Category : Equipment Reviews

Bahtinov Masks Review

I have heard so much about Bahtinov masks lately on the web and in magazines, so I thought I should check them out for myself.

Kendrick 80mm Bahtinov Mask Bahtinov masks designed by Pavel Bahtinov, basically aid you when focusing your telescope for either visual or imaging use. They appear to be an improvement on the Hartmann mask (which I also own but I only use it to hold a smaller screw-in solar filter). The Hartmann mask (if you have three holes in it) will produce three blurry images of your target, and then once you bring the object into focus, the images merge into one. But the Bahtinov mask is a far superior focussing aid than the Hartmann mask as it uses diffraction spikes to help you with your focussing.

Luckily Bahtinov masks come in a variety of sizes from 80mm to 12”+ sizes, as I have two scopes, one is an 80mm and the other my 10” LX200, prices vary on size.

I got my hands on an 80mm size Bahtinov for my Skywatcher ED80 Pro telescope from Green Witch.

The Bahtinov mask itself was made by the Canadian company Kendrick, their version is quite flexible and comes with three rubber type bungs which hold the mask in place, as I have seen a lot of Bahtinov masks sold with just the mask and no fixings.

My Meade 10” LX200 Bahtinov Mask came from the astronomy retailer SCS Astro.

Farpointastro Meade-Bahtinov MaskThis mask was made by a company called FarPointAstro.

The design of this mask is very different from the smaller 80mm Bahtinov Mask as this larger mask does not have rubber bungs, but slips onto the secondary mirror hub on the front of the telescope.

So it is really easy to slip it on and off of the telescope, a great design.

SCSAstro Bahtinov Mask Amended I actually decided to amend the design of it slightly by adding some white adhesive pads to each corner of the SCSAstro Bahtinov Mask. I did this to raise the height of the mask away from the main glass on the front of the telescope so I had less chance of putting fingerprints on the front of my telescope glass.

You begin by directing your telescope towards a star and then place the Bahtinov mask over the end of your telescope. The Bahtinov mask then produces three sets of spikes. The great thing is that the position of the spikes will tell you all you need to know about how well your telescope is focused.

Bahtinov FocussingIf you change the focus knob you on your telescope you will see that two of the spikes stay in the same place, acting like a cross-hairs, whilst the third spike moves up and down across the image. Once the moving spike is centered you are in focus, simple.

Then lock your focus in, and remove your mask and then start observing or imaging. If you need to re-focus just follow the same procedure again.

Kendrick Bahtinov Mask on 80mm One of the benefits of these masks is that they are so light and are easy to place on the end of your telescope, so there is little chance of you moving your scope when attaching a Bahtinov mask.

Most good astronomy retailers now sell Bahtinov masks in various sizes for all of the most popular telescope sizes. My Bahtinov masks came from Green Witch and SCS Astro and both were very reasonably priced, you can find the range of Bahnitov Masks at Green Witch here and Bahtinov Masks at SCS Astro here.

scsastro on meade lx200This is a photo of the SCSAstro Bahtinov mask on my Meade 10″ LX200. It’s easy to fit and easy to remove once your telescope is focused.

If you really want to make your own Bahtinov mask (which can be very fiddly to cut out and a lot of effort is required) then you can get an image file off of the internet which can be sized in a photo editor program to fit your scope and then the template can be printed out. The choice of raw material for the mask would be up to you.

Astronomik OIII CCD Filter Review

I have now moved over to collecting Astronomik filters, I did have a selection of both Baader and Astronomik filters. I have now settled on Astronomik filters for my narrowband filter set.  It’s important to always stick with the same brand of filters, as they should then all be parfocal.

But don’t get me wrong I still like Baader filters as I still have a fringe killer, uv/ir  and solar continuum filters from them.

The thing I like best about the Astronomik filters is how slim they are, and I never have any trouble screwing them into filter wheels, they also don’t catch on filter wheels like the height of the Baader filters.

Due to the cost of 2″ versions of filters I have gone with the 1.25″ range of filters, plus the filters wheels in the 1.25″ versions are also cheaper, this one was from

OIII CCD Filter The OIII CCD filter comes in the standard Astronomik no-frills box with a black foam backing. I was getting confused by the labels Astronomik put on their boxes, but now I think the white and black labels are the newer versions of the filters.

As the name suggests the OIII CCD filter comes with  a built-in IR-blocker up to 1150nm, so you don’t need an additional IR-blocker with this filter.

The Astronomik OIII CCD filter is a narrow band emission-line-filter for CCD photography. The filter lets the light of double ionized Oxygen of emission nebulae pass and blocks nearly the whole remainder of the spectrum where the CCD is sensitive.

The Astronomik OIII CCD increases the contrast between objects, in this case between the OIII emission line and the skyglow background. Our Astronomik OIII CCD completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na)) and skyglow.

The full width at half maximum (FWHM) of 12 nm is optimal suitable for common CCD cameras and allows the use of very fast optics The optimal aperture ratio for the use of the filter is 1:3 to 1:15 with apertures of more than 6″ (150mm).

When using the Astronomik OIII CCD filter together with the H-alpha, OIII CCD and the SII CCD filters you can obtain three-color images of emission line objects (gas nebulae) from locations with very strong light pollution. To do so, you would take an image in three different wavelengths, select each one as a color-channel in Photoshop and paste them together as one single color image.

  • 95% transmission at 496nm (OIII)
  • 95% transmission at 501nm (OIII)
  • Full width at half maximum 12nm
  • Transmission from 494nm to 506nm
  • Parfocal with other Astronomik filters
  • Glass thickness: 1mm
  • Completely resistant against high humidity, scratches and aging effects
  • Diffraction limited, the filter will not reduce the optical performance of your telescope!
  • Astronomik filters are delivered in a high-quality, long lasting, filter box

Astronomik OIII filters and other Astronomik filters can be purchased from

Netgear DGN3500 Review

I have been waiting for a Netgear Gigabit modem/router for ages, and at last one has been released. It’s called the DGN3500. At the time of writing it seems to be retailing for around £110 delivered, but I did not want to pay this much, so I decided to buy it from Pixmania for £81 + P&P. I had only ever purchased one thing from Pixmania before and that was my astronomy webcam my Philips SPC900.

I ordered the Netgear DGN3500 on a Thursday morning at 8am and received the item via Fedex on Monday morning, not too bad considering it came from South of France. It’s also fun tracking your parcel on the Fedex website as I saw it come up to Paris and then arrive in Stansted and then come to Cambridge.

I previously had a Netgear DG834G for around 5 years, and it was the first wireless router I ever bought. It has been rock solid for all those years and is still going strong, and it never needed rebooting or anything. All I did was keep feeding it the latest firmware. So I opted for another Netgear.

The first thing that strikes you is the increased size of the DGN3500 compared to my DG834. Something you’ll see below in the image:

Netgear dgn3500 size versus dg834

I had hoped that I would export all my settings from my old router and then just import them into the new router, but unfortunately this did not work, so I had to manually enter my settings. This is not really a problem as the admin panel looks the same as I was used to.

As most of my PC’s now have gigabit ethernet I was looking forward to increased speed over the network. I currently had a mixture of Cat5 and Cat5E network cables. I was happy to see that the Cat5E cables all provided gigabit connectivity as on the router it shows gigabit in green and 10/100 as orange.

Even though the Cat5E cables are fine for gigabit I still ordered a couple of 3m Cat6 cables to see if I could get more speed, but I can’t really tell that I have gotten any extra speed.

One new thing with the DGN3500 is that it has a USB socket on the back allowing you to connect a USB hard drive or stick pen for network attached storage. I have plugged in a 16GB USB pen for temporary storage purposes. You can set this up via the netgear control panel and provide password access, or add folders to it, you can even specify if only certain USB drives are allowed to be connected to the DGN3500 modem router.

Something new for me is that the DGN3500 has an on/off switch on the back as well as a reset switch.

As Pixmania is a French company some people are worried about plugs being 2 pin plugs etc. But don’t worry Pixmania provide a 3 pin plug adaptor which just clips onto the 2pin adaptor – brilliant!

Pixmania Plug Adaptor

The only other difference from buying from Pixmania is that they the European version does not include the standard UK white phone filters, but instead you get some strange French phone adaptors pictured below. But if you already have phone filters you probably won’t need any more of them, and if you do I am sure they are cheap to buy.

French Modem Adaptors

Overall the Netgear DGN3500 seems a very good wireless modem router. It’s early days yet, but I have had no problems yet. Speed is good, although I would have thought that signal strength could be better, but that could be down to my wanting great signal strength when I am in my observatory in the garden, it could also be that my wireless router usb adaptor needs some new drivers.

I could not fault the price at Pixmania as I think I paid about £88 including delivery for the DGN3500-PES version from Pixmania, where as everyone else wants about £110 delivered for the DGN3500-UKS version.

Get your Netgear DGN3500 from Pixmania here.

Philips SPC1300 Webcam for Astronomy?

Philips SPC1300 WebcamI noticed today that Philips have released a new range of webcams, and there are a couple of Pro models. The main one to look at is the SPC1300 or SPC1330 as it’s called on the Philips web site. The SPC1300 is said to be a 2 Megapixel webcam, unlike the SPC900 which is a 1.3 Megapixel camera.

The major downside of the new SPC1300 is that the sensor is a CMOS sensor where as the SPC900 is a CCD sensor. But will this make a lot of difference when undertaking astrophotography?

Is the SPC1300 the new SPC900? Can the SPC1300 be taken apart and the lens removed and a standard plastic lens adaptor be screwed in? I suppose the only way to find out is to purchase one and try and take it apart.

Philips SPC1300 Webcam BoxThe cheapest place to buy from seems to be Amazon or Pixmania for around £50.

The weight of the webcam is only 110g and the fixed lens is f/2.8

If anybody has more information on this, or has one and has adapted it, I would love to know about it, so please leave some comments about it.

Canon 450D Digital SLR Camera Review

Canon 450D CameraMy first DSLR purchase was a Canon 400D, which I purchased in July 2007, so about 14 months ago. A great camera and the only reason I bought it was to use it for astronomy. But once I heard about the new 450D being released, I thought why not upgrade? Well I left it a while then after hearing a talk be Nik Symanchek I decided to go for it.

I ended up selling my 400D camera on Amazon and then purchased my new Canon 450D from Dixons, for £446 which luckily included a £50 cashback offer from Canon as well as free delivery at the time.

The main reason for the upgrade was the Live View mode, my main problem with doing astrophotography for me was getting the object in focus in the small cameras viewfinder. I did invest in a right angled viewfinder with 2x magnification, but even that was not that easy to use, but it did help.

Canon 400D vs Canon 450DThere is not a great deal of difference cosmetically between the cameras. The menus and layout of the camera are very similar. If you already have a 350d or 400d then you will find using the 450d really easy.

The new 450D is lighter than the 400D, it also has a nice feel to the grip now, with a kind of mottled effect. The 450D now comes with a Image Stabilised lens (IS) which is a nice touch.

On the back of the 450D are the biggest changes, with the buttons moved around in order to accommodate the new slightly larger 3 inch screen.

The Canon battery type has changed and the Compact Flash card slot has been replaced with an SD card, which is useful, as it seems most cameras have now gone back to SD cards, as my HD camcorder also takes SD cards.

The 450D now has 12 mega-pixels instead of the 10 mega-pixels in the 400D.

The Live View mode works in all modes except in Automatic mode, so don’t expect to use the live view just like a compact digital camera. After pressing the “Set” button to enter Live View mode you can zoom in on the object by 5x or 10x magnification, which should help with focusing whilst doing astrophotography. I think you can also get a live view through a PC or laptop, even more useful.

The standard ISO settings are still there. I would have thought we would have seen an ISO setting of 3200 available, but maybe that will be on the next model, 500D? I also think the next model will have 15 megapixels and probably an HD video recording facility. But we will have to wait and see.

Overall the 450D seems worth upgrading to if you really think you need an extra 2 megapixels or the live view mode, otherwise stick with the 400D if you have it. If you don’t have a DSLR then the Canon 450D is a great camera and worth a purchase.

The best price for the Canon 450D Digital SLR Camera seemed to be from either Dixons or Amazon when I was looking.

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