John

Great report, I enjoyed reading it

I sympathize re: your LP issues - I have the Bristol glow to the NE and the Newport / Cardiff glow to the SW so those horizons are not productive unless targets are well above them.

I find that using a bit more magnification does increase the contrast between the darker and brighter parts of the Orion Nebula as well. Last night 200x was wonderful for examining that central area (fishes mouth etc) with my 12 inch dobsonian.

49 minutes ago, GazOC said:

The distance from the Barlow to the eyepiece gives the magnification by increasing the focal length of the system. The further away, the greater the magnication. So although you should get x2 before the diagonal, by putting the Barlow after the diagonal (nearer the eyepiece) you'll get a lot less.

This also moves the focal point differing amounts. With the Barlow before the diagonal the focal point will be further out than with the Barlow after the diagonal 

 

I've just been doing some experiments with my Vixen ED102SS (focal length 663mm), the Baader 2.25x barlow and the Baader T2 prism and zoom eyepiece at 21.5mm. Target was the top of a conifier about 200 metres away. Interesting results:

- No barlow = focuser drawtube 55mm extended at focus.

- Barlow in the diagonal (so 2.25x amplification) = focuser drawtube 49mm extended at focus so a manageable amount of inward focuser travel.

- Barlow before the diagonal (much higher amplification - maybe 4x-5x ?) = ran out of OUTWARD travel of focuser. With focuser drawtube at max extension and holding the barlow / diagonal / eyepiece unit at sharp focus I reckoned the extension would be around 115mm so much, much further out. Matches @GazOC's prediction but more so than I expected.

How relevant to your situation this is Mr Jones, I don't know and the proximity of the target might have made a difference as well but it did demonstrate that the difference in focus point, depending on where you place the barlow, can be very significant. I expect the optical element of the Baader 2.25x has a shorter focal length than that of the Tak 2x barlow.

Kept me busy on a boring Sunday morning anyway

I've owned a couple of the Baader 8-24 zooms, a Mk II and a couple of Mk III's.

I thought they were pretty good eyepieces although I found the AFov restrictive at the 24mm end so really treated them as 8-20 zooms. The field stop edges get mushy as well at the longer end which I'm not keen on.

I found the light transmission when observing galaxies and nebula suffered a bit with the zooms compared with a good fixed focal length eyepiece. Not massively but noticeable when I changed eyepieces from zoom to fixed FL when observing Messier 82, for example.

I would not have a zoom as my only eyepiece but I find the couple that I currently have (not Baaders as it happens) useful tools to have in the eyepiece case.

The only barlow that I use with my FC100-DL is the Baader 2.25x Q-Turret which is used after the diagonal and, while eating up a bit of inward travel, comes to focus OK.

If I put that before the diagonal it gives more amplification (3.5x I'd guess) but also needs a lot more inwards travel so a similar situation. The Baader has the optical elements within the 1.25 inch barrel though so the risk of it impacting the prism is much lower.

The Baader is probably not as good optically as the Tak of course. I'm fortunate to have a good range of short / very short focal length eyepieces so I tend to opt for those more often than using a barlow.

It seems to be quite complex to assess the impact that a barlow will have on the focal point when used in different configurations. I guess someone with optical design expertise could work it out if the focal length of the barlow is known 

Is the focal length of the Tak 2x barlow given anywhere ?

Is this the barlow ?:

https://www.rothervalleyoptics.co.uk/takahashi-2x-barlow-lens-125.html

It does say that the amplification if used after the diagonal will be diminished.

It seems an odd design to me - a "shorty" body and 1.25 inch barrel but a rather long optical element section with the potential, as you say, to impact a diagonal prism / mirror surface

There is a very recent thread on another forum where folks discuss similar issues that they have had with this barlow:

https://www.cloudynights.com/topic/749134-takahashi-2x-barlow-vs-others/

As Jeremy says, probably one of the very best 4 inch refractors made, or possibly ever made. Congratulations

Out of production as well now

The Nexstar 6SE optical tube will fit onto the mount and be carried very well by it. You might need to check where the finder mount will end up if you switch from the SE alt-azimuth mount to the EQ5.

The 200mm F/6 optical tube of the Zhumell Z8 will be just about OK on the EQ5 for visual observing but the mount is not capable of handling that tube for imaging.

Great report Rob

The Hippalus Rilles were showing wonderfully well tonight !

21 minutes ago, LeeHore7 said:

Beautiful image John, the moon was looking amazing tonight, lovely capture of the 3 Riles, I pushed the imaging mag on my skymax 127 tonight to get in close but nowhere as good as yours. 👍

Thanks, but it's not my image (I rarely take any)

That one was from the Lunar Orbiter IV I think. I should have given a credit for it.

Excellent stuff !

You did well on those fainter face on galaxies (M33 and M101) they can be hard even without the moon around.

We are getting some great reports on the forum with these clear skies (at last)

And you did manage to find some words ......

Super report - nice to read your enthusiasm !

I've just bought my 12 inch dob in after a nice session.

Thin cloud is creeping across the sky so no point in hanging around out there. Finished on high notes of Sirius B followed by the Eskimo Nebula. The planetary nebulae such as the Eskimo hold up quite well even with a bright moon in the sky.

The moon was really lovely as well wasn't it ?

Glad you are having fun - that's what it's all about

Very crisp moon here. 454x with the 12 inch dob. Alpine Valley rille and 6/7 Plato craterlets, possibly more. Hadley Rille really well defined. Highlight at the moment are the Rimae Hippalus. Three concentric rilles and a faint 4th one, running for around 190 km:

20 minutes ago, mikeDnight said:

I did read somewhere, probably on CN, that Takahashi used their influence to stem the flow of this five element Masuyama design from Japanese manufacturers to such companies as Celestron, so as to keep it for themselves. Have you any idea if there's any truth in this Don?   Having said that, I think the 25mm Parks Gold and 35mm Ultima are leaps and bounds better than the 25 & 30mm Tak LE's.

Sounds like a possible plot for a thriller novel / movie: "The Masuyama Conspiracy"

8 minutes ago, Stu said:

Well worth it Robert, makes a big difference. A pic from summer last year.

If Zaphod Beeblebrox has a solar setup, that would be it !

I have the 12 inch dob out but according to "Clear Outside" I've got until around 10:00 pm until clouds arrive.

Between now and then I can pretend to be an Apollo astronaut nearing the moon using my new 4.7mm Ethos eyepiece

10 minutes ago, Fedele said:

C8HD???

Review.

Buyed, Tested, selled, in two weeks

End of the review

This thread is about the Rowan AZ100 alt-azimuth mount. Have you posted this in the wrong place perhaps ?

33 minutes ago, Pixies said:

.... Your scope is pretty fast, though. So it will be demanding of EPs.

That's the challenge. You might actually be best to stick with the 25mm Tele Vue plossl as your low power for now. They are well corrected eyepieces and the exit pupil generated (eyepiece focal length divided by focal ratio of scope) is 5.3mm which is useful.

You can get eyepieces that show more sky but to get such eyepieces that show well corrected wide fields in an F/4.7 scope, has quite a price tag associated with it.

If the mount is perfectly polar aligned the declination drive is not needed, in theory. You could make any declination adjustments using the manual slow motion.

You can get single axis drive systems but, with the hand controller and battery pack, they seem to cost a good chunk of a dual drive system.

I only ever used such drives for tracking when observing so where imaging is concerned, my knowledge runs out real fast !

What scope will you be using the eyepiece in ?

The GPD is a heavier duty version with higher load capacity.

I recently had the GP mount and found that the Skywatcher EQ5 motor drives fitted straight onto it. I used this set:

https://www.firstlightoptics.com/sky-watcher-mount-accessories/enhanced-dual-axis-dc-motor-drives-for-eq-5.html

Not GOTO of course but at least you can plug an autoguider into it.

This is less expensive but no autoguider connection:

https://www.firstlightoptics.com/astronomy-mount-upgrade-kits/dual-axis-dc-motor-drive-for-eq5.html

These are a lot less expensive than the Vixen drive systems although the quality is less as well. They do work though.

I did not image with the mount although I'm sure it is capable in the right hands.

On 21/01/2021 at 11:26, Saganite said:

Traded all of last  years FLO vouchers for a long coveted eyepiece.  It will be mostly used in my 12" Dob, but will grace each of my scopes !

I'd like to try one of those again. It's been a long time since FLO loaned me one to compare with the Nagler 31 and the UWAN / Nirvana 28mm - 11 years in fact

During the intervening period Pentax / Ricoh have dropped the 2 inch XW's, the used prices sky rocketed, and then recently they re-launched them again !

If the time ever comes when I decide that I want to settle on a single range of eyepieces for all my scopes / needs, I strongly suspect the XW series would be "it" 

I came across this one a while back:

doublestarlist.pdf

This database is good as well:

https://www.stelledoppie.it/index2.php?section=1

I really like that minimal look. No fuss, no cables, just plonk it down and get observing

25 minutes ago, RobertI said:

Thanks for sharing John, good to know there’s something worth seeing. I have been thinking about some white light solar with my ED102R and you’ve encouraged me to give it a go. I was a bit concerned about pointing my lovely new scope at the sun, but I don't think I should worrying about that. 👍

I used to worry a bit but I figure that these instruments are made to be used so the Tak gets lots of use. It's probably my most used refractor. It's not an ornament

I find that 200x - 250x is needed, if the conditions (the seeing) allows that to be used.

Mars is very small now and getting smaller so seeing any details on it is pretty challenging.

A cooled and colimated scope is essential and lots of patience !