iPeace

Just now, Stu said:

I'm watching you young Mike  

*Sigh* And so it begins...

Just now, nightfisher said:

If you buy one it will come with a rather cheap plastic 90 degree star diagonal, swap that out for a better one, i use a Circle T prism in mine.....but most of the time it has a 1000D fitted

Looking forward to trying something cheap.

Just now, John said:

They are really neat little scopes

Just don't tell anyone I'm trying one. People tend to get the wrong idea, and I can't afford a spin doctor...

Just now, nightfisher said:

get one, they are a great little Mak, no idea how it performs on deep sky but wont be terrible, but as a Luna imaging scope its top notch

I may well, if only to see what it can do.

On 1/7/2017 at 18:46, nightfisher said:

There's just something about this...

I want one.

Just now, Racey said:

"Screwed on to a block of wood"...

said the man who claims he doesn't know one end of a screwdriver from another !!!

or did you commission someone to turn said screwdriver ??

?

I don't remember explicitly making that literal claim, but I understand why you got that impression.

For me, the great thing about sharing dumb ideas with you is that it helps me reflect on them and improve.

So say you have a frac and a Telrad and you don't mind your frac looking a bit daft because it has to earn its keep and you'd like to attach the Telrad only not permanently and you suspect that repeatedly using the metal screws in the plastic base of the Telrad will eventually ruin it. In addition, you don't like the idea of a wooden block because that's just naff.

Got that picture? Good.

Forget about the base of the Telrad. Just use the riser. Attach a small dovetail to the bottom (which is conveniently flat) with some double sided sticky tape.

Then attach a dovetail clamp to the scope with a tube ring.

Now you can just clamp the Telrad on when you need it, and it will be up where you don't have to crouch in whatever is down by the feet of your tripod in order to actually use it.

Still ugly, but less so without a wooden block and lighter, too. You can always take it off for publicity photos.

That last sentence sounds horribly wrong. Yes, that's my coat, thank you.

So far, it would seem that the Telrad would function just fine, but your setup might get some disapproving looks.

2 minutes ago, kerrylewis said:

I use a Telrad on my 100ED and it's fine. You won't need another Tetrad,  just the base.

I agree that the Tetrad is prone to dew but it is easily wiped. And the batteries do last for ever even if, like me, you always forget to switch it off! I've not tried a Rigel but I did have another red dot finder some time ago and I was always buying batteries for it. The fact that the Tetrad does not use the button type is a big advantage I think. 

It is indeed nice that the Telrad takes standard penlight batteries. And I like its extra red circle over the Rigel's two, but this is hardly a deal-breaker. There are dew heaters available for both the Telrad and the Rigel, if, like me, you must have one. My Rigel has taken just as long to drain its coin-sized battery (still using the first one), so that's good. The coin-sized batteries are traditionally not as easy to find as the standard penlights, but recently I seem to be spotting large blister-packs of them everywhere - perhaps becoming more ubiquitous?

In my opinion, a Telrad works because it works; it doesn't depend on the scope. Is there any particular reason why you think it might not work?

I use a Telrad with my SW ED120. It works the business.

I attach it in a specific way so as to always be able to remove it easily. This is wholly unnecessary, you can attach it any way you like, it will be great.

Block of wood, painted black (thank you, Jagger), serves as base; Telrad riser is screwed onto base. Dovetail clamp screwed to side of block of wood. Dovetail clamp clamps (as it would) to bit of dovetail forward of clamp which holds scope on mount. Recently, I have used an extra tube ring to attach a dedicated short dovetail bar for this purpose.

Alternatively, you could go for a Rigel, which works by the exact same principle as a Telrad, but has a much smaller form factor and fits more easily on smaller scopes:

Here you see my Rigel - with anti-dew band - attached to the TV85 using the same block-of-wood construction. You can also just bolt the base on somewhere convenient:

So if you're worried about a Telrad fitting on the tube, I would advise you to go for a Rigel. Both great finders.

3 minutes ago, dobbie said:

 

Love that scope.

29 minutes ago, Racey said:

Mike, might I enquire as to where you sourced the "tripod extension pier" (between tripod and mount) please ? 

PM sent.

1 minute ago, Racey said:

Mike, might I enquire as to where you sourced the "tripod extension pier" (between tripod and mount) please ? 

Sure, give me a few minutes, I'll get back to you.

TS do a nice one - see pic:

On 2/19/2017 at 20:29, scarp15 said:

Not entirely though ruling this option out, I am also looking at another alternative, a Berlebach Dovetail Clamp with Pressure Saddle. This unit is much more compact, matching the profile of the porta housing mount. Since it comes from Berlebach, it will be very well engineered and looks to be functional and secure (there are a few short reviews). I am in the process of enquiring, but it appears to be compatible with fitting to a Porta Mount. It has however only one locking bolt, but looks better tailored to fit a vixen dovetail bar and will be a marked improvement over the stock version.

These are absolutely lovely. Haved used them to hold a TV85 to an Ercole; should do you fine.

EDIT: sorry, only now do I read that the bolt size is wrong. My sincere apologies.

5 minutes ago, John said:

I think Baader have really minimised the effect with this product but my understanding is that it's inevitable to some degree. It's probably only going to show on the brightest of objects and then you may have to look for it. If the fully corrected image is a priority then this is probably as good as it will get from any manufacturer currently and I can fully see why you went for it.

Like on Venus? Is it something that would have really jumped out, grabbed me by my whatever, and said: I'm why people don't buy amici prisms?

As per my report, the worst I saw at max. mag. was a definite rainbow fringe either side of perfect focus.

Anyway, I've got a herd of diagonals to compare this season.

There's the 2" TeleVue Everbrite Dielectric I can use as a baseline.

Then there's the 2" Baader Zeiss prism, standard reverse-image (mine was sold as produced to Zeiss standard, it doesn't seem to be described the same way now):

http://www.baader-planetarium.com/en/accessories/optical-accessories/prism-and-mirror-star-diagonals/baader-2"-bbhs-r-prism-star-diagonal-prism-with-2"-clicklock-clamp.html

Then there's the 2" Baader Amici prism, explicitly not of astro quality, but I have used it for astro anyway to create a uber-RACI:

http://www.baader-planetarium.com/en/accessories/optical-accessories/prism-and-mirror-star-diagonals/baader-2"-amici-erecting-prism-90°-with-2"-holder-and-2"-sleeve.html

And finally, my most recent, the T-2 Baader Zeiss astro amici prism:

http://www.baader-planetarium.com/en/accessories/optical-accessories/prism-and-mirror-star-diagonals/baader-t-2--90°-baader-roof-prism-with-bbhs-r-coating-(t-2-part-02).html

Any specific ideas on how to compare the performance of these are most welcome.

1 minute ago, John said:

Ah, yes I can see there are slight differences in the casing design. The one you have uses an amici prism design and has a clear aperture of 31mm wheras mine uses a standard prism with a 35mm clear aperture.

Baader stuff is great but it can be confusing working out which componant is which !

It will be interesting to see if you witness the amici spike effect.

I suppose I'll know it if I see it?

And comparing the two pictures, I do see a difference between them...

...is yours more of a square, where mine is more of a rectangle, on the connection sides?

1 minute ago, John said:

The picture looks just like the one I have and use with my Tak 100. Mine shows an upright image but left & right reversed

Maybe there is more than one version that looks the same ?

There is indeed. Yours will have a different part number:

http://www.baader-planetarium.com/en/accessories/optical-accessories/prism-and-mirror-star-diagonals/baader-t-2-stardiagonal-(zeiss)-prism-with-bbhs-r-coating-(t-2-part-01b).html

33 minutes ago, John said:

Is this the one you are trying Mike ?:

http://www.rothervalleyoptics.co.uk/baader-2-90-degree-amici-erecting-prism.html

Well John, that's the one I've had my eye on, but Baader have not had them in stock for some time now. I've sprung for this T-2 model:

http://www.baader-planetarium.com/en/accessories/optical-accessories/prism-and-mirror-star-diagonals/baader-t-2--90°-baader-roof-prism-with-bbhs-r-coating-(t-2-part-02).html

Don't see this one on the RVO site.

Have added 2" nosepiece and ClickLock for eyepieces. And the T-2 spacers for their usefulness, as you related elsewhere.

The German description explicitly promotes it as the "astro quality" version. Whether it's as good as the other (the one you mention), who knows? It's produced to Zeiss standard.

7 minutes ago, John said:

I'll take the optical quality every time and handle the (for me minor) issue of the reversed left and right. I've sort of got used to it over the 35 years I've been using scopes with diagonals. I'd probably get confused if I changed to a fully corrected image in the main scope !

Also I can't see the point in using a top end objective and eyepiece and having something in between that is less than that

My quandary exactly. If it turns out that I have to make the choice between image orientation and image quality, well...

Hopefully, my attempt to insert the best I can find between objective and eyepiece will make the choice moot, at least for me.

Just now, ronin said:

No worse: Send him to Twente.

Who says I don't already live there...?

Whoops...

2 minutes ago, Highburymark said:

Nice post ipeace. 

Like men-only golf clubs, cheque books,  and five day cricket matches, maybe astronomers' upside down/reversed images of the night sky will be an anachronism by 2040

Thanks.

Double-edged, this. I miss five day cricket matches. But I haven't bought or read a book printed on paper for years.

I do have great hopes for improvements in optical equipment for us to use. Make it lighter, less involved to use! Wouldn't it be great if a pair of digital eyeglasses would suffice?

Of course, DSO hunters would have to look like Elton John...just as well it would be after dark.

23 minutes ago, Timebandit said:

But " every photon counts" so need as many as possible, even the lazy ones ?

Is that why all those dark-art AP imaging folk don't use diagonals at all?

It's my - limited - understanding that those who image go to considerable lengths to give all photons every possible opportunity, as well as plenty of time, to reach whatever it is that they eventually reach in order to create the digital image.

(Imagine that - you, the photon, go all that way, and don't even make it to an actual eyeball. You're eventually eaten by a machine. Bummer.)