95 replies to this topic

[avarakin]

Has anyone tried solar imaging with this lens with shutter closed at F22 and without solar filter?
I am thinking of using this lens for Venus transit, may even try with my 12nm Ha filter!

Alex

[Samir Kharusi]

IMHO not advised. You could damage your viewfinder-screen/shutter/CMOSsensor/focus-sensor. Take your pick. The Sun is VERY bright!

[Nils_Lars]

That is a great result there and im stoked you finally got a good Ha filter , should be an awesome combo with the gear you have including this lens and it looks to be an excellent performer.

[Falcon-]

Alex: I think I am with Samir on this one... I know I am not going to try shooting the sun unfiltered regardless of the f-stop used!

Erik: Ya, I am rather happy about this too Been shooting more data on that same frame yesterday night and am shooting what *might* make a odd-shaped mosaic tonight. Now if only I could get the CI-700 properly set up I should be in good shape

[ghataa]

You guys got me thinking about the dual Tair setup. I found the photo sniper version for $75 so I picked up a second one while the opportunity was in front of me as it was the full version (looks really cool).I have no immediate plans to buy a second modded Canon DSLR but do have an unmodded family/general use Nikon D7000.

Is there any downside to going dual Tair with a modded T3i and an unmodded D7000? The Nikon will be less sensitive to red of course but any thoughts if this would be viable when combining data from each? I don't have a clip-in Ha yet but could play with 2x RGB for the time being. Also need to get it mounted up on CG5.

Best,

George

[dp297]

I have been meaning to ask....
in your setup how do your perform multiple star alignment with the Ha filter on?
I have clip-on filters and it is just not possible to do that.

[Falcon-]

I already mostly answered this in another thread, but to be a bit more specific it turns out that with a 50mm finder-guider and the SSAG guide cam the FOV the SSAG sees is actually relatively close to what the Tair-3 produces for an APS-C sensor DSLR. So I:

- make sure the Tair-3 is *securely* attached to the mount
- Attach the camera to the Tair-3 without the clip-in Ha filter installed and make sure the mount is balanced
- with the mount still not powered on I use a terestrial reffrence object (distant tree, hill, tower, light, whatever) to align the guide-scope and camera so both have the same center point.
- Remove the camera from the lens (but not the lens from the mount!) and install the clip-in filter
- Power on the mount, turn on PHD, turn on the bulls-eye overlay in PHD, set PHD to 1s exposure cycling and use *that* view to do my mount align.

That method worked very well for me. last thing I do is slew to something very bright like Vega or Arcturus and use a bahtinov mask and 30s exposures to nail the focus. At that point I am ready to slew to my target and image!

[Falcon-]

So... uh.... I may have been on my local craigslist and accidentally purchased a Tair-3s.

The full kit.

So... ya - guess I can do a Tair-3a vs Tair-3s comparison now!

My quick impression is that there is much less slop in the 3s then the 3a - though that might be related to the near-mint condition of the 3s and the "well used" condition of my 3a I think it has just as much to do with the fact that much less of the lens itself is designed to shift in/out.

My totally un-rigours comparison so far is:

Tair-3a Pros:

- can focus much closer (not much use for astro I know, but still!)
- Has built-in lens shade
- Has tripod collar (can rotate orientation easily!)

Tair-3s Pros:

- MUCH sturdier/tighter build (no visible shift in components when "wiggled")
- Can be used with rings for more stable astro-configuration.
- That *BLEEP* and trigger-release aperture mechanism is just plain cool

I have a feeling that the Tair-3s is the superior version for AP-focused work. I have not compared their optical performance (expecting similar or identical results) and more crucially have not tested how easy it is to reach critical focus with that funky focus dial mechanism.

Edit: hah - gota love censoring filters... no concept of context

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[Nils_Lars]

Haha that is cool , I didnt know such a thing ever existed.

[ghataa]

I just picked up a full kit too and it is very cool! I now have a 3s and 3c. Sean is right, the 3s is sturdier and offers the better opportunity for ring mounting than the 3c but I did manage to use rings on the 3c. I have been using the inexpensive Orion rings. I haven't trianyang imaging yet so the jury is still out for my setup.

George

[Chris_H]

That gun grip has to be the coolest thing I've seen attached to a lens!

[Dan Watt]

Here is a mosaic I've been working on with my dual tair setup. Still have a ton of processing to do but the edges are lining up quite nicely when imaging at f8.

http://www.astrobin....11553/?mod=none

[Falcon-]

Dan: That is looking nice so far

Erik & Chris: Ya, the pistol/rifle stock mount *does* make it a lot easier to get a steady shot with that monster heavy lens then simply hand-held would. Tripod is of course better, but much less portable. I suspect image stabilization would be better then the gun grip of course... but that is hardly what these lenses are about.

Only problem is.... not many situations I can think of where I can use that mount without causing great consternation!


George: Could you post a picture of your 3c and 3s next to each other here? I am going to do the same with my 3a and 3s when I get the chance next weekend...

[ghataa]

Hi Sean,

I will take some pics this weekend and post here.

George

[Falcon-]

Here are a couple of side-by-side pictures of the Tair-3a and Tair-3s

First shot shows both focused at infinity with the lens shade retracted or not attached.

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[Falcon-]

Second shot is focused as close in as possible.

Notice on the Tair-3a the front 3/4 of the lens moves - everything in front of the tripod collar. This is why rings would be difficult for the 3a.

Also notice that the 3a has quite a lot more movement - this means the 3a can focus on things MUCH closer then the 3s.

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[Falcon-]

Last here is a shot showing the 3s focused as far out as possible showing the rack-and-pinion type focus mechanism.

My only concept of dating on these two lenses is that the the 3a has a label saying it was made in the USSR while this one (as you can sorta see here) was "made in Russia".

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[saemark30]

Great lens. Got one. But it might not reach infinity focus.

Does anyone know how to adjust the lens focus for infinity?

[Falcon-]

saemark30: If you are talking about the Tair-3a I found that the tripod collar can sometimes get in the way of infinity focus but if you loosen the tripod collar rotation-lock **** can get that extra tiny bit more of back focus to reach infinity. You can then re-tighten the tripod collar rotation lock and it is fine.

[avarakin]

I was able to remove any limit on movement of my lens by doing the following steps:
1. remove collar
2. under collar, you will find a screw which needs to be removed
That's it!
YMMV: I see a huge variation of this lens design.
My lens looks like this (it seems to be the original design) :
http://www.dreamstim...58-image7934486

Alex

Alex

[saemark30]

I believe I have a FS 3S.

[saemark30]

I can focus to infinity but Polaris looks reddish.
Should I focus in a bit?

[Dan Watt]

Is your white balance correct? And what f-stop are you at? Wide open and you'll have color problems unless you are doing narrowband.

[avarakin]

You need to find optimal focus point, where you have smallest stars without too much color. You may also have to close the aperture a little to get acceptable star size and minimal color. So you need to shoot several images with different focus position and pick the best you like.

It is much simpler if you do narrowband imaging because you focus only one wavelength.

Alex

[ghataa]

Hi Sean,

Sorry I didn't get a chance until today to take a few pics of the 3c and the 3s.

The big difference is the aperture control ring. Otherwise very similar.

Best,

George

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