Comparison of Pentax SP 50 WP 10x50 and Nikon Action EX 10x50 CF
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By andyrawlins
Here is a review and then a couple of questions to the forum
The experience I gained assessing my new Nikon Action EX 10x50s https://stargazerslounge.com/topic/369052-comparison-of-pentax-sp-50-wp-10x50-and-nikon-action-ex-10x50-cf/?tab=comments#comment-4009551 led me to dig out my old Vivitar Series 1 8x25. I bought these in 1995 for £99, so not an insignificant amount then. Series 1 was Vivitar's premium range at a time when (I believe) they were well regarded for their optics (now they seem to sell basically children's toy binoculars). Anyway, despite their price/apparent pedigree and excellent build (made in Japan) I never got on with them, finding them very difficult to focus and to keep in focus. They rarely got used and indeed got superseded for general use by the Inpro 10x50 mentioned in the thread above.
Using what I learned when assessing the Nikon's I decided that the focus problems were down to four things: 1. a small exit pupil, quoted as 3.12mm, so you need to have the eyepieces correctly positioned over each eye; 2. a short eye relief that I estimated to be about 11mm. I found the view (without glasses) to be best with the short (4.5mm) rubber eye cups folded down. Wearing glasses, it was like looking down a drain pipe with a severely vignetted view; 3. difficulties getting the interpupillary distance right: for some reason the image is significantly brighter when the binoculars are set wider than the correct distance. However, at this, what would appear to be the correct separation, they will not come completely to focus. When they are brought down to the correct distance (60mm for me) the image suddenly gets darker but actually focusses well; 4. a very 'low geared' focus wheel and seemingly very short depth of field which necessitates a lot of focus twiddling every time you change view (not for objects at infinity, obviously). Because of these things, its crucial to get the binoculars correctly positioned over the eyes and to keep them in that position. Once they are correct the image is actually not bad. To be specific, the image is almost exactly like it looks with the naked eye: the same colour balance, the same detail and resolution, the same clarity, the same brightness - just a bit bigger. Its quite uncanny really. In contrast, the Nikons give an almost hyper-real clarity, detail and brightness and as serious wow factor.
Compared to the 10x50s they really didn't seem to magnify that much (I found the objectives to actually be 23mm so 7.4x not 😎 but maybe this is something to do with AFoV. FoV is quoted as 'Wide Field 8.2°'.
So basically they magnify the image but not the brightness which is fine for daylight use but fairly useless as night. The big advantage, however, is that whereas the Nikon's are over a kilogram and will only just fit inside my zipped up coat when round my neck, these weigh a third as much (350g) and are a fraction of the size (105x120mm). They easily fit in my coat pocket.
So I think I should give them more of a chance by keeping them in my coat pocket so they are there when I need them (the best binocular is the one you have with you!).
On to my question then: does anyone know anything more about these older Vivitars: whether they are actually any good and when and why the company seemed to give up with proper optics? I can find nothing on the internet. All I have is the Vivitar brochure from the time (attached) in which the certainly seem to regard themselves as makers of 'proper optics'.
I'd also welcome comments on the issues I found and whether my conclusions are correct.
IMG_20210113_0002.pdf
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By anyela
Hello, my eight yeard old child wants to get into astronomy so she asked for a telescope. I have read that binoculars are as good as telescopes. Since I have always wanted to get into astronomy but never found the time, I thought I tag along and buy one that both can use. Can anybody recommend me a telescope that is good enough for astronomy but can also be used by a small child.
Thanks
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By Lee_P
I recently bought an Askar FRA400 f/5.6 Quintuplet APO Astrograph. I couldn’t find much info about it in advance – the best was a thread on Cloudy Nights – so thought it might be useful to other folks to jot down some of my feedback. I’m happy to answer any specific questions or clarify any points written in this review.
One-line review
This is a great telescope that’s fun and easy to use, but with a few issues potential buyers should be aware of.
Background
I got into astroimaging a few years ago, using a Sky-Watcher Evostar 80ED DS-Pro and ASI1600 mono camera plus filters. I enjoyed it, but the arrival of a new baby took a lot of my time (and energy!) so I sold everything with the intention of coming back to the hobby a little later. Barely a year on and I was missing astroimaging a lot, so decided to get back into it, but this time trying to create a simpler set up that would get me imaging on a clear night with the minimum of hassle.
I bought a William Optics Zenithstar 73 II APO 2019 with reducer / flattener, but had terrible issues with streaky corner stars due to backfocus problems. I tried a few things with the help of FLO (great customer support, of course) but in the end returned the telescope as it looked like I’d gotten a duff one. Luckily, at this time FLO started stocking Askar FRA400 f/5.6 Quintuplet APO Astrographs. Its Petzval design promised to be free of backfocus issues (assuming no reducer), which given recent experiences was music to my ears. I decided to go for it, and pushed the button.
I’d be coupling it with a ZWO ASI 2600MC-PRO USB 3.0 Cooled Colour Camera. I went OSC to keep things simple. However, I live in Bristol city centre – Bortle 8 light pollution – so added an Optolong L-eXtreme to my basket so I could still do narrowband imaging.
I decided to forego the optional Askar f/3.9 Full Frame Reducer for FRA400/5.6. This was for four reasons. 1) The L-eXtreme isn’t as effective with very fast systems; 2) 400mm is good to frame the targets I’m most interested in; 3); with the reducer I’d need to get the backfocus spot-on, and I’d had enough of that with the WO ZS73; 4) I’d save £269!
My kit
Askar FRA400 f/5.6 Quintuplet APO Astrograph
ZWO ASI 2600MC-PRO USB 3.0 Cooled Colour Camera
William Optics 32mm Slide-base Uniguide Scope
ZWO ASI 120MM Mini USB 2.0 Mono Camera
ZWO EAF - Electronic Automatic Focusmotor
ZWO ASiair Pro Wireless Astrophotography Controller
Optolong Dual-Band L-eXtreme Filter (2”)
ZWO 2″ Filter Drawer with M48 / M42 Connections
Primaluce Lab 30mm PLUS Spacers
William Optics DSD 245 Plate
Dew heater straps
Orion Sirius EQ-G mount
Image quality
Not being a pixel peeper, I’m not qualified to write a detailed analysis of image quality here, but I will post a single sub so people can make up their own minds. I can say though that I’m very happy with the views – both through the eyepiece and via the camera. There are some aberrations (fringing maybe?) around stars at the edges of the frame -- zoomed examples included below.
Issues and solutions
Build quality on the whole is good, a different league to the 80ED, but not quite up there with the WO ZS73. The dew shield is a little loose, and on the cusp of sliding down under its own weight when the telescope is pointing straight up. I solved this by putting a white elastic band on the main tube, just behind the dew shield – a DIY fix but works just fine. The lens cap also feels a bit loose, but hasn’t fallen off. The default focusser is ok, but doesn’t quite have the premium feel of the WO ZS73. I upgraded with a ZWO EAF, which was very easy to install, and works perfectly. I'd consider this a must if you're astroimaging.
The supplied dovetail is quite short, and makes it difficult to achieve balance if using a heavy camera. I solved this with Primaluce Lab 30mm PLUS Spacers and a William Optics DSD 245 Plate. This allows for good balance, plus there’s room for an ASIAIR PRO to be attached at the back.
All my accessories are attached to the left-side of the telescope, making it slightly off-balance. However, there are enough holes in the spacers and tube rings to allow for the dovetail to actually be attached slightly off-centre to the telescope, allowing for it to all be well balanced. You can buy a Finder Plate to open up more options.
The telescope comes with a conical M68 to M48 adapter. Askar say this is threaded for 48mm filters – ideal for my L-eXtreme, or so I thought. I couldn’t really see where there was a thread in the adapter. I e-mailed Askar customer support, and got a reply two days later saying that the thread is inside the adapter. Fair enough, there is a thread in there, but no way of actually getting a filter inside and screwing it tight. It’s really odd. I e-mailed Askar again to ask for clarification, but this time didn’t get a reply. So, I don’t rate their customer service. From more research online, it looks as if some of the adapters come in two parts that screw together, presumably to give access to the thread. In the end I bought a ZWO 2″ Filter Drawer with M48 / M42 Connections. This fixed the issue, and is very convenient, but is an extra cost that should be considered.
The ASKAR FRA400 doesn’t come with a carry case, which is a bit of a shame.
Summary
I’m really happy with my ASKAR FRA400, and think it’ll serve me well for years to come. Once the initial issues were overcome, I’ve been finding it a lot of fun. It’s compact and light -- I can carry the OTA with all attached accessories in one hand. It pairs well with the ASI2600 and L-eXtreme. The ASIAIR PRO controls everything very neatly as well. If I see a gap in the clouds, I can set everything up (tripod and mount in the garden, attach telescope, polar align, autofocus, start imaging) in 20 – 25 minutes. I’m looking into a DIY pier in the garden, which should reduce this to 5 – 10 minutes.
Images
Single FITS sub, straight from the camera (with L-eXtreme):
Light_IC1805_300s_Bin1_gain100_20201224-224655_-9.7C_0039.fit
Single 300s sub with L-eXtreme, debayered, stretched, and resized to 50%:
Random star from the centre of the frame:
And the edge of the frame:
8.5 hours of integration time. One of my very first attempts at processing with PixInsight, so definitely not the limit of what the telescope can do, but more an indication of what a beginner can achieve in Bortle 8 skies:
Views of the Askar FRA400 in my garden:
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By WiltsStarGazer
Hi,
I have Skytee 2 mount, on which I use the side mount for my 200p and use the top mount for my 127 Mak, sometimes at the same time. (Yes, I got carried away with secondhand bargain madness during the first lockdown 😏)
What I would like to do is use the top mount to mount my 15x70 binoculars so I can let the family see what I'm looking at without having change the height of eyepieces on the scope or them using steps.
For this I would need a sturdy adaptor which has a dovetail (vixen?) base with the normal screw fit for the tripod mounting bracket between the lenses.
Does such a thing exist? If it does, I haven't been able to find it.
Does anyone know of one?
Thanks
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By tylersk90
Some say 10x50 can be held, other say it’s shakey, or at the limits of what’s possible. We all know the YMMV differences between each of us, but what I find misleading is the weight of the bins are never mentioned. Some 10x50s are twice as heavy as other brands. (I have some APM apo ED 10x50 that are over 3lbs, while the Orion Scenix 10x50 is like 1.7 lbs.)
How much are the recommendations we read speaking in strictly magnification terms? Or is it possible the wide range of opinions from the community come from unwittingly comparing apples (3lb 10x50s) to oranges (1.5lb 10x50s)?
Cheers!
Tyler
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