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I recently saw FLO were selling a new light pollution filter: IDAS LPS-P3. I shoot OSC from Bortle 8, and figured this might help for broadband targets! (I use an L-eXtreme for narrowband, which works brilliantly). I already own an older-style IDAS D1, but don't routinely use it as I'm not sure of its effectiveness. Well, with these two filters in my possession, why not have a shootout and see the results?
For this test I used an Askar FRA400 f/5.6 72mm Quintuplet APO Astrograph and ZWO ASI 2600MC-PRO USB 3.0 Cooled Colour Camera. All shots were from Bristol (UK) city centre. 120-second exposures. The target was M81 / M82.
First up, I took a single sub using No Filter, D1, and P3. Each sub I edited slightly in the same way using PixInsight, just enough to make as fair a comparison as possible. Then I cropped very close into M82.
Hard to make out much difference! The D1 produces a colour cast that takes a bit of work to even out in post-processing. The P3 retains natural colours well, and perhaps gives slightly better definition than no filter. More testing needed... so next I gathered three hours of data for each filter:
Same again, to my eyes: all images very similar, but the D1 giving a slight colour cast.
Time for round 3. When imaging I aim for long integration times, so let's try that here. I'd need to cut one filter out just because there are only so many clear skies. So bye-bye D1! Now it's No Filter versus P3. 10 hours of integration time for each. Who will emerge the victor?
These are the stacks right out of PixInsight. The P3 has a bit of a colour cast, and a gradient -- to be expected actually, as the Moon was up more during the P3 test. Let's do some basic edits...
They look essentially the same to me. Some very slight differences in the background, but explained by my use of Pixinsight's DBE tool to remove the Moon's gradient. Let's have a tight crop on M81:
I really can't see any difference! These tests are leading me to conclude that the sources that make up Bristol's light pollution don't lend themselves to being suppressed by a filter. Maybe I've got lots of LED lights nearby.
It feels almost heretical to say, but is there any point in light pollution filters from a city centre? Sure, from towns or areas with particular street lights (e.g. sodium), but from the middle of a big city? It seems to me that long integration times are the only way to claw back some of that signal to noise ratio. This Iris Nebula photo was taken with the same kit as the above tests, and is 20.5 hours of integration time -- no filters at all.
I'm probably going to return the L3, and put the D1 up for sale. Unless anyone can see something I'm missing?!
After much research, primarily on this site and The Binocular Sky, I got hold of the above binoculars. I spent ages writing a review specifically for this site of what I found, as a thanks for all the advice I had received. By the power of idiocy I then managed to post it on Cloudy Nights instead (I had both open in my browser). Too much Christmas port I guess
Anyway, too late to take it down as some have already replied and I guess I shouldn't post the same thing on two sites so here is a link to my review on completely the wrong site No offence at all to Cloudy Nights but I wrote it with the Stargazers Lounge audience in mind and it may make less sense on a US site.
Comparison of Pentax SP 50 WP 10x50 and Nikon Action EX 10x50 CF
It seems that I got less active lately in this hobby, mostly due to the pandemic, directly or indirectly.
However, I'm planning to move from where I'm living now in the close future so I started replacing my gear with lighter and better items.
One of the items was the mount. I still have a tuned SkyWatcher AZ-EQ5 and a stock SkyWatcher EQ6-R. I used both quite a lot, I passed with them long time ago 1000h of exposure. And recently I bought an iOptron GEM45.
The AZ-EQ5 is in the lightweight mount class, but performs quite poor for astrophotography. The original RA worm was a crappy one and I sent the mount to DarkFrame for tuning. I received it back the same, I only lost time and money. I then purchased 2 new worms from China via OVL with some help from FLO. The new one (I didn't test both) have a larger PE than the original one, but a smoother one. The p2p PE of the new worm results in a >60" deviation. When pointing close to the NCP, it guides well below <1.0" total RMS. When pointing towards the celestial equator, the performance drops significantly to 1.0"-1.8" RMS. I always need to use short exposures in PHD to guide it smoother.
In total I spent for the AZ-EQ5 perhaps more than 1800 euros with the tuning, the new worms and deliveries. A lot pricier than stock in the end, but it still has 2 big advantages: mine came with a foldable (towards the mount) pier style tripod and it's light, I can carry the mount with the tripod folded in one hand. The mount and the tripod weight less than 15kg. The other advantage is that I can use the second saddle for the second scope. I used this combo more than a couple of times, with short focal length refractors and all went well. A SW 72ED + an ASI1600 + a finder/guider mounted as counterweight as close as possible to the RA axis, perfectly balances a SW Esprit 80 and a Canon 550D.
The EQ6-R is a lot heavier mount. The head itself weights about 17.7kg, it has a handle, but even standalone it seems a lot harder to carry than the AZ-EQ5 assembled on the tripod. The 2" tripod for the EQ6-R weights about 8kg. Definitely I cannot carry both the mount and the tripod in a single trip for a longer distance. The performance and weight capacity are decent though. Mine has quite a large backlash on both axis, I cannot feel it at hand, but it's obvious when slewing at slow speed. It doesn't bother me for imaging, anyway, since I balance the mount a little east heavy. At most I put a single 200/1200 newtonian and camera on it or a dual setup consisting of a 150/750 newtonian and + a 102/714 refractor and camera, one on top of the other. Weight was not an issue, but a larger momentum + wind affected the guiding performance a little. Towards the NCP it guided excellent at 0.4"-0.6" RMS, but closer to the celestial equator, the performance varied and dropped for this mount too. On Orion, at times the guiding stayed below 1.0" total RMS, but many times it went worse than 1" total RMS. I believe that I never put a scope on this mount and looked through it, I only used it for AP. One thing that bothered me for a while was that the mount was stalling at times due to insufficient power. None of my domestic 12V power sources that I used for the AZ-EQ5 was good enough so I used a 15V 8A source to power the mount. I recall paying around 1300-1400 euros for the mount about 2 years ago.
I used the SynScan app on Windows to drive the SkyWatcher mounts. The app mimics the functionality of the hand remote. The AZ-EQ5 doesn't have a polar scope and I believe I never used precisely the polar scope on the EQ6-R either. The app allows you to perform a 2/3 star align, then it figures out the polar error and you can then perform a polar alignment routine aided by the software. You can select a star for polar alignment, slew to it automatically after select, align in center, then the mount moves a little and the software tells you to adjust the altitude and bring the star in center, then it moves again and tells you to adjust the azimuth and bring the star in center. Simple as that. If you're way off initially with the polar alignment, you might need to realign once or twice again. The SynScan app + drivers are also much simpler than the EQASOM and can be used for controlling the mount from other programs via ASCOM or for pulse guiding.
Now, to the more recently acquired mount, the iOptron GEM45. I spent a lot of time researching what mount would suit my needs. Lightweight, good performance and not astronomically expensive. After many reviews read for the CEM40, I decided to go for the GEM45 as both share the same components. I only saw CEM60's and the older 45 eq. All my astrofriends' CEM60's perform better and more consistent than my EQ6-R.
The GEM45 is supposed to have a PE resulting in an error less than 14" p2p. The graph for mine says that it's less than 10".
The first thing that I noticed when I received the mount it was how small the box it came in was. The mount head is light at about 7kg and the tripod 5-7kg. The second thing that I noticed was what a poor design was made for mounting the mount's head on the tripod. It is unbelievably stupid compared to the SkyWatcher mounts and it's horribly difficult to mount and tighten the mount on the tripod in dark and cold.
Again, comparing to the SkyWatcher, a minus is that you always need to disengage very carefully the gear switches and never leave them engaged. The mount does not have a friction clutch as the SkyWatcher has and hitting or pushing hard the components can lead to damaging the gears. So the mount seems very sensible to handling, it requires a lot of care and mounting the telescope(s) on the mount while holding the CW rod with the other hand can be quite damn hard sometimes. However, there is no backlash.
After setting all the hardware, the next thing was to connect the remote control + the software. It was clear the day I received the mount. It arrived at 5PM and at 8PM I was out of the city with all the software installed.
The iPolar was easy to use, however, you need to connect a separate USB cable for this, the mount does not have a USB hub.
You can perform a star align from the hand controller, but not from the Commander app. You can perform a polar iterate align from the hand controller, but not from the Commander.
Speaking of star alignment, if you choose a 2 or 3 star alignment procedure, I was used to the fact that the first star can be way off when initiating the alignment. The SkyWatcher mounts' software (hand controller or PC app) took into account the error and corrected it for the next stars. iOptron's software (hand controller only, the PC Commander can't align at all) does not. So you need to search again for the second (and third) star to bring it into the view and center it. Only then the model is taken into account. Moreover, the polar iterate align is a pain and, surprise, the polar iterate align and a retry of star alignment after polar adjustment does not take into account the model it computed at the previous star alignment so all the stars are way off if the zero position is not set very accurate. Searching automatically for zero position seems rather a poor joke. So, after being used to the SkyWatcher software, the iOptron seems soooo limited and counterintuitive.
Due to this, I had quickly to learn to drift align with PHD when Polaris isn't visible (it my the case at home on the terrace).
Leaving all the poor engineering and software designs, things are getting better. The mount looks very nice and rotates around both axes very very smooth. You can also pull cables through the RA and DEC axis and have them available at the DEC saddle. There's only a USB 2.0 connector on the saddle, that was rather useless for me so I needed to pull a USB 3.0 cable. However, the 12V power available on the saddle is very welcomed to power the cameras' coolers.
As I type, I'm imaging with 2 ~70mm refractors one on top of the other + 2 mono ASI cameras. Both scopes weight about 10kg. Guiding performance is always below 1.0" total RMS, ranging between 0.4" and 0.8" total RMS, regardless of the pointing position on the sky. If I manage to convince either the mount or PHD to compensate for the PE, I believe it should perform much better as the error increases to >0.6" only when the guiding switches from East to West or viceversa. Plus, being backlash free, it responses very fast to dithering commands and settles quick and, with the small refractors, it didn't seem bothered almost at all by a mild wind.
In the end, I'm very happy with the consistent very good performance of the mount, but still disappointed by the mount attachment to the tripod and the poor designed software and alignment procedures.
I'll come back with more reviews for cameras and telescopes that I own or owned. And images, after I manage to process them. I've more than 100h of data waiting in the queue to be processed.
Clear skies and stay safe!
Hi everyone, about a month ago i got my first telescope. Wasn't sure what to get but i wanted something portable and easy to setup and use. After some internet "research" i decided to go for a refractor on a manual alt/az mount. The telescope was on a 50% sale so i decided to go for it , the Meade infinity 90.
The scope came in one big box, everything was inside. Included was the optical tube, the mount, 3 eyepieces (6.3mm, 9mm and 26mm), a 2x barlow lens, 90 degree diagonal, red dot finder, an eyepiece holder for the mount and a few manuals. The optical tube:
The tube has a 90mm (3.5in) aperture and 600mm focal length. It looks and feels as a quality instrument, it has a small dew shield and the focuser is smooth when you move it back and forward. As expected the lens looks to be coated. It has a dovetail bar on it with 3 holes for screws. The mount:
Light but stable, made of aluminium. It has 3 extendable legs, and 2 slow motion cables (alt/az). One screw to mount the tube on on top (adjustable back and forward). The eyepieces and barlow:
All 3 are modified achromat eyepieces, the lenses are made of glass and are OK for the beginner, but i would suggest upgrading if you can. The barlow is bad i even think that the optics are plastic (not sure), it is usable if you don't have other options but this should be the first upgrade in my opinion. Observing: First light:
The telescope arrived in the morning so the first thing i did after a quick setup was to adjust the red dot finder. I looked at some mountains about 20km away, the view was nice and very detailed using all eyepieces. Combining the 6.3mm with the barlow got me a bit blurry view, but the barlow in combination with the other eyepieces was ok. Night came and it was a moonless and clear night (only light pollution from the city i live in). I saw orion right infront of me, "marked" it with the red dot finder where i thought M42 should be and looked through the 26mm eyepiece. It was a bit blurry but after adjusting the focus i could see some nice pinpoint stars and also something fuzzy, i realized it was the orion nebula. After letting my eyes adjust to the view for a few minutes i started seeing 2 faint "wings" on both sides and in the center were 4 very tiny stars, i didn't expect to see that on my first night. I followed my target for about 15 minutes using the slow motion controls , it was easy to do. Also tried the 9mm eyepiece and with it the 4 stars were more easily seen but the faint clouds got fainter so i moved back to the 26mm. Next target was venus, i tried all eyepieces + with combination with the barlow. It looked like a very bright half moon without any details. When using the barlow the view was ok but purple glow was showing around the planet, without the barlow the purple wasn't noticeable. I also looked at the star Sirius which looked nice, bright and much bigger then any other star i could see that night. After Venus went down i decided it was enough for day one. Moon:
I expected it to look good, but not this good. I was observing the moon for a couple of nights until it got full. I could see a lot of details at the terminator , with low and high magnification. When the moon was full it was very very bright and it looked best with the smallest magnification using the 26mm eyepiece. Jupiter and Saturn:
I got 2 opportunities to look at these 2, the first time i think the "seeing" was bad. I could only see Jupiters 4 moons and the planet was a bright disc without any details at any magnification i tried. Saturn also wasn't very good, i could see the rings but they were blurry and "dancing" around. But the next time i had the chance to look at these planets the conditions were much better, first target was again Jupiter. With the 26mm eyepiece i could see a white disc with 4 moons.With the 9mm i could see the moons again but now the disc had very faint 2 bands without any color. The view was best with the 6.3mm eyepiece, the 2 bands were clearly visible and on the upper belt on the right side there was a small dark dot, i am not sure if it was anything . Next target was Saturn, event with the 26mm eyepiece i could see that it has rings, i switched to the 6.3mm right away and wow there it was, Saturn and its rings clearly visible, i even think i could spot the cassini devision, but it might have been my eyes playing tricks. I tried using the barlow on both targets but it was making the image blurry, but at this point i had purchased a higher quality barlow and the views were very nice with it , but the max magnification i could use that night was 133x, anything higher and the image was getting wobbly (probably that was due to the atmosphere that night). After that some clouds came in and it was time to get back to bed (got up just to see the planets in 4am). Conclusion:
I think i got what i wanted, a small and very portable telescope for some basic amateur observing. I do recommend this telescope to anyone as a first telescope or even to an experienced astronomer who is looking for something light, portable and being able to set it up and start observing in 2 minutes. Also i would recommend you replace all of the eyepieces and the barlow. I got me a few plossl eyepieces and a nice barlow, it was worth it.
Feel free to ask me anything regarding this telescope i will be more than happy to answer.
Sorry for any spelling mistakes this review probably contains
Also i am attaching a few images i took directly off the eyepiece using my smartphone (handheld).
IAS 2019 Review - Friday 15 November
My second show (first was last year), as before got there on Friday 15th, soon after 0900hrs.
Despite the weather, seemed to be fairly busy in the main hall. Had a few good discussions with different vendors, 365 Astronomy in particular. Even the guy on the Vixen stand near the entrance, remembered me from last year!
RVO had a whole hall to themselves, not really sure why? They did seem a bit 'lost' in there. All that space and not much kit...
Again, there to 'window shop' only, but still managed to spend £90! Got a good price on a WO 1.25" Dura-Bright Dielectric diagonal.
(Thanks Widescreen) Best online price I'd found, prior to the show, was about £100 inc. postage/delivery, so saved a tenner!
Restaurant was a big improvement over last year. Coffee was OK, lunch was pretty good too. Choice of Fish 'n' Chips or Cottage Pie.
All gone by 1345hrs...
All in all a good day. Looking ahead to 2020, might make three in a row!
"Humour is reason gone mad" Groucho Marx