Icesheet

15 minutes ago, steppenwolf said:

If the OAG protrudes into the light path, the machined edges of the prism support could easily cause diffraction artefacts - can you adjust the prism outwards?

I suspect and had an inkling it might be something like that. I pretty much just screwed it in place but I assume there must be some way to adjust it. Hopefully that should be a fairly straight forward fix. Thanks!

I recently had first light with my new  ASI2600MC on an Esprit 100. In terms of the sensor itself I think I’ll be very happy. The data was extremely clean. It basically didn’t need any noise reduction. However, it is also the worst I’ve seen stars on the Esprit.

Can anyone comment on what I’m seeing here. Is this tilt, spacing or a combination of both? It was also the first time using a ZWO EAF and OAG so that may complicate things. The OAG in particular was causing vignetting at the top of the image. Flats sorted it but it now appears to have introduced some diffraction on the stars. Could it do that?

I know I’ll have to do some investigating but hoping someone can point me down the right path before I go down the rabbit hole!

11 hours ago, gorann said:

Sorry if I am partly responsible for this RASA8 hype

Celestron should have you on commission! I’m pretty sure your images have resulted in a good few RASA purchases!

44 minutes ago, michael.h.f.wilkinson said:

I notice clear improvements up to 13h of exposure time with my Meade SN6 Schmidt-Newton (6" F/5) and (non-cooled) ASI183MC on M27 using an Optolong L-eNhance filter which gives quite a dark background. I am certainly interested in getting a RASA 8, but as stop-gap will go for a Starizona Night Owl 0.4x reducer on my C8, giving me roughly the same focal length at F/4.

I think I’m heading towards the RASA 8 too. Just trying to find ways to convince myself otherwise and save another hit to my pocket!

Thanks for the info! Yeah my skies are similar to yours, so I realised I wouldn’t necessarily achieve Göran like results. In fact I doubt I could regardless of how long I integrate and how good the skies are. Improving my processing would probably make a bigger difference than all of this.

23 minutes ago, wimvb said:

For real stars and details in galaxies, the truth lies somewhere in the middle of course, but for most nebulae, you can apply the formula I gave.

I’m curious then. Do you think the formula applies here and do you arrive at the same result as me? I did expect the RASA to be even further ahead than it was but there’s every chance my math is wrong!

46 minutes ago, michael.h.f.wilkinson said:

If we assume the fields of view are similar, quite clearly the RASA will be gathering roughly 4x the the number of photons. The 6D will most likely have a lower QE than the ASI2600, which may offset the slight increase in photons per pixel, compared to a camera with smaller pixels. To match the performance of the RASA at 4 hours integration, you would need to nearly quadruple the exposure time on the Esprit.

Yes, I didn’t make it clear enough. On paper the RASA is better in all aspects. Although based on my calculations using @wimvb formulas it wouldn’t need 4x exposure time, it’s more like 3. I presume this is also partly because the Esprit options are under-sampling somewhat. This 6D is modded but I take your comment on board, it’s not going to be as sensitive as the 2600MC. 
 

My thinking here is what difference will I see in my final images from typical night of imaging and would I get the value for the extra money I pay out? I’m sure there is diminishing returns in SNR as integration time increases too? So that 3x extra exposure time and resolution may not translate completely to the final image. Having said that it will have a greater impact on those nights weather cuts a session even shorter than normal which was part of the reason I looked at the RASA in the first place 🙈

Been an interesting exercise for me and I will definitely be considering these things more in the future. The Esprit offers me a bit more flexibility as (cough, cough) I’m partial to popping an eye piece in now and again

I wanted to resurrect this discussion as I have a real world example of this and was curious as to what’s best to do.

I have limited time to image, weather, family, work etc. I have an Esprit 100ED and ASI1600mm but have became frustrated with partial datasets due to unpredictable weather and I always felt I wanted a bit more in FOV. 
 

A Rasa 8/ 2600MC combo seems to produce great images with relatively short integration times (particularly from @gorann). So, when a good deal on a 2600MC appeared I snapped it up, with the intention of swapping out the Esprit for a RASA at some point. Then I learned about the Starizona Apex-L. It would give me a slightly wider, but comparable FOV to the RASA at f3.6. Then I stumbled upon this f-ratio myth and realised I already had an other option available to me and that’s the Esprit at native focal length with a modded Canon 6D (picked up on a whim last year). See snaps from astronomy tools below for FOV comparisons 👇. 
 

Rasa combo = 1.94”/pixel

Esprit & Apex = 2.17”/pixel

Esprit & 6D = 2.45”/pixel

Obviously, the RASA is the best option on paper. My maths (please correct me if I’m wrong) shows the Rasa is 3.2x more efficient than the Esprit and Apex and 2.5x more efficient than the Esprit and 6D. 
 

I thought doing this would make the choice clear. I suppose it does but the results, particularly with the 6D have cast doubts in my mind. For instance if I imaged a target for 4 hours with all systems would there likely be a noticeable difference in the images when considering SNR and image resolution? Would I actually be better saving my money by not buying a reducer or a RASA and actually put money in my pocket by selling the 2600MC?

I think I’m actually more confused than I was before 😆

What would you do??
 

Edit to add: I was really surprised at the results using the Esprit natively with the 6D. The bigger pixels of the 6D made more of a difference than the reduction of f ratio in the Esprit! I know it’s not as simple as that as lots of other things will come into play. However, it’s showed me there is more than one way to skin a cat and it doesn’t necessarily need to empty your wallet further 😂

I would say before you jump in and spend $1200 work with what you have first. You should definitely be able to get some great results with your camera and a 70-200 f.28 lens. If focus is the problem then perhaps focus to infinity during the day and either mark the position or tape it down. Then you will at least be close to focus at night.

If you are going to spend some money then a mount should be your first purchase (and a sturdy tripod if you don't already have one). A star tracker from Sky Watcher or Ioptron could be a good start and will give you a very nice portable set up that you could still keep if you move on to something more substantial in the future. You could perhaps add in a light pollution filter as well but the best thing you could do is travel to somewhere darker if you can!

If you read through the posts here you will find plenty of information on how to get started and how to get the best of the equipment you already have, which is pretty good to start with!

For some idea of what your lens can produce look here:

https://www.astrobin.com/search/?q=Canon EF 70-200mm f2.8 L

Good luck

Can’t really comment on lens aberrations but I’m curious about the tracking you’re getting with the Fornax. I agree, looks like you’re getting good tracking at 3mins at 400mm. That’s pretty amazing unguided. Are you happy with the mount?

Zeiss generally have a good reputation. I would contact them and explain. 

50 minutes ago, Stefan87 said:

There have been solid points made about the weight of the HEQ5 and travelling. I'm travelling in a Campervan and have freed up/created more space since my last trip for this specifically. Well, for photography in general. I will prematurely work out some rough weights and make sure I'll still be under before getting too excited.

If you’re travelling in a camper van and will be setting up close to it then it’s maybe not as much of an issue as I thought. However, still a good idea to check it all out as you say 👍🏻

2 hours ago, Stefan87 said:

Thanks for the responses. You make a very good point regarding the SCT not being the most suitable for travelling. I'm very close to deciding to sell my 6se and just take the HEQ5 and a new refractor. The trip has been delayed somewhat with the current Covid situation in Australia so I have some time to breathe and get it right. Thanks for the help and thoughts!

 What do you guys think of this Scope for imaging Nebula/Galaxies? If I purchase a ZWO OAG and an ASI120mm mini, will this be a guiding setup I can use with any configuration? Including the 6se? https://skywatcheraustralia.com.au/product/120-az3-refractor/

Thanks again
 

If I’m understanding you correctly you’re planning on taking the HEQ5 on the trip? I’m not sure how you are planning to travel but that that would be a bigger hassle than even the SCT in my mind. That’s going to be ~20kg of weight when you factor in counter weights and tripod. I even gave up carrying that in and out my house 😆

I agree with the others regarding a portable refractor but if you are planning to do astrophotography as you travel I would seriously consider one of the portable star trackers on the market paired with a short focal length refractor. 

14 hours ago, James said:

Nice images Icesheet - from Bergen I'm guessing it's hard to get the brighter bits of the milky way (I'm spoiled on the south coast of England). Others have made more useful comments than I can, but I like the fact you've gone all-in to try and get as much out of the Milky Way as you can - I must admit, I hadn't thought of trying PixInsight to process my images, I've just stuck with Lightroom.. I'm no expert on composition but if you want to crop the right you'll lose the snow on the hills which I quite like

But, of course, from bergen you get more aurora than we do...

James

Thanks James! Yes, unfortunately the core of the Milkyway is only above the horizon during daylight hours. I suppose the occasional Aurora is not a bad substitute though 😉

I did like the snow too to be honest but the random bush just seemed out of place otherwise plus there was nothing much happening in the sky there either. 
 

Definitely worth giving PI a go for nightscape stuff. I was surprised what I managed to get out of it. 

Thanks, I’ll check him out 👍🏻

2 hours ago, FenlandPaul said:

Well at least you’ve got some guaranteed sleep for a while! I usually put mine in the “Photography” section of SGL (not sure why!) and they usually have the subject “AstroLandscapes #”.  There are a few recent ones I’ve not yet uploaded, which I may do soon.

I had a look through them, really fantastic stuff. I love the way you highlight your foreground subject. Are you doing all through some form of light painting? I wasn’t sure about light painting but if done right it can really make a photo. 

1 hour ago, FenlandPaul said:

Well I think that last edit it my favourite of the bunch - well done! The MW is nicely detailed for an untracked image and you’ve not gone nuts with over-brightening.  My own taste is to have it a little more saturated as I like how it makes horizon glow from lights look, but that’s just taste and yours is definitely a more natural feel.

I also am new to nightscapes but find them quite addictive!!

Thanks for the comments. You’re right they are addictive! I thought it would be a breeze doing this with some deep sky experience but there’s so much more to it than you think. 
 

I’ve lost the darkness now until September so plenty of time to plan. Be good to see some of yours too 👍🏻

Ok, last edit for now I think!

5 hours ago, davew said:

I think you've done an exceptional job gathering so much data and blending it all together. I would never have guessed it was a Panorama done with a 24 mm lens on APSC.

How did you manage to include PI in your workflow ?

Dave.

Thanks Dave!

I used PI for DBE and to remove the stars to work on the structure of the Milkyway. I was able to bring a lot more out that way. 
 

Chris

Thanks for the comments and feedback  @davew and @Knight of Clear Skies. Exactly the sort of thing I was looking for. Landscape stuff is quite new to me so always good to get opinions. 
 

You are both right. There is heavy noise reduction, more than I would usually apply. Also, I lowered the highlights not specifically for the town lights but it did bring them down. 
 

Composition wise I’m starting to think I should crop from the right up to the bush. There’s not much happening to the right. I’ll take your comments on board and have a play around again tonight 😆

Ok, I’m supposed to be working from home so better leave it now 😂Here’s a more subtle version of Milkyway. Jeez and I thought the deep space stuff was bad for fiddling. 
 

18 minutes ago, Knight of Clear Skies said:

It's a nice image but I think a more subtle version would work better.

Thanks for the feedback 👍🏻 I think I will go back to the Milkyway and tone it down a bit

Ok, I wasn’t sure about posting this since I think it may look a bit fake, even although it wasn’t! If you look at the water in the image above you’ll notice a green tinge. That’s because as I was taking the long exposure in the foreground unbeknown to me there were Aurora going on. When I realised and tried to take a proper exposure they were gone. I tried to see if there was a way to get them in and this is the best I could come up with trying to blend it in to the existing sky.
 

Thoughts? Too fake looking?

Love that little arm to hold the iPad! When you’ve already got a solid package that’s the attention to detail that makes a difference

Thanks Mick 👍🏻

Looking for some good constructive criticism on this one. 

I have recently been taking more and more interest in nightscape stuff and this is the first time I’ve attempted a panorama. I really had to push the Milkyway to get detail here and I think I may have overstepped 

4 pane panorama 

Canon 550D and Samyang 24mm

2x120” f4 @ISO800 for each of the two landscape panes

20x20” f2 @ISO1600 for each of the two Sky panes. 
 

Editing in a combination of PS, LR and PI. 
 

If you’re using a phone probably best to tip on its side.