Sharpstar 61 EDPHII CA Issues

[Juno16]

Hi Everyone,

I figured that I would post this information in case anyone here is impacted.

I purchased a Sharpstar 61 EDPHII earlier this year. I liked the review by “Cuiv, The Lazy Geek” on Youtube, and chose it over the Radian Raptor for the price difference.

I imaged with it several times on large nebulae targets using the L-eNhance filter. I was very pleased with the results.

Recently, I imaged M31 and more recently, M33 broadband using the IDAS LPS D-1 filter (LP) and saw pretty horrible CA especially on the larger stars. After star removal, huge blue rings were left all over the starless image. It took thousands of Clone Stamps to attempt to get rid of them which was only partially successful.

There is a huge > 281 post thread on CN relating to the issue. https://www.cloudynights.com/topic/7337 ... bberation/

On the CN thread, some users of the Radian Raptor are reporting the same issue.

I sent a message to Cuiv on his YouTube channel. He responded and had also imaged narrowband with the Sharpstar 61 EDPHII at first and after imaging M33 broadband he noticed the same issue.
He contacted Sharpstar and they sent him a replacement objective. He posted a video on installation on his YouTube channel (super easy).
I also contacted Sharpstar. They responded on the next business day (10/25/21) and asked for images to show the issue which I promptly provided.

I received a new objective last week (only 10 days after reaching them). I installed the objective (5 minutes) and imaged M33 for two hours last night to test it.

To test the new objective, I loaded 2 hours of lights from the night that I imaged M33 with the bad objective into Pixinsight WBPP. I only used darks for calibration.

I shot 2 hours of lights with the new objective last night, loaded them in to PI WBPP with only darks for calibration.

In Pixinsight, I opened the bad objective Masterlight and applied Dynamic Crop, ABE, Background Neut, Color Calibration, SCNR, and a masked stretch with a target background of 0.125.

I then opened the new objective Masterlight and applied each process from the bad objective Masterlight History Explorer to the new objective Masterlight.

The image with the bad objective is on the left and the image with the new objective is on the right.

Another comparison with more zoom.

If you have a Sharpstar 61EDPHII and have noticed this issue, you might want to contact Sharpstar soon. I messaged them on their Facebook page.

If you have a Radian Raptor and have noticed this or a similar issue, you might want to contact the seller.

I hope that this information/comparison can help someone!!!!

NOTE: The CA does not show in individual frames. These images were from 2 hours of integration. Increasing integration increases the CA.

[JayTee]

That's kind of a crazy issue. Thanks for writing this up Jim and telling folks how they can resolve the problem.

[Juno16]

That's kind of a crazy issue. Thanks for writing this up Jim and telling folks how they can resolve the problem.

You are welcome JT. Yeah, it is a crazy issue and I wasted several nights of imaging because of it.
It really is a great little scope and now it is performing like it should.
Sharpstar did great and corrected the issue promptly.

I bought the scope from Agena Astro who I have purchased a good bit of astro gear from. Very dissatisfied how they responded when I contacted them. It was explained that the performance was adequate the price. I think not.

From the looks of the CN thread, some folks that purchased the Radian Raptor had the same or similar issue. That scope is over $300 difference than the Sharpstar at $999.

Just wanted to make anyone here that owns the Sharpstar and has this issue that it is not acceptable and they should contact Sharpstar very soon.

[SkyHiker]

That is a big difference Jim. I browsed through the CN thread, I suspect the large number of responses played a role in the ease of replacement. Congrats with the fix.

[Juno16]

That is a big difference Jim. I browsed through the CN thread, I suspect the large number of responses played a role in the ease of replacement. Congrats with the fix.

Very well could be Henk. The power of numbers. That is a huge thread.

Either way, minus a few nights, I think that I have come out good. The scope is really a joy to use and very affordable. The only modification that I made (besides adding a filter drawer and ASI EAF) was to add a 10" dovetail so that it could be balanced well. Actually, now with the upgraded objective, I will probably use this scope for the majority of imaging. I will swap back to the ED ED102 occasionally for galaxies.

[STEVE333]

Hi Jim - I just saw this post. Congratulations on pursuing the issue and getting a good resolution. Not everyone would have taken the time to do this. Hopefully anyone else who encounters this will find your post. Well done.

Steve

[Juno16]

Hi Jim - I just saw this post. Congratulations on pursuing the issue and getting a good resolution. Not everyone would have taken the time to do this. Hopefully anyone else who encounters this will find your post. Well done.

Steve

Thanks Steve. I posted my findings on the CN thread also.

I hope that if anyone is effected with the CA issue on the Sharpstar 61 EDPHII would have contacted Sharpstar. I have heard that there is a time limit.

I must give credit to Cuiv as he first reported on the CA issue on his YouTube channel. He helped me contact Sharpstar.

Besides a short test on M33 with the new objective, the scope with the new objective performed well on the first target, M45 that I posted recently.

Thank you Steve!

[notFritzArgelander]

That's an extremely odd manifestation of CA. Is there an explanation of the problem origin?

[Juno16]

That's an extremely odd manifestation of CA. Is there an explanation of the problem origin?

Absolutely nFA. Especially considering it is an APO!

No explanation except that they offered to send me a replacement objective lens assembly. Received it from China rather quickly (10 days) and was literally a 10 minute swap. The scope behaves nicely now.

[notFritzArgelander]

That's an extremely odd manifestation of CA. Is there an explanation of the problem origin?

Absolutely nFA. Especially considering it is an APO!

No explanation except that they offered to send me a replacement objective lens assembly. Received it from China rather quickly (10 days) and was literally a 10 minute swap. The scope behaves nicely now.

OK. Then I'd guess at the spacing in the objective was just a tad out. But it's only a guess.... Thanks.

[JayTee]

Given the quantity of complaints on the CN thread I wonder if the Quality Control guy still has a job?

[Juno16]

That's an extremely odd manifestation of CA. Is there an explanation of the problem origin?

Absolutely nFA. Especially considering it is an APO!

No explanation except that they offered to send me a replacement objective lens assembly. Received it from China rather quickly (10 days) and was literally a 10 minute swap. The scope behaves nicely now.

OK. Then I'd guess at the spacing in the objective was just a tad out. But it's only a guess.... Thanks.

Could be nFA. I just know that it performs well now. Disappointed that I had some poor results initially, but Sharpstar made it right and I am happy with that.

Initially, I reached out to Agena Astro Products, the vendor that I purchased the Sharpstar from. I was disappointed that they told me that the CA was in the acceptable range for a scope at this price point. I think not!

[notFritzArgelander]

Absolutely nFA. Especially considering it is an APO!

No explanation except that they offered to send me a replacement objective lens assembly. Received it from China rather quickly (10 days) and was literally a 10 minute swap. The scope behaves nicely now.

OK. Then I'd guess at the spacing in the objective was just a tad out. But it's only a guess.... Thanks.

Could be nFA. I just know that it performs well now. Disappointed that I had some poor results initially, but Sharpstar made it right and I am happy with that.

Initially, I reached out to Agena Astro Products, the vendor that I purchased the Sharpstar from. I was disappointed that they told me that the CA was in the acceptable range for a scope at this price point. I think not!

Glad it worked out for you. Sorry to hear about that nonsense from Agena. I've bought much from them but on two occasions found them less than helpful.