Astronomik UHC

[Isophotons]

Hello, I purchased a clip in Astronomik UHC filter for a Sony A7 and tested it out. Attached is a 3 minute shot and the hue is horrific. Would anyone know if this.is complete user error or is this normal. What advice would one have on how to correct It?

Thanks in advance!

[ronin]

Suspect it is about right. Would have preferred a more uniform hue rather then the blue middle and the red outer.

The astronomuc passes at the Ha region and the OIII region so a chunk of Red and a chunk of Blue/Green, you have: Hb (blue), [OIII] doublet (green), Ha (red) and [SII] doublet (cyan).

Not sure if the A7 is modified, so if not then that internal filter needs to be taken into account, which likely removes an amount of the red. Have a Sony and I asked but ASony said they did not know the characteristics of the internal filter. Basically don't think they could be bothered.

This is the plot for the Astronomics I have, hope it is still relevant. Also as mentioned the presence or absence of an internal filter causes the image to alter. As much by what the siftware does to any image. Unfortunately these days the image is likely not just what you take it can have software applied.

As said not sure about the Red-Blue-Red across the image but the actual 2 colors is understandable.

[Adam J]

wow I would not have expected that effect if I am honest. It may be worth setting a custom white balance with the filter in place? But the thing that worries me more than the odd colour is that it is not consistent across the image..why not e-mail astronomik? I have done so in the past and they are very helpful. 

[John78]

What does it look like if you take a flat?  Your image might be correctable using a flat frame - but it does look odd.

[Isophotons]

Thank you all for taking the time. While I have never used a filter as such before it didn't look right to me so at least I can see I'm not crazy for thinking that. I have emailed Astronomik and am awaiting a reponse. It was from one of their first batches so maybe it's just bunk. Also, I just read about flats and will give this a try regardless. Looks like it will help with the vignetting. This was what I got out of 20 of those images. I want color though.

[Adam J]

 

15 hours ago, Isophotons said:

Thank you all for taking the time. While I have never used a filter as such before it didn't look right to me so at least I can see I'm not crazy for thinking that. I have emailed Astronomik and am awaiting a reponse. It was from one of their first batches so maybe it's just bunk. Also, I just read about flats and will give this a try regardless. Looks like it will help with the vignetting. This was what I got out of 20 of those images. I want color though.

Out of interest what F-ratio are you imaging at? There is a small possibility that the optical system is too fast for the filter to work correctly (light towards the outside of the image is striking the filter at a higher angle of incidence. It would also explain the way that the centre of the image is blue and the outside is pink. Lots of filters struggle below F3 ish. 

EDIT:

Just found this quoat on the Astromonik web page I would not be shocked to hear that you are imaging at F4 or below and with a Full frame camera the effect would be more pronounced: 

(Astronomik): The filters are optimized for use with focal ratios of f/4 to f/15. Unlike other filters on the market, loss of transmission and color displacement with the Astronomik filter occurs only on telescopes with extremely fast focal ratios of f/3 on up. Compared to the UHC filters sold by other manufacturers, the Astronomik UHC filter shows you more stars and more details in nebulas, and because of the high quality of the glass, you will see stars as small pinpoints.

[Isophotons]

1 hour ago, Adam J said:

 

Out of interest what F-ratio are you imaging at? There is a small possibility that the optical system is too fast for the filter to work correctly (light towards the outside of the image is striking the filter at a higher angle of incidence. It would also explain the way that the centre of the image is blue and the outside is pink. Lots of filters struggle below F3 ish. 

EDIT:

Just found this quoat on the Astromonik web page I would not be shocked to hear that you are imaging at F4 or below and with a Full frame camera the effect would be more pronounced: 

(Astronomik): The filters are optimized for use with focal ratios of f/4 to f/15. Unlike other filters on the market, loss of transmission and color displacement with the Astronomik filter occurs only on telescopes with extremely fast focal ratios of f/3 on up. Compared to the UHC filters sold by other manufacturers, the Astronomik UHC filter shows you more stars and more details in nebulas, and because of the high quality of the glass, you will see stars as small pinpoints.

I was at 2.8 and now that you say that it could explain the non uniform color cast. I'll try a slower aperture. Thank you very much!! It sounds promising!!

[John78]

17 hours ago, Isophotons said:

Thank you all for taking the time. While I have never used a filter as such before it didn't look right to me so at least I can see I'm not crazy for thinking that. I have emailed Astronomik and am awaiting a reponse. It was from one of their first batches so maybe it's just bunk. Also, I just read about flats and will give this a try regardless. Looks like it will help with the vignetting. This was what I got out of 20 of those images. I want color though.

So is that with a flat subtracted from the colour original image above??  It shouldn't have made it mono, if you subtracted using DSS it does have an annoying tendency to make everything look mono but you can fix it by playing with the histogram sliders...

[Isophotons]

No flat yet. It's 20 lights and 5 darks. I converted it to mono because I was struggling trying to keep color.

[TareqPhoto]

In Photoshop if you have or similar editing software try to eliminate or reduce that tint or color cast or the dominant color you don't like, here it is Magenta, or try with red channel so it may turn down the vibrancy a bit.

So, is your Sony AZ modified [or modded as they call it]?

Did you shoot in a dark site or dark sky? if not then which zone?

Which lens did you use? 

I wish if i bought that clip in filter, and from Astronomik, but i was poor enough so i went with a cheap 1.25" one because i use more than one camera so i better get the one of the scope mount size to be used on any camera.

I still didn't use the filter, because my mount isn't ready, but maybe i should try it with the normal tripod and see if i get similar issue.

A7 is a full frame, and mostly full frame gathering more light than APC-S cameras, so maybe you should crop a bit, or try another filter, or better if you use a scope then go with one of those scopes standard filter sizes.

 

[Isophotons]

8 hours ago, TareqPhoto said:

In Photoshop if you have or similar editing software try to eliminate or reduce that tint or color cast or the dominant color you don't like, here it is Magenta, or try with red channel so it may turn down the vibrancy a bit.

So, is your Sony AZ modified [or modded as they call it]?

Did you shoot in a dark site or dark sky? if not then which zone?

Which lens did you use? 

I wish if i bought that clip in filter, and from Astronomik, but i was poor enough so i went with a cheap 1.25" one because i use more than one camera so i better get the one of the scope mount size to be used on any camera.

I still didn't use the filter, because my mount isn't ready, but maybe i should try it with the normal tripod and see if i get similar issue.

A7 is a full frame, and mostly full frame gathering more light than APC-S cameras, so maybe you should crop a bit, or try another filter, or better if you use a scope then go with one of those scopes standard filter sizes.

 

My camera is not modified. I used a Sony/Ziess 55mm 1.8 @ 2.8 ISO 1600 @ 180 seconds. The area I imaged from is a Class 5 in Southern NJ, USA. Long story but I was kind of forced to that area because of a lot of rain and coastal flooding. The best I can get semi close by is Class 4. Astronomik got back to me and stated it was not normal. They asked for the serial number and now I'm waiting to hear back.

[Adam J]

3 hours ago, Isophotons said:

My camera is not modified. I used a Sony/Ziess 55mm 1.8 @ 2.8 ISO 1600 @ 180 seconds. The area I imaged from is a Class 5 in Southern NJ, USA. Long story but I was kind of forced to that area because of a lot of rain and coastal flooding. The best I can get semi close by is Class 4. Astronomik got back to me and stated it was not normal. They asked for the serial number and now I'm waiting to hear back.

Did you let them know that you were imaging at F2.8 when you e-mailed them?

[Isophotons]

7 hours ago, Adam J said:

Did you let them know that you were imaging at F2.8 when you e-mailed them?

I did not for one reason only. I wanted to have them validate what you posted. Guess what? You get a good star Adam! They stated that the lens I used was to wide and that I should stop down to at least f4. They also stated a custom WB should be set in the day with the filter in. I have been inundated by crappy weather and hope to give a go Saturday into Sunday coming up.

[TareqPhoto]

Hope it will work for you then, post results when you did.

[TareqPhoto]

Any news about your filter?