ollypenrice

Super, Rodd. I think refractors are fine on globulars. My TEC140 did well on M13, too.

Olly

It will probably have no visible effect whatever, though it might just create a slight diffraction spike on brighter stars. If it does, try covering it (on the outside) with something black, like a small piece of electrical tape or black paint. Avoid straght lines on this tiny  blackout patch.  If this seems odd, remember that many telescopes have large, opaque obstructions slap in the middle of the objective.  Ours, for instance...

The obstruction is far too far out of focus to form an image.

Olly

Clearly you're going to have to find the right power supply if using it in the field but, running on mains and a regular 12V transformer, ours is fine. It's a great camera and you did the right thing going for a bigger chip. In fact the Redcat covers full frame very sweetly.

Olly

I used a motorhome for going to dark sites before going to live at one permanently. It can work well but there are issues. Motorhomes are often totally useless on soft surfaces and get stuck at the drop of a hat. This may explain the campsite rules mentioned earlier. The trouble is that the best places for astronomy are, therefore, often the worst places for campervans. This was a major stumbling block for me. It also proved disappointing not to be able to Certified Locations (minimalist campsites) because, again our coachbuilt got stuck too easily.

Olly

Sometimes tilt is improved by rotating the camera in the OTA, probably because a number of imperfections cancel themselves out. There might be a bit of tilt in one component which goes the opposite way to that of another in one particular orientation. It might be worth a try. If you find such a sweet spot, as we did with our RASA, you can still rotate to frame a target by rotating the entire OTA/camera in the tube rings.

Olly

15 hours ago, Elp said:

Why is a UV/IR cut filter recommended (for cameras with all pass front glass), and the lum is useless? The lum also cuts UV/IR?

I was assuming the camera would be appropriately filtered in this regard. This has been the case with all my OSCs but maybe some just have a clear filter, in which case you'd be right.

Olly

Let's think it through. An OSC camera has either a red, a green or a blue filter permanently fixed in front of every pixel. That is what makes it an OSC camera. 

If you put a red filter in front of this, only the camera's red-filtered pixels pixels will get any light. The same applies to the other colours. With a green filter in front, only the camera's green-filtered pixels will get any light. Clearly, therefore, RGB filters would be pointless.

What's a Luminance filter? It's one which passes R and G and B. But your camera's filters are only going to pass the colour they pass, so R or G or B. A luminance filter would, therefore be useless.

Basically, you are going to be imaging with the camera's in-built RGB or with the dual band filter which further restricts what you capture to the light emitted by two gasses. Some targets will be best unfiltered, some filtered and some combining filtered with unfiltered. The worse your light pollution, the more favourable the filter becomes.

Olly

25 minutes ago, 900SL said:

Wega rings and autofocus rig for Samyang 135mm. Without a doubt the biggest pile of junk I've bought for astro, beating a Skywatcher Star Adventurer 2i by a length

Review here. 

 

Utter rubbish unfit for purpose. I think @ollypenrice had a similar experience

Certainly did. The most feckless piece of junk ever brought to market. Almost every component has now broken on the one I bought, as the people responsible for it must have known they would., and it has long since gone to the bin, like the considerable sum I laid out to buy it.

Olly

16 hours ago, ONIKKINEN said:

Im afraid i have no video to link as ive not seen one for the subject. Im using a workflow that @ollypenrice shared here on the lounge in a thread not too long ago. Cant find that thread now though, but the basic gist of it is:

Process both the RGB image and whatever image you're using for an Ha image (like a duoband, L-extreme, or whatever you are using) to a point where they have a similar level of stretch and open both as layers in Photoshop. Put the narrowband image in the blend mode "lighten" and create a layer mask for that. Create the layer mask in a way that only the interesting parts get put through, for example by selecting with the color range tool or by simply copying the image to the layer mask.

Just tried this with GIMP and a similar workflow does work. You can put the narrowband image on top of the RGB image as its own layer and put that to the mode "lighten only", which seems to be the exact same as Lighten in Photoshop. From the Select menu choose by color and click on the background to choose that color. Then invert that selection and you are left with a selection that includes everything but the background - so all the interesting parts you want to have. Now you can easily adjust the strength of the process by either modifying the layer mask itself (by clicking on it with alt+left click) or by modifying the narrowband image itself, by curves, contrast, levels, so all the usual stuff. Seems to be fairly straight forward. Definitely more so than the pixel math route which often does not do what you want it to.

For an even better result you could separate the stars from the image with Starnet, and apply the narrowband only to the starless versions of both images and then recombine later with just the RGB stars.

That's actually more complicated than my method. Rather than layer mask my NB when adding it to the chosen colour channel in blend mode lighten, I give it the kind of stretch which I think will make it play well over the colour channel. I go for a very, very hard, contrasty stretch and ignore noise where it is darker than the same region in the colour channel. It won't be applied anyway. I make sure my background is not brighter than the colour background and that the bright features in NB are brighter than the colour (or they won't do anything.) I adjust this stretch of the NB while it is in situ over the colour in BM Lighten so I can blink it on and off to see what it's doing.

In short I see a NB image to combine with a colour channel as a completely different thing from a nice standalone NB image for publication.

Your NB masking seems a sound idea, though.

Olly

1 hour ago, AndyThilo said:

Thanks, as long as I get good subs around new moon it should get the dust to pop more and tighten up the details.......maybe

More colour, as well.

Olly

This is going in the right direction! It's such a hard target to do.

Olly

To me, it's a sea horse and, yes, I struggled to bring it out in an HaLRGB rendition. This is beautifully clear.

Olly

I can't say I've ever heard anybody say you can't shoot DSOs uncooled, but it's a very successful image.

Cooling remains an advantage, however.

Olly

2 hours ago, Oddsocks said:

 

Don’t know why, but writing this summary I can feel @ollypenrice peering over my shoulder, trying hard not to laugh…..🫢😅🫢.

HTH.

William.

Not at all! I'm always an admirer of your expertise. 

Of all the things, though, that go into the making and processing of an image, I cannot believe that much will change under the niceties of different stacking software. My office is always open, and my data available, to anyone wanting to prove me wrong. I'll even put the kettle on!

lly

22 hours ago, DaveS said:

I side-stepped the whole guiding problem by going to encoder guiding.

Some of my robotic shed clients did likewise but nobody is still doing so...  It's like anything else, when it works, it works. Go with it when it does.

What is a guiding problem? I don't have one. I just bung on a cheapo ST80 as guidescope and get on with it. Changes to the imaging scopes, camera rotation, etc etc, have no effect on anything.

In over ten years of imaging, my venerable Mesu 200 never dropped a sub. That's a pretty good definition of not having a problem. To be fair, the same mount ran an OAG for the first three years and, once I'd stopped the thing rocking about by adding a strap to the top of the guide cam, it was as reliable as a guidescope.

Mini finder-guiders? Very pretty and super neat, but a royal pain compared with the ratty old ST80. They lose focus easily and have this deeply unconvincing  'easy focus' ring wottsit. Why? My ST 80s haven't been refocused in 10 years.

Olly

Given that an image circle is - ahem - a circle, the best non-circular chip is a square one.

lly

2 minutes ago, Elp said:

Buying AP equipment on finance is a fools errand.

Agreed. If you can't afford it, you can't afford it. Wait till you can.

Download some free data and start to learn processing.

Olly

Deep, clean, sharp and well composed, with the objects seeming to race away from each other.

We don't stop down at all with our Samyang... Pedal to the metal!!! 

Olly

Go for it. Put it in the middle of your frame and shoot some data. The asymmetry of what you've posted makes it look promising and not just star bloat.

Olly

1 hour ago, Albir phil said:

Hi I am in RGB mode not sure what I mean by extra channel or selection in place hidden 

This is Photoshop, right? Go to Window - Channels and open the channels. If all is normal it will look like this, but you may have an extra channel as indicated by the green arrow. This is often the cause of problems when trying certain operations on an image. Just delete the extra channel if it's there.

Olly

Things to check:

1) Are you in Mode RGB?

2) Open Channels and see if you have an extra channel like a star selection or other.

3) Do you have a selection in place, possibly hidden? Ctrl D to deselect.

Olly

Just now, Franklin said:

Important stuff then.

Oh yes! It's not just about orchestrating the assassination of heads of state...

Olly

Very good. I'm pretty sure there are processing tweaks still available to you, as well. Most beginners bring the black point in far too far and clip out faint data. I think your black point could come in a bit and give you more contrast - but softly, softly!

Maybe ease the green down a whisper as well?

Olly

30 minutes ago, tomato said:

I do believe ahem, that the facility is used to enable reliable communication to at least one remote imaging facility in Spain. It's an ill wind...

Spain? Spain? Never heard of it!

Olly

6 hours ago, Franklin said:

Why so many? What are they all going to be doing? Other than what the original few were doing.

To enable important communication along the lines of...  Waitrose. Waitrose. I'm in Waitrose. Near the beans. Here, I'll send you a seflie. Hang on. There we go. Oooh, hang on. I missed my nails. I went to Nailgun next to Macdonalds. What do you think? Union Jacks ahead of the rugby semi finals. I wanted to please Darren. Oh, listen to me, I mean Dave. Don't go to B and Q. Their nailguns don't look safe to me. 

Olly