CCD Imager

Many moons ago (around 20), I lived in Dulwich, so can sympathise with you. You best bet is to concentrate on narrowband imaging of nebulae, of which there are many many targets. There are some bright objects like open star clusters and globular clusters that are worthwile imaging. Then secondly, if you can, take you kit out of London to a much darker sky and image broadband objects. As long as you are enjoying your hobby, then it doesnt matter how much light pollution you have and I think you have done very well with the above image from near central London. Adrian

This faint galaxy group high in Ursa Major is a struggle from a semi-rural site, i.e. my back garden, I totalled around 15 hours of data. Other astrophotographs show a predominantly blue galaxy except for the center, but using Astrodon true colour filters and APP's calibrate star colours, my version shows very little blue. C'est la vie! Taken with a SW Esprit 150mm and ASI 183 camera. With a pixel scale of 0.47 arc sec/pixel, high resolution imaging is possible with relatively small scopes. I do think this galaxy group is very attractive and infrequently photographed, so pleased to get something a bit dfferent.

Hi Francki, I'm please the good seeing extended to Southern France Makes the lockdown more bareable... This image was taken over the nights 14th/15th April and I have a couple more images from last week where seeing was even better. Adrian

Another one from our lockdown period. Around 8 hours of data taken over a couple of nights. I used an Esprit 150 and ASI 183 on top of a 10 micron mount. Seeing was very good and fair transparency. Adrian

I managed to see the full resolution version here

Excellent image, defintely need to see the full res image to see its full glory Adrian

Wonderful run of clear skies here in the East of the UK, what a week we could have had at Kelling Heath! Here is one I have now completed processing. Taken with an SW Esprit 150 and ASI 183 camera. Around 6 hours of total integration time. Edit - Just tweaked the colour balance, after a review the next day! Adrian

I'm guessing there will be a flood of images with clear skies galore and lockdown. Here is my first of the lockdown period, NGC4565 taken with a 12 inch ONTC and ASI1600MM camera. A total of around 8 hours data. The sharp eyed among you will notice the odd spider vane spikes, a result of rotated images during a couple of sesions to get the data.

I bought mine in May and used it about 3 times, its a superb lightweight mount which is so easy to pick up, set up outside and get going. Its quiet and handles small scopes easily. Periodic error, which I measured was around 15 arc secs and nice and smooth. I also bought and fitted the Ipolar which works like a charm. The CEM40 was released shortly after and I ended up buying that to support my FSQ which would have been at the CEM25p's limit. I am planning on selling the CEM25p, although havent advertised as yet. Adrian

As the rear elements are fixed at the factory, they are very unlikely to move. The front two elements are adjustable and would be the likely source of any miscollimation, as it was in my case. I had an FSQ with exactly the issue you describe and that needed to go back to Japan and I had a replacement. I don't have much luck with small refractors!

Steve's right, you need to be knowledgeable about optics before attempting collimation of a refractor, especially ruling out other potential causes of mis shapen stars in an image.

Hi Steve I would agree, if you are inexperienced with refractor collimation, then don't start. I've done a few in my time, previously using the Tak collimating scope to good effect, but I dont have that any more. A petzval design is two doublets, one at the front of the scope and one at the rear. In the Redcat, the one at the rear is fixed and cannot be altered. The front two elements have 2 sets of screws at the 12, 3, 6 and 9 position. It's honestly as easy as collimation a Newtonian, if the coma becomes worse, just reverse the change you made. Can you do harm? Over tightening can cause pinched optics and worse, damage the cell, I tighten the collimation screws until I feel resistance, no more. My only issue is that I dont know how the collimation screws work as mentioned above, but Im finding out by trial and error Steve, I didn't buy from FLO and this is my second Redcat. I returned the first because of mis collimation, but as it was also present in the second and I really wanted to keep the scope, I just had to collimate myself. Once collimated, it is a very nice little widefield imaging platform. I did also note that the collimation screws were a little loose when I first got the scope, I checked this after I found collimation changed when pointing the scope 120 degrees to a different part of the sky. Adrian

Been a busy last few months, but I have recently been able to assess my Redcat more. I did post a mini review a few months ago and there were some comatic stars in a corner due to mis-collimation (as it transpires). If you unthread the dew shield exposing the lens, you can see 4 sets of 2 collimation screws, each pair seperated by 90 degrees. I really dont know what they are doing, is there a set screw and adjustment screw per pair or perhaps they sit either side of the lens cell. Any way, by experimenting, I managed to improve the collimation by going back and forth between opposite pairs in the direction of the coma. If any one actually know what the pairs of screws do, I would love to know. My second observation is that the Redcat is not a typical Petzval design. Usually there are 2 doublets at a fixed distance apart in the OTA and focus is achieved by moving the telescope focus to achieve the correct distance from sensor to rear doublet optics. However, the redcat is focused by moving the front two elements and hence the distance from the rear 2 elements from the sensor is crucial and fixed. Therefore, please insert the correct adapters to achieve the required distance of 77.7mm. This may explain the comatic stars in some peoples images? My collimation is nearly there and I am much happier than before. Of course you can return the scope to the supplier, or if you are confident, adjust the collimation yourself. Adrian