alacant

Astrophotography and perfection? I'll have to check my English, but I think it's called 'mutually exclusive'!

Think of images either side of a meridian flip. Stars left before are stars right after. Or just take a photo of a tree frame right then rotate the camera about the same centre. Where's the tree now? Upside down and on the left? The problem is that many cameras' default is to rotate the image to what they think is the correct orientation. Best to disable this auto-rotate.

You need to adjust tilt and collimation until the vignetting is more evenly distributed; central with dark corners is good. Does your software rotate the images?

The vignetting should be central so something is not square. Collimate, tighten, dismantle, secure main mirror... Unless you have patience, the flats are working and you have decent stars, probably best to just leave it. Cheers

All OK then:)

Hi 360º, so you're back to where you started. The vignetting should be the same. Same for all filters, so not the filters. Not tested without coma corrector, so we don't know if that's the issue... Our money is on the camera not being replaced at the same angle after rotation; we've never come across a Newtonian focuser out of the box which didn't tilt, threaded connections or not. But you wouldn't rotate the camera after an imaging session before taking flat frames so if the flats are working... Cheers

JTOL: it's threads such as these which make small, high-end refractors seem like an awfully good proposition!

Hi everyone Something from last night's full moon. Noisy? Yes, but not so much to prevent having a go. 700d 30 x 2 1/2 minutes ISO800

Yes, of course. But everything else has to be as perfect as you can get it too. No single modification is going to get you over the line. Tube reinforcement consists of a sleeve which is riveted/bolted to the existing tube. @laser_jock99 has a post on this. Here's his reinforcement insert:

Put springs over those as well and leave the screws loose so as to retain the springs; 6 springs in total. At this game, every little counts. The main source of mirror movement is however lateral movement within the cell, hence the silicone. And in our opinion too. They are just another source of mis-collimation. As soon as you've used them, you'll see the issue immediately;)

To cover other sources of flex and movement, you'll also need a stron(er) and longer dovetail and top bar the finder rings bolted directly to it (or a heavy clamp), silicone sealant and a light plastic secondary holder. If you don't want to fiddle around, it may be better to simply fit the springs and go with an OAG. The problem then is holding collimation during and between sessions; still no free lunch. Then there's the focuser... Anyway, well done for having narrowed it down. EDIT: AliExpress take under a week. To Spain at least.

Hi They ship worldwide, including UK. Just choose standard shipping:

Don't overthink it;) The only extra item you need is in this post.

Spacer? You need a simple 4mm or 5mm m48 extension ring and your m48 adapter. That's it. This one would be fine: https://a.aliexpress.com/_vEqo1X Which do you have? Post a photo?

The end of the corrector from which you just removed the adapter has a m48 male thread; there.

Use the blade of a -blunt- knife in the two slots in the M42 thread.

https://a.aliexpress.com/_vT4R7B Choose a size a bit bigger than the size you need then specify the exact dimensions at the checkout. Correction to previous post: we normally go with 1.4 wire for newer (thinner) 150 mirrors. HTH

Yes. nice optics, shame about... The Photon series are the economy versions and many corners have been cut. But hey, an hour or so's investment -mainly in time- will make it just as good as as the ones TS knock out at twice the price. And still don't work out of the box! Here is an example. The supplied GSO 200 springs alongside supplied SW 200 springs. In fact, to stand a chance even with the 150, you need the next size up. Yes... we speak from bitter experience!

If it has to be metal, then this one. But as they tend to get lost/left-in-pockets/in the bar, we use these. Cheers and HTH

Hi AH, OK. It's the GSO. Lots of opportunity for components moving;) In particular, but not limited to... The mirror cell (stronger springs and fixing the floating mirror), the mounting of the guide telescope (on a separate rigid top rail but with hard nylon retaining screws under compression) and the distance between the tube rings need to be further apart and with a wide dovetail. Another GSO speciality: the metal secondary holder is too heavy for the spider causing droop and tilt away from the vertical. The only way we could get our Newtonians guiding reliably using a separate guide telescope was just that. Of course the easiest way to guide an off the shelf Netwonian is to simply use an OAG. Here is one of our bashed around 150mm teaching reflectors. As well as that which you can see, the mirror springs are 6 off 1.6mm wire and the secondary holder of light plastic. The main mirror is held by neutral silicone sealant to prevent it floating as the tube angle changes.

Hi Is the primary mirror sealed to the cell or sitting therein under gravity? Send shots so we can see... -how the guide camera is attached to the guide telescope -the latter is attached to the imaging telescope -the cabling. Remove the guide telescope and shake it. Is the lens secure? Cheers

Yes. I applied banding and green reduction. I've no hands on experience with a 350, but generally not a good idea -for us at least- as directly after stacking we pass the processing to StarTools where anything even slightly non linear just doesn't go. But hey, to get anywhere near with a 15 year old camera and the 75-300 is going some. To get something as good as you have, amazing.

Hi We regularly use the Takumar 55, Zeiss mc-s 135, Takumar 200 and the Tair 3, the latter, a 70mm f4.5 triplet, producing near telescope quality. All are available around €100. They were designed to cover full frame, so there is an excellent flat field on a 700d. You'll need an eos to m42 adapter. We'd recommend an adjustable one and either cut the auto pin in the lens or file a notch in the flange on the adapter. Cheers and HTH

Use the bias as bias. Don't use a dark of any description. Lose any script you maybe using which forbids you to do such; much better when the operator rather than the computer is in control! Get to know Siril manually. Nudge each axis a little between every say three frames. For this to be effective it is best (essential?) to move the camera relative to the sky abruptly between frames, not constantly during them. Cheers and good luck.

Hi Nice shot. A few bits: - Use bias as bias or simply enter the median bias value in the bias field. - Dither between frames - Use Siril's banding reduction on each frame after pre-processing. Then register the un-banded sequence. - Stack using sigma clip at say, 3,3. HTH