Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

ST120 First Light

alowen

By alowen
in Member Equipment Reviews

Recommended Posts

alowen

alowen

Posted
Posted

After nearly 2 weeks (of expected) cloud, last night was my new scopes first light. As far as polar aligning was concerned, I got it level with the 'N' leg facing north.

After a cool down of a good 45 mins the toe nail shaped moon was the first target using a Meade 26mm ep. Lovely suprisingly crisp view. Even though the moon was waxing so much its brightness affected my night vision, which suprised me. I noticed no CA at all.

Next up was M42, a crisp clear view and after a few moments the Trapezium was visible, very happy indeed. I was buzzing between 2 scope at the time and next time will get to learn mine a bit better.

The Telrad dew'd up pretty quickly even with a plastic sheath on it along with the RDF. More alarmingly even with the scopes dew shield attached after about an hour the dreaded dew made its appearance on the lense.

Next up was M41, due to the Telrad dewing so rapidly it wasn't as easy as i'd thought it would be to locate. But after a few minutes there she was, looking slightly feint but still great.

Finally Saturn, first through the 26mm ep, the planet looked small and clear with the rings and 1 moon visible. Then with the 12.4mm ep, a fantastic view. Again i noticed no CA and the image literally had doubled in size.

All in all i am very pleased with the scope and the EQ3-2 mount, positioning the mount was easy and the optics were very good. Its mainly going to be used for DSO's but i'm suprised how well it performed on the plants.

I'm lucky that I had the oppurtunity to use Meade 4000 ep's as they gave great views. I've heard said that short focal length scopes are quite demanding on ep's.

Now to consider anti dewing options for the telrad and scope, possibly heated.

Al

Link to comment
Share on other sites
  • Replies 47
  • Created
  • Last Reply
philj

philj

Posted
Posted

Congrats on your 1st light. The 120ST certainly pulls in the faint fuzzy stuff.

Sounds like youve got a good un, my old St120 had very poor CA on the moon and planets but I didnt care that much because it was fine for DSOs.

Philj

Link to comment
Share on other sites
lw24

lw24

Posted
Posted

I've got the ST120, and have to agree, it's a great scope.

There is a fair bit of CA on the moon, when it's gibbous, and full.

It shows certain DSO very nicely, expecially M42, M45, M37, M35, M36 and the Double Cluster.

I'm going to have mine mounted on an AZ4 soon, to enable some relaxing 'sky surfing'.

Have fun with it!

Clear Skies

Link to comment
Share on other sites
John

John

Posted
Posted
Planetwise it was only tested on the moon and Saturn, and I didn't notice any CA. Maybe its been addressed with the newer models ?!

Al

CA in fast achromat refractors is a matter of physics - I don't think it can be "designed out" as such without resorting to exotic glass types and / or additional lens elements, in which case you then have an apochromat and even expensive F/5 apochromats, such as the Tele Vue Genesis, show some CA.

I do reckon some folks are bothered by it more than others though - if it doesn't bother you then it's great :)

Link to comment
Share on other sites
alowen

alowen

Posted
  • Author
Posted
I'm going to have mine mounted on an AZ4 soon, to enable some relaxing 'sky surfing'.

I too have thought about an AZ4 mount, the eq is nice but a contortionists dream.

I do reckon some folks are bothered by it more than others though - if it doesn't bother you then it's great :)

That may well be just like me, i didnt see anything that made me think it was a problem.

Al

Link to comment
Share on other sites
John

John

Posted
Posted

That may well be just like me, i didnt see anything that made me think it was a problem.

Al

I was like that - until I looked though a scope that showed no CA - then I started to notice it :)

Link to comment
Share on other sites
Rob

Rob

Posted
Posted

The ST120 is a little gem of a DSO scope. Best view I've ever had of M27 was in mine at the time.. almost 3D looking. Sure The CA on a f5 Achro is going to be bad on moon & planets, but to be fair its not really designed for that. That said the images of those targets are pleasing also.

Glad your enjoying it

Rob

Link to comment
Share on other sites
lw24

lw24

Posted
Posted

Yeah, I find that the ST120 is a cracking little scope for looking at the Moon.

Some people say that the view starts to go 'mushy' over 80x magnification, but I can safely say, that the view of the Moon is still extremely crisp and sharp at 120x.

Can't wait to see M27 and the Veil (Maybe with a UHC/OIII) for the first time :)

Link to comment
Share on other sites
SiriusB

SiriusB

Posted
Posted

Al,

I'm sure you will enjoy the ST120 even more as time progresses, great scope, especially at the price.

Yeah, CA's nowhere near as bad as i had expected, & a pleasant suprise on the moon.

Mind you,It's a wee bit horrific on Jupiter.:)

Link to comment
Share on other sites
lw24

lw24

Posted
Posted

By the sounds of it, I think we should set up an ST120 Appreciation Club :)

The great thing about it, is that it can really challenge against 6 inch reflectors, on a number of fronts; practicality, ease of use, sharp images, portability etc.

Reflector users just come back with "yeah, but it's got loads of CA", when they haven't even tried it. :)

ST120 all the way! :(

Link to comment
Share on other sites
Moonshane

Moonshane

Posted
Posted

CA is 'chromatic aberration' which is usually worst on the brightest objects like the moon. it usually means that you see a yellow edge on one side of the moon and a blue edge on the other. this is due to the light not converging exactly in one place and hence a mild spectrum effect. I had a 120mm f8.3 and there was a little CA on that but it never bothered me. I was thinking about maybe a small 72mm e.g. Megrez for a wide field view. maybe I should consider the ST120! on the whole I prefer reflectors but to some extent miss the wider field given by these fracs.

Link to comment
Share on other sites
hunterz

hunterz

Posted
Posted
CA is 'chromatic aberration' which is usually worst on the brightest objects like the moon. it usually means that you see a yellow edge on one side of the moon and a blue edge on the other. this is due to the light not converging exactly in one place and hence a mild spectrum effect. I had a 120mm f8.3 and there was a little CA on that but it never bothered me. I was thinking about maybe a small 72mm e.g. Megrez for a wide field view. maybe I should consider the ST120! on the whole I prefer reflectors but to some extent miss the wider field given by these fracs.

Thank you

Link to comment
Share on other sites
Kef9

Kef9

Posted
Posted

Glad you liked your ST120. I have the ST150 and CA on mine is pretty bad when looking at the moon, planets and bright stars but its great for portability, general use & deep sky.

When doing moon and planets I swicth to the C100ED :)

Link to comment
Share on other sites
thommo10

thommo10

Posted
Posted

Hi all

I have read this thread with intrest because I am thinking of getting a st120 or 150 one question I would like to ask. is the ca worse in the 150 than the 120. I would be using it for dso's with probably some general viewing.

Link to comment
Share on other sites
John

John

Posted
Posted
Hi all

I have read this thread with intrest because I am thinking of getting a st120 or 150 one question I would like to ask. is the ca worse in the 150 than the 120. I would be using it for dso's with probably some general viewing.

Yes the ST150 F/5 will show more CA than the ST120 and the 120 shows more than the 102, and so on.

Link to comment
Share on other sites
thommo10

thommo10

Posted
Posted

so the 150 would be better for dso's being a bigger aperture but the 120 is ok for dso's and better on moon and Planets, on saying that I would be using it more for dso's as I have my etx for the moon and planets.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.