alacant

The 9mm oag can be used with a variety of connectors, eos included. If you're only using EOS, obviously go for the dedicated EOS oag. No confusion, unless you try including T2 rings of course!

You don't use a t ring. The OAG has the EOS connection. The one you recommend to the OP! How do you connect your oag to your 130pds?

The OAG works fine with the -any- coma corrector. We use it in preference to the separate guide telescope. On an eq3 it has the advantage of weighing much less.

We haven't! It's the best and easiest way to go. Cheers

Hi You can either modify the telescope [1] to make it acceptable for autoguiding using a separate telescope, Or you can use your OAG method. Both the items to which you liked will work fine although we'd recommend the 120mm, monochrome version of the camera for both guide telescope and OAG applications. Both methods will work fine for the baby pds. We prefer the OAG and have never failed to find suitable guide stars, even in the barren depths of Leo. To get really solid guiding, use both the OAG and do the modifications. 10 minute plus frames guaranteed. [1] Here's the list of stuff to do for the separate guide telescope. The main cost is in time. Fit six 1.4mm wire springs. 3 replacements, plus three passive springs over the locking screws. Leave the latter loose. Seal the primary mirror to the cell using three generous blobs of neutral silicone sealant to coincide with skywatcher's cork. Leave to seat under gravity for 24h. Remove the mirror clips Set the tube rings at least 30cm apart on a Losmandy dovetail Tie the top of the rings with a rigid aluminium box section Remove the rubber o-ring spacers in the focuser Replace any metal or metal/plastic guide telescope retaining screws with all nylon types Mount the guide telescope directly to the top rail Drill and tap a third screw to the focuser collar

Hi Be sure to read both seronik and telia's collimation myths;) If you are simply using the telescope with an eyepiece to look at stuff, get the secondary somewhere near, then leave it; other than reflection, it has no optical properties. Then go out and observe. Cheers

+1 for indi/kstars. We do local and remote. Client-server under Linux is the only way we've found to go all night, every night.

No. Any method which aligns the lens is fine. The advantage of the laser is that it doesn't depend upon the focuser being correctly aligned.

Hi We have already ascertained that this is not to blame. Or rather, the OP can only assess any issue with the compression ring after the objective lens has been aligned. Cheers

Assuming you have entered the camera pixel size correctly, we can eliminate pixel scale being wrong.

Hi Start with this. If you want a specific answer to why your calibration fails, you need to upload your log files. This is also covered by the link. Cheers

Hi How about the 'Mount' tab. Any clues there? Maybe post that one too?

Seasonal fashion perhaps? My gf thinks they look 'dead cute', especially as they come with a choice of colours. You can be sure they'll match any outfit perfectly. A far cry from our tatty reflectors which 'don't even look like telescopes'.

The laser enters via the lens. Have the lens about 50cm from a wall. No. But anyway, the focuser should be OK as it is; we've yet to see a misligned ES focuser. The main issue with the ES's 80 is the backfocus; the camera needs to be held so far from the tube. Why the tube couldn't be made a few cm longer, we've no idea. You must first set the lens square to the tube. Only then can you assess tilt. Cheers

Hi Post -a link to- the .fits? We can then see if we can solve it. That may narrow the debugging.

? You don't really need hours upon end with StarTools, but if you so wish, you can replay your session as many times and over as many days as you like. Or just close the computer lid/sleep/suspend (or whatever it's called when you press the power button)... Cheers

Native mac? kstars, siril and startools. HTH

https://www.astronomyscope.com/astronomy-clubs-in-london/ Any good?

+1 I can remember when this first hit me. We had a visitor with the then popular and oft recommended sw 80. I had an 200mm Newtonian. m33. We both had dslrs. The first thing you notice is each frame as it is downloaded. Whilst the 80 just about showed the core as a fuzzy patch, the 200 showed a galaxy. Enlarging the image from the 80 to make it the same size as the 200 made it fuzzy and no amount of processing would get anywhere near. I got the impression that's you'd need a lot more frames from the smaller telescope to be able to get close. On the other hand, it was much easier to image m31 with the 80 than with the 200. Other stuff may become important; an eq5, a sw 80 and a rpi go as checked in baggage on Ryanair. Airlifting an eq6 with a 200mm f5 would cost you a fortune. @dazzystar most will tell you that the redcat will give better images than your 102 because it focuses light better. Only you can decide what better means though. Maybe go along to an astro club and do a comparison. Words don't really do it justice. Cheers

We haven't tried either I'm afraid. Start a 'best guide camera' thread? We use t7ms, bin 1 on guide telescopes, bin 2 on OAGs.

Hi Modern lens? Autofocus on the moon then switch the lens to manual. HTH

Good question. Does mount reaction to guide star motion on an OAG differ from that of the same camera on a guide telescope? I really don't know. I think that's why we setup guiding using stuff like size of pixels and focal length. Why we get more usable frames when using an OAG on a Newtonian is I believe, almost all due to its ability to offset flexure; one is examining the same light cone as is arriving at the imaging camera. I'd guess there is less movement to have to pass to the mount to correct. Why then do we get more usable frames with a separate guide telescope but using a Newtonian with a non floating mirror cell and with a properly supported tube? I'd go for elimination of flexure once again.

With the modifications we outlined here, this is all but eliminated. Having said that, we've never been able to get 100% success on frames of over 5 minutes duration without using an OAG. I'd be willing to concede however that this is due to the state of our mounts rather than the integrity of our tubes. Cheers

Up to 1200mm, that's not what we find, so the OP at 900mm should be fine. For which targets have you found problems? I think that's it. But if you do put the OAG on a smaller telescope, what you lose in light gathering is made up by larger field of view from which to find guide stars. On a -very similar to the OPs sw- 203mm f5 with a t7m ( an asi120 clone) binned 2x2 in firmware (i.e. before it hits the computer) and with the prism aligned correctly along the long side of a dslr frame, we have never yet failed to find guide stars. Note the plural. The worst case was m106 where there were only two; one is the minimum requirement. Strangely, our preferred galaxy telescope, a 6" f8 finds just as many stars. Maybe because it doesn't need a cc. Here is the setup with the t7m and the 150/1200mm. For completeness I've included the guide telescope on the f5 showing the mounting rail. Note the all nylon retaining screws under tension for the guide telescope. I'll add this to the modification list. With a properly modified Newtonian, I think that a separate guide telescope is fine for anything up to 5 minutes. For longer exposures use the OAG. Or just use the OAG throughout. Cheers

Ridiculous... 500 x 15 x 100mm aluminium plate and an angle grinder;)