ollypenrice

8 hours ago, tomato said:

Looking very smart, but might I suggest a wire brush and a coat of paint on the door hasps to complete the refurb, they are now the only giveaway that your dome is located in the rain blessed West of England. Oh, I forgot about the lush surrounding vegetation.☺️

Yes, those hasps are a disgrace!  I'd ditch the wire brush and go straight on with Hammerite, though. Bone idle.

Actually I suspect that kind of detail is something that you'll notice straight away in a photo but hardly register at all in real life. That's why I never take photos of my house..

Olly

It's odd that the flats have corrected the green imbalance. That isn't their job and they don't normally do that. Are you sure you didn't also apply a background extraction or gradient tool of some kind?

Your attempt is, in my view, the better of the two. In the second one the reds have been killed completely whereas, in yours, the Eagle and Swan show some red Ha signal and you have more star colour. The second one has also stretched the data beyond their limit and raised quite a bit of banding into visibility. All data have their limit and successful processing remains just inside them.

I don't know GIMP but, in Photoshop, you can go to Image-Adjustments-Selective Colour and move the top slider in Reds to the left to lower the cyans in red. This helps Ha signal to stand out.

Olly

I think a lot of the potentially 'new objects' have been overlooked because they are too large to have been perceived as single structures.

Olly

In astrophotography capture is the easy part. (Not always too easy but when you can do it you can do it.) Next comes stacking and calibrating. Again, a mechanical process which can quickly be learned.

And then there is post processing, which is a huge field and not one which can be covered in a single thread like this. You have to start somewhere and this might be a good place. https://www.firstlightoptics.com/books/dark-art-or-magic-bullet-steve-richards.html

Be aware that You Tube is full of clowns who flounder around throwing sliders this way and that without a clue as to what they are really doing. Get a good eye for what are good and bad images and go to the websites of the good ones. Warren Keller, Rob Gendler, Adam Block etc.

Olly

On 21/05/2024 at 14:04, JeremyS said:

 

I have tried various waxes (including v expensive Brazilian boat wax). 

Really, Jeremy!

Honestly, where are the moderators these days?

I must say that your marine gloss looks very good, though my own solution (in advancing years) is simply to embrace decrepitude!

Olly

10 hours ago, Josef said:

Thanks Olly!

That is indeed another reason why I'm worried about this. The small imaging circle (and thus, vignetting) and distortions introduced by the f/3.3 could be a nightmare. That's why, in truth, using the f/6.3 with the 460EX would be better. With the f/6.3, the 428EX would have a small FoV, just below what I would have liked to have.

Might just have to save up some more from the look of things

 

You could buy a 460EX for peanuts these days, since nobody wants to buy CCDs, despite their fantastic performance. I have one not in use myself but am not yet ready to sell it because it is such a gem when used with my TEC140 (also not in use at the moment.)

Olly

See what it says on my catchphrase below.

lly

The F3.3 reducer is years past its sell-by date. It was designed to work with the tiny webcam chips (eg Toucam) of that period. I tried it on a small Sony 16.9mm diagonal chip about thirteen years ago and it was just a nightmare of distortions off axis. I don't know the diagonal on your camera but that of the Toucam is just 4.5mm (!!!)

Olly

14 hours ago, Bluesboystig said:

Using Siril and Topaz Denoise I’m not sure I can apply sharpening and denoising selectively, 

It is absolutely vital to be able to apply any and every processing operation selectively. This lies right at the heart of image processing and is sometimes called 'the zone system.'  Once you can do this, you're off. There are two systems which are used widely, layering or masking, though they are in some ways the same thing.

I use Photoshop layers but a quick glance at GIMP, the free alternative, shows that the method I use is available in GIMP. It is simplicity itself with a real time preview of results.

- Create two layers by pasting the original on top of the modified (eg noise reduced) version.

- Use the Colour Select option in the Selection Tools to select, by colour, the regions that want the most NR. You do this by moving the cursor over them. The software will throw an outline around what you've selected. If it looks like what you wanted, keep it. If not try again. You can now expand and feather your selection so that its boundaries will be gradual and invisible at the end.

- Use the eraser to remove the top layer within your selection and reveal the modified bottom layer. You can do this in iterations by making the eraser only partially effective (set it to 20% or 50% etc). Alternatively you can erase at 100% and then go to Edit-Eraser and backtrack the eraser effectiveness to any percentage you like. Just look at the image to see what you like.

- Flatten the image (ie blend the layers as you see them now in layers.)

You can do the same process after altering colour saturation, after sharpening etc., so you only get the modification where you want it.

Olly

PS Purists will tell me off for erasing directly rather than through and black and while transparency mask but I've never felt the need to use a mask for this.

12 hours ago, Elp said:

Very early I I tried mounting my GS like you have, you better be absolutely certain the mount doesn't have other ideas about how to rotate in Dec.

The result from that scope is crazy.

12 hours ago, aramitsharma said:

Yep. I think so.. haven't noticed any issues in rotation

I was thinking along the same lines as Elp. Sometimes mounts go spontaneously mad and rotate in any direction they can, so if you're relying on the mount behaving properly you'd be taking a risk if collision between guidescope and power cable were physically possible.

8 hours ago, Ags said:

Nice pictures!

My little 135 IS the guide camera! Although there is the theoretical possibility I will use it as my imaging scope sometimes and use the RC6 as a monster guider!

I am also thinking of adding an Evoguide 50 as a third scope although I'll need a second capture computer as the ASIAIR seems to be a one camera only thing - annoying.

Reflectors make poor guiders because of mirror movement...

Olly

I think the colour is much better in the second but that there is way too much indiscriminate noise reduction in both. The first thing I see when I look at these images is... noise reduction. I see that before I see M31.

By 'indiscriminate NR' I mean NR applied where it isn't needed. Also applied beyond what is needed. I would urge you to leave a little grain in the image and to apply NR only to parts of the image which need it. Beware of the 'vaseline on the lens' look. Use NR where you need it and sharpening where yu can but, in neither case, apply either universally.

It's very, very rare that I feel an imager has left the black point too high since black clipping is such a temptation. However, in this case, I think the black point might come in a point or two.

I say all this because the image is very good, not because it isn't.

Olly

5 hours ago, Rallemikken said:

I'm a Linux guy, and use Siril and Gimp only. As Pixinsight is developed under Linux, I should feel at home. I'll download the trial later this summer.

I use StarNet++ in Siril, but can't get the starmask as I would like it. I can have well defined spikes and small stars, but not bright and shiny at the same time. If I want bright stars they get fat, and the spikes becomes diamonds... Have to work on that a bit more. Maybe Pixinsight will be the right choice.

Essentially stars which are both small and bright will arise from a very high contrast curve. If you're working on a stars only layer, don't hesitate to black clip the layer, either. What you do with this high contrast curve is pull down the outer, fainter, parts of the stars while holding up the cores.

Olly

My robotic customers get this fairly regularly and contact TV to plead innocence, whereupon they get re-instated. The business model is obvious - get people addicted for free then make them pay.

I like Vroobel's info and will follow it up.

9 hours ago, Vroobel said:

That's why I prefer RDP and/or VNC. No payments, no clouds. 

Olly

Mesu? Didn't appeal to you? Just curious.

Olly

4 minutes ago, gonzostar said:

Thanks Olly, That's  a challenge way beyond my capabilities 😁

No, honestly, it's not. When I learned how to do this I was close to computer illiterate. I followed this explanation by that very nice man, Mr Jerry Lodigruss.

https://www.astropix.com/html/processing/laymask.html

The tutorial is as relevant today as it was over 10 years ago. Try it!

Olly

24 minutes ago, gonzostar said:

Hi

Is this the same technique you could use as if Processing M42 as to get the core and fainter nebula with photoshop? l am also having a go at processing M27. Amazed by everyone's effort getting the faintness of the dumbbell. 

 

Cheers

Dean

It is indeed. As things stand there is still no hope of revealing the dynamic range of M42 in a single stretch.  (Stands back to be proven wrong! )

Olly

Great result and a classy little setup. This may be a silly question but does the power cable clear the guide camera?

Olly

On 21/06/2024 at 14:06, tomato said:

Hopefully when folks see that this top notch image was taken with an “old tech” CCD camera folks will get some interest when these cameras come up for sale.

Seconded.

Olly

Absolutely spot on. A reference image of this region.

Olly

11 hours ago, Elp said:

Just stack as normal, then remove/copy the red channel in image editing software Photoshop/gimp/affinity etc.

I've never done this but, assuming the stack has been debayered, the debayering algorithm will have made its 'educated guesses' as to what the red channel will be doing on pixels blinded by the green and blue parts of the array. Still, one piece of hard information in 4 seems a bit dubious in theory. If it works it works, though.

Then again, in lucky imaging, the red pixels will doubtless get a good random scattering across the target.

Olly

I don't think you'll find much difference in resolution between 0.9"PP and 1.3"PP. I had both from a pair of TEC 140s on a dual rig, with a guide RMS of around 0.33 arcsecs. The cameras had different pixel sizes. I used the smaller pixels for the luminance but, quite honestly, I never found any obvious difference in resolution. I never did a meticulous comparison but a casual one was distinctly underwhelming, even when shooting Ha in both barrels.

Have you considered the Mn190?

Olly

8 hours ago, tomato said:

I did it all wrong apparently, a cubic metre of concrete and a rat’s cage with the Altair pier but I had my reasons:

1. There was no way I was going to under size the concrete base with a hefty dual rig going on there.

2. Without the cage I would have nowhere to put my mug of tea down.☺️

3. The Altair pier came free with my second hand dome.

Now we all know that, never in a million years, are you going to reach for that mug, in the dark, while imaging. What could possibly go wrong? You need one of our hot drink-bearing, hands-free hats and, knowing your other tastes, I think the Biggles model would be for you...

lly

1 minute ago, Mr Spock said:

For the record, I just plonked it down on the patio 🤣 I haven't polar aligned it or levelled the tripod for about 18 months... I know where to put it and it just works.

Yes, if you hold your polar axis still then you can loosen off the mount bolts and swing it around. Plays havoc with my OCD though and would most likely make me feel queasy. I'll settle for level 

Certainly a level mount will help calibrate an obsessive-compulsive disorder to zero.  

Olly

On 20/06/2024 at 18:01, Swoop1 said:

I get it that a pier does not have to be perfectly level on the vertical and horizontal planes but, what about the mount that is affixed to the pier?

Should the base of the mount be level?

I ask this because, to my not too robust intellect, a mount that is not level will cause issues won't it?

You spend time reaching perfect polar alignment but, when the mount is directed to aim the OTA at a particular celestial target, the non level mount will cause tracking issues wont it?

Shirely tracking accuracy will depend massiveley on a level platform to work from?

Signed Swoop1 D&C (Dazed and Confused)

No.

This is really very easy if you try a thought experiment...

Spend 3 hours leveling the top of your pier to perfection. Polar align your mount to perfection. Now pass a snug fitting steel shaft through the polar axis of your mount and weld it to brackets fixed on the floor and wall. Your polar axis (polar alignment) is now absolutely fixed and cannot go wrong. Agreed?

Now unbolt your pier from the ground and loosen your mount's altitude and azimuth adjusters. Your polar alignment cannot change because of that steel shaft through the polar axis - but you can now point your pier where the hell you like and doing so has no effect whatever on your polar alignment.

On 21/06/2024 at 19:58, Mr Spock said:

Tracking with a 'level' EQ5 

This is with a Nikon D500 and StellaLyra 6" CC at 1836mm. Image purpose is to determine field scale and magnitude limit for future variable star estimates. It isn't meant to be aesthetically pleasing. Image is of ε Boö.

Not bad tracking I would say  Scope looks good too!

 

Tracking looks fine but this has absolutely nothing to do with where your pier or tripod was pointing. See above. My watch keeps excellent time and has a black face. This does not mean that only watches with black faces keep excellent time. You mention programs which track in RA and Dec but these don't exist, unless you mean encoder-guided mounts. Unguided mounts can only track in RA. Where would they get information about accumulating errors in Dec? Guided mounts get this information from the guide star position and encoder-guided mounts get it from the encoders which have been calibrated against a sky model.

On 21/06/2024 at 18:58, saac said:

If not level it will impair pointing accuracy and repeatability I think for the particular sky model. It will certainly do so when using manual setting circles. 

Jim 

Using a fixed sky model on a mount which which was assembled and disassembled would be very optimistic and I don't think anybody does that, do they? High grade, fixed observatory mounts with absolute encoders bolted to 6 tonne concrete bases need their sky models renewing maybe 2 or 3 times a year. I host a couple of these. Similarly, re-using an alt-az sky model after moving a mount really ain't going to work.

If you get a good polar alignment (which has nothing to do with level piers) you really only need a one star alignment for a perfect sky model, but a perfect polar alignment is difficult so a 3 star alignment will give one with built in PA error (and cone error) correction. The sky model is made from the position of the star relative to the polar axis, not relative to the top of the pier - about which the software knows nothing.

If a level pier top is needed, please explain how the Mesu seen earlier in the thread, with its pier top tilted to the equatorial angle, can give a periodic error around ten times better than an EQ6 on a level pier.

Olly

47 minutes ago, Clarkey said:

🦕🦖😉

PI even has curves🤣

If it didn't, the data would remain linear - which wouldn't get us very far!

Olly