CCD Imager

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 you are using a DSLR, then taking photographs of bright stars looking for blue bloat would be helpful.

I'm always wary of Trevors reviews, great chap that he is, he never says anything bad about any astro kit.....

I would be interested in whether focus changes between filters, FWHM of blue images compared with red and green and of course, stars at the periphery of the FOV.

Adrian

Yeah, three years late, lol 

I actually bought the WO Redcat earlier this year, but I would still be interested in seeing how the Tecnosky performs.

1 hour ago, Adam J said:

Yes don't do this, you are adjusting the front element but you cant even be sure that is the one that is out of place, for all you know its the rear element pair and you just changed moved the front element out of alignment. 

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!

4 hours ago, FLO said:

It is good to hear you saw an improvement but I promise you there is more to collimating a 4-element refractor than simply tweaking a few screws. It is not like collimating a Newtonian. Your supplier should do or arrange the collimation for you.

I don’t want to sound melodramatic but, seriously, if you encourage people to collimate their RedCats it will almost certainly end in tears. Please don’t. 

Steve 

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.

1 hour ago, FLO said:

Eek!

I am sure Adrian meant well when he posted his advice but my advice to anyone reading this is please do not attempt to adjust your RedCat’s optics at home. Four element designs are not easy to collimate. If your RedCat requires realignment then we recommend you contact your supplier (I don’t think Adrian purchased his from FLO). 

HTH, 

Steve

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

Most astro software programs have combine sigma reject algorithms that will do a good job. The secret is to have many sub exposures for the software to be effective. Generally, more than 10 subs will easily deal with aircraft trails. You shouldnt need to buy new software!

Very nicely done

Any one own this scope and can share experiences, especially for CCD Imaging

I saw one at Kelling this weekend and it quite takes my fancy, but with a bad history of short FL  triplet, Petzval refractors in this field, I am apprehensive. I am particularly looking for a FL of 300-350mm. I can't find any reviews or even images taken with this scope.

Cheers

Adrian