alacant

Hi You haven't pre-processed the flat frames before stacking. HTH

Hi 600d, so no dark frames of any description. Instead simply use a master bias or even easier -and just as effective - subtract a constant bias value per pixel. For the 600d, 2048. Don't forget to stack using a modern clipping algorithm -available in Siril- and take more frames of longer exposure. +1 for the suggestions to dither. Cheers and HTH

Hi How is the guide telescope mounted? Could you post a photo? It looks as though it is moving relative to the main telescope as the tube angle changes. I think the English term is 'differential flex' OWTTE. Before you begin any software analysis and after you have secured the guide telescope, it is essential to make certain the mount mechanics are as perfect as possible. This means dismantling, cleaning, re-greasing and adjusting, even -especially some would say- new new mounts as described here. Guiding a ~1000mm refractor with a small guide telescope on a low end mount, everything must be perfect. Cheers and HTH.

Hi That should do it. Not sure of the best ISO on the 3300, 100 maybe? Anyway, start bracketing exposures at either side of 1/500s. You're up against atmosphere wobble, so take several at each shutter speed. With a bit of luck, you'll get one which you'll be able to pass to hard, especially on -very forgiving- canvas. Good luck and HTH **EDIT: ISO. Our Nikon expert refers me to this. So ISO800. So start bracketing around 1/1000s perhaps?

Hi I can't see what telescopes you have, but to fill APS-c (with a little wiggle factor along the narrow edges) with the moon, you need something around 1000mm focal length.

Hi everyone We had a slew [1] of small carry-on-baggage refractors this weekend and an interesting discussion on the current trend of obliterating stars in images. To redress the balance, and with no narrow band glass anywhere near, here is our contribution to the campaign for real stars. Cheers, thanks for looking and do post your starry images. 700d on sw 72ed [1] Where it would need a whole sentence in Spanish, my boss uses the English term if he's heard it said sufficiently elsewhere. For example 'el slewing', 'el focusing' and his current favourite, 'el marketing'. Hence my claim of 'slew' as collective noun for 'small carry on baggage refractors'. If he can, so can I.

Hi That's what we normally do if it's a dedicated fixture. This is my first experience of a domestic installation where humans take priority over telescopes. I next have to work out where I can plug the adapter and the Ethernet cable at the house end so it's invisible. What a struggle!

Ok. Getting there. I still need WiFi from the main router to the vnc client, both of which will be in the same room. Do I retain this?

Perfect. Thanks. That looks like it. Presumably I need in addition to the two adapters, two ethernet cables. One for the router and one for the telescope NUC? Un saludo

There is grid (?) electricity -as in you can plug stuff in like a fan or a computer- at the telescope, but it's too complicated as I think mains adapters need to be on the same circuit. The wiring seems to indicate several individual circuits. Dunno. This is way beyond providing astro!

Thanks so much everyone. Oh, how I hate home wifi! Unfortunately, as per the original post, the only thing I can change is the interim box. @Elp do you know if your netgear alternative will be any better than the existing box? The latter is a mi-home. Cheers and clear skies.

I'm just looking for something to replace the black box. The white box is 600/600 fibra óptica. Cheers

Hi everyone I'm trying to get a home wifi (not designed for heavy traffic) so that a disabled guy can vnc into his computer at the mount. It's working fine, but it's slow. I've traced to weak point to the interim wifi extender; vnc with the two computers in the same room -without the extender- is instantaneous. This must be doable without having to plug or switch anything and without cables. The telescope end is taken care of. The total distance which needs to be covered is 50m. Question: home lan experts, what would you recommend as the middle wifi-extender thing? Cost: not that important but if you could give a top of the range and an affordable model, that would give me something to go on. TIA

Hi and welcome By far the best way to get started is to go along to an astronomy club meeting and see your proposed equipment setup and working. Between them, the members will be able to put together anything you had in mind, and more. Only when you've seen it can you really decide. Cheers and HTH

Exactly that. On the vx -and most other modern Newtonians- the secondary is fixed such that when the holder is centred and the telescope is collimated, the offset ensures as evenly illuminated field as possible. Be sure to read Telia's collimation myths and Seronik's no nonsense guide, both of whom tell it just as it is; simple. HTH

Hi None of the low end rolled steel tubes we've witnessed hold the mirror cell and focuser fixed relative to each other sufficiently well so as to hold collimation as the tube changes angle, especially with a camera attached. There are some simple modifications which are needed on such telescopes to make them into reliable astrographs, These include fitting stronger primary mirror springs, sealing the mirror to its cell, and replacing the secondary support with a light plastic version. However, before replacing the focuser [1], I believe in the case of the vx, the most urgent change you'll need is to spread the tube rings at least 50cm apart on a Losmandy dovetail plate. Then tie the top of the same using rigid aluminium profile. We use 2mm wall 2 x 6 cm aluminium box section for this. This should make the tube rigid enough to obviate the need for the CF upgrade and so eliminate tube flexure from your debugging. Install the other modifications until the collimation holds at all angles. Visualisation here. Cheers and HTH [1] IIRC the focuser on the vx example we used was fine after adjustment of the tension, but note we only tried it with a dslr. If you're monochrome, you're probably going to have to reinforce the tube around the focuser circumference as well as the other modifications we outlined.

We didn't think so either until we tried with and without. No obligation of course, but making an astrograph from a bottom of the range Newtonian, you need every bit of help you can get. Of course, the locking screws are left in place merely to retain the extra springs; loose. @laser_jock99 is the pioneer of the technique. All credit to him. Cheers

Hi We've yet to find a low end reflector -the ones with with three weak springs- hold collimation at varying tube angles. Cheers and HTH

For 200mm mirrors, we use 1.6mm. This covers all 200mm SW possibilities, including the older thick Pyrex glass type. You'll find that if the mirror is held to prevent lateral motion by silicone, you'll rarely need to touch the adjusters. Cheers

For future reference (at sensible prices), simply specify your dimensions at the checkout in the message box here: https://a.aliexpress.com/_uI3HoG The dimensions to give are as below. Ask for Europe shipping. HTH

Well done. You're on your way to a Newtonian which holds collimation at all tube angles, not just the one at which you collimated. One less thing to have to compensate for:)

If you're staying with it (it can be done, but the telescope has to be mechanically perfect), the guide telescope needs mounting directly to a rigid rail joining the top of the tube rings. We use 2mm wall 60 x 20 box section aluminium. The rings themselves need mounting further apart on a Losmandy dovetail. For a 203 f4, go for 45cm separation. This provides adequate support for the flimsy gso tube. If flex remains, the next step is a lightweight secondary support. Or just go for an OAG. HTH

No, no. The washers go on the outer part of the cell such that when the spring is fully compressed, the screw has not travelled far enough to foul the glass. To save on washers, we use nuts with a washer either side:

The focuser doesn't mount to the tube, rather its base. The latter -mercifully- mounts metal-to-metal to the tube.

Also forgot. Again... Don't forget to replace the springs. As a minimum, 1.4mm wire. 3 replacements and a further three using the white-knob screws as retainers. Cheers