Vintage Venus

[Stu]

I thought I would change things around a bit tonight and have a vintage achro evening on Venus and as it turned out, a few doubles too. 
 

The two scopes are a TAL 100r, I believe from the second version but with the original purple coatings, and a Zeiss Telementor II. The TAL is on a Vixen Super Polaris Mount, which does have a drive in RA but I was just using it manually tonight. The Telementor is on a Unitron AltAz Mount, with slow motion controls too.

Impressions on Venus were that sharpness was fairly evenly balanced between the two, but the TAL showed a fair amount more CA. I guess that is to be expected with its larger aperture (100 vs 63mm) and faster focal ratio (f10 vs f13.3) if anything the Zeiss was showing a slightly sharper image of the two, perhaps dealing with the seeing better? I was using the TAL 6.3mm in the TAL (x158) and the Nag Zoom in Telementor set to about 5.5mm (x152) to balance the mags. Switching the Nag to the TAL did not improve it and I’ve been fairly impressed by the TAL eyepieces so I don’t think that was making the difference.

Moving up to Castor, here the Zeiss definitely won the evening, producing two beautiful, slightly uneven airy disks with a single diffraction ring around each, pretty much text book stuff just like white bullet holes on black. The TAL has a slight miscollimation which I need to sort so this is perhaps a little unfair. But even so it seemed to me that it just wasn’t quite up to the same level. Scruffier stars and messy diffraction rings in comparison. It will be interesting to see how it fairs once tweaked.

Izar was a similar story. Gorgeous in the Zeiss, just beautiful, with the grey blue secondary plonked on the first diffraction ring, clear separation showing. Again the TAL struggled in comparison, largely because the primary was scruffier. The split was there but more difficult to see.

The TAL scored a win on Polaris however, largely down to aperture I guess. The secondary here was a tiny, perfect pinpoint of light, far enough away from the primary to be unaffected. I could not spot the secondary in the Zeiss at that power (perhaps too light still), except once or twice fleetingly with AV. Dropping down to 12.5mm didn’t help much but going to a 24mm Panoptic giving x35 showed it clearly, much closer in obviously but very nice again, particularly with that beautiful neat primary.

So, the Zeiss is the real deal. The focuser is a bit stiff and challenging to nail perfect focus. I may try a helical focus to make life easier providing I have enough in focus range. Optically it is lovely, particularly on doubles and the Moon, but we already knew that I guess. I’ve had it up to x280 on a good night with the Nag Zoom and it keeps giving even at those crazy exit pupils.

This TAL is nearly lovely. It is the best of the three I have owned, and whilst the focuser is very basic, it does the job and if the collimation can be sorted I’m sure it will be a cracking scope. I may try the old ‘hold the scope vertically, loosen the front ring and tap gently’ trick before opting for anything more radical or costly. I’ll revisit this when I have it sorted.

A fun evening exploring the quirks of these two lovely old scopes.

To be continued.....

[Ruud]

That was a wonderful read, Stu. The Zeiss may have won, but it's not the most handsome tube. It sits on some gorgeous legs though. How are the slow motion control and the stability of the Unitron mount?  

[Helen]

That's a nudge for me to get my telementor out again Stu - it's been a while! The Tak100 tends to be my go-to refractor, but a change would be fun.  The decision will be whether to use the Zeiss mount, or find a way of attaching a standard dovetail ... I wonder whether the azgti could cope 🤔

Helen

[RobertI]

Lovely report Stu, the Zeiss sounds like a special scope. I also find it fun using and comparing different scopes on different objects, adds another dimension to our great hobby.

[Stu]

10 hours ago, Ruud said:

That was a wonderful read, Stu. The Zeiss may have won, but it's not the most handsome tube. It sits on some gorgeous legs though. How are the slow motion control and the stability of the Unitron mount?  

Thank you 😊

It has a kind of handsome ruggedness to it, much like a tank barrel! It seems to be made out of similar material! 😉 The good thing is it does feel quite indestructible as a result.

I do love the Unitron Mount. It was a spur of the moment purchase and I think suits the Telementor very well. I’ve never been particularly taken by the original Telementor mounts although I’m sure they are very good. The head itself is excellent, very solid and with adjustable tensioning so that you can pan it by pushing the scope, or use the slow motion controls. These are much more effective than I thought they would be, and always face you so are easy to find in the dark. They have limited travel so need resetting every now and then, but that has only been once or twice since I’ve had the mount and is easy to do. They are smooth and accurate to use.

The legs are very lovely, although they do allow some vibration, mainly when focussing but the mount is very stable when using the slow motion controls. It is very handy that you can easily adjust the height by spreading the legs more, works well on grass where the spiked feet can dig in. It’s a fun little setup that I can use for quick grab and go sessions, and also for a bit of bird spotting in the garden.

[Stu]

10 hours ago, Helen said:

That's a nudge for me to get my telementor out again Stu - it's been a while! The Tak100 tends to be my go-to refractor, but a change would be fun.  The decision will be whether to use the Zeiss mount, or find a way of attaching a standard dovetail ... I wonder whether the azgti could cope 🤔

Helen

That’s good then Helen! About the only thing I don’t like about my Tak is that it is so good it puts me off using other scopes. It replaced any need for scopes from 80mm to 120mm for me. So, that’s one reason why I’ve been trying out a number of different types of old scope, they are full of character and whilst not necessarily as good as the Tak, definitely bring something to the table in terms of observing enjoyment.

My Telementor has a narrow dovetail on it which is very handy. I found that by placing a short length of stainless steel bar alongside it, a standard Vixen dovetail saddle works fine. Does yours have a dovetail?

[Stu]

28 minutes ago, RobertI said:

Lovely report Stu, the Zeiss sounds like a special scope. I also find it fun using and comparing different scopes on different objects, adds another dimension to our great hobby.

Thank you Robert. Yes, definitely. My skies are not amazing, so I find using a variety of different scopes on the familiar objects I can see well keeps my interest going. I have a range of nice refractors now which I will hopefully continue to compare over the coming months.

[RobertI]

42 minutes ago, Stu said:

Thank you Robert. Yes, definitely. My skies are not amazing, so I find using a variety of different scopes on the familiar objects I can see well keeps my interest going. I have a range of nice refractors now which I will hopefully continue to compare over the coming months.

I shall look forward to that! I guess the signature area will not accomodate your full list of equipment?

[Stu]

42 minutes ago, RobertI said:

I shall look forward to that! I guess the signature area will not accomodate your full list of equipment?

Tee hee. I tend not to list kit there, not sure why.

Current relevant refractors are:

Zeiss Telementor (63mm f13.3)

Televue Genesis (100mm f5)

Tak FC100DC (100mm f7.4)

Vixen Fluorite FL102S (102mm f8.8)

TAL 100R (100mm f10)

Should have some fun with that lot. I really need a Lyra Optics 102mm f11 to complete the set! 🤣🤣

[Helen]

3 hours ago, Stu said:

That’s good then Helen! About the only thing I don’t like about my Tak is that it is so good it puts me off using other scopes. It replaced any need for scopes from 80mm to 120mm for me. So, that’s one reason why I’ve been trying out a number of different types of old scope, they are full of character and whilst not necessarily as good as the Tak, definitely bring something to the table in terms of observing enjoyment.

My Telementor has a narrow dovetail on it which is very handy. I found that by placing a short length of stainless steel bar alongside it, a standard Vixen dovetail saddle works fine. Does yours have a dovetail?

Thanks Stu. I completely agree with your assessment on the TAK!  Sometimes in this hobby you hit upon a 'one'  that just hits a spot perfectly.  I love it every time I use it 🙂 

My telementor also has the original narrow grey mounting bar, so I need to experiment.  That said the engineering on the zeiss mount is really lovely, including smooth slo-mos, so its no hardship using it (its just not particularly lightweight!)

I might get it out this afternoon and do some solar, and have it ready for Venus 🙂 

Helen

[RobertI]

3 hours ago, Stu said:

not sure why

Perhaps you're worried that people will think you're boasting! That's a lovely selection of fracs.

[JeremyS]

3 hours ago, Stu said:

Tee hee. I tend not to list kit there, not sure why.

Current relevant refractors are:

Zeiss Telementor (63mm f13.3)

Televue Genesis (100mm f5)

Tak FC100DC (100mm f7.4)

Vixen Fluorite FL102S (102mm f8.8)

TAL 100R (100mm f10)

Should have some fun with that lot. I really need a Lyra Optics 102mm f11 to complete the set! 🤣🤣

Come on Stu, you're not even trying!

🙂

 

[Stu]

2 hours ago, Helen said:

Thanks Stu. I completely agree with your assessment on the TAK!  Sometimes in this hobby you hit upon a 'one'  that just hits a spot perfectly.  I love it every time I use it 🙂 

My telementor also has the original narrow grey mounting bar, so I need to experiment.  That said the engineering on the zeiss mount is really lovely, including smooth slo-mos, so its no hardship using it (its just not particularly lightweight!)

I might get it out this afternoon and do some solar, and have it ready for Venus 🙂 

Helen

Yes indeed!

This is how I fit the Zeiss dovetail to a standard Vixen saddle. If you get the right diameter of bar it works well, too big and it just pops out from under the saddle bevel so be careful. I’ve also used an Allen key before which also feels secure.

[Stu]

41 minutes ago, JeremyS said:

Come on Stu, you're not even trying!

🙂

 

I did say relevant... 😉