chiltonstar

1 hour ago, spaceboy said:

I have often wondered why SW don't sell at least the larger MAK's with tube rings but it actually doesn't look that bad on an AZ mount. Do you find you have any problems with balancing or the diagonal fouling the focuser knob ??

I think tube rings would be a good idea in the sense that things would feel 100% secure, and rotation would be useful to get the finder away from the head a bit particularly when I use the scope on my EQ mount, but would add more weight. Fouling? No problems - the 2" diagonal supplied clears the focuser  by about 10mm.

Balancing is fine on the end position of the SkyTee; if the tube is approximately balanced (which seems to work ok with my EPs and finders given the long dovetail on the Mak), then you can nudge to position like a dob almost and it holds position, thanks maybe to the SW viscous grease.

Chris

The RDF to arrive roughly where I want to go, and the RACI to locate exactly. I sometimes use the EDS80 instead of the RACI, but of course the image is not correct orientation, which I struggle with.

The RDF is a metal gunsight type - it stays aligned very well compared with the SW variety.

Chris

2 hours ago, wimvb said:

I like your "view down the barrel".

As you can see, I'm a Nikon-man!

Chris

To wake the thread up again after a bit of Summer holiday........... My current doubles set-up. 180 Mak with an ED80 on a SkyTee2 mount:-

Chris

8 hours ago, John said:

 

If I ever write a book it will be called "Astronomers Excuses and Justifications for Equipment"

It might be a best seller........can I pre-order a copy?

Chris

I'm impressed you can split Lambda Cyg with 130mm John at 0.92 arcsec (?). With my 127 Mak, it takes a blue filter to split the pair (smaller Airy disk) although with my 180mm Mak, it is relatively easy to get the "dark line".

Chris

2 hours ago, John said:

I agree with Chris - despite the brightness difference between the components, it's the low altitude that makes it awkward. If you can get a lowish and clear horizon then a small frac should do it.

I thought the secondary star looked grey-green but with all the "scintilating" going on with the primary I'd not swear to that !

 

Electric blue-green with the ED80, faded lilac with Mak 180.

Chris

11 minutes ago, Stu said:

Without wishing to take this thread off topic, I just checked, and the primary is listed at 3500 K, and the secondary 20900 K, which seems quite blue to me . I've never had a decent chance to try with Antares, must give it a go sometime. Would the FC100 do it under excellent conditions?

You're right Stu - quite blue.

My little ED80 can do it, so your FC100 should manage! I don't think it is a resolution/aperture issue, just getting the seeing good enough for a horizon-grazing star to see the secondary.

Chris

Wonderful stuff John. Obviously quite a scope!

Delta Cygni is quite a challenge, isn't it? I managed a split two nights ago with seeing 4/5, but 5/5 would have been better. Antares gets easier the more often you split it, I think; the colour contrast is really impressive, even in a small scope but I wonder whether the companion is really blue or if it's just the colour contrast with the primary.

Chris

Very nice image John! It's a lovely pair to see visually, even though it's very difficult from these northern skies because it barely rises above the horizon.

Chris

2 hours ago, Mark at Beaufort said:

Chris - thanks for that. I will have a go with the Orion VX8 to see if I can separate.

I've just had a try with my 180 Mak. At x225, it's visible as two disks very close together, but the seeing here needs to be a bit better for this one I think (at the mo, it's about 2 to 3/5).

Good luck!

Chris

Nice report!

7 Tau is marked as 0.8 arcsec separation in the 2nd Ed of CDSA, making it a minimum 150mm aperture pair - one to look at though. Thanks for flagging it up....

Chris

That's not the right adaptor then, the simple ones do work but don't reach infinity. Can still be useful for close-ups and macro work though. I tried putting an M42 lens on a friend's Nikon and ran into these issues, it took a while to find the correct information.

This is the one I've seen - different from the macro adaptor you may be talking about??

http://srb-photographic.co.uk/nikon-to-m42-lens-adaptor-6050-p.asp

Chris

Yes, the do reach infinity using an adapter with a lens element, but they aren't cheap, it changes the focal ratio and can impact image quality. There are some good M42 primes lens that are available for around £15-£50 so this is a factor worth considering for lens imagers. (There are probably some good vintage Nikon mount lenses out there too, but I've never seen an image taken with one.)

£22 apparently......I'm not sure about the lens element, they appear not to have in the image on the website.

Chris

I've recently upgraded to a Nikon D750 (from a D300), and I have to say the high ISO performance is very impressive, with very decent images up to ISO 1600 or so before colour noise starts to be visible.

The standard SRB adaptors for M42 lenses to Nikon do maintain infinity focus, according to SRB, although I'm unlikely to use one as some of my Nikon manual and auto lenses are sharper than any M42 lenses I've tried! 

The WiFi connection to my Samsung 7" tablet (Android) seems to work well, and I've plans to use it soon for Moon imaging.

Chris

Chris, (Chiltonstar)

That's a lovely scope. Who made the Lena, do you know? I think F13 is a great balance between depth of focus and low CA and the portability of an F10 such as the TalRS.

Dave

The objective was made by Vixen and was sold for a time in the UK before they switched to a shorter fl. I agree, F13 is a good compromise, good detail, cheaper EPs and still (just about) manageable on an EQ mount!

Chris

Talking of anti-aircraft missiles, my first ever frac - ca 1983, home made OTA, still in use! It's an f13 102mm achromat and still (last night!) gives gorgeous views of planets and doubles. Last night's views of delta Cygni and Saturn were still impressive, with a beautiful rendition of the peachy-cream colour of Saturn and its rings.

Chris

how did you fit the red dot finder to your optical finder, brilliant idea, any close up pics please

Pic below. Essentially, I removed the base from the RDF and attached it with two macho nylon cable ties. It's tight/loose enough I can rotate it to refocus the RACI if I need to.

To align, I pointed the RACI at a brightish star, centred it, and then adjusted the RDF until it covered the star. In use, I swing the scope using a rough aim with the RDF, and then use the RACI.

Chris

Thanks John. I forget that Chris is like one of those 'eagle eye' action men I had when I were a lad

Perhaps just better seeing, with a field in front of me - the fact that the split shows up well in an image shows it's not just eyeball factor?

Chris

Nice! And with all that frackery, you still can't split Zeta Her?

Chris

My mini (grab 'n go) frac set-up. One day I hope it will grow up and acquire some more inches round its waist.....

Chris

With all these wonderful fracs, we should organise a FracFest somewhere....

Chris

Yes, easily do-able. A gem.

Chris

Celestron 15x70s, Pentax 6.5x21s (close focus for macro) and a Bresser Sprite 10x50 monocular (surprisingly good!).

Chris