White light OTA.

[bomberbaz]

I recently was asking after wedge advice and have since bought a Lunt, great piece of kit. Really like it, used it several times already and practice is now starting to bring out granulation with difficulty. Struggling to get great results mainly due to the OTA I am using. An F7.5 80mm frac. Can't really take it much over x150.

On the previous thread there was mention of a 4" OTA being the best real starting point due to I believe aperture allowing to squeeze this up to x200.

I am looking for is any comments or personal experience and what they are using for white light viewing. 

[laudropb]

I think the main problem is the seeing conditions. Only when it is good can I get up to near 200x using using a SW ST 102 mm scope. Of course using my ED 120 makes things much easier.

[bomberbaz]

25 minutes ago, laudropb said:

I think the main problem is the seeing conditions. Only when it is good can I get up to near 200x using using a SW ST 102 mm scope. Of course using my ED 120 makes things much easier.

Thanks Laudropb, although I would have thought a part of the problem with the startravel 102 would be chromatic issues, think I got that right.

Although I am not sure how or indeed if that affects the overall view of the sun. Part of the reason I am asking tbh.

[Stu]

3 minutes ago, bomberbaz said:

Thanks Laudropb, although I would have thought a part of the problem with the startravel 102 would be chromatic issues, think I got that right.

Although I am not sure how or indeed if that affects the overall view of the sun. Part of the reason I am asking tbh.

Chromatic aberration is less of an issue than spherical aberration. CA can be filtered out with a Continuum filter, but SA really kills the fine detail needed to get good views of granulation. A decent 4” apo would certainly do the job, but so would a 102mm f11 as these are well corrected in SA generally. As said by John, a 120ED is a great choice too.

[bomberbaz]

8 minutes ago, Stu said:

Chromatic aberration is less of an issue than spherical aberration. CA can be filtered out with a Continuum filter, but SA really kills the fine detail needed to get good views of granulation. A decent 4” apo would certainly do the job, but so would a 102mm f11 as these are well corrected in SA generally. As said by John, a 120ED is a great choice too.

Thanks Stu, I was looking at OTA's in various focal lengths but always the issue of weight kicks in as you get bigger and longer.  If I do decide to get another OTA, I would probably look to keep it useable on my existing mount. 

Therein lies another problem, it's rated up to 5kg but I wouldn't like to slap a long ota at that weight on it, it would be really unstable.

If I do keep the existing mount, get a longer focal length OTA and keep the weight down I am looking along the lines of a Skywatcher Black Diamond Line Refractor 102/1000mm OTA LINK  Fairly certain its the Evostar 102mm, weight though quoted at 3.5KG. Sweet spot!

Anyway, not going to do anything for now, think I will spend more time at the eyepiece with the existing OTA and now I have received my zoom, try tweaking the magnification a little and get more out of this with patience. 

 

[vlaiv]

8 minutes ago, bomberbaz said:

Thanks Stu, I was looking at OTA's in various focal lengths but always the issue of weight kicks in as you get bigger and longer.  If I do decide to get another OTA, I would probably look to keep it useable on my existing mount. 

Therein lies another problem, it's rated up to 5kg but I wouldn't like to slap a long ota at that weight on it, it would be really unstable.

If I do keep the existing mount, get a longer focal length OTA and keep the weight down I am looking along the lines of a Skywatcher Black Diamond Line Refractor 102/1000mm OTA LINK  Fairly certain its the Evostar 102mm, weight though quoted at 3.5KG. Sweet spot!

Anyway, not going to do anything for now, think I will spend more time at the eyepiece with the existing OTA and now I have received my zoom, try tweaking the magnification a little and get more out of this with patience. 

 

What mount do you have?

I have that scope and it feels under mounted on AZ4 - because it is long. I see that you have AzGti mount? I would not even think of putting such a long scope on AzGti.

[bomberbaz]

14 minutes ago, vlaiv said:

What mount do you have?

I have that scope and it feels under mounted on AZ4 - because it is long. I see that you have AzGti mount? I would not even think of putting such a long scope on AzGti.

You would not put which OTA on the AZ GTi, the Evostar 102 ?

[AdeKing]

I've used my ED100 on the AZGTi, but I've found that it's a bit much for the mount.

I know that several of the users on here are using 100mm f/7 OTAs on it quite happily though.

I tend to only use it for my ST102, ZS66 or Lunt now as I'm much happier with the stability.

[John]

I agree with Stu about optical quality mattering. The best white light views I've had are with my ED120 and my Tak 100mm F/9. My Vixen ED102SS is F/6.5 and also pretty good but the Tak is even better

 

[bomberbaz]

25 minutes ago, John said:

I agree with Stu about optical quality mattering. The best white light views I've had are with my ED120 and my Tak 100mm F/9. My Vixen ED102SS is F/6.5 and also pretty good but the Tak is even better

 

Mind made up John thanks, I am definitely doing nothing. 

If I did buy anything it needs to be worthwhile and with all that is currently going on it isn't justifiable.

thanks everyone, I shall carry on as I am.

[Stu]

That’s the beauty of the FC100DC, fantastic views from an OTA that will go on pretty much any mount very easily.

[bomberbaz]

15 minutes ago, Stu said:

That’s the beauty of the FC100DC, fantastic views from an OTA that will go on pretty much any mount very easily.

Just had a look at this on FLO, tis a truly, very nice looking OTA. Think If I do buy a upgraded frac then as I said before, its going to be something worthwhile having. 

[vlaiv]

2 hours ago, bomberbaz said:

You would not put which OTA on the AZ GTi, the Evostar 102 ?

Indeed Evostar 102 would be too much. Not in terms of the weight but in terms of moment arm.

[parallaxerr]

I'm considering a wedge at the moment to use with my Vixen A80MF. I use that scope on an AZ4 and it's perfect weight and length wise.

Being F11.4 it also has a very well corrected objective, SA is very well controlled. There's one of these for sale at ENS optical, but even better there's a skywatcher version for sale on ABS for £50 listed as Skywatcher 80/910 (wish I'd seen it before buying mine, new). May be worth a punt for a comparison.

Of course, it wont offer any more resolution than your current scope but does offer a very well corrected lens and CA is a non issue with a continuum filter. It copes with X200 on the moon very well.