30 replies to this topic

[Anony]

I'd say stick with the Moon and crank up magnification as high as you can go with each scope. The 6", at least normally, should obviously be better.

 

While the 90mm and 102mm refractors should be pretty close to the same, with the 102mm a smidge better.

 

I wouldn't bother with Mars, not the right time for it.

 

If you can find a globular cluster, that may be worth a shot ... Hercules may resolve somewhat in that 6" dob, while it'll look like a puffball in your refractors.

[Powerstroke]

I'd say stick with the Moon and crank up magnification as high as you can go with each scope. The 6", at least normally, should obviously be better.

 

While the 90mm and 102mm refractors should be pretty close to the same, with the 102mm a smidge better.

 

I wouldn't bother with Mars, not the right time for it.

 

If you can find a globular cluster, that may be worth a shot ... Hercules may resolve somewhat in that 6" dob, while it'll look like a puffball in your refractors.

When is the best time for mars? 

The 102 seems alot better than the 90. I know it shouldnt but maybe its the difference in glass? Im using the same diagonal because it  is the only normal one i have . 

I have looked at some cloudy looking  spots near the milkyway.  Maybe those are globular?  Or nebula?  They were about the same on the 102 and the dob. The 102 is exceptional in my opinion.  

 

I was able to hook my dslr directly to the 102 and achieve focus and get pictures of the stars but really faint unfortunately 

Im going to try prime and then eyepiece projection on the dob also. 

[Anony]

When is the best time for mars? 

The 102 seems alot better than the 90. I know it shouldnt but maybe its the difference in glass? Im using the same diagonal because it  is the only normal one i have . 

I have looked at some cloudy looking  spots near the milkyway.  Maybe those are globular?  Or nebula?  They were about the same on the 102 and the dob. The 102 is exceptional in my opinion.  

 

I was able to hook my dslr directly to the 102 and achieve focus and get pictures of the stars but really faint unfortunately 

Im going to try prime and then eyepiece projection on the dob also. 

Next optimal time I think is... 2025? So that may be a bit too long for you to wait for it... kind of a long, long night.

 

If you have a smartphone, download sky safari. Then simply choose compass, point at the sky and it'll tell you what everything is. You can also choose the best objects for the night/search.

 

I think your 90 is a Celestron 90GT F/10 and 102 is 102GT F/10, right? I wouldn't think there should be any difference besides the 102mm having a bit more light gathering + perhaps a teensy bit wider?

 

Maybe do a star test with the 90GT, check if it's in collimation. Also make sure the glass isn't dirty. For the dob, you probably know the drill by now -- center spot it, collimate it, star test... and should be good to go.

 

But for testing you want to pick the right targets and right magnifications. Such as if I test my dob on Venus vs a small mak/refractor on Venus, I may walk away thinking they are kind of the same. I'd see a bright object that has phases (was around half last time I checked). I wouldn't think one scope was much better than another.

 

Fainter DSOs should be visible in the dob, while probably hard to see at all in the refractor. Moon should show no CA.... allow higher mags. Not sure if you have the greatest high mag eyepieces though.

Edited by Anony, 29 May 2023 - 06:08 PM.

[Powerstroke]

Next optimal time I think is... 2025? So that may be a bit too long for you to wait for it... kind of a long, long night.

 

If you have a smartphone, download sky safari. Then simply choose compass, point at the sky and it'll tell you what everything is. You can also choose the best objects for the night/search.

 

I think your 90 is a Celestron 90GT F/10 and 102 is 102GT F/10, right? I wouldn't think there should be any difference besides the 102mm having a bit more light gathering + perhaps a teensy bit wider?

 

Maybe do a star test with the 90GT, check if it's in collimation. Also make sure the glass isn't dirty. For the dob, you probably know the drill by now -- center spot it, collimate it, star test... and should be good to go.

 

But for testing you want to pick the right targets and right magnifications. Such as if I test my dob on Venus vs a small mak/refractor on Venus, I may walk away thinking they are kind of the same. I'd see a bright object that has phases (was around half last time I checked). I wouldn't think one scope was much better than another.

 

Fainter DSOs should be visible in the dob, while probably hard to see at all in the refractor. Moon should show no CA.... allow higher mags. Not sure if you have the greatest high mag eyepieces though.

One of the refractors says f10 and one says 9.8 the 102 was actually dirty i cleaned it. Its alot heavier than the 90mm. It also visually looks much bigger. Like when i compare a 60mm to a 70mm or a 80. They arent really much bigger from one another.  This looks alot bigger 

Havent seen ca on the 102 but some on 90. None one dobsonian. 

Im seeing dso in all 3 scopes. Using the celestron 10mm almost exclusively.  I find what i want with the 25mm first. The 4mm worked better in one of the scopes. I cant remember which one now. These are the $59 celestron ep kit. It came w 4mm, 9mm, 15mm , the 10mm is from the astromaster 130mm.  And i have another identical 10mm from the celestron 80mm travel scope.  The eyepieces i dont like are the .965 ones. The meade MA 25mm (modified acromatic lens) and a Galileo branded 25mm ep that is real touchy with the distance you peer into it or the angle. The celestron ep all seem good to me.

 

So for my dob mount i put bearing grease between the 2 peices of wood and im surprised how well it works. The way the bearing mount is too small works well. It was made for a smaller dob bearing. But it works great with this one.

 

 

Edited by Powerstroke, 29 May 2023 - 07:12 PM.

[Powerstroke]

This thing is pretty good with the 4mm ep. Its so close in on the moon. Its really too much . I prefer the 25mm and the moon fills the entire ep. Took some pics with my s23 very carefully 25mm ep

[Powerstroke]

The photos for some reason are no where near the quality of the originals. I guess the website automatically resizes them?