Evolux 62ed producing deep blue stars advice needed. Please help

[Chibster86]

Hey folks!

 

First time here because I'm at my wit's end. I've been amatuer imaging for about 2 years new. Mostly with camera and lens (50mm the 135mm etc) and finally decided to upgrade some gear to get serious into the hobby. 

Back in August I decided to buy the Evolux 62ed to go with the SWSA GTi. But I've had nothing but problems since and the disappointment is really grating me. Nothing like the reviews and various YouTube videos praising the scope. 

I first started with a cheaper Stella Mira field flattener because of budgeting issues and my first image showed very strong blue stars. I asked and researched and everything was pointing to the field flattener. 

I gave up for a few months until I could afford the official SW field rotator. Which I purchased last week. It turned up yesterday so I eagerly when out to a Crisp night sky last night. 

Reset up back up. Target: M42, Kept to a 19second exposure. Iso 800 on an unmodded canon 250D 

Only to find Blue stars.. again! 

I'm at a loss. None of the reviews state anything about the scope suffering from chromatic aberration and even more so with the 62ed lens when combined with the field flattener and state color corrected pinpoint stars when used together.

 Or should I contact FLO to have the scope checked? Perhaps a filter would resolve it? 

once I've downloaded the images off the camera I'll post them up 

[The Lazy Astronomer]

Hi and welcome to the forum. Definitely post up the pics (preferably a linear stack, and maybe one sub). Without seeing them, I'd hazard a guess at bloating caused by UV light if you're not using any kind of UV/IR cut filter. 

[Chibster86]

Thank you! Heres a pic of ones before I purchased the SW field flattener with the astronomics M48 adapter. I haven't stacked any because I discounted them as any form of useable data.

The images on the camera are identical to this one taken on the original Stella Mira field flattener on the 62ed. So you can get a general idea I'll post up the latest single subs alittle later when I'm back home

Both my cameras (600d and 250d) are not modded and should still have the IR/UV cut filter attached. Therefore the filter wouldn't have that much of an impact? Or am I reading this incorrectly? 

What bothers me is no review I have read have mentioned about the scope suffering from chromatic aberration and shows crisp color corrected stars. But I most definitely not seeing this. So I'd like to discount any potential issue with the scope

 

[StevieDvd]

Just to be clear, you now have the SW focal reducer for the Evolux 62 which comes with the rotator.  Have you an tried an image without a flattener as well?

 

 

[Chibster86]

6 minutes ago, StevieDvd said:

Just to be clear, you now have the SW focal reducer for the Evolux 62 which comes with the rotator.  Have you an tried an image without a flattener as well?

 

 

Yeah. The official one designed for the 62ed. Purchased it from FLO just before the weekend. I havent connected it directly without the FF because I originally used a M42 thread but I should be able to connect the  new m48 thread t ring adapter direct to the telescope shouldn't I? I'll try that tonight and hopefully find a gap in the clouds. I am hesitant to think it's the FF though as both the old and the new produce the same effect and I can discount the cameras as they're perfect on the 135mm. 

 

[ONIKKINEN]

Its a fast doublet, so some colour is to be expected, but not sure if this much. You are imaging a group of extremely bright and exceptionally blue stars here, so perhaps the worst case scenario and its possible the scope is working as expected.

You might want to add an Astronomik L3 filter to cull out some purple and blue with a colour camera, that one has a tighter UV/IR cut range than most other UV/IR cut filters.

[Chibster86]

11 minutes ago, ONIKKINEN said:

Its a fast doublet, so some colour is to be expected, but not sure if this much. You are imaging a group of extremely bright and exceptionally blue stars here, so perhaps the worst case scenario and its possible the scope is working as expected.

You might want to add an Astronomik L3 filter to cull out some purple and blue with a colour camera, that one has a tighter UV/IR cut range than most other UV/IR cut filters.

It's a shame a filter is needed to be used to correct what most reviews and skywatcher says about the scope. 2 ED lens for color correction isn't doing it's job. Something im struggling more considering I also image with a samyang 135 with a similar sort of lens and don't get anything such as this in any of my subs. That's why I'm struggling to brush it aside.

I can agree it's definitely the hotter stars that it happens on as it's very well balanced for m31. Ill pull last night's M42 images shortly. 

Just to confirm as I have two unmodded cameras. An IR/UV filter can still be used? And can I use other filters alongside this? 

[ONIKKINEN]

34 minutes ago, Chibster86 said:

It's a shame a filter is needed to be used to correct what most reviews and skywatcher says about the scope. 2 ED lens for color correction isn't doing it's job. Something im struggling more considering I also image with a samyang 135 with a similar sort of lens and don't get anything such as this in any of my subs. That's why I'm struggling to brush it aside.

I can agree it's definitely the hotter stars that it happens on as it's very well balanced for m31. Ill pull last night's M42 images shortly. 

Just to confirm as I have two unmodded cameras. An IR/UV filter can still be used? And can I use other filters alongside this? 

Affordable small doublets are often the first scopes new astrophotographers buy, so there is a lot of rose tinted review kind of thing going on where it looks good to most beginning users but those who expect true photographic apochromatic performance will be disappointed (for visual use these are more or less true apochromats). Realistically a fast doublet will always have CA even with premium glass. Even longer focal ratio doublets will have some CA too unless we get into very long and cumbersome f-ratios, you really do need a triplet if the goal is true colour free imaging with a colour camera that captures all of the visible spectrum at once.

That being said, more restrictive filters are a good choice as the worst performance is at the far end of the blue and red spectrum (which the L3 cuts mostly). You can use a filter with your unmodded camera and i would recommend that for this case. Unmodded DSLRs still let trough a little bit of the purple/near UV wavelengths that the Astronomik L3 would cut off. The red side is not nearly as affected as the stock IR cut filter in DSLRs is quite aggressive already.

The M31 looks just about what one would expect, i think the scope is doing a pretty good job with more normal temperature stars.

[Chibster86]

3 hours ago, ONIKKINEN said:

Affordable small doublets are often the first scopes new astrophotographers buy, so there is a lot of rose tinted review kind of thing going on where it looks good to most beginning users but those who expect true photographic apochromatic performance will be disappointed (for visual use these are more or less true apochromats). Realistically a fast doublet will always have CA even with premium glass. Even longer focal ratio doublets will have some CA too unless we get into very long and cumbersome f-ratios, you really do need a triplet if the goal is true colour free imaging with a colour camera that captures all of the visible spectrum at once.

That being said, more restrictive filters are a good choice as the worst performance is at the far end of the blue and red spectrum (which the L3 cuts mostly). You can use a filter with your unmodded camera and i would recommend that for this case. Unmodded DSLRs still let trough a little bit of the purple/near UV wavelengths that the Astronomik L3 would cut off. The red side is not nearly as affected as the stock IR cut filter in DSLRs is quite aggressive already.

The M31 looks just about what one would expect, i think the scope is doing a pretty good job with more normal temperature stars.

Yeah Im getting what you're saying. And I think Im guilty of being sucked into those rose tinted views. I honestly think there's a fair few content creators that stand up the astro community that do rose tint the difficulty level of the hobby and do hide the cons of scopes, The gear and worst of all, The work needed to turn several nights worth of data into the masterpieces you see at the end of a video. 

 

Coming from using a camera lens (especially the phenomenal lens Samyang 135mm f2) on a star tracker I've been able to not require the need to consider the smaller things such as filters and reduce the exposure time needed at f2.8 so I've come to expect that from a "capable scope" I think I've also fallen into the fallacy of new gear = better performance, for mounts yes very true. But scopes are a very different matter

 

I'm determined to get something out of this scope though and a search on astrobin has shown it is a capable scope none the less. Just I need to buckle down, consider targets within its limitations and put more work in to get the results I'm looking for. I'm just glad that the scope isn't looking like it's defective and have to accept that it does have its limitations so appreciate your insight on that. 

 

By way of filters. I'll definitely consider looking into the L3 thank you. Is there a list of targets by "best" filter that I can look at? And can I pair that with a light pollution filter together as I am in a bortle 5/6 area? 

[ONIKKINEN]

19 minutes ago, Chibster86 said:

Yeah Im getting what you're saying. And I think Im guilty of being sucked into those rose tinted views. I honestly think there's a fair few content creators that stand up the astro community that do rose tint the difficulty level of the hobby and do hide the cons of scopes, The gear and worst of all, The work needed to turn several nights worth of data into the masterpieces you see at the end of a video. 

 

Coming from using a camera lens (especially the phenomenal lens Samyang 135mm f2) on a star tracker I've been able to not require the need to consider the smaller things such as filters and reduce the exposure time needed at f2.8 so I've come to expect that from a "capable scope" I think I've also fallen into the fallacy of new gear = better performance, for mounts yes very true. But scopes are a very different matter

 

I'm determined to get something out of this scope though and a search on astrobin has shown it is a capable scope none the less. Just I need to buckle down, consider targets within its limitations and put more work in to get the results I'm looking for. I'm just glad that the scope isn't looking like it's defective and have to accept that it does have its limitations so appreciate your insight on that. 

 

By way of filters. I'll definitely consider looking into the L3 thank you. Is there a list of targets by "best" filter that I can look at? And can I pair that with a light pollution filter together as I am in a bortle 5/6 area? 

In bortle 5 i wouldn't use a light pollution filter for broadband targets, and probably not in B6 either. Depends on the target, and the filter i would say. For broadband targets: Galaxies, reflection nebulae, dark nebulae i would not use a generic wide band light pollution filter because there is hardly a point (these targets radiate on the same spectrum as light pollution so blocking LP blocks the target = no point). For emission nebulae, you will see a significant improvement, but here i would rather use an emission line filter rather than a generic light pollution filter like a CLS type filter or an L-Pro. Coupling a UV/IR filter with another type of broadband or narrowband filter is not necessary as those filters also block UV and IR wavelengths, unless stated otherwise (few filters need both).

Options for an easier to begin with narrowband filter would be something like the Optolong L-enhance or Antlia Triband RGB ultra which pass a fair bit around Ha and OIII (and the Triband RGB passes additional blue) and so dont require uber long exposures to make use of. If you want a more restrictive filter that ultimately results in more emission signal trough and less anything else you have options like L-extreme, L-ultimate and many others from Idas, Antlia, Askar etc (every manufacturer has their version). These more restrictive filters pass less light trough, so exposure times will need to be much longer.

However there is a problem, the factory UV/IR filter in DSLRs blocks most of H-alpha so you will need to expose for really long and still not get much signal in the red channel. So for a stock DSLR i would not suggest using a very restrictive filter as the Ha layer will undoubtedly be very noisy even in long exposures. Oxygen III emissions in the green/blue colour will pass very nicely through a stock DSLR though so its not all lost.

I would say dont worry about the CA too much, get a more restrictive UV/IR filter like the Astronomik L3 and forget about the CA as not much else to be done about it. Only very bright and blue stars will be significant trouble, and you can try to reduce that glow in processing later for instance by selectively desaturating the specific type of purple found around those stars or using masks and/or starless processing to not stretch those bright blue stars as much as the rest of the image (or simply the color fringe tool in Camera raw in Photoshop if you have it). Apart from the Pleiades there wont be many stars so bright and blue that you have to worry about. And even with the Pleiades you can work around them in postprocessing so knowing the limitations and that some processing tricks are needed you can definitely get a pretty image out of it.

[Chibster86]

That's really informative thank you! I was going to ask as on FLO website as it actually suggests using a CLS filter on the astronomics L3 filter at the bottom. But the info sheet doesn't suppess blue as much as the L3 . Reading the reviews and the info on there is something I definitely need though so I appreciate that. 

 

So the below pics are 

 

M42 Orion with the 62ed with the SW rotator and FF and the wider one is an example of a 29 second sub at f2.8 with the Samyang for comparison taken in the same location. No star bloat. (Ignore the orangey tang on the bottom of the 62ed that's a telegraph cable)  

For post I'm not that Photoshop savvy sadly. Wish I was. I do everything in Siril as it tends to be quite intuitive. But I'll definitely look into some tutorials with Photoshop and camera raw.  

 

 

Edited January 16, 2023 by Chibster86
Adding more info about pics

[alacant]

19 hours ago, Chibster86 said:

discount any potential issue with the scope

Hi

Any low end refractor will give the same aberration. A few bits which work for us [1]:

• Use compromise focus as you would with an old camera lens... Don't use a focus mask. Or rather, do use a focus mask to get you close. Now, remove the mask and focus away so that the blue halo almost disappears. A whitish yellow star is good for this. Capella, ideal.
• Split rgb. Use deconvolution of the blue channel. Now recombine.
• Use a #8 yellow filter
• Give the stack a decent stretch

Not much I could do with a .jpg, but you'll get the idea.

Cheers and HTH

 

[1] disclaimer, these tips are NOT with a 62ed, they're with the 72ed, but from what we can see, the 62 looks pretty much identical to the 72.

 

[Chibster86]

9 hours ago, alacant said:

Hi

Any low end refractor will give the same aberration. A few bits which work for us [1]:

• Use compromise focus as you would with an old camera lens... Don't use a focus mask. Or rather, do use a focus mask to get you close. Now, remove the mask and focus away so that the blue halo almost disappears. A whitish yellow star is good for this. Capella, ideal.
• Split rgb. Use deconvolution of the blue channel. Now recombine.
• Use a #8 yellow filter
• Give the stack a decent stretch

Not much I could do with a .jpg, but you'll get the idea.

Cheers and HTH

 

[1] disclaimer, these tips are NOT with a 62ed, they're with the 72ed, but from what we can see, the 62 looks pretty much identical to the 72.

 

Thanks for your advice! And apologies I'm not sure why that was a jpg. I shoot always in Raw weird! But I can definitely see you've managed to reduce the ugliness  considerably! That's incredible and gives me faith that even off a single exposure it's reducible with careful processing

What program do you use for your post processing Photoshop? 

Siril does let me spilt the RGB. I use a similar process before whereby I have used the green channel for luminance on the Cygnus wall previously to great effect but I haven't had much joy with it to reduce star bloat.  

By meaning of a #8 yellow filter. Is that the same filter for planetary observing? I have a 1.25" for visual observing of mars pretty useless for the but if so would I combine that with the previously mentioned L3 it/cut filter?

 

[Adam J]

On 15/01/2023 at 15:15, Chibster86 said:

Thank you! Heres a pic of ones before I purchased the SW field flattener with the astronomics M48 adapter. I haven't stacked any because I discounted them as any form of useable data.

The images on the camera are identical to this one taken on the original Stella Mira field flattener on the 62ed. So you can get a general idea I'll post up the latest single subs alittle later when I'm back home

Both my cameras (600d and 250d) are not modded and should still have the IR/UV cut filter attached. Therefore the filter wouldn't have that much of an impact? Or am I reading this incorrectly? 

What bothers me is no review I have read have mentioned about the scope suffering from chromatic aberration and shows crisp color corrected stars. But I most definitely not seeing this. So I'd like to discount any potential issue with the scope

 

I would say that's quite strong especially if you have a unmodified DSLR. I have a FMA180 which has some CA I correct using a L3 filter but the L3 is wider than the standard filters on canon DSLRs and so I am not sure it would help much here. I don't remember seeing someone complain of this level of CA from 62ED before although it clearly has some..it's not totally unknown for some example of a product to perform worse than others due to spherical aberration that is poorly balanced with wavelength (spherochromatism) it usually results from incorrect spacing between the two lens elements. Might be worth contacting other members with the same scope and if they find your results unusual then get in touch with FLO and they should be able to have it tested for you. 

In all honestly though it may just be like this. Manufacturer's have started to really push the limits of what they can get away with calling apochromatic in recent years. 

Edited January 16, 2023 by Adam J

[Chibster86]

2 hours ago, Adam J said:

I would say that's quite strong especially if you have a unmodified DSLR. I have a FMA180 which has some CA I correct using a L3 filter but the L3 is wider than the standard filters on canon DSLRs and so I am not sure it would help much here. I don't remember seeing someone complain of this level of CA from 62ED before although it clearly has some..it's not totally unknown for some example of a product to perform worse than others due to spherical aberration that is poorly balanced with wavelength (spherochromatism) it usually results from incorrect spacing between the two lens elements. Might be worth contacting other members with the same scope and if they find your results unusual then get in touch with FLO and they should be able to have it tested for you. 

In all honestly though it may just be like this. Manufacturer's have started to really push the limits of what they can get away with calling apochromatic in recent years. 

I did think that about the L3. Because both cameras are unmodified. I'd surely not that much benefit out from it surely?

 

I'd really hate to think the level of CA on subs taken on a modded camera. And that's what I can't shift. Im Already cutting so much out and frankly the subs are awful. 

 

I'm not sure how to contact other members without a forum wide call to arms and some members doing a controlled experiment with the 62ed to gather some reference data to work from. That would be interesting though. 

 

But I genuinely think the scope does need to be checked. Im really struggling to try to ignore that there's a flaw with the elements here somewhere. Especially more so now that I have the field flattener for this scope. That should be giving more colour correction and I'm frankly seeing zero difference. 

 

 

Thanks for your opinion. Really appreciate it

[Chibster86]

Hmm. So I've taken everything off and rescrewed the skywatcher field flattener onto the scope then attached the camera.

Gave a quick polar align (it's not perfect but it'll do.) on the GTi and aimed towards Orion. 30 seconds iso 800 but this time softened the focus just off the bahtinov centre the CA is still quite apparent but it is better

 

Ignore the orange blur, that is a telegraph cable that BT decided to install 9 months ago. 

The second shot is a quick hop to ic434 to grab a single 30 second exposure to test the stars around there. They are better. 

 

I'll recheck the seven sisters again tomorrow. 

[stefanvg]

I'm also in the search for a small refractor around that price and i came also to the evolux 62ed.

I did some research online and like you said; there were a few users who claim there is absolutely no CA with this scope. 🤔

Now i doubt that these pictures were posted straight from the camera without any manipulation whatsoever...

Then i saw this youtube review - (it's in french ; https://youtu.be/CdXmCJdS9HM)

In this review you can clearly see in the pictures taken, that some stars have really bad CA just like yours. (some pictures are better than others)

As he likes some blue colors (stars) in his images; it doesn't bother him but he is aware that this is alot of CA.

So i think there is nothing wrong with your scope, it's just the performance to expect.

 

So after this video and your post here; i'm really in doubt if i should buy this scope or look for something different.

Anyway, i just wanted to let you know that you 're not alone with this problem.

 

Clear skies!

 

 

 

 

 

[Oxize]

He Chibster, i am owning also an Evolux 62ED. I have also a little blueish tint in my photos, but not that much as you. Mostly purpleish, like in thoser others picture. You can all remove that with post processing. Dont expect to get a perfect color balanced photo out of a single DSLR frame. Will never happen. Atleast not with this scope and other scope below 1000 euro. 

Stack all images, do you darks and flats, and post process in PS, and you should come up something like this. The glass is pretty sharp compared to other scopes.

 

 

 

Edited January 21, 2023 by Oxize

[Shaun_Astro]

IMHO there is wayy too much CA evident, it looks like an achromat nearly, considering it's 62mm ED and F6.5 I would expect minimal CA, clearly something is amiss with your example. I have seen processed pics with little to no CA.

Also seeing as the Samyang f2 delivers much better stars with being 2x faster (and cheaper than Evolux with flattener), I would return and perhaps get a Redcat.

 

**Edit**

I've just watched the French Review, and the stars seem similarly affected by CA. So perhaps this is what a single unedited frame gives, has put me off the Evolux somewhat.

Edited January 30, 2023 by Shaun_Astro

[Adam J]

On 20/01/2023 at 15:43, stefanvg said:

 

I did some research online and like you said; there were a few users who claim there is absolutely no CA with this scope. 🤔

 

Yep and lots of people on the internet think that the world is flat. The trick is not being seduced into believing things just because they tell you what you want to hear.

Adam

[Adam J]

10 hours ago, Shaun_Astro said:

IMHO there is wayy too much CA evident, it looks like an achromat nearly, considering it's 62mm ED and F6.5 I would expect minimal CA, clearly something is amiss with your example. I have seen processed pics with little to no CA.

Also seeing as the Samyang f2 delivers much better stars with being 2x faster (and cheaper than Evolux with flattener), I would return and perhaps get a Redcat.

 

**Edit**

I've just watched the French Review, and the stars seem similarly affected by CA. So perhaps this is what a single unedited frame gives, has put me off the Evolux somewhat.

People are expecting too much from a scope that is not using permium ED glass.

This is the equiverlent:

https://www.rothervalleyoptics.co.uk/rvo-horizon-60-ed-doublet-refractor-ota.html

Or the TS, they are proven and much better corrected than the Evolux.

the redcat and certainly the Samyang 135 are much shorter focal lengths.

Adam

Edited January 31, 2023 by Adam J

[Shaun_Astro]

20 hours ago, Adam J said:

People are expecting too much from a scope that is not using permium ED glass.

This is the equiverlent:

https://www.rothervalleyoptics.co.uk/rvo-horizon-60-ed-doublet-refractor-ota.html

Or the TS, they are proven and much better corrected than the Evolux.

the redcat and certainly the Samyang 135 are much shorter focal lengths.

Adam

Fair enough, it's not much more of an outlay. I was looking at the Altair 60EDF doublet, the Horizon 60 looks good also!

Altair 60 EDF Doublet Refractor Telescope V3 (altairastro.com)

Edited January 31, 2023 by Shaun_Astro

[symmetal]

A very useful tool to remove the blue halos if you have Photoshop is its camera_raw_filter which can be used on any image and not just camera .raw images.

Here's your first posted image with just one click of the Optics defringe module 'Sample fringe' eyedropper on one of the star blue halos. It doesn't just neutralize the colour making it grey but attempts to determine the residual colours below the halo and bring them forward. No image masking is normally required as only colours in the selected hue/saturation range are affected.

This is the latest Photoshop CC version. Earlier PS versions don't have all the latest camera raw features, so this may not be fully available as shown.

Here's your first image defringed. 🙂

Alan

[Skyline]

I can happily say, mine does not exhibit this problem. I am using the optical matched reducer/flattener for the 62. I cannot comment on other reducers as I do not own any to try out.

I have posted up subs on my short review without them processed indicating the CA your experiencing is not evident.

You might have had a bad scope, you should approach your seller for a replacement or a refund, whatever your happy with.

With regard to it using Premium Glass or not, that's the purchasers choice.  The same thing not long ago was said about the Evostar 72ED, but still it has been proven to be a good scope for imaging.

Edited February 7, 2023 by Skyline

[Chibster86]

On 07/02/2023 at 15:39, Skyline said:

I can happily say, mine does not exhibit this problem. I am using the optical matched reducer/flattener for the 62. I cannot comment on other reducers as I do not own any to try out.

Hi Skyline! Sorry for resurrecting this thread. 

Your short review actually convinced me to get this scope  truly fantastic images! which is why I'm very surprised at the amount of CA it's showing. 

Over a month in and with only a handful of clear skies here in the UK I haven't had much of a chance to get out. But still having the same problems. I managed to borrow a uv/ir cut filter and  it's still showing CA at the level I would consider acceptable for an apochromatic. Considering the scope with its field flattener combined is almost the price of a redcat I'd rather wished id just brought the Redcat even with its shorter focal length. I know there's examples showing how to remove it. But i didn't purchase an achromat at the end of the day

Would you possibly have any singluar light frames of M45 you could post for comparative uses? 

I've now decided to reach out to FLO to have the scope examined.