Outdoor Ontario

Off Topic => Anything Goes => Topic started by: Howieh on April 02, 2020, 08:20:30 pm

Title: Venus meets the Seven Sisters
Post by: Howieh on April 02, 2020, 08:20:30 pm
The planet Venus is rapidly approaching the Pleiades and will enter the cluster tomorrow (Apr 3) night, presenting a great photo-op, even for a small sensor camera. I've taken some fairly good hand held astro-shots but will try tonight using a cheap, lightweight tripod that I haven't used for years! Even if you are not interested in photographing the 'meeting' it should make a beautiful sight in a decent pair of binoculars; for anyone here who does not know, Venus is the bright 'star' halfway up the western sky just after sunset. And btw, tonight's moon, which is just past first quarter, is a great target anyone with a long zoom camera, which in my case is the SX50. Hope everybody here is well and coping with the Covid-19 event as best they can! :)
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 03, 2020, 09:37:24 am
I have not observed the night sky in the last little while so the presence of a brilliant Venus
has escaped my notice. Since Venus is in the western sky just after sunset and remains there
for a while after darkness descends its declination remains low, which is not the best location
for photography due to pollution (both atmosphere and scattered city light).

What exposure settings are you using to capture Venus and the Pleiades? I've found that an
open iris (open f-stop) does not work well because it picks up too much light pollution. What
f-stop works for you? If your old tripod is flimsy you might be better served by collapsing the
tripod as short as possible, closer to the ground and therefore sturdier. Even weighing it
down with something can help.
Title: Re: Venus meets the Seven Sisters
Post by: Howieh on April 03, 2020, 11:41:25 am
Hi Shortsighted,

I took your advice before(?) reading it and did indeed use the tripod at a low setting, even though I was sheltered from the wind and probably could have been more comfortable (back problems!) with a higher setting. The 50D and the 75-300 lens were too heavy for the tripod and my A650 is zoom deficient so I had to use the SX50. I had it repaired a couple of years ago but the rear dial still doesn't work properly and I went crazy while trying to set the shutter speed slower than 1 second, which is impossible when the ISO is above 80! To make a long story short, I got a few shots, which I still haven't downloaded, at 1 sec, F5.6, ISO 800, and when I zoom in I can see that exposing for more than 1 second changes the stars from points of light to star trails. I'll download a few shots later today to get the focal length and, weather permitting, I will try again tonight. The old A650 does allow for longer exposures at higher ISO's so I will try it as well.
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 03, 2020, 01:42:49 pm
You know, when I stop to think about it, I don’t even know how to set my Canon T4i for a time exposure. I’ll have to look it up at some point. My understanding is that a high ISO setting on a sensor will capture too much stray light thus rendering the night sky gray, instead of black. The ISO noise can also be an issue. Shooting at a nice low setting, say ISO 100, would give better results but this setting mandates a much longer shutter speed, or using a fast lens set wide open. Do you have a faster lens? Even if it has only a standard focal length. I’m surprised that you are getting star trails at 1 second exposure. I remember using a small telescope and got away with 8 – 10 seconds. I have an equatorial mount on a flimsy wooden tripod but there is no clock drive to track. I tried to track manually back at the U of T using an old beat-up 10” reflector and couldn’t achieve much. I have an old 3” refractor (fits on the equatorial mount) so I always wanted to strap a DSLR onto the barrel of the refractor and then use it as a guide scope employing the largest ocular lens that I had (giving 60x). If you heat up a small piece of styrene plastic from a model kit using a propane torch and then quickly stretching the heated plastic you can make a very thin delicate strand of sprue. You can cut a couple of small pieces of it a glue it to the back of the barrel of the eye piece lens to act as cross-hairs. That way you can see cross-hairs through the telescope and keep some bright star in the cross-hairs by making tiny adjustments using the micro-adjustment cables on the equatorial mount. The problem is making a DIY mount for the camera onto the telescope barrel. To do that you need brains and I looked, the cupboard is bare.

(https://photos.smugmug.com/photos/i-ptXncb2/0/af477f52/M/i-ptXncb2-M.jpg) (https://www.smugmug.com/gallery/n-358cgw/i-ptXncb2/A)
(https://photos.smugmug.com/photos/i-s6HksjT/0/3a7b8017/M/i-s6HksjT-M.jpg) (https://www.smugmug.com/gallery/n-358cgw/i-s6HksjT/A)
Title: Re: Venus meets the Seven Sisters
Post by: Howieh on April 03, 2020, 03:59:45 pm
I still have my 60+ year old Skyscope, a 3.5" reflector with very good optics and a terrible mount. Mine did not come with a finder scope.

http://www.philharrington.net/skyscop.jpg (http://www.philharrington.net/skyscop.jpg)

Do you remember Comet Kahoutek? It was supposed to be the comet of the century but I decided to have the telescope mirror re-silvered and Kahoutek promptly fizzled!! So now we have Comet Atlas and this time I will lay low until it either shows up brilliantly or disappears without a whimper (or a glimmer?), so I shall remain blameless no matter what happens! And, barring a miracle, it looks like tonight's conjunction will be obscured by an overcast sky, but don't fret, we only have to wait eight years until it happens again.

https://spaceweather.com/ (https://spaceweather.com/)

I am also a DIYer. I've built several attachments for the telescope, including a couple that fit around the eyepiece so I could project the solar disk image onto a ground glass. They worked very well during sunspot maximum and for viewing a transit of Mercury. The home built spectroscope also worked really well but only after my hand slipped while making the slit using two razor blades. I still have a scar but the reattachment (I fingertip) WAS successful! :)
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 03, 2020, 05:41:02 pm
Wow, that is an old telescope. Longer focal length than I would have imagined. I should have gone with a reflector back in the day. I have no recollection of my reasoning at the time. It was probably simply a matter of cost. A 6” reflector has so much greater resolution and light gathering power than a 3” refractor. What I really wanted was a Schmidt-Cassegrain design so that the telescope barrel would not be so long, a liability in anything but dead-calm conditions. Obviously that kit was way too expensive. I even bought a 6” mirror blank and started to grind it myself but I never managed to finish it. I now know that a Dobson design would have been the biggest bang for the buck, but I don’t recall it even existing at the time.
The scope at U of T was an old 10” Celestion (Schmidt-Cassegrain) but as I mentioned the clock drive was kaput and the university had no intention of rectifying that situation. They also had a few 3.5” Questars but none of those drives worked either. After I left they finally bought a 14” Celestion and replaced the make-shift wind barrier with an aluminum dome observatory. Figures! The only reason that the astronomy department gave me the keys to use the telescope whenever I wanted because my astrophysics professor saw some photos I had taken using the old 10” and the Nikon SLR body. I mostly used Tri-Xpan film (400 ASA – ISO). Royal-Xpan was too grainy (1000 ASA). Without a clock-drive deep sky objects were out of the question, but I did try M42. The B&W film was not sensitive enough to pick up anything beyond the brightest center cluster and center patch of the nebula due to the limited exposure time I could handle.
How did you mount the camera to your telescope barrel?
I find people tend to cut themselves with things like razor blades and saw blades because they do not have a healthy fear of such sharp tools and therefore get sloppy. When using a table saw, for instance, I think of nothing else but that spinning blade and my proximity to it. I let absolutely nothing distract me.
Title: Re: Venus meets the Seven Sisters
Post by: Howieh on April 03, 2020, 09:05:44 pm
Yup, sharp objects can be harmful to one's health and I'm sure I was aware of the dangers involved, but when you are young and engrossed with the task at hand, such things never cross your mind (until it is too late!). I've never tried mounting a camera on my Skyscope but my son has a 4.5 inch reflector that he won in a contest several years ago and never uses so I could probably borrow it, but how do you attach a P&S camera, with or without the eyepiece, etc.? Btw, I still remember the good old days when people would set up their telescopes on the David Dunlap Observatory grounds (I think it was on Saturdays during July and August?) and the general public could park and look through the telescopes, all free of charge. I also recall the beautiful, clear July night at the DDO when I spotted a little smudge of light directly overhead and made a bold prediction, which actually came true, to everyone within shouting distance. The 'smudge' quickly expanded and within half an hour the sky was covered with northern lights that completely obliterated all but the few brightest stars. I probably missed a great photo-op but back then it never occurred to me to have a camera with me at night.
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 04, 2020, 12:49:57 pm
Attaching a P&S camera, bridge camera, or even a DSLR to the barrel of a telescope could be handled with engineering or with crude brute force. I reckon that even a cinch strap encircling the scope and the barrel of a DSLR’s telephoto lens might work provided the cinch is not so tight as to strain the bayonet coupling between the camera and its lens. A P&S camera would be much lighter, especially if it has a polycarbonate body but then there is no way any cinch strap can get anywhere near the telescoping zoom lens otherwise the mechanism would be immediately damaged. I suppose you could amputate the screw mount from a really cheap tripod to serve as a lock on the camera and then rig the underside of the decapitated tripod head. Another option might be to use one of those offset attachments that used to come with SLR electronic flash rigs. It screws onto the underside of the camera body and then projects sideways for the flash. Just turn it around to point forward and then pass a cinch strap across it and around the telescope’s barrel. The strap hold the flash bracket and the flash bracket holds the camera, and telescope itself serves as a guide scope with cross-hairs on the ocular lens. The low power of a telephoto lens would cover a n area of the sky to include a large start cluster and the telescope is trained and moves to keep the camera’s lens pointed in more or less the same spot of space. You might be able to keep this up for an exposure of several minutes before decrepitude sets in. Several minutes at f5.6 at say ISO 200 might reveal a star cluster like the Pleiades well enough.
Title: Re: Venus meets the Seven Sisters
Post by: Howieh on April 05, 2020, 04:58:02 pm
It just occurred to me that his telescope might have an equatorial mount and if he ever calls his aging parents to see if we are still around, I'll ask him about it. Ok, I'm just kidding; he has offered to food shop for us but so far we are not starving and I look forward to getting out once a week for groceries and meds! On the pretense of cleaning up the yard I just raked and filled a large bag with last years' dead leaves. Wow! using muscles that have been dormant for several months is really a shock to the system - of course what I'm really doing is clearing away stuff that allows my migratory birds to hide when foraging under the feeder.

It cleared up quite a bit last night so I grabbed my binoculars and went comet hunting. Unfortunately, it's still very faint and the light pollution was too much so I could not find it, but if it brightens sufficiently during the next few weeks my backyard should be a good vantage point for viewing and photographing it. In the meantime I looked back through several years worth of images and found A650 shots of Comet Lovejoy from 2015 and Canon G3 aurora shots from 2005 that might be worth sharing. The A650 shots are very noisy and the G3 shots are not too bright but a little (very!) post processing should help.
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 06, 2020, 04:28:34 pm
I hope your son finds his 4.5” reflector. If he is like most people he will not have the slightest idea of where he put it, or may have gifted it to some kid just developing an interest in amateur astronomy. I think I will look for my mount as well. I'm pretty sure I know where it is. Using the 3” refractor as a guide scope would only work if I could get an angle finder. All I have right now is a terrestrial erecting prism and looking through the scope when the tripod is collapsed as low as it will go is just not going to happen. I will also look for my old flash bracket and see if I can strap that to the barrel. Finding that item may be problematic. I also have a straight spotting scope that could guide the camera but that presents the same logistical problem. Then there is that “cross-hairs” issue. Guiding without crosshairs is much too difficult. Then again, I also have a rifle scope with cross-hairs but I don’t know how good the optics are on that item. Either way, I may try some time exposures of the sky this summer even though the city lights are murder.
I had a look at Venus last night, now located at 4 o’clock to the Pleiades, therefore no longer within its clutches. While I was looking I heard a Great Horned Owl across the street. It was here a couple of months ago for several days and then vanished. Well, its back! Previously, it arrived early so there was still some ambient light to locate it but last night it was so dark I couldn’t see dick all! Where is this comet ATLAS located? Is there some myth out there about comets and owls making their appearance at the same time?
Title: MOON
Post by: Napper on April 06, 2020, 11:26:46 pm
The moon at 6 am this morniong  over Gerogian Bay  was

spooktackular I tried to take a few shots with camera,  Not  good.

This evening I tried a number of times to get at least a half decent shot.

This is hand shot leaning up against the gazebo,  look at he EXIF settings,

interesting lights near or behind the Moon.

Dunno how I did that, most of My pics are blury.

At Cottage, switched to all season tires today
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 07, 2020, 06:37:07 pm
Please use a tripod if you are attempting to photograph a celestial object. You can turn off your image stabilization because it will very likely fail to mitigate the frequency-of-vibration caused by wind, or footfalls on a wooden deck, which is in no way similar to movements due to handheld photography.
Don’t focus to infinity and assume that is the best focus position. Switch to manual focus and use live view on the screen. If you have it, engage the digital magnification feature, either 5x or 10x and then focus manually until the star, planet, or moon seems in best focus. If you have a delayed shutter trip feature then use it so that you do not need to touch your camera. If the selected celestial target is not as bright as the moon and you are getting motion trails during the time-exposure from the earth’s rotation then try taking multiple images and then stacking them in PS after repositioning them into alignment and then adjust levels. Obviously this will not result in deep sky penetration. You need to burn the sensor over a long time to achieve that.
Title: Re: Venus meets the Seven Sisters
Post by: Howieh on April 08, 2020, 01:20:52 pm
Good news and bad news:

https://spaceweather.com/ (https://spaceweather.com/)

The bad news relates to Comet Atlas. I don't think it's my fault but Atlas appears to be breaking up. I hope the pundits are wrong; stay tuned and I will keep things up to date.

The good news concerns photographing the moon and contains a detailed article on focus stacking. It seems like a lot of work but, if you have the required equipment, the time and the patience, the final results can be really impressive.

And please note: if you are looking at Spaceweather after April 8, 2020, you can search the archives (upper right) for pages from earlier dates.
Title: Re: Venus meets the Seven Sisters
Post by: Shortsighted on April 10, 2020, 04:59:25 pm
I had a look for my old 77mm refractor and found it soon enough, including the almost useless wooden tripod and the counterweight for the equatorial mount but not the mount itself. That’s weird. You would think everything would be together in the same place. Can’t find the mount anywhere. I did find a very cheap angle finder from a cheap telescope that is barely beyond a toy. I might be able to retrofit it to the refractor and use it as a guide scope for a camera/telephone time exposure of the sky. If I can’t locate the mount then this plan is defeated even before it begins.
Attached: shot of Jupiter taken with a 10” reflector. Several seconds of exposure at whatever the speed of the telescope was (probably f 10). ISO equivalent was 200, I think.

(https://photos.smugmug.com/photos/i-994bMLN/0/73ad8c53/M/i-994bMLN-M.jpg) (https://www.smugmug.com/gallery/n-358cgw/i-994bMLN/A)