For larger FOV but not completely wide - look at Televue Delite range. For larger FOV - Baader Morpheus should be considered. Do keep in mind that you don't have to spend a lot of money with F/10 scope to get good planetary performance with even wider field eyepieces.

I don't need anything particular - as long as I define / discover device. I can't do that from SGP because of the way it was written. There is ASCOM device chooser dialog, and SGP does not use that, but instead asks ASCOM to list defined devices. ALPACA device that uses dynamic drivers can only be created from ASCOM dialog. Once you create / add device - it stays there and you can subsequently choose it in SGP and use it normally. This is small deviation from normal workflow people are used to and someone trying to do it for the first time - will get lost. I first started off with idea of using INDIGO alone for portable setup, and controlling it from my phone via web browser. Some time passed from that point and I changed the way I look at things. I'd rather now have remote setup as I moved to dark location in the mean time and don't have the need for portable setup any more (I won't be traveling to the dark site as I'm already at dark(ish) site). Since winter is about and my observatory is not yet complete - I'd rather sit in my study in warm and image with equipment in the back yard - hence remote setup. I learned that INDIGO released new version in the mean time including some apps - like AIN imager which should make this thing easy. Then I also learned that it supports ALPACA and wanted to try it out - instead of using / learning new piece of software I could use windows software with many features that I already know - PHD2 and SGP. INDIGO is exposing its drivers / devices via ALPACA interface so I can connect to them remotely. I don't need ALPACA drivers for any particular piece of hardware as INDIGO has drivers for all my kit implemented. In principle - this setup works, but there are some glitches that I don't like and those are the reason why I won't be using it like this (I outlined those in previous post). I'll experiment with ALPACA more as support grows.

Findings so far: In this combination, at least for me, it is still not usable combination - running INDIGO server + ALPACA agent and using ASCOM software on Windows machine to control equipment. Issues that I found so far: 1. Software does not seem to work well in this combination - you can't define/discover new devices from either PHD2, SharpCap or SGP. I need to use ASCOM diagnostics to be able to add new dynamic drivers (discover equipment). Granted - this only has to be done once and then device stays in list of devices for further use. 2. SharpCap simply crashes when I try to open ASCOM camera with ALPACA driver (no entry point found exception) 3. Download is painfully slow. ALPACA uses rest / JSON protocol and image data is base64 encoded - which adds size. Even with compression it takes 10-15s to download single sub that is otherwise few meg. This is true both for slow wifi and fast ethernet. On the other hand AIN imager produces multiple FPS in preview mode and downloads full sub in less then second - even 12mb sub (this was on ethernet - will try wifi again just to see how it fares) 4. No easy way to configure camera parameters with these ALPACA drivers - you need to access INDIGO control panel via web and configure cameras prior to connecting by ALPACA driver (very counter intuitive for ASCOM users)

In that case, 6.7mm will be suitable without barlow as will be 4.7mm Barlow will be useful with say 11mm ES82 or with above two eyepieces for very special tasks such as double star splitting, but not for general planetary observing. LER should be long eye relief, but realistically long eye relief is 18mm and above. Most of 82° line (original) have short eye relief. Even without glasses it takes some getting used to them. 6.5mm one is claimed to have 16.5mm eye relief (from ES website), but I'm skeptical of that - it needs to be confirmed by someone that actually has that eyepiece.

I think it is alpaca thing. If I'm using web panel image updates every second for 3000x2000px image and every half second for 1920x1220px image (main camera and guide camera). This is jpeg preview in browser - but it shows that download of images is fast enough in RPI and for some reason it is very slow even over gigabit (measured ~940mbps) link. Will now try AIN imager to see what will happen.

Just switched to gigabit ethernet and for some reason, frame download is still slow! Trying to figure out what is happening.

Yeah, but that is 80/480 and not 80/400

Small update. Cameras also work but there are couple of issues. First - forget about wifi. With wifi, frame download is painfully slow. Even if I do all optimization - it still takes couple of seconds to download frame from guide camera for example. That is simply no go for guiding where we want corrections every few seconds. I measured my wifi speed to be 20mbps, so half of 802.11g standard of 54mbps. 1000mbps on ethernet sounds much better. SharpCap crashes when using alpaca ascom drivers. SGP works properly with both of my cameras. Did not test PHD2 yet. Need to get small gigabit switch and 50m ethernet cable.

Excellent 80/400 with metal OTA and focuser? https://www.firstlightoptics.com/esprit-professional-refractors/skywatcher-esprit-ed-80-pro-triplet.html You might be slightly annoyed by the lack of purple fringing, but otherwise it will be rather good

Yes, you can also look at color balance if you have camera without IR/UV cut filter - clear will have "washed" out colors in comparison to uv/ir cut filter.

what scope will you be using those with? I feel that EP in 6-7mm range with barlow will give too much magnification in almost any scope. These focal lengths are best suited for F/5-F/10 scopes. With Maks or Cassegrain scopes that are F/12-F/15 and slow refractors - these EPs are starting to push past useful magnification (that will depend on your eyesight as well).

It looks like LRGBC interference filter set. You could possibly use L filter with ASI224MC. Others won't really be useful with that camera and scopes you intend to use it with. ASI224MC has AR coated window (that is the same as C - or clear filter). You want IR/UV cut filter - which is L filter in that set. Not sure how are you going to differentiate between the two - they both look like clear glass when looking thru them - no color what so ever. L or UV/IR cut filter might show reflections when looked at from an angle - but effect will be subtle. Clear/C filter on the other hand should be transparent at any angle (except for perhaps anti reflexive coating).

https://www.firstlightoptics.com/uv-ir-filters/astro-essentials-uvir-cut-filter-125-2.html 2" filters all have M48 thread so if your flattener has M48 on front side that goes into telescope - you can use 2" filter.

I followed this tutorial for collimation of my RC: https://deepspaceplace.com/gso8rccollimate.php except I did not use Bahtinov mask (which I'm finding useless), but rather FWHM readings in SharpCap (there is focus help utility that will read FWHM values)

Don't think so. Large pixels usually make stars smaller. I think you missed a bit of focus there and guiding will help. 80mm aperture with 4"/px is capable of this sort of sharpness: Focus, atmosphere and tracking all play a part and you need to sort out all that is up to you so (focus and tracking / guiding) - and hope for good conditions in atmosphere.

Yes, guiding is rather simple thing once you have it all sorted and it becomes part of the routine. You can also use it to dither between subs which is another benefit.

I'm using ImageJ for that sort of processing. You can use super pixel mode as first step in DSS, but first look at that collimation issue. You want your stars to be nice and round. Here are my test shots when I was in process of collimation - corner stars (same scope - RC8"): See - similar to your stars - ill defined not pin point After one round of collimation - things got better (center of the field): But I was still not happy with corner stars: I the end, I managed to get even corner stars to look nice: Gain setting depends on your exposure length. Lower the gain (or slower the scope) - longer exposure you'll need for your subs. With said scope, I'd say that unity gain is ok - so keep that at 90. As far as offset - well, you need to measure that. Point of offset is that you avoid clipping to the left. Way you measure it is rather simple - you need to take bias subs. Set your working gain and start with some offset - you can start at offset zero, and take several bias subs (camera covered like for darks but exposure length set to minimum). Take say 10 or 16 of subs. Stack those subs using minimum as stacking operation and after that do statistic on resulting stack. Look at minimum pixel value in the image. If it is equal to zero - raise offset and repeat procedure. If it's not equal to zero - you are done. From now on, use that offset with gain you used for the measurement.